a r X i v :0708.3716v 2 [a s t r o -p h ] 4 M a r 2008
Mon.Not.R.Astron.Soc.000,000–000(0000)Printed 4March 2008
(MN L A T E X style ?le v2.2)
The Impact of a Percolating IGM on Redshifted 21cm
Observations of Quasar HII Regions.
Paul M.Geil &J.Stuart B.Wyithe
School of Physics,University of Melbourne,Parkville,Victoria,Australia Email:pgeil@https://www.doczj.com/doc/0d5908925.html,.au,swyithe@https://www.doczj.com/doc/0d5908925.html,.au
4March 2008
ABSTRACT
We assess the impact of inhomogeneous reionization on detection of HII regions sur-rounding luminous high redshift quasars using planned low frequency radio telescopes.Our approach is to implement a semi-numerical scheme to calculate the 3-dimensional structure of ionized regions surrounding a massive halo at high redshift,including the ionizing in?uence of a luminous quasar.As part of our analysis we brie?y contrast our scheme with published semi-numerical models.We calculate mock 21cm spectra along the line of sight towards high redshift quasars,and estimate the ability of the planned Murchison Wide?eld Array to detect the presence of HII regions.The signal-to-noise for detection will drop as the characteristic bubble size grows during reionization be-cause the quasar’s in?uence becomes less prominent.However,quasars will imprint a detectable signature on observed 21cm spectra that is distinct from a region of typical IGM.At epochs where the mean hydrogen neutral fraction is ≈30%or greater we ?nd that neutral gas in the IGM surrounding a single quasar will be detectable (at a signi?cance of 5σ)within 100hour integrations in more than 50%of cases.1000hour integrations will be required to detect a smaller neutral fraction of 15%in more than 50%of cases.A highly signi?cant detection will be possible in only 100hours for a stack of 10smaller 3proper Mpc HII regions.The accurate measurement of the global average neutral fraction ( x HI )will be limited by systematic ?uctuations between lines of sight for single HII regions.We estimate the accuracy with which the global neutral fraction could be measured from a single HII region to be 50%,30%and 20%for x HI ≈0.15,0.3and 0.5respectively.
Key words:cosmology:di?use radiation,theory –galaxies:high redshift,intergalac-tic medium
1INTRODUCTION
The reionization of cosmic hydrogen is commonly believed to have been due to UV photons produced by the ?rst stars and quasars and was an important milestone in the history of the Universe (e.g.Barkana &Loeb 2001).The recent dis-covery of very distant quasars has allowed detailed absorp-tion studies of the state of the high redshift intergalactic medium (IGM)at a time when the Universe was less than a billion years old (e.g.Fan et al.2006;White et al.2003).Several studies have used the evolution of the ionizing back-ground inferred from these spectra to argue that the reion-ization of cosmic hydrogen was completed just beyond z =6(Fan et al.2006;Gnedin &Fan 2006;White et al.2003).However,other authors have claimed that the evidence for this rapid change is the result of an incorrect choice for the distribution of overdensities in the IGM (Becker et al.2007).
Several of the most distant quasars exhibit complete Gunn-Peterson troughs,the red edges of which do not ex-tend as far as the redshifted Ly αwavelength.The sim-plest interpretation of this feature is the presence of an
HII region in a partially neutral IGM (e.g.Cen &Haiman 2000).This idea has been used to argue that there is a sig-ni?cant fraction of neutral hydrogen in the IGM beyond z ≈6(Wyithe &Loeb 2004a;Mesinger &Haiman 2004;Wyithe et al.2005),with a lower limit on the hydrogen neutral fraction that is as many as two orders of mag-nitude larger than constraints provided by direct absorp-tion studies.On the other hand,more detailed numerical modeling has shown that this interpretation is uncertain (Lidz et al.2007a;Bolton &Haehnelt 2007),and that the observed spectra could either be due to an HII region or a classical proximity zone.
The di?culties in interpreting spectra of high redshift quasars arise because the large optical depth for Ly αab-sorption in a neutral IGM limits its e?ectiveness in probing reionization at redshifts beyond z ≈6.A better probe of the
c
0000RAS
2Geil&Wyithe
reionization history involves the redshifted21cm emission from neutral hydrogen in the IGM.Several probes of the reionization epoch in redshifted21cm emission have been suggested.These include observation of the emission as a function of redshift averaged over a large area of sky.This observation would provide a direct probe of the evolution in the neutral fraction of the IGM,and is referred to as the global step(Shaver et al.1999;Gnedin&Shaver2004).A more powerful probe will be provided by observation of the power spectrum of?uctuations together with its evolution with redshift.This observation would trace the evolution of neutral gas with redshift as well as the topology of the reionization process(e.g.Tozzi et al.2000;Furlanetto et al. 2004a;Loeb&Zaldarriaga2004;Wyithe&Morales2007; Iliev et al.2006).Finally,observation of individual HII re-gions will probe quasar physics as well as the evolution of the neutral gas(Wyithe&Loeb2004b;Kohler et al.2005). Kohler et al.(2005)have generated synthetic spectra using cosmological simulations and conclude that quasar HII re-gions will provide the most prominent individual cosmolog-ical signals.Recent work by Datta et al.(2007)has focused on the detection of ionized bubbles in redshifted21cm maps using a visibility based formalism.Their results suggest it may be possible to blindly detect spherical HII regions of radius>～22comoving Mpc during the epoch of reionization.
Various experiments are planned to measure21cm emission from the pre-reionization IGM,including the Low Frequency Array1(LOF AR;Vald′e s et al.2006)and the Murchison Wide?eld Array2(MWA).The MWA is being constructed on a very radio quiet site in Western Australia and will consist of512tiles,each containing16cross dipoles, which operate over the range80-300MHz.The tiles will be spread to cover baselines of up to1.5km.In collecting area the MWA would be comparable to the Very Large Array (VLA).However,the correlator/receiver system will be able to handle a much larger number of channels than are avail-able on the low frequency VLA.In this paper we focus on the observation of individual HII regions around known quasars with emphasis on the capabilities of the MWA.In particular we address the in?uence of the percolating IGM on the red-shifted21cm signal from the neutral hydrogen surrounding a quasar HII region.Our analysis extends ideas presented by Wyithe et al.(2005)by including calculations of a realistic structure for ionization of the IGM,as well as estimates of the achievable signal-to-noise.
We discuss a simple detection strategy consisting of a spectral?t to the21cm signal along the line of sight to-wards a known high redshift quasar.The following back-of-the-envelope calculation gives a comparitive gauge of the statistical signi?cance required by this strategy relative to a blind search for individual HII regions,embedded in a par-tially ionized IGM.
For a blind search,the number of independent samples within a single MWA?eld is given by
N s=V MWA
πR2
b×2R q
,(1)
where V MWA is the comoving volume of the MWA?eld and V q(z,R q,R b)is the intersection of the synthesized beam(of 1https://www.doczj.com/doc/0d5908925.html,/
2https://www.doczj.com/doc/0d5908925.html,/ast/arrays/mwa/comoving radius R b)with the HII region(of comoving radius R q).For a4.5proper Mpc region at z=6.5using a synthe-sized beam of widthθb=3.2′we obtain V q～104comoving Mpc3.Together with V MWA～π47002×260～1010comoving
Mpc3(Bowman et al.2006),we have N s～106.
Given a signal-to-noise level of nσfor detection of the mean IGM,the number of false positive detections per MWA ?eld is
N false～N s erfc
…n
2σ
?,(2)
where erfc(x)is the complimentary error function.For exam-ple,if the mean IGM can be detected with a signal-to-noise level of2σ,we expect～104false detections per?eld,but only one true detection of a quasar HII region.The chance of obtaining only one false detection requires n≈5.There-fore,in order to reduce the chance of a false detection and have con?dence in the reality of the HII region we require N false?1or n?5.This level of signi?cance will probably not be possible with the expected sensitivity of the MWA which will make a blind search impractical.
On the other hand,by making an observation around a quasar,we are able to take a Bayesian approach by uti-lizing the likelihood of detection given that an HII region is known a priori to be present.In this case a detection at a given signi?cance level is not diluted by the possibility of false detections.We stress that even when the impact of the quasar is no longer dominant,the method of detecting the 21cm signal a posteriori along the line of sight to a known quasar will still succeed,because neutral gas is known a pri-ori to be absent in a large volume surrounding the quasar.
In addition to its physical con?guration,the sensitivity of a radio telescope is limited due to di?culties in achiev-ing a perfect calibration and to problems introduced by foregrounds and the ionosphere.There has been signi?cant discussion in the literature regarding foregrounds.While ?uctuations due to foregrounds are orders of magnitude larger than the reionization signal(e.g.Di Matteo et al. 2002;Oh&Mack2003),foreground spectra are anticipated to be smooth.Since the reionization signature includes?uc-tuations in frequency as well as angle,they can be removed through continuum subtraction(e.g.Gnedin&Shaver2004; Wang et al.2006),or using the di?erences in symme-try from power spectra analysis(Morales&Hewitt2004; Zaldarriaga et al.2004).In this paper we concentrate on theoretical limitations of the MWA and the impact of the inhomogeneous reionization of the IGM.The practical dif-?culties introduced by calibration and foreground removal etc.need to be addressed by full simulations of interfer-ometric observations,and ultimately with early data sets from new facilities.
We begin by describing the inclusion of stellar reioniza-tion and a luminous quasar within a semi-numerical scheme to produce realistic?uctuations in the ionized gas distribu-tion(§2).We then use this model to describe the evolution of the ionization structure of the IGM surrounding a mas-sive quasar host(both with and without the presence of a quasar HII region)in§3,before discussing the detectability of these regions in§4.We present our conclusions in§5. Throughout this paper we adopt the set of cosmological pa-rameters determined by WMAP(Spergel et al.2007)for a ?atΛCDM universe.
c 0000RAS,MNRAS000,000–000
Quasar HII Regions3 2SEMI-NUMERICAL MODEL FOR THE
GROWTH OF QUASAR HII REGIONS IN A
PERCOLATING IGM
In this section we describe our model for the reionization of
a3-dimensional volume of the IGM using a semi-numerical
scheme that is similar in spirit to the models described by
Zahn et al.(2007)and Mesinger&Furlanetto(2007),based
upon Furlanetto et al.(2004b).We begin with a brief de-
scription of the generation of the Gaussian initial conditions
in the density?eld surrounding a massive quasar host halo
at z～7.We then describe a semi-analytic model for the
density dependent reionization of the IGM,including the in-
?uence of a nearby quasar,before combining the numerical
realization of the density?eld with our semi-analytic calcu-
lations to generate3-dimensional realizations of the ioniza-
tion state of the IGM.
2.1Construction of density?eld surrounding a
massive halo
We simulate the linear density?eldδ(k)inside a periodic,
comoving,cubic region of volume V=L3,by calculating
the density contrast in Fourier space?δ(k)corresponding to
aΛCDM power spectrum at a speci?ed redshift.The power
spectrum used has been normalized usingσ8and is given by
P(k,z)∝k n T2(k)D2(z)where T(k)is an analytic approxi-
mation of the present day transfer function(Bardeen et al.
1986),n=0.96is the primordial power spectral index
(Spergel et al.2007)and D(z)is the linear growth factor
between redshift z and the present.
Numerically,this procedure is carried out by laying
down a cubic grid of size N3and approximating the con-
tinuous Fourier relationship betweenδ(x)and?δ(k)with its
discrete form,
?δ(k)=V
dt =
N ion
dt
+(1?Qδ,R)
dF col(δ,R,z,M min)
D(z obs)–(1+z)3Qδ,R,(4)
where N ion is the number of photons entering the IGM per
baryon in galaxies,αB is the case-B recombination coe?-
cient,C is the clumping factor(which we assume,for sim-
plicity,to be a constant value of2)and D(z)is the growth
factor between redshift z and the present.The production
rate of ionizing photons in neutral regions is assumed to be
proportional to the collapsed fraction F col of mass in ha-
los above the minimum threshold mass for star formation
(M min),while in ionized regions the minimum halo mass
is limited by the Jeans mass in an ionized IGM(M ion).
We assume M min to correspond to a virial temperature
of104K,representing the hydrogen cooling threshold,and c 0000RAS,MNRAS000,000–000
4Geil &Wyithe
M ion to correspond to a virial temperature of 105K,repre-senting the mass below which infall is suppressed
from
an
ionized
IGM
(Dijkstra
et
al.
2004).
In a region of comoving radius R and mean overdensity δ(z )=δD (z )/D (z obs )(spec-i?ed at redshift z instead of the usual z =0),we use the extended Press-Schechter (Press &Schechter 1974)model (Bond et al.1991)to calculate the relevant collapsed frac-tion
F col (δ,R,z )=erfc 0@δc ?δ(z )2[σ2gal ?σ2(R )]1
A ,(5)where erfc(x )is the complimentary error function,σ2(R )is
the variance of the density ?eld smoothed on a scale R ,and σ2gal is the variance of the density ?eld smoothed on a scale R gal ,corresponding to a mass scale of M min or M ion (both evaluated at redshift z rather than at z =0).
Equation (4)may be integrated as a function of δ.At a speci?ed redshift this yields the ?lling fraction of ionized regions within the IGM on various scales R as a function of overdensity.We ?nd that this model predicts the sum of astrophysical e?ects to be dominated by galaxy bias,and that as a result overdense regions are reionized ?rst.This leads to the growth of HII regions via a phase of percolation during which individual HII regions overlap around clustered sources in overdense regions of the universe.We may also calculate the corresponding 21cm brightness temperature contrast
T (δ,R )=22mK (1?Q δ,R )
…
1+z
R q
??3
,(7)
where R q is the radius of the HII region centered on x q that would have been generated by the quasar alone in a fully neutral IGM.In contrast to stellar ionization the quasar contribution comes from a point source,and so the contri-bution to Q originates from a single voxel only (rather than all voxels within |x ?x q |).Following this addition we ?lter the ionization ?eld as described in §2.3.
3
THE EVOLUTION OF HII REGIONS IN A PERCOLATING IGM
In this section we describe one example of the evolution of the IGM during the reionization epoch.We ?rst show a model for the evolution of ionized regions due to stellar ionization alone in §3.1,before adding the presence of a luminous quasar in §3.3.3.1
Fiducial model for reionization
Throughout this paper we consider a model in which the mean IGM is reionized at z =6(Fan et al.2006;Gnedin &Fan 2006;White et al.2003).In this model we assume that star formation proceeds in halos above the hy-drogen cooling threshold in neutral regions of IGM.In ion-ized regions of the IGM star formation is assumed to be suppressed by radiative feedback (see §2).We compute the 3-dimensional structure for this model using the prescrip-tion outlined in §2.In the left-hand panel of Figure 1we present snapshots of the ionization fraction Q (x )for slices through a realization of this model when the mean,volume-weighted neutral fraction of the IGM is ≈0.5,0.3,0.15and 0.1corresponding to redshifts z =7.5,7.0,6.7and 6.5re-spectively.The simulation presented corresponds to a linear density ?eld of resolution 2563,with a comoving side length of 219h ?1Mpc.Each slice is 0.86h ?1comoving Mpc deep.Since the box is centered on a massive halo the simulation shows a large HII region growing in the center of the ?eld.As reionization progresses we see this central region merge with adjacent HII regions.This process of overlap is seen in detailed numerical simulations (e.g.McQuinn et al.2007)and leads to an irregular structure of neutral gas ?laments late in the reionization era.The overlap of some HII re-gions,combined with the fact that our model does not allow for the ionizing ?ux from one source to contribute to the ionization due to another results in a violation of photon conservation (e.g.Zahn et al.2007).Although this e?ect is expected to be small during the early stages of reioniza-tion when there are fewer HII region mergers,it does lead to more severe discrepancies at later times when the global ionization fraction approaches unity.Figure 2illustrates this e?ect by plotting the global neutral fraction as a function of redshift from our simulations.The dashed line shows the evolution of mean neutral fraction by mass as expected from
c
0000RAS,MNRAS 000,000–000
Quasar HII Regions
5 Figure1.Ionization maps of the IGM showing the evolution of global ionization fraction,Q,with and without the ionizing contribution
of a quasar.The slices shown correspond to epochs when the global,volume-weighted neutral fraction is x HI ≈0.46,0.28,0.16and 0.08(top to bottom)corresponding to z=7.5,7.0,6.7and6.5respectively.Each slice has a comoving side length of219h?1Mpc and is0.86h?1comoving Mpc deep.The ionization maps were computed within boxes of dimension2563.Left:Evolution with no quasar. Middle left:Corresponding ionization maps with an embedded R q～34comoving Mpc quasar HII region.Dashed circles represent the HII region that would have been generated by the quasar alone in a fully neutral IGM.Middle right:Corresponding synthetic maps with θb≈3.2′(corresponding to central peak to?rst null?θ≈5.5′)including quasar HII region using the MW A and1000hr integrations. Right:Corresponding synthetic maps withθb≈5.8′(corresponding to central peak to?rst null?θ≈10.0′)including quasar HII region using the MW A and1000hr integrations.
the analytic model which provides the input density depen-dent ionization fraction.We?nd that our semi-numerical scheme yields results that conserve photons at the～15% level for neutral fractions x HI >～0.2.
3.2Comparison with other semi-numeric models We note that our scheme correctly assigns the ionization fraction on scales that are not resolved by the simulation cube.This is not necessarily the case in similar models that approximate the ionization?eld as a two-phase medium(e.g.Mesinger&Furlanetto2007),although a two-phase approx-imation may be justi?ed depending upon the resolution of the simulation.Implementing our scheme with increased res-olution would improve the accuracy and dynamical range of our simulations.However,we maintain a high resolu-tion relative to the synthesized beam.The assignment of regions as either fully neutral or fully ionized may also lead to an overestimate of the brightness temperature contrast across ionization fronts which are observed at?nite resolu-tion.Our implementation achieves approximately the cor-rect relation between neutral fraction and epoch over most
c 0000RAS,MNRAS000,000–000
6Geil&Wyithe
Figure2.Global,mass-weighted neutral fraction as a function of
redshift.The dashed line shows the evolution of neutral fraction as
expected from the density dependent model described in§2.2(for
an overlap at z≈6).The data show the mass-weighted globally
averaged neutral fraction from our simulations.Hollow squares
indicate the approximate epoch for which simulations were used
to obtain the mock line of sight spectra shown in Figure4.
of the reionization history and produces soft transitions at
the edges of large HII regions by smoothing over HII re-
gions not resolved by the simulations.However,as noted by
Mesinger&Furlanetto(2007)a two-phase approximation is
appropriate for the purposes of describing the morphology
and evolution of HII regions.We also point out that there
are several features not incorporated in our model.These
include the galaxy distribution(which will enhance?uctu-
ations on small scales due to Poisson noise)and the veloc-
ity?eld of the gas(see Mesinger&Furlanetto2007).How-
ever these additional considerations are not important on
scales larger than10comoving Mpc,and so do not in?uence
our results regarding HII regions surrounding high redshift
quasars.
3.3The in?uence of a quasar in the?ducial
model for reionization
We next add quasar luminosity to the simulations shown
in the left-hand panels of Figure1using the prescription
outlined in§2.4.The value of R q is subject to large un-
certainties,including the quasar duty cycle,lifetime and lu-
minosity.Assuming a line of sight ionizing photon emission
rate of˙Nγ/4πphotons per second per steradian,a uniform
IGM and neglecting recombinations,the line of sight extent
of a quasar’s HII region(from the quasar to the front of the
region)observed at time t is(White et al.2003)
?1/3…1+z
R q≈4pMpc x?1/3
HI…˙Nγ107yr
√
A e?
Quasar HII Regions7 is the Boltzmann constant.Instrumental noise is uncorre-
lated in the frequency domain.As shown by McQuinn et al.
(2006),the average integration time t U that an array ob-
serves the visibility U is
t U≈A e?t int
8?2.6…?ν100hr??1/2.(12)
We?nd that the prefactor takes values of T(θb)≈11mK
forθb=3.2′(corresponding to?θ=5.5′central peak to
?rst null)and T(θb)≈65mK forθb=2.9′(?θ=5.1′).
For comparison,the radiometer equation(e.g.Wyithe et al.
2005)estimates the noise within a synthesized beam of width
θb to have corresponding values of T(θb)≈20and22mK
forθb=3.2′and2.9′respectively.These di?erences are
reconciled by noting that the radiometer equation assumes
a uniform antenna densityρant,while using equations(10)
and(11)to calculate the rms noise?uctuation in visibil-
ity space accounts for an arbitrary antenna density.For the
ρant∝r?2antenna density pro?le of the MWA,the reduced
antenna density at large r leads to a reduced baseline density
at large U(Bowman et al.2006),and hence increased noise
levels at high angular resolution.Figure3demonstrates the
increased noise levels for the largest values of U～800for
the MWA operating atν=165MHz.In summary,in the
case of the MWA,using the radiometer equation(and hence
assuming a uniform antenna density)results in an underes-
timate of noise for large baselines and an overestimate for
small baselines.
c 0000RAS,MNRAS000,000–000
8Geil&Wyithe
Figure4.Left:Sample mock spectra of quasar HII regions using the MW A showing the recovered step function(dashed).Center and Right:Marginalized probability functions of recovered neutral fraction x HI and radius R for an ensemble of simulations(grey).One
example(bold)corresponds to the mock spectrum in the left-hand panel.Likelihood functions L(x HI| x HI )for an observed neutral fraction x HI are shown by the dashed curves.The vertical lines show the global neutral fraction of the surrounding IGM and the modeled
region radius R q.Six cases are shown corresponding to t int=100hr and1000hr when x HI ≈0.15,0.3and0.5(top to bottom).The
√
same IGM realization and system noise(scaled by1/
Quasar HII Regions9
4.2Continuum foreground subtraction Foreground contamination and its removal can have signif-
icant consequences for the detectability of the weak,red-
shifted21cm cosmic signal.Both spatial and frequency char-acteristics of foreground emission will a?ect our ability to
subtract these contaminants su?ciently in degree and accu-
racy.For the remainder of this paper we concern ourselves with the detection of HII regions surrounding known high
redshift quasars in the spectral regime.We defer discussion
of the detectability of such HII regions in the full image regime using a?lter matching technique(e.g.Datta et al.
2007)to future work.
Foreground contamination will be brighter than the cos-
mological21cm signal by at least four orders of magni-
tude.We assume that the total foreground signal,which is dominated by galactic synchrotron radiation(Shaver et al.
1999),has had extragalactic point sources removed,leav-
ing a spectrally smooth foreground signal that will be re-movable through continuum subtraction(Gnedin&Shaver
2004;Wang et al.2006).
The process of continuum foreground removal will
remove any cosmological signal for line of sight modes
with k <～2π/y,where y is the depth of the survey (McQuinn et al.2006).Since HII regions may have sizes cor-
responding to a signi?cant fraction of the frequency band
pass,the insensitivity to large scale modes may hamper the detectability of HII regions.The MWA will operate with a processed bandwidth of32MHz.For comparison,the fre-quency domain of our synthetic spectra is?ν<～20MHz. Thus,foreground modes along the line of sight with wave-lengths longer than the32MHz band pass are not present in our mock spectra,with the exception of an overall constant corresponding to the DC mode of the spectrum.
In this paper we make the assumption that foregrounds could be removed over the20MHz of our simulated spec-trum,given access to the32MHz of spectrum that will be available for the MWA.
4.3Estimate of signal-to-noise ratio in detection
of neutral IGM surrounding HII regions
We next present mock spectra of HII regions surrounding known high redshift quasars at times when the global neu-tral fraction is x HI ≈0.15,0.3and0.5,and discuss the prospects for their detection.
Line of sight spectra are simulated using a synthesized beam of widthθb=3.2′.Figure4shows sample mock spec-tra for100hr and1000hr integrations centered on186,175 and164MHz(corresponding to z=6.7,7.1and7.65re-spectively).Instrumental thermal noise in these spectra is generated following the prescription described in§4.1.The presence of an HII region could be inferred from this data via the detection of a brightness temperature contrast be-tween the ionized IGM within the HII region and the neutral hydrogen outside.We do not know a priori the radius of the HII region.However from observations of the proximity zone surrounding a high redshift quasar we know that if an HII region is present,its size must be larger than the redshift corresponding to the observed transmission blueward of the Lyαline in near-IR spectra.
To test whether the mock spectra are of su?cient signal-to-noise to detect an HII region we?t a step function T model(ν)=T IGM??T×Θ(R region?R)(13) which has three free parameters.These parameters cor-respond to the brightness temperature outside the region T IGM,a radius R region(which we assume to have a value R>R q)and a temperature brightness contrast across the HII region boundary?T.The parameter T IGM includes the contribution of the DC component of foregrounds which is therefore removed during the?tting procedure.We note that our?t is made to the spectrum in only one pixel of the syn-thetic map,which includes contributions of foregrounds from all regions within the synthesized https://www.doczj.com/doc/0d5908925.html,ing the calculated thermal noiseσT in each of N ch channels for the MWA with an assumed integration time t int,we then calculate the value ofχ2,where
χ2=
N ch
X i=1?T i?T model(νi)
d?T dR region dT IGM
∝L(?T,R region,T IGM)dP prior dR region dP prior
d?T∝1,
dP prior
dT IGM∝1.(17) HereΘis the Heaviside step function,R min=R q and R max=15proper Mpc.The value of R max represents an upper limit on the size of a proximity zone within which the quasar ionizing?ux is dominant.If the HII region extends beyond R max along a particular line of sight,we e?ectively count this ionization as part of the general two phase IGM. R min is set by the observed radius of Lyαtransmission(indi-cating a highly ionized IGM).Provided the quasar is beamed with an opening angle>α,whereα=arctan(R b/R q),this assumption will be valid.This is likely since at z≈6.5with a synthesized beamwidth of～4′,α≈13?.We then marginal-ize the probability distribution to obtain constraints on the parameters of interest(?T and R region).Finally,the neu-tral fraction is linearly related to the retrieved temperature contrast through x HI=?T/{22[(1+z)/7.5]1/2}mK.
The uncertainty in an observation should arise from a combination of IGM?uctuations and instrumental noise. This instrumental noise is thermal and therefore Gaussian, whereas IGM?uctuations are highly non-Gaussian(e.g. Lidz et al.2007a;Wyithe&Morales2007).A non-Gaussian noise component renders theχ2statistic suboptimal.How-ever,in the case of the MWA,instrumental noise will domi-nate in narrow frequency channels which justi?es the use of χ2in estimating the likelihood.
c 0000RAS,MNRAS000,000–000
10Geil&Wyithe
4.3.1Recovered parameters from mock spectra In the central and right-hand panels of Figure
4we show
marginalized a posteriori probability density functions for the recovered neutral fraction x HI and radius R region for 100hr and1000hr integrations.These parameter estimates correspond to the mock spectra in the left-hand panels of Figure4.The vertical lines show the global neutral fraction of the surrounding IGM and the modeled region radius R q.
In addition to the telescope noise,the spectra plotted in Figure4show that the recovered radius will be sensitive to the large?uctuations in brightness temperature due to the inhomogeneous ionization state of the IGM(Lidz et al. 2007b).In contrast,the estimates of neutral fraction along a particular line of sight average over many?uctuations for a range of recovered radii.As a result the neutral fraction along a particular line of sight should be measured in an unbiased way.On the other hand,di?erent lines of sight will show a varying systematic o?set from the mean due to the inhomogeneous reionization of the IGM.
To investigate the extent of systematic o?set due to patchy reionization we have analyzed mock spectra from an ensemble of HII regions and lines of sight.Probability distri-butions for the best?t parameters R and x HI are estimated from this ensemble and are shown as grey lines in Figure4. These distributions quantify the level of systematic uncer-tainty that is present.In cases where the telescope noise is small,the systematic o?sets may be larger than the statisti-cal uncertainty in the neutral fraction.This is demonstrated by the1000hr examples in Figure4.The inhomogeneous nature of the IGM,combined with system noise conspire to
make the determination of R very uncertain despite high statistical precision.
We de?ne the con?dence for detection of an HII region
C by the ratio of the mean recovered neutral fraction to the standard deviation of the marginalized a posteriori proba-bility density functions for the recovered neutral fraction. Cumulative probabilities of detection are calculated using
an ensemble of mock line of sight spectra.Figure5shows the cumulative probabilities of detection using single line of sight spectra for100hr and1000hr integrations(dark
lines).These results indicate that it will be possible to reg-ularly detect bubbles at high signi?cance[P(C>5)>0.5] from spectra of individual HII regions using integrations of
1000hr,even at redshifts close to overlap when the neutral fraction is as low as≈15%.However at neutral fractions of >30%,measurement will be possible in only100hr.This
is despite the fact that at these late times the typical HII region becomes comparable in size to the HII regions gener-ated by the quasar(at z<～7in this model).As stressed in §1,even when the impact of the quasar is no longer domi-nant,the method of detecting the21cm signal a posteriori along the line of sight to a known quasar will still succeed,
because neutral gas is known a priori to be absent in a large volume surrounding the quasar.
4.4Extracting neutral fraction from observations The discussion in§4.3describes estimation of the certainty with which an HII region can be detected.Once the exis-tence of neutral gas is established,the interesting question becomes whether the HII region can be used to measure the Figure
5.Cumulative probabilities of detection for100hr (dashed)and1000hr(solid)integrations using single(black)and stacked spectra(grey)when the globally averaged neutral fraction is x HI ≈0.15,0.3and0.5(top to bottom).
global neutral fraction.Below we outline how this might be achieved.
The modeling described could be used to generate a likelihood function for an observed neutral fraction x HI given a trial global mean x HI ,
L(x HI| x HI )=1dx HI
???
? x HI ,(18)
where N is some large number of model spectra and the dP i/dx HI are the corresponding probability distributions for x HI(e.g.those shown as grey lines in Figure4).The resulting likelihood functions for the example neutral fractions are shown in Figure4by the dashed curves.These likelihood functions give an idea of the uncertainty on a measurement of x HI based on an observation of a single HII region.In the case of a1000hr integration,we?nd the variance of these likelihood functions to beσx
HI≈0.07,0.09and0.1 for x HI =0.15,0.3and0.5respectively.The corresponding
relative errorsσx
HI
/ x HI are0.5,0.3and0.2.These values represent estimates of the achievable uncertainty.
Given an observed spectrum with probability dP obs/dx HI for x HI along that line of sight,it would then be possible to?nd the a posteriori probability for the
c 0000RAS,MNRAS000,000–000
Quasar HII Regions11 globally averaged neutral fraction x HI ,
dP prior
dP
dx HI L(x HI| x HI )
12Geil&Wyithe
search was supported by the Australian Research Council (JSBW).
REFERENCES
Bardeen J.M.,Bond J.R.,Kaiser N.,Szalay A.S.,1986, ApJ,304,15
Barkana R.,Loeb A.,2001,Phys.Rep.,349,125 Barkana R.,Loeb A.,2005,ApJL,624,L65
Becker G.D.,Rauch M.,Sargent W.L.W.,2007,ApJ, 662,72
Bharadwaj S.,Ali S.S.,2005,MNRAS,356,1519
Bolton J.S.,Haehnelt M.G.,2007,MNRAS,374,493 Bond J.R.,Cole S.,Efstathiou G.,Kaiser N.,1991,ApJ, 379,440
Bowman J.D.,Morales M.F.,Hewitt J.N.,2006,ApJ, 638,20
Cen R.,Haiman Z.,2000,ApJL,542,L75
Datta K.K.,Bharadwaj S.,Choudhury T.R.,2007,MN-RAS,382,809
Di Matteo T.,Perna R.,Abel T.,Rees M.J.,2002,ApJ, 564,576
Dijkstra M.,Haiman Z.,Rees M.J.,Weinberg D.H.,2004, ApJ,601,666
Efstathiou G.,1992,MNRAS,256,43P
Fan X.,Strauss M.A.,Becker R.H.,White R.L.,Gunn J.E.,Knapp G.R.,Richards G.T.,Schneider D.P., Brinkmann J.,Fukugita M.,2006,AJ,132,117 Furlanetto S.R.,Zaldarriaga M.,Hernquist L.,2004a,ApJ, 613,16
Furlanetto S.R.,Zaldarriaga M.,Hernquist L.,2004b,ApJ, 613,1
Gnedin N.Y.,Fan X.,2006,ApJ,648,1
Gnedin N.Y.,Shaver P.A.,2004,ApJ,608,611
Iliev I.T.,Mellema G.,Pen U.-L.,Merz H.,Shapiro P.R., Alvarez M.A.,2006,MNRAS,369,1625
Kohler K.,Gnedin N.Y.,Miralda-Escud′e J.,Shaver P.A., 2005,ApJ,633,552
Lidz A.,McQuinn M.,Zaldarriaga M.,Hernquist L.,Dutta S.,2007b,ApJ,670,39
Lidz A.,Zahn O.,McQuinn M.,Zaldarriaga M.,Dutta S., Hernquist L.,2007a,ApJ,659,865
Loeb A.,2006,ArXiv Astrophysics e-prints
Loeb A.,Zaldarriaga M.,2004,Phys.Rev.Lett.,92,211301 McQuinn M.,Lidz A.,Zahn O.,Dutta S.,Hernquist L., Zaldarriaga M.,2007,MNRAS,377,1043
McQuinn M.,Zahn O.,Zaldarriaga M.,Hernquist L., Furlanetto S.R.,2006,ApJ,653,815
Mesinger A.,Furlanetto S.,2007,ApJ,669,663 Mesinger A.,Haiman Z.,2004,ApJL,611,L69
Mo H.J.,White S.D.M.,1996,MNRAS,282,347 Morales M.F.,Hewitt J.,2004,ApJ,615,7
Oh S.P.,Mack K.J.,2003,MNRAS,346,871
Press W.H.,Schechter P.,1974,ApJ,187,425
Quinn T.,Katz N.,Efstathiou G.,1996,MNRAS,278,L49 Richards et al.2006,AJ,131,2766
Shaver P.A.,Windhorst R.A.,Madau P.,de Bruyn A.G., 1999,A&A,345,380
Sirko E.,2005,ApJ,634,728
Spergel et al.2007,ApJS,170,377
Thoul A.A.,Weinberg D.H.,1996,ApJ,465,608Tozzi P.,Madau P.,Meiksin A.,Rees M.J.,2000,ApJ, 528,597
Vald′e s M.,Ciardi B.,Ferrara A.,Johnston-Hollitt M., R¨o ttgering H.,2006,MNRAS,369,L66
Wang X.,Tegmark M.,Santos M.G.,Knox L.,2006,ApJ, 650,529
White R.L.,Becker R.H.,Fan X.,Strauss M.A.,2003, AJ,126,1
Wyithe J.S.B.,Loeb A.,2004a,Nature,427,815 Wyithe J.S.B.,Loeb A.,2004b,ApJ,610,117
Wyithe J.S.B.,Loeb A.,2007,MNRAS,375,1034 Wyithe J.S.B.,Loeb A.,Barnes D.G.,2005,ApJ,634, 715
Wyithe J.S.B.,Loeb A.,Carilli C.,2005,ApJ,628,575 Wyithe J.S.B.,Morales M.F.,2007,MNRAS,379,1647 Zahn O.,Lidz A.,McQuinn M.,Dutta S.,Hernquist L., Zaldarriaga M.,Furlanetto S.R.,2007,ApJ,654,12 Zaldarriaga M.,Furlanetto S.R.,Hernquist L.,2004,ApJ, 608,622
c 0000RAS,MNRAS000,000–000
乙肝表面抗体阳性、核心抗体阳性（Hepatitis B surface antibody is positive, core antibody is positive） Hepatitis B surface antibody positive, hepatitis B core antibody positive Hepatitis B surface antibody is a protective antibody of human body, which can protect the body from HBV infection. Hepatitis B core antibody positive is infection or previous infection marker. These two simultaneous positive, indicating that the body was originally infected with hepatitis B, is in recovery or has recovered. Is hepatitis B antibody positive to be vaccinated? Whether to need to fight hepatitis B vaccine has the following two kinds of circumstances: 1, if you are through hepatitis B vaccine to obtain hepatitis B antibody, it is recommended that every three years you strengthen the injection of a hepatitis B vaccine. Since the production of antibody by hepatitis B vaccine, the antibody level decreases with time. Most of our scholars suggest that it is better to strengthen the injection once three years after immunization. No matter how long apart, as long as the surface antibody titer in 10 international units more than /ml, indicating that the body has immunity to hepatitis B virus (variation hepatitis B invalid). Conversely, if the hepatitis B surface antibody titer is below this value, the injection should be enhanced.
On the contrary Onthecontrary, I have not yet begun. 正好相反，我还没有开始。 https://www.doczj.com/doc/0d5908925.html, Onthecontrary, the instructions have been damaged. 反之，则说明已经损坏。 https://www.doczj.com/doc/0d5908925.html, Onthecontrary, I understand all too well. 恰恰相反，我很清楚 https://www.doczj.com/doc/0d5908925.html, Onthecontrary, I think this is good. ⑴我反而觉得这是好事。 https://www.doczj.com/doc/0d5908925.html, Onthecontrary, I have tons of things to do 正相反，我有一大堆事要做 Provided by jukuu Is likely onthecontrary I in works for you 反倒像是我在为你们工作 https://www.doczj.com/doc/0d5908925.html, Onthecontrary, or to buy the first good. 反之还是先买的好。 https://www.doczj.com/doc/0d5908925.html, Onthecontrary, it is typically american. 相反，这正是典型的美国风格。 222.35.143.196 Onthecontrary, very exciting.
恰恰相反，非常刺激。 https://www.doczj.com/doc/0d5908925.html, But onthecontrary, lazy. 却恰恰相反，懒洋洋的。 https://www.doczj.com/doc/0d5908925.html, Onthecontrary, I hate it! 恰恰相反，我不喜欢！ https://www.doczj.com/doc/0d5908925.html, Onthecontrary, the club gathers every month. 相反，俱乐部每个月都聚会。 https://www.doczj.com/doc/0d5908925.html, Onthecontrary, I'm going to work harder. 我反而将更努力工作。 https://www.doczj.com/doc/0d5908925.html, Onthecontrary, his demeanor is easy and nonchalant. 相反，他的举止轻松而无动于衷。 https://www.doczj.com/doc/0d5908925.html, Too much nutrition onthecontrary can not be absorbed through skin. 太过营养了反而皮肤吸收不了. https://www.doczj.com/doc/0d5908925.html, Onthecontrary, I would wish for it no other way. 正相反，我正希望这样 Provided by jukuu Onthecontrary most likely pathological. 反之很有可能是病理性的。 https://www.doczj.com/doc/0d5908925.html, Onthecontrary, it will appear clumsy. 反之，就会显得粗笨。 https://www.doczj.com/doc/0d5908925.html,
试卷911--网上考试 单位__________姓名__________学号__________成绩__________ 一、判断题(共34题,共8.4分) 1．以泪腺、唾液腺病变为主的自身免疫性疾病是干燥综合征。( ) 2．皮肤、肌肉病变是诊断皮肌炎不可缺少的依据。( ) 3．系统性红斑性狼疮有CH50、C3下降，示SLE有活动性。( ) 4．ANA阳性，就可诊断为红斑性狼疮。( ) 5．结缔组织的疾病，都是自身免疫性疾病。( ) 6．在强直性脊柱炎患者中，HLA-B27（人类白细胞抗原-B27）阳性率高达90%以上。( ) 7．慢性多关节炎和寡关节炎，如为对称性，则多为类风湿关节炎、SLE、成人Still病等炎性关节炎。( ) 8．慢性多关节炎和寡关节炎，如为非对称性，多为血清阴性脊柱关节病，或晶体性关节炎。( ) 9．类风湿因子是针对IgGFc段上抗原决定簇的抗体，也是一种自身抗体。( ) 10．长期、严重类风湿关节炎患者中20%可合并继发性淀粉样变，累及肾者可表现肾病综合征，终致慢性肾衰竭。( ) 11．类风湿关节炎所造成的关节痛的性质是对称、持续、但时轻时重。( )
12．类风湿结节是类风湿关节炎较特异的皮肤表现。( ) 13．SLE患者体内雌性激素水平增高，雄性激素降低，以及泌乳素水平增高可能对SLE的病情有很大的影响。( ) 14．抗ds-DNA抗体阳性是确诊系统性红斑狼疮和判断活动性有参考价值的标记性抗体。( ) 15．DLE的好发部位是两颊及鼻背。( ) 16．SLE最常见的心脏损害为心肌炎。( ) 17．SLE致死的常见原因是肾脏损害和感染。( ) 18．关节疼痛的SLE患者常见的症状。( ) 19．DLE慢性角化明显的损害晚期可继发黑色素瘤。( ) 20．日光照射可使红斑狼疮的症状减轻。( ) 21．自身抗体的产生可能是抑制性T淋巴细胞功能受损。( ) 22．过敏性紫癜不属于结缔组织病。( ) 23．系统性红斑狼疮多见于中青年男性。( ) 24．DLE样皮损可出现在SLE患者。( ) 25．SCLE狼疮带试验阳性通常出现于非曝光处正常外观皮肤。( ) 26．SCLE较常见的全身症状为关节痛。( ) 27．我国皮肌炎患者最常见的合并肿瘤为鼻咽癌。( ) 28．SLE患者若出现贫血，通常考虑缺铁性贫血。( )
乙肝五项说明： 1.乙肝表面抗原：是乙肝病毒的外壳蛋白，本身不具有传染性，但它的出现常伴随乙肝病毒的存在，所以它是已感染乙肝病毒的标志。在感染乙肝病毒2个月～6个月后，可在血清中测到阳性结果。它的出现表明是急性乙肝、慢性乙肝患者或病原携带者，急性乙肝患者大部分可在病程早期转阴，慢性乙肝患者或病毒携带者表面抗原可持续阳性。 2.乙肝表面抗体：是对乙肝病毒免疫和保护性抗体。它的阳性表明既往感染过乙肝病毒，但已经清除乙肝病毒，或者接种过乙肝疫苗，产生了保护性抗体。血清中乙肝表面抗体滴度越高，保护力越强。但也有少数人乙肝表面抗体阳性而又感染了乙肝，可能为不同亚型感染或是乙肝病毒发生了变异。 3.乙肝e抗原：急性或慢性乙肝患者体内可查出乙肝e抗原，它的阳性说明乙肝病毒在体内复制活跃，传染性强。 4.乙肝e抗体：它的阳性表明患者的传染性降低，乙肝病毒复制降低或缓解。也有个别人e抗体阳性，病情迁延不愈，多为感染了变异的乙肝病毒所致。 5.乙肝核心抗体：为曾经感染过或正在感染者都会出现的标志。核心抗体IGM是新近感染或乙肝病毒复制标志，核心抗体IgG是感染后就会产生的，对于辅助乙肝两对半检查有一定意义。 乙肝五项指标结果怎么看?武汉国中堂肝病研究所专家在这里简单给我们做个介绍： 1)第一项乙肝表面抗原(HBsAg)阳性，其余阴性。说明被乙肝病毒感染了。很多单项乙肝表面抗原阳性者体内的乙肝病毒已被清除，不再具有传染性。但是仍有一部分患者体内可以查到乙肝病毒的存在，仍具有传播性，应注意传染，更不能献血。 2)第一项、三项阳性，即乙肝表面抗原(HBsAg)和乙肝e抗原(HBeAg)阳性，其余三项阴性。表示感染了乙肝病毒，可能处在急性乙肝、慢性乙肝或乙肝携带者活动期，病毒复制活跃，传染性强;一、三、五项阳性就是常说的乙肝大三阳，意义与一、三项阳性差不多。
乙肝五项对照表 1乙肝表面抗原（HBsAg） 2乙肝表面抗体（抗-HBs） 3乙肝E抗原（HBeAg） 4乙肝E抗体（抗-HBe） 5乙肝核心抗体（抗-HBc） 第1、3、5阳为大三阳，1、4、5阳为小三阳 乙肝五项检查对照表内容如下： 1、乙肝五项第1项阳性，其余四项阴性。说明是急性病毒感染的潜伏期后期。 2、乙肝五项第135项阳性，其余两项阴性。俗称乙肝大三阳，说明是急、慢性乙肝，传染性相对较强。 3、乙肝五项第145项阳性，其余两项阴性。俗称乙肝小三阳，说明是急、慢性乙肝，传染性相对较弱。 4、乙肝五项第13项阳性，其余三项阴性。说明是急性乙肝的早期。 5、乙肝五项第1345项阳性：说明急性乙肝感染趋向恢复或者为慢性乙肝病毒携带者。乙肝两对半对照表 6、乙肝五项第14项阳性，其余三项阴性。说明慢性乙肝表面抗原携带者易转阴或者是急性感染趋向恢复。 7、乙肝五项第15项阳性，其余三项阴性。说明是急、慢性乙肝即：①急性HBV感染; ②慢性HBsAg携带者;③传染性弱。 8、乙肝五项第5项阳性，其余四项阴性。说明①既往感染未能测出抗-HBs②恢复期HBsAg 已消，抗-HBs尚未出现③无症状HBsAg携带者。 9、乙肝五项第245项阳性，其余两项阴性。说明是乙肝的恢复期，已有免疫力。 10、乙肝五项第2项阳性，其余四项阴性。说明：①曾经注射过乙肝苗并产生了抗体，有免疫力;②曾经有过乙肝病毒的感染，并且有一定的免疫力;③假阳性。 11、乙肝五项第25项阳性，其余三项阴性。说明是接种了乙肝疫苗以后，或是乙肝病毒感染后已康复，已有免疫力。 12、乙肝五项第45项阳性，其余三项阴性。说明是急性乙肝病毒感染的恢复期，或曾经感染过病毒。 13、乙肝五项全阴说明过去和现在未感染过HBV，但目前没有保护性抗体
一般过去式 时间状语：yesterday just now (刚刚) the day before three days ag0 a week ago in 1880 last month last year 1. I was in the classroom yesterday. I was not in the classroom yesterday. Were you in the classroom yesterday. 2. They went to see the film the day before. Did they go to see the film the day before. They did go to see the film the day before. 3. The man beat his wife yesterday. The man didn’t beat his wife yesterday. 4. I was a high student three years ago. 5. She became a teacher in 2009. 6. They began to study english a week ago 7. My mother brought a book from Canada last year. 8.My parents build a house to me four years ago . 9.He was husband ago. She was a cooker last mouth. My father was in the Xinjiang half a year ago. 10.My grandfather was a famer six years ago. 11.He burned in 1991
第七章风湿免疫科 一、名词解释 1、抗核抗体：是一组针对核内多种成分的自身抗体的总称，是筛选结缔组织病的主要试验。 2、类风湿因子：是抗人或动物IgG分子Fc片断上抗原决定簇的特异性抗体。 3、类风湿结节：在20%~75%类风湿关节炎患者皮下、几件或骨膜上出现结节，也可见于肺、胸膜、心肌等内脏深层，是类风湿关节炎的关节外表现，提示关节炎活动。 4、抗磷脂抗体：指与体内不同磷脂成分发生反应的抗体。 5、抗磷脂抗体综合征：是指由抗磷脂抗体引起的一组临床征象的总称，主要表现为血栓形成、习惯性流产、血小板减少等。 6、抗CCP抗体：抗环瓜氨酸肽抗体，对类风湿关节炎诊断有较高的特异性。 7、抗ENA抗体：为抗可提取的核糖核蛋白抗体。 8、中性粒细胞胞浆抗体（ANCA）：是指与中性粒细胞及单核细胞的胞浆中溶酶体酶发生反应的抗体，分为胞浆型（cANCA）和核周型（pANCA）。与血管炎的发病有关。 9、光过敏：暴露于日光或紫外光源下，可见面部蝶状红斑加重或出现新的皮肤损害，甚至可使全身病情加重。 10、皮肤狼疮带试验：皮肤表皮、真皮交界处有免疫球蛋白沉积。 11、赖特综合征：以关节炎、结膜炎、尿道炎为特征的感染反应性关节炎。 12、笔帽征：是银屑病关节炎的典型X光改变，近断指骨变尖，末节指骨近端增生变宽。 13、未分化脊柱关节病：有脊柱关节病的某些临床特点，又不能分类为某种明确的脊柱关节病的临床状态。 14、干燥综合征：是一组侵犯外分泌腺，特别是唾液腺、泪腺为特征的自身免疫性疾病。 15、Gottron征：四肢关节伸侧面可见红斑性鳞屑性皮疹，常见于皮肌炎。 16、CREST综合征：是系统性硬化症的一个亚型，主要表现为钙盐沉积、雷诺现象、食管功能障碍、指（趾）硬化及毛细血管扩张。 17、雷诺现象：指患者在寒冷或紧张刺激后，肢端小动脉间歇性痉挛引起的周围血管病变，表现为肢端阵发性发白、发绀、发红，伴局部发冷、感觉异常和疼痛的临床表现。 18、Heberden结节：远端指间关节骨肥大，发生于骨关节炎。 19、Bouchard结节：近端指间关节骨肥大，发生于骨关节炎。 20、Felty综合征：类风湿关节炎并有中性粒细胞减少及脾肿大的综合征。 21、RS3PE：又称血清阴性滑膜炎综合征，是类风湿关节炎的特殊类型，多见于老年男性，多累及腕、屈肌腱鞘和手的小关节，起病突然，呈对称性分布，伴手背明显的可凹性水肿。类风湿因子一般为阴性，对小剂量激素反应良好。对非甾体抗炎药不敏感。 22、系统性血管炎：是一组原发性、异质性的以血管壁炎性细胞浸润或坏死为基本病变的全身性结缔组织病，可引起相应的组织器官炎症、缺血、坏死或栓塞。 23、间歇性跛行：因下肢动脉痉挛或狭窄、缺血引起该侧下肢行走时无力、发麻、酸痛，行走至一段距离后被迫停下休息，待肢体血供恢复后才可重新行走。 24、白塞病：是以复发性口腔溃疡、生殖器溃疡、眼色素膜炎及皮肤脓疱疹为临床特征的系统性血管炎病。 25、混合结缔组织病（MCTD）：类似于系统性红斑狼疮、系统性硬化症、多发性肌炎和类风湿关节炎的临床表现，但又不能满足其中任何一种诊断，且伴血清高滴度抗RNP抗体诊断MCTD。 26、未分化结缔组织病（UCTD）：结缔组织病早期仅有较少症状，如雷诺现象、关节痛、肌痛
姓名：科室：得分： 一、单选题1、哪项不属于继发型肺结核 A. 浸润性肺结核 B. 菌阴肺结核 C. 结核球 D. 纤维空洞性肺结核 E. 干酪样肺炎 2、脑卒中病人主要表现的病理步态特点是 A. 偏瘫步态 B. 共济失调步态 C. 剪刀步态 D. 前冲步态 E. 疼痛步态 3、肺结核的诊断程序不包括 A. 可疑症状病人的筛选 B. 是否为进展性 C. 是否为肺结核 D. 是否排菌 E. 是否耐药以及明确初、复治 4、下述哪项所致心排血量减少，不宜用血管扩张药治疗 A. 心包积液 B. 室间隔缺损 C. 二尖瓣关闭不全 D. 高血压性心脏病 E. 充血性心脏病 5、肺结核大咯血时，应采取的体位是 A. 患侧卧位 B. 健侧卧位 C. 坐位
D. 俯卧位 E. 仰卧位 6、下列哪项生活方式或生活环境不是骨质疏松的危险因素 A. 长期卧床 B. 酗酒 C. 体力活动过少 D. 充足日照 E. 吸烟 7、主要通过增加外周组织对葡萄糖摄取和利用的降糖药物是 A. 磺脲类 B. 双胍类 C. 葡萄糖苷酶抑制剂 D. 胰岛素增敏剂 E. 硫脲类 8、下列哪项不属于心血管病预防的健康咨询内容 A. 避免长时间阳光照射 B. 预防和控制高血糖 C. 预防和控制高血压 D. 适度运动，避免过度劳累 E. 避免情绪过于激动 9、母乳喂养的优点不包括下列哪一项 A. 含白蛋白多而酪蛋白少，在胃内的凝块小 B. 脂肪颗粒小，且富有解脂酶 C. 含较多的消化酶，有利于消化 D. 含钙磷比牛乳高，较少发生低钙血症 E. 含铁与牛乳相同，但吸收率高 10、食管胃底静脉曲张出血药物治疗，不包括 A. 生长抑素 B. 奥曲肽 C. PPI
乙肝核心抗体阳性是什么意思 乙肝核心抗体阳性是什么意思?许多人并不是很了解，当看到乙肝核心抗体阳性时，就会误以为得了乙肝。通过国家的宣传和乙肝携带者自身的努力，乙肝歧视现在有着改观，完全没有歧视的心理或者恐慌的心理需要一段时间，当经常接触的人在乙肝五项检查中有问题时，对乙肝知识缺乏深入的了解和学习，心理还是有所担心和犹豫。 乙肝核心抗体呈阳性的临床意义： 1）无症状乙肝表面抗原携带者滴度太低不能检测出来，而乙肝核心抗体可以。 2）在恢复期时，当乙肝表面抗原已减少止不能测出，而乙肝表面抗原尚未转为乙肝表面抗体之际，可以测乙肝核心抗体。 3）乙肝核心抗体比乙肝表面抗体持续的时间长。 4）乙肝核心抗体阳性表示曾经感染过乙肝病毒，现处于急性感染恢复期，或处于急、慢性感染。 核心抗体是什么？核心抗体的作用： 由于乙肝核心抗原在血中很快被裂解，所以在血清中查不出来，但是它具有抗原性，能刺激身体的免疫系统产生特性抗体，即乙肝核心抗体，所以检测乙肝核心抗体可以了解人体是否有过核心抗原的刺激，即是否有过乙肝病毒的感染。所以说乙肝核心抗体是一项病毒感染的标志。HBcAb是乙肝核心抗体的英文缩写，它是病毒刺激肝细胞产生的一种免疫球蛋白，也叫抗-HBc，其中有IgG、IgM、IgA和IgE型，临床上常规检测的有IgM和IgG型。它和HBcAg是一对相对应的抗原抗体系统。HBcAb阳性的出现表明肝内乙肝病毒复制活跃,肝细胞受损较重，并且传染性较强。
在急性HBV感染中，HBcAb的产生通常在HBsAg出现后3~5周。此时，HBsAg 已经消失，HBsAb尚未阳转。HBcAb的检出反映乙肝病毒在复制，无保护作用，不能中和乙肝核心抗原。 HbcAb阳性并不能说明任何问题 如果乙肝表面抗体和乙肝核心抗体表现阳性，单独后者是阴或者是阳都说明不了任何问题，因为它是感染病毒后最早呈阳性，也是最晚转阴性的一项，而且有些人一辈子都是阳性，前者是阳性说明你曾经感染过乙肝病毒，现在已经对病毒有了免疫。 HBcAb弱阳性的出现可以有以下几种情况 1、HBcAb弱阳性说明以前感染过乙肝病毒，目前已经康复，但没有产生保护性抗体乙肝表面抗体。或者乙肝表面抗体已经消失，但乙肝核心抗体依然存在。这是因为乙肝核心抗体比乙肝表面抗体的存在时间要长很多，有些人感染乙肝病毒康复后，HBcAb可终身阳性或者弱阳性。此时HBcAb弱阳性只是说明曾经感染过乙肝病毒。 2、HBcAb弱阳性也可能是隐性乙肝病毒感染后的一种表现。 3、乙肝患者经过治疗，其他各项指标已经转阴，只剩下少量乙肝核心抗体也可出现HBcAb弱阳性。 有必要检查抗-HBc IgM和抗-HBc IgG 1、抗-HBc IgM是HBV感染出现较早的抗体，90%出现在发病的第一周，在血清中可持续2~134周。IgM的高滴度出现，是诊断HBV急性感染的重要指标。抗-HBc IgM的表达，在一定程度上反映了肝组织的炎症活动状态。抗-HBc IgM与HBV 复制的标志物(HBeAg、HBV DNA)有相关性，但不是HBV复制的敏感指标。因此，抗-HBc IgM即是HBV的感染性指标，也被认为是传染性指标。
●I wonder if it’s because I have been at school for so long that I’ve grown so crazy about going home. ●It is because she wasn’t well that she fell far behind her classmates this semester. ●I can well remember that there was a time when I took it for granted that friends should do everything for me. ●In order to make a difference to society, they spent almost all of their spare time in raising money for the charity. ●It’s no pleasure eating at school any longer because the food is not so tasty as that at home. ●He happened to be hit by a new idea when he was walking along the riverbank. ●I wonder if I can cope with stressful situations in life independently. ●It is because I take things for granted that I make so many mistakes. ●The treasure is so rare that a growing number of people are looking for it. ●He picks on the weak mn in order that we may pay attention to him. ●It’s no pleasure being disturbed whena I settle down to my work. ●I can well remember that when I was a child, I always made mistakes on purpose for fun. ●It’s no pleasure accompany her hanging out on the street on such a rainy day. ●I can well remember that there was a time when I threw my whole self into study in order to live up to my parents’ expectation and enter my dream university. ●I can well remember that she stuck with me all the time and helped me regain my confidence during my tough time five years ago. ●It is because he makes it a priority to study that he always gets good grades. ●I wonder if we should abandon this idea because there is no point in doing so. ●I wonder if it was because I ate ice-cream that I had an upset student this morning. ●It is because she refused to die that she became incredibly successful. ●She is so considerate that many of us turn to her for comfort. ●I can well remember that once I underestimated the power of words and hurt my friend. ●He works extremely hard in order to live up to his expectations. ●I happened to see a butterfly settle on the beautiful flower. ●It’s no pleasure making fun of others. ●It was the first time in the new semester that I had burned the midnight oil to study. ●It’s no pleasure taking everything into account when you long to have the relaxing life. ●I wonder if it was because he abandoned himself to despair that he was killed in a car accident when he was driving. ●Jack is always picking on younger children in order to show off his power. ●It is because he always burns the midnight oil that he oversleeps sometimes. ●I happened to find some pictures to do with my grandfather when I was going through the drawer. ●It was because I didn’t dare look at the failure face to face that I failed again. ●I tell my friend that failure is not scary in order that she can rebound from failure. ●I throw my whole self to study in order to pass the final exam. ●It was the first time that I had made a speech in public and enjoyed the thunder of applause. ●Alice happened to be on the street when a UFO landed right in front of her. ●It was the first time that I had kept myself open and talked sincerely with my parents. ●It was a beautiful sunny day. The weather was so comfortable that I settled myself into the
高中英语~词性~句子成分~语法构成 第一章节：英语句子中的词性 1.名词：n. 名词是指事物的名称，在句子中主要作主语.宾语.表语.同位语。 2.形容词;adj. 形容词是指对名词进行修饰~限定~描述~的成份，主要作定语.表语.。形容词在汉语中是（的）.其标志是: ous. Al .ful .ive。. 3.动词：vt. 动词是指主语发出的一个动作，一般用来作谓语。 4.副词：adv. 副词是指表示动作发生的地点. 时间. 条件. 方式. 原因. 目的. 结果.伴随让步. 一般用来修饰动词. 形容词。副词在汉语中是（地）.其标志是：ly。 5.代词：pron. 代词是指用来代替名词的词，名词所能担任的作用，代词也同样.代词主要用来作主语. 宾语. 表语. 同位语。 6.介词：prep.介词是指表示动词和名次关系的词，例如：in on at of about with for to。其特征：
介词后的动词要用—ing形式。介词加代词时，代词要用宾格。例如：give up her（him）这种形式是正确的，而give up she（he）这种形式是错误的。 7.冠词：冠词是指修饰名词，表名词泛指或特指。冠词有a an the 。 8.叹词：叹词表示一种语气。例如：OH. Ya 等 9.连词：连词是指连接两个并列的成分，这两个并列的成分可以是两个词也可以是两个句子。例如：and but or so 。 10.数词：数词是指表示数量关系词，一般分为基数词和序数词 第二章节：英语句子成分 主语：动作的发出者，一般放在动词前或句首。由名词. 代词. 数词. 不定时. 动名词. 或从句充当。 谓语：指主语发出来的动作，只能由动词充当，一般紧跟在主语后面。 宾语：指动作的承受着，一般由代词. 名词. 数词. 不定时. 动名词. 或从句充当. 介词后面的成分也叫介词宾语。 定语：只对名词起限定修饰的成分，一般由形容
乙肝抗原抗体检查是什么 我们要想知道自己是否感染乙肝，就要去医院进行乙肝抗原抗体检查，那么到底乙肝抗原抗体检查是什么呢？对此，云南新华肝病医院青光枝主任作出了详细解答。 云南新华肝病医院青主任指出，临床上运用最广泛的乙肝抗原抗体检查，就是我们常听说的乙肝两对半检查，是我国最常用的乙肝血清标志物检查。具体乙肝抗原抗体检查有五项：乙肝表面抗原、乙肝表面抗体、乙肝e抗原、乙肝e抗体和乙肝核心抗体，以下对其检查意义进行分别介绍： 一、乙肝表面抗原：是乙肝病毒的外壳蛋白，本身不具有传染性，但它常伴随乙肝病毒而存在，因此是感染乙肝的标志。 二、乙肝表面抗体：它可以和表面抗原特异地结合，在体内与人体的其他免疫功能共同作用下，可把病毒清除掉，保护人体不再受乙肝病毒感染。通常乙肝表面抗体作为中和性抗体标志，判断是否康复或是否有抵抗力。 三、乙肝e抗原：是可溶性蛋白，核心抗原的亚成分，当核心抗原裂解时，乙肝e抗原就溶于血清中，存在于血液循环中，临床检查意义为病毒复制标志，持续阳性3个月以上则有慢性化倾向。 四、乙肝e抗体：由e抗原刺激人体免疫系统产生出来的特异性抗体是，是病毒复制停止标志，病毒复制减少，传染性较弱，但需注意e抗体不是保护性抗体，不代表患者有了免疫力。 五、乙肝核心抗体：检测乙肝核心抗体可以了解人体是否有过核
心抗原的刺激，也就是说是否有过乙肝病毒的感染，因此作为病毒感染的标志之一。 以上就是肝病专家青主任对“乙肝抗原抗体检查”的详细解答，最后青主任提醒，在进行乙肝抗原抗体检查的时候，一定要到正规的肝病医院，才能保证检查结果的准确性，云南新华肝病医院位于昆明市北市区金实小区南门小庄立交桥旁，是云南省重点三甲肝病医院，已有20多年的专业治肝历史，医院拥有先进的诊疗设备和专业的专家团队，能保证每一位到诊的患者，都得到有效的治疗，是检查和治疗的首选！
乙肝五项要称为乙肝两对半，包括乙肝表面抗原(用HBSAg表示)、乙肝表面抗体(用抗-HBS表示)、e抗原(用HBeAg表示)、e抗体(用抗-HBe表示)、核心抗体(用抗-HBc表示)。乙肝五项检查，便是抽出患者静脉血，检测血液中乙肝病毒的血清学标志。但是，很多人看不懂乙肝五项检查结果。那么，乙肝五项检查结果该怎么看呢? 乙肝五项指标详解： 1、HBsAg(乙肝表面抗原) 它是乙肝病毒的外壳物质，本身没有传染性。它的阳性往往提示有完整的病毒颗粒存在。 2、抗一HBs(乙肝表面抗体，HbsAb) 它是HBV自然感染人恢复期出现的抗体，此时HBsAg自然消失了。它的存在提示人对乙肝有了抵抗力，不会再得乙型肝炎了。我国有27.42%的人口有此抗体。 3 、HBeAg(乙型肝炎e抗原) 它产生于病毒内部，可分泌血液中，e抗原阳性提示病毒有活动，乙肝病毒复制速度很快，而且是具有传染性的指标。 4 、抗～HBe(乙肝e抗体，HBeAb) 是人体针对e抗原产生的一种蛋白物质，阳性结果提示病毒的传染性变弱，病情已处于恢复阶段。但另一种情况可能是乙肝病毒发生了变异，此时血清中无HBeAg，但可产生抗一HBe，出现这种情况就需要查HBV—DNA来判定是否还有病毒存在。 5 、抗一HBc(乙肝核心抗体，HbcAb) 这种抗体分IgM和lgG两种：抗HBc—IgM阳性提示病毒活动，有传染性;抗HBc—IgG阳性提示为以往感染，无传染性，不需抗病毒治疗。 乙肝五项指标阳性的含义： 1、乙肝五项指标第1阳性：表示是乙肝病毒感染者，伴有第35项阳性就是大三阳，伴有45项阳性就是小三阳。但不论上述何种情况，只要伴有第2项阳性就表示乙肝在恢复期，趋于痊愈。 2、乙肝五项指标第2项阳性：表示乙肝已痊愈或有效接种乙肝疫苗后。伴第5项阳性意思差不多。 3、乙肝五项指标第3、4项阳性：极少见，建议重新复查。伴有第1项和第5项表示大三阳或小三阳。 4、乙肝五项指标第5项阳性：在潜伏期肝炎患者，隐匿性肝炎患者，乙肝病毒携带者，痊愈患者，接种疫苗后的健康人中都可能出现单五阳，单五阳不可大意，建议去查查有无肝炎、丙肝，是否是病毒携带者等。第五项阳性代表的意义没有针对性，所以伴有其他阳性时可以忽略不看，多作为其他项的辅助判断项。 乙肝五项指标全阴性说明机体没有被乙肝病毒感染过。但是人体也没有对乙肝病毒的免疫力。这类人群在流行病学中被称为“乙肝易感人群”，即一旦接触或被病毒感染就很容易发病。所以乙肝五项全阴性者应积极地接种乙肝疫苗，使体内产生乙肝抗体(抗-HBs),就不怕乙肝传染了。 乙肝五项检查的正常结果： 乙肝五项检查有很多结果，正常的结果有以下三种： 一、乙肝五项全部阴性
M A: Has the case been closed yet? B: No, the magistrate still needs to decide the outcome. magistrate n.地方行政官，地方法官，治安官 A: I am unable to read the small print in the book. B: It seems you need to magnify it. magnify vt.１．放大，扩大；２．夸大，夸张 A: That was a terrible storm. B: Indeed, but it is too early to determine the magnitude of the damage. magnitude n.１．重要性，重大；２．巨大，广大 A: A young fair maiden like you shouldn’t be single. B: That is because I am a young fair independent maiden. maiden n.少女，年轻姑娘，未婚女子 a.首次的，初次的 A: You look majestic sitting on that high chair. B: Yes, I am pretending to be the king! majestic a.雄伟的，壮丽的，庄严的，高贵的 A: Please cook me dinner now. B: Yes, your majesty, I’m at your service. majesty n.１．［Ｍ－］陛下（对帝王，王后的尊称）；２．雄伟，壮丽，庄严 A: Doctor, I traveled to Africa and I think I caught malaria. B: Did you take any medicine as a precaution? malaria n.疟疾 A: I hate you! B: Why are you so full of malice? malice n.恶意，怨恨 A: I’m afraid that the test results have come back and your lump is malignant. B: That means it’s serious, doesn’t it, doctor? malignant a.１．恶性的，致命的；２．恶意的，恶毒的 A: I’m going shopping in the mall this afternoon, want to join me? B: No, thanks, I have plans already. mall n.（由许多商店组成的）购物中心 A: That child looks very unhealthy. B: Yes, he does not have enough to eat. He is suffering from malnutrition.
第七章风湿免疫科 (总分133,考试时间600分钟) 一、名词解释 1. 抗核抗体 2. 类风湿因子 3. 类风湿结节 4. 抗磷脂抗体 5. 抗磷脂抗体综合征 6. 抗CCP抗体 7. 抗ENA抗体 8. 中性粒细胞胞浆抗体（ANCA） 9. 光过敏 10. 皮肤狼疮带试验 11. 赖特综合征 12. 笔帽征 13. 未分化脊柱关节病 14. 干燥综合征 15. Gottron征 16. CREST综合征 17. 雷诺现象 18. Heberden结节 19. Bouchard结节
20. Felty综合征 21. RS3PE 22. 系统性血管炎 23. 间歇性跛行 24. 白塞病 25. 混合结缔组织病（MCTD） 26. 未分化结缔组织病（UCTD） 二、单项选择题 1. 下列有关弥漫性结缔组织病特点的叙述中，错误的是：（） A. 自身免疫异常是结缔组织病的发病基础 B. 血管炎和结缔组织慢性炎症是该病的病理基础 C. 病变累及多系统，临床个体差异大 D. 均需糖皮质激素治疗 E. 疗效与早期诊断、合理治疗有关 2. 下列关于风湿病的分类，正确的一项是：（） A. 系统性血管炎属弥漫性结缔组织病 B. RA不属弥漫性结缔组织病 C. 风湿热与RA均属弥漫性结缔组织病 D. AS与RA属同一类别 E. 银屑病关节炎与HLAB27无关，与AS不属同类 3. 下列发病因素中，与自身免疫性疾病无明显关系的是：（） A. 遗传因素 B. 感染因素 C. 性激素 D. 心理、神经、免疫效应 E. 气候与季节 4. 下列有关MHC分子功能的叙述，错误的是：（） A. 与自身抗原结合，在胸腺进行T细胞选择 B. 与异体抗原结合，提呈给成熟T细胞，引起免疫反应 C. 决定抗原的免疫表型，使不同个体生成相同的免疫反应 D. 刺激自身（auto）和同种异体（allo）混合淋巴细胞反应 E. 与自身免疫病的发病明显有关 5. 下列对于抗核抗体(ANA)的描述，错误的是：（）
---------------------------------------------------------------最新资料推荐------------------------------------------------------ 乙肝相关抗原和抗体 乙肝相关抗原与抗体乙肝表面抗原(HBsAg) 乙肝表面抗体(HBsAb) 乙肝 e 抗原(HBeAg) 乙肝 e 抗体(HBeAb) 乙肝核心杭体(HBcAb) 乙肝病毒的生命周期： 乙肝病毒(HBV)---肝细胞表面---脱掉外衣，进入肝细胞---脱掉内衣，将 HBV DNA 注入肝细胞核---肝细胞核内形成 DNA（每个肝细胞核内含有 10-20 个 DNA 分子，也有报告每个肝细胞核内含有30-50 个 DNA 模板）以肝细胞核内 DNA 为模板，生产出各种乙肝病毒蛋白合成所需要的核糖核酸（RNA），然后在肝细胞浆内生产出乙肝病毒的各种蛋白质（抗原），包括： HBsAg(表面抗原) HBcAg(核心抗原) HBeAg(e 抗原) 这些病毒蛋白质合成后，即发挥病毒复制的各种功能： HBsAg(表面抗原)--- 给病毒 DNA 穿上外衣，包装病毒，或释放入血，形成空的表面抗原 HBcAg(核心抗原)--- 给病毒 DNA 穿上内衣，包装病毒 DNA，等待包装外衣 HBeAg(乙肝 e 抗原)---经过肝细胞浆的内质网，直接分泌到肝细胞外，进入血液及全身一、乙肝表面抗原HbsAg 来源： HbsAg 是 1963 年由 Blumberg 在澳大利亚土著人的血清中首先发现的，故开始被称为澳大利亚抗原，即很长一段时间内人们一直说的奥抗，后又被称为肝炎相关抗原（HAA），1974 年被正式定名为乙型肝炎表面抗原。 1 / 7