432 research outputs found
The Evolution of the Fractions of Quiescent and Star-forming Galaxies as a Function of Stellar Mass Since z=3: Increasing Importance of Massive, Dusty Star-forming Galaxies in the Early Universe
Using the UltraVISTA DR1 and 3D-HST catalogs, we construct a
stellar-mass-complete sample, unique for its combination of surveyed volume and
depth, to study the evolution of the fractions of quiescent galaxies,
moderately unobscured star-forming galaxies, and dusty star-forming galaxies as
a function of stellar mass over the redshift interval . We
show that the role of dusty star-forming galaxies within the overall galaxy
population becomes more important with increasing stellar mass, and grows
rapidly with increasing redshift. Specifically, dusty star-forming galaxies
dominate the galaxy population with at . The ratio of dusty and non-dusty star-forming galaxies as
a function of stellar mass changes little with redshift. Dusty star-forming
galaxies dominate the star-forming population at , being a factor of 3-5 more common,
while unobscured star-forming galaxies dominate at . At , red
galaxies dominate the galaxy population at all redshift , either because
they are quiescent (at late times) or dusty star-forming (in the early
universe).Comment: 7 pages, 4 figures, 1 table. Accepted by Astrophysical Journal
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Endocytotic formation of vesicles and other membranous structures induced by Ca2+ and axolemmal injury
Vesicles and/or other membranous structures that form after
axolemmal damage have recently been shown to repair (seal)
the axolemma of various nerve axons. To determine the origin
of such membranous structures, (1) we internally dialyzed isolated
intact squid giant axons (GAs) and showed that elevation
of intracellular Ca21 .100 uM produced membranous structures
similar to those in axons transected in Ca21-containing
physiological saline; (2) we exposed GA axoplasm to Ca21-
containing salines and observed that membranous structures
did not form after removing the axolemma and glial sheath but
did form in severed GAs after .99% of their axoplasm was
removed by internal perfusion; (3) we examined transected GAs
and crayfish medial giant axons (MGAs) with time-lapse confocal
fluorescence microscopy and showed that many injuryinduced
vesicles formed by endocytosis of the axolemma; (4)
we examined the cut ends of GAs and MGAs with electron
microscopy and showed that most membranous structures
were single-walled at short (5–15 min) post-transection times,
whereas more were double- and multi-walled and of probable
glial origin after longer (30–150 min) post-transection times; and
(5) we examined differential interference contrast and confocal
images and showed that large and small lesions evoked similar
injury responses in which barriers to dye diffusion formed amid
an accumulation of vesicles and other membranous structures.
These and other data suggest that Ca21 inflow at large or small
axolemmal lesions induces various membranous structures (including
endocytotic vesicles) of glial or axonal origin to form,
accumulate, and interact with each other, preformed vesicles,
and/or the axolemma to repair the axolemmal damage.This work was supported by grants from National Institutes of Health (NIH;
NS31256) and the State of Texas (Advanced Technology 3658-446).Neuroscienc
Linear and nonlinear analysis of normal and CAD-affected heart rate signals
Coronary Artery Disease (CAD) is one of the dangerous cardiac disease, often may lead to sudden cardiac death. It is difficult to diagnose CAD by manual inspection of electrocardiogram (ECG) signals. To automate this detection task, in this study, we extracted the Heart Rate (HR) from the ECG signals and used them as base signal for further analysis. We then analyzed the HR signals of both normal and CAD subjects using (i) time domain, (ii) frequency domain and (iii) nonlinear techniques. The following are the nonlinear methods that were used in this work: Poincare plots, Recurrence Quantification Analysis (RQA) parameters, Shannon entropy, Approximate Entropy (ApEn), Sample Entropy (SampEn), Higher Order Spectra (HOS) methods, Detrended Fluctuation Analysis (DFA), Empirical Mode Decomposition (EMD), Cumulants, and Correlation Dimension. As a result of the analysis, we present unique recurrence, Poincare and HOS plots for normal and CAD subjects. We have also observed significant variations in the range of these features with respect to normal and CAD classes, and have presented the same in this paper. We found that the RQA parameters were higher for CAD subjects indicating more rhythm. Since the activity of CAD subjects is less, similar signal patterns repeat more frequently compared to the normal subjects. The entropy based parameters, ApEn and SampEn, are lower for CAD subjects indicating lower entropy (less activity due to impairment) for CAD. Almost all HOS parameters showed higher values for the CAD group, indicating the presence of higher frequency content in the CAD signals. Thus, our study provides a deep insight into how such nonlinear features could be exploited to effectively and reliably detect the presence of CAD
Stellar and Dust Properties of a Complete Sample of Massive Dusty Galaxies at from MAGPHYS Modeling of UltraVISTA DR3 and Herschel Photometry
We investigate the stellar and dust properties of massive (log) and dusty () galaxies at by modeling
their spectral energy distributions (SEDs) obtained from the combination of
UltraVISTA DR3 photometry and \textit{Herschel} PACS-SPIRE data using MAGPHYS.
Although the rest-frame U-V vs V-J (UVJ) diagram traces well the star-formation
rates (SFR) and dust obscuration (A) out to , 15-20\% of
the sample surprisingly resides in the quiescent region of the UVJ diagram,
while \% at fall in the unobscured star-forming region. The
median SED of massive dusty galaxies exhibits weaker MIR and UV emission, and
redder UV slopes with increasing cosmic time. The IR emission for our sample
has a significant contribution () from dust heated by evolved stellar
populations rather than star formation, demonstrating the need for panchromatic
SED modeling. The local relation between dust mass and SFR is followed only by
a sub-sample with cooler dust temperatures, while warmer objects have reduced
dust masses at a given SFR. Most star-forming galaxies in our sample do not
follow local IRX- relations, though IRX does strongly correlate with
A. Our sample follows local relations, albeit with large scatter, between
ISM diagnostics and sSFR. We show that FIR-detected sources represent the
extreme of a continuous population of dusty galaxies rather than a
fundamentally different population. Finally, using commonly adopted relations
to derive SFRs from the combination of the rest-frame UV and the observed
24m is found to overestimate the SFR by a factor of 3-5 for the galaxies
in our sample.Comment: Accpeted for publication in Ap
Precision sketching with de-aging networks in forensics
Addressing the intricacies of facial aging in forensic facial recognition, traditional sketch portraits often fall short in precision. This study introduces a pioneering system that seamlessly integrates a de-aging module and a sketch generator module to overcome the limitations inherent in existing methodologies. The de-aging module utilizes a deepfake-based neural network to rejuvenate facial features, while the sketch generator module leverages a pix2pix-based Generative Adversarial Network (GAN) for the generation of lifelike sketches. Comprehensive evaluations on the CUHK and AR datasets underscore the system’s superior efficiency. Significantly, comprehensive testing reveals marked enhancements in realism during the training process, demonstrated by notable reductions in Frechet Inception Distance (FID) scores (41.7 for CUHK, 60.2 for AR), augmented Structural Similarity Index (SSIM) values (0.789 for CUHK, 0.692 for AR), and improved Peak Signal-to-Noise Ratio (PSNR) metrics (20.26 for CUHK, 19.42 for AR). These findings underscore substantial advancements in the accuracy and reliability of facial recognition applications. Importantly, the system, proficient in handling diverse facial characteristics across gender, race, and culture, produces both composite and hand-drawn sketches, surpassing the capabilities of current state-of-the-art methods. This research emphasizes the transformative potential arising from the integration of de-aging networks with sketch generation, particularly for age-invariant forensic applications, and highlights the ongoing necessity for innovative developments in de-aging technology with broader societal and technological implications
Beyond UVJ: Color Selection of Galaxies in the JWST Era
We present a new rest-frame color-color selection method using "synthetic
and '', colors to identify star-forming and
quiescent galaxies. Our method is similar to the widely-used versus
() diagram. However, suffers known systematics. Spectroscopic
campaigns have shown that -selected quiescent samples at
include contamination from galaxies with dust-obscured star
formation and strong emission lines. Moreover, at , colors are
extrapolated because the rest-frame J-band shifts beyond the coverage of the
deepest bandpasses at (typically /IRAC 4.5 or
future /NIRCam observations). We demonstrate that offers
improvements to at , and can be applied to galaxies in the
era. We apply selection to galaxies at from the (observed)
3D-HST and UltraVISTA catalogs, and to the (simulated) JAGUAR catalogs. We show
that extrapolation can affect color by up to 1 magnitude, but changes
color by 0.2 mag, even at . While
-selected quiescent samples are comparable to in completeness
(both achieve 85-90% at ), reduces contamination in
quiescent samples by nearly a factor of two, from 35% to 17% at
, and from 60% to 33% at . This leads to
improvements in the true-to-false-positive ratio (TP/FP), where we find TP/FP
2.2 for at , compared to TP/FP 1 for
-selected samples. This indicates that contaminants will outnumber true
quiescent galaxies in at these redshifts, while will provide
higher-fidelity samples.Comment: Submitted to Ap
Hydrogen bonding in water under extreme confinement unveiled by nanoscale vibrational spectroscopy and simulations
Fluids under extreme confinement exhibit distinctly new properties compared
to their bulk analogs. Understanding the structure and intermolecular bonding
of confined water lays the foundation for creating and improving applications
at the water-energy nexus. However, probing confined water experimentally at
the length scale of intermolecular and surface forces has remained a challenge.
Here, we report a combined experiment/theory framework to reveal changes in
H-bonding environment and the underlying molecular structure of confined water
inside individual carbon nanotubes. H-bonding is directly probed through the
O-H stretch frequency with vibrational electron energy-loss spectroscopy and
compared to spectra from molecular-dynamics simulations based on
density-functional-theory. Experimental spectra show that water in larger
carbon nanotubes exhibit the bonded O-H vibrations of bulk water, but at
smaller diameters, the frequency blueshifts to near the 'free' O-H stretch
found in water vapor and hydrophobic surfaces. The matching simulations reveal
that, in addition to steric confinement, the tube's vibrations play a key role
in breaking up the H-bond network, resulting in an orientationally-dispersed,
non-H-bonded phase. Furthermore, the temperature-dependence of the vibrations
is investigated, providing insights into phase transitions and the
confined-water density. This research demonstrates the potential of the
experiment/theory framework to explore unprecedented aspects of structure and
bonding in confined fluids
New insights into the wheat chromosome 4D structure and virtual gene order, revealed by survey pyrosequencing
AbstractSurvey sequencing of the bread wheat (Triticum aestivum L.) genome (AABBDD) has been approached through different strategies delivering important information. However, the current wheat sequence knowledge is not complete. The aim of our study is to provide different and complementary set of data for chromosome 4D. A survey sequence was obtained by pyrosequencing of flow-sorted 4DS (7.2×) and 4DL (4.1×) arms. Single ends (SE) and long mate pairs (LMP) reads were assembled into contigs (223Mb) and scaffolds (65Mb) that were aligned to Aegilops tauschii draft genome (DD), anchoring 34Mb to chromosome 4. Scaffolds annotation rendered 822 gene models. A virtual gene order comprising 1973 wheat orthologous gene loci and 381 wheat gene models was built. This order was largely consistent with the scaffold order determined based on a published high density map from the Ae. tauschii chromosome 4, using bin-mapped 4D ESTs as a common reference. The virtual order showed a higher collinearity with homeologous 4B compared to 4A. Additionally, a virtual map was constructed and ∼5700 genes (∼2200 on 4DS and ∼3500 on 4DL) predicted. The sequence and virtual order obtained here using the 454 platform were compared with the Illumina one used by the IWGSC, giving complementary information
CDM not dead yet: massive high-z Balmer break galaxies are less common than previously reported
Early JWST observations that targeted so-called double-break sources
(attributed to Lyman and Balmer breaks at ), reported a previously unknown
population of very massive, evolved high-redshift galaxies. This surprising
discovery led to a flurry of attempts to explain these objects' unexpected
existence including invoking alternatives to the standard CDM
cosmological paradigm. To test these early results, we adopted the same
double-break candidate galaxy selection criteria to search for such objects in
the JWST images of the CAnadian NIRISS Unbiased Cluster Survey (CANUCS), and
found a sample of 19 sources over five independent CANUCS fields that cover a
total effective area of arcmin at . However, (1) our SED
fits do not yield exceptionally high stellar masses for our candidates, while
(2) spectroscopy of five of the candidates shows that while all five are at
high redshifts, their red colours are due to high-EW emission lines in
star-forming galaxies rather than Balmer breaks in massive, evolved systems.
Additionally, (3) field-to-field variance leads to differences of
dex in the maximum stellar masses measured in the different fields, suggesting
that the early single-field JWST observations may have suffered from cosmic
variance and/or sample bias. Finally, (4) we show that the presence of even a
single massive outlier can dominate conclusions from small samples such as
those in early JWST observations. In conclusion, we find that the double-break
sources in CANUCS are not sufficiently massive or numerous to warrant
questioning the standard CDM paradigm.Comment: V2: correction of display problem of Fig.1 in Chrome browser.
Submitted to MNRAS, 10 pages (+4 in Appendix), 5 figures (+4), 1 table (+1
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