scholarly journals A STUDY OF GAUSSIANITY IN CMB BAND MAPS

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1405-1409 ◽  
Author(s):  
A. BERNUI ◽  
M. J. REBOUÇAS ◽  
A. F. F. TEIXEIRA
Keyword(s):  
Early Universe ◽  
Alternative Models ◽  
W Band ◽  
Alternative Scenarios ◽  
Inflationary Models ◽  
Rule Out

The detection of non-Gaussianity in the CMB data would rule out a number of inflationary models. A null detection of non-Gaussianity, instead, would exclude alternative models for the early universe. Thus, a detection or non-detection of primordial non-Gaussianity in the CMB data is crucial to discriminate among inflationary models, and to test alternative scenarios. However, there are various non-cosmological sources of non-Gaussianity. This makes important to employ different indicators in order to detect distinct forms of non-Gaussianity in CMB data. Recently, we proposed two new indicators to measure deviation from Gaussianity on large angular scales, and used them to study the Gaussianity of the raw band WMAP maps with and without the KQ75 mask. Here we extend this work by using these indicators to perform similar analyses of deviation from Gaussianity of the foreground-reduced Q, V, and W band maps. We show that there is a significant deviation from Gaussianity in the considered full-sky maps, which is reduced to a level consistent with Gaussianity when the KQ75 mask is employed.

scholarly journals NON-GAUSSIANITY IN THE HILC FOREGROUND-REDUCED THREE-YEAR WMAP CMB MAP

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1411-1416 ◽  
Author(s):  
A. BERNUI ◽  
M. J. REBOUÇAS
Keyword(s):  
Early Universe ◽  
Large Angle ◽  
Single Frequency ◽  
Considerable Effort ◽  
Frequency Bands ◽  
Alternative Models ◽  
Wmap Data ◽  
Inflationary Models

The detection or non-detection of primordial non-Gaussianity in the CMB data is essential not only to test alternative models of the physics of the early universe but also to discriminate among classes of inflationary models. Given this far-reaching consequences of such a non-Gaussianity detection for our understanding of the physics of the early universe, it is important to employ alternative indicators in order to have further information about the Gaussianity features of CMB that may be helpful for identifying their origins. In this way, a considerable effort has recently gone into the design of non-Gaussianity indicators, and in their application in the search for deviation from Gaussianity in the CMB data. Recently we have proposed two new large-angle non-Gaussianity indicators which provide measures of the departure from Gaussianity on large angular scales. We have used these indicators to carry out analyses of Gaussianity of the single frequency bands and of the available foreground-reduced five-year maps with and without the KQ75 mask. Here we extend and complement these studies by performing a new analysis of deviation from Gaussianity of the three-year harmonic ILC (HILC) foreground-reduced full-sky and KQ75 masked maps obtained from WMAP data. We show that these full-sky foreground-reduced maps present a significant deviation from Gaussianity, which is brought down to a level of consistency with Gaussianity when the KQ75 mask is employed.

scholarly journals Inflationary universe models and clustering of quasar red shifts

1986 ◽  
Vol 119 ◽  
pp. 509-510
Author(s):  
C. Sivaram
Keyword(s):  
Cosmological Model ◽  
Early Universe ◽  
Hubble Constant ◽  
Matter Density ◽  
Inflationary Universe ◽  
Expansion Phase ◽  
Exponential Expansion ◽  
The Universe ◽  
Inflationary Models ◽  
Universe Models

Recently it has been shown that many of the puzzling features of conventional cosmological models (such as the horizon and flatness problems) could be explained by invoking inflationary models of the early universe with an exponential expansion phase at very early epochs. These models have the added advantage that they are able to make a definite prediction about the present matter density in the universe, i.e. they require that the density be exactly equal to the closure density which in turn can be easily estimated from the Hubble constant now known to within a factor of two. Now if one goes back to an earlier idea that explored the possibility of unusual clustering of quasar redshifts around z = 2 or 3, we get an example of another cosmological model with a definite prediction for the present overall matter density. This is a modified version of the Eddington-Lemaitre type of model which naturally accommodates such features as a clustering of quasars at certain epochs. From these models one can get a prediction for the present matter density which would be an involved function of the Hubble constant and the redshifts at which such clustering occurs. It can be shown that if such clustering had occurred at any z, the present matter density predicted would be substantially smaller than the corresponding closure density. The conclusion is that any clustering of quasar redshifts is incompatiable with inflationary universe models, indirectly providing observational support for these new theories.

scholarly journals Large Fermi Surface of Heavy Electrons at the Border of Mott Insulating State in NiS2

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
S. Friedemann ◽  
H. Chang ◽  
M. B. Gamża ◽  
P. Reiss ◽  
X. Chen ◽  
...  
Keyword(s):  
High Pressure ◽  
Fermi Surface ◽  
Quantum Physics ◽  
Mott Transition ◽  
Electrostatic Repulsion ◽  
Strong Correlations ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Alternative Scenarios ◽  
Rule Out

Abstract One early triumph of quantum physics is the explanation why some materials are metallic whereas others are insulating. While a treatment based on single electron states is correct for most materials this approach can fail spectacularly, when the electrostatic repulsion between electrons causes strong correlations. Not only can these favor new and subtle forms of matter, such as magnetism or superconductivity, they can even cause the electrons in a half-filled energy band to lock into position, producing a correlated, or Mott insulator. The transition into the Mott insulating state raises important fundamental questions. Foremost among these is the fate of the electronic Fermi surface and the associated charge carrier mass, as the Mott transition is approached. We report the first direct observation of the Fermi surface on the metallic side of a Mott insulating transition by high pressure quantum oscillatory measurements in NiS2. Our results point at a large Fermi surface consistent with Luttinger’s theorem and a strongly enhanced quasiparticle effective mass. These two findings are in line with central tenets of the Brinkman-Rice picture of the correlated metal near the Mott insulating state and rule out alternative scenarios in which the carrier concentration vanishes continuously at the metal-insulator transition.

scholarly journals EARLY UNIVERSE SOURCES FOR CMB NON-GAUSSIANITY

2002 ◽  
Vol 17 (29) ◽  
pp. 4273-4280
Author(s):  
ALEJANDRO GANGUI
Keyword(s):  
Power Spectrum ◽  
Cosmic Microwave Background ◽  
Early Universe ◽  
Microwave Background ◽  
Scale Invariant ◽  
Invariant Model ◽  
Primordial Power Spectrum ◽  
Initial States ◽  
Non Gaussian ◽  
Inflationary Models

In the framework of inflationary models with non-vacuum initial states for cosmological perturbations, we study non-Gaussian signatures on the cosmic microwave background (CMB) radiation produced by a broken-scale-invariant model which incorporates a feature at a privileged scale in the primordial power spectrum.

scholarly journals Confirmation of double peaked Lyα emission at z = 6.593

2018 ◽  
Vol 619 ◽  
pp. A136 ◽  
Author(s):  
Jorryt Matthee ◽  
David Sobral ◽  
Max Gronke ◽  
Ana Paulino-Afonso ◽  
Mauro Stefanon ◽  
...  
Keyword(s):  
High Resolution ◽  
Direct Evidence ◽  
Line Emission ◽  
Flux Ratio ◽  
Peak Separation ◽  
Low Metallicity ◽  
Extensive Collection ◽  
Alternative Scenarios ◽  
The Universe ◽  
Rule Out

Distant luminous Lyman-α emitters (LAEs) are excellent targets for spectroscopic observations of galaxies in the epoch of reionisation (EoR). We present deep high-resolution (R = 5000) VLT/X-shooter observations, along with an extensive collection of photometric data of COLA1, a proposed double peaked LAE at z = 6.6. We rule out the possibility that COLA1’s emission line is an [OII] doublet at z = 1.475 on the basis of i) the asymmetric red line-profile and flux ratio of the peaks (blue/red=0.31 ± 0.03) and ii) an unphysical [OII]/Hα ratio ([OII]/Hα >  22). We show that COLA1’s observed B-band flux is explained by a faint extended foreground LAE, for which we detect Lyα and [OIII] at z = 2.142. We thus conclude that COLA1 is a real double-peaked LAE at z = 6.593, the first discovered at z >  6. COLA1 is UV luminous (M1500 = −21.6 ± 0.3), has a high equivalent width (EW0,Lyα = 120−40+50 Å) and very compact Lyα emission (r50,Lyα = 0.33−0.04+0.07 kpc). Relatively weak inferred Hβ+[OIII] line-emission from Spitzer/IRAC indicates an extremely low metallicity of Z <  1/20 Z⊙ or reduced strength of nebular lines due to high escape of ionising photons. The small Lyα peak separation of 220 ± 20 km s−1 implies a low HI column density and an ionising photon escape fraction of ≈15 − 30%, providing the first direct evidence that such galaxies contribute actively to the reionisation of the Universe at z >  6. Based on simple estimates, we find that COLA1 could have provided just enough photons to reionise its own ≈0.3 pMpc (2.3 cMpc) bubble, allowing the blue Lyα line to be observed. However, we also discuss alternative scenarios explaining the detected double peaked nature of COLA1. Our results show that future high-resolution observations of statistical samples of double peaked LAEs at z >  5 are a promising probe of the occurrence of ionised regions around galaxies in the EoR.

scholarly journals ALTERNATIVES TO THE INFLATIONARY PARADIGM OF STRUCTURE FORMATION

2011 ◽  
Vol 01 ◽  
pp. 67-79 ◽  
Author(s):  
ROBERT H. BRANDENBERGER
Keyword(s):  
Structure Formation ◽  
Early Universe ◽  
String Gas Cosmology ◽  
Conceptual Problems ◽  
Alternative Scenarios ◽  
Early Universe Cosmology

The inflationary paradigm, although very successful phenomenologically, suffers from several conceptual problems which motivate the search for alternative scenarios of early universe cosmology. Here, two possible alternatives will be reviewed. - "string gas cosmology" and the "matter bounce". Their successes and problems will be pointed out.

Inflation

2018 ◽  
Author(s):  
Michael Kachelriess
Keyword(s):  
Early Universe ◽  
Temperature Fluctuations ◽  
Big Bang ◽  
Microwave Background ◽  
Scale Invariant ◽  
Slow Roll ◽  
Exponential Expansion ◽  
Fixed Phase ◽  
Big Bang Model ◽  
Inflationary Models

This chapter introduces inflation as a phase of nearly exponential expansion in the early universe. The slow-roll conditions are deribed and possible inflationary models are discussed. Reheating connects the end of inflation with the standard hot big-bang model. The spectrum of fluctuations generated by inflation is calculated and it is shown that it is nearly scale-invariant and Gaussian. The fluctuations have fixed phase relations on superhorizon scales that cause characteristic oscillations of the temperature fluctuations of the cosmic microwave background.

A rapid method for the direct identification of paramyxovirus in canine CSF by ultracentrifugation and negative staining as a rule out for distemper

1990 ◽  
Vol 48 (3) ◽  
pp. 594-595
Author(s):  
W.L. Steffens ◽  
M.B. Ard ◽  
C.E. Greene ◽  
A. Jaggy
Keyword(s):  
Subacute Sclerosing Panencephalitis ◽  
Clinical Signs ◽  
Viral Disease ◽  
Etiologic Agent ◽  
Mucosal Inflammation ◽  
Worldwide Distribution ◽  
Negative Stain ◽  
Viral Particles ◽  
Systemic Manifestations ◽  
Rule Out

Canine distemper is a multisystemic contagious viral disease having a worldwide distribution, a high mortality rate, and significant central neurologic system (CNS) complications. In its systemic manifestations, it is often presumptively diagnosed on the basis of clinical signs and history. Few definitive antemortem diagnostic tests exist, and most are limited to the detection of viral antigen by immunofluorescence techniques on tissues or cytologic specimens or high immunoglobulin levels in CSF (cerebrospinal fluid). Diagnosis of CNS distemper is often unreliable due to the relatively low cell count in CSF (<50 cells/μl) and the binding of blocking immunoglobulins in CSF to cell surfaces. A more reliable and definitive test might be possible utilizing direct morphologic detection of the etiologic agent. Distemper is the canine equivalent of human measles, in that both involve a closely related member of the Paramyxoviridae, both produce mucosal inflammation, and may produce CNS complications. In humans, diagnosis of measles-induced subacute sclerosing panencephalitis is through negative stain identification of whole or incomplete viral particles in patient CSF.

Impairment Questions and Answers

1999 ◽  
Vol 4 (4) ◽  
pp. 4-4
Keyword(s):  
Symptom Validity ◽  
Validity Testing ◽  
Symptom Validity Testing ◽  
Negative Results ◽  
Tunnel Vision ◽  
Questions And Answers ◽  
Blurry Vision ◽  
Fatigue Evaluation ◽  
Choice Testing ◽  
Rule Out

Abstract Symptom validity testing, also known as forced-choice testing, is a way to assess the validity of sensory and memory deficits, including tactile anesthesias, paresthesias, blindness, color blindness, tunnel vision, blurry vision, and deafness—the common feature of which is a claimed inability to perceive or remember a sensory signal. Symptom validity testing comprises two elements: A specific ability is assessed by presenting a large number of items in a multiple-choice format, and then the examinee's performance is compared with the statistical likelihood of success based on chance alone. Scoring below a norm can be explained in many different ways (eg, fatigue, evaluation anxiety, limited intelligence, and so on), but scoring below the probabilities of chance alone most likely indicates deliberate deception. The positive predictive value of the symptom validity technique likely is quite high because there is no alternative explanation to deliberate distortion when performance is below the probability of chance. The sensitivity of this technique is not likely to be good because, as with a thermometer, positive findings indicate that a problem is present, but negative results do not rule out a problem. Although a compelling conclusion is that the examinee who scores below probabilities is deliberately motivated to perform poorly, malingering must be concluded from the total clinical context.

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