330 research outputs found
Adjusting Laser Injections for Fully Controlled Faults
Hardware characterizations of integrated circuits have been evolving rapidly with the advent of more precise, sophisticated and cost-efficient tools. In this paper we describe how the fine tuning of a laser source has been used to characterize, set and reset the state of registers in a 90 nm chip. By adjusting the incident laser beam’s location, it is possible to choose to switch any register value from ‘ 0 ’ to ‘ 1 ’ or vice-versa by targeting the PMOS side or the NMOS side. Plus, we show how to clear a register by selecting a laser beam’s power. With the help of imaging techniques, we are able to explain the underlying phenomenon and provide a direct link between the laser mapping and the physical gate structure. Thus, we correlate the localization of laser fault injections with implementations of the PMOS and NMOS areas in the silicon substrate. This illustrates to what extent laser beams can be used to monitor the bits stored within registers, with adverse consequences in terms of security evaluation of integrated circuits
An integrated perspective linking physiological and psychological consequences of mild traumatic brain injury
Despite the often seemingly innocuous nature of a mild traumatic brain injury (mTBI), its consequences can be devastating, comprising debilitating symptoms that interfere with daily functioning. Currently, it is still difficult to pinpoint the exact cause of adverse outcome after mTBI. In fact, extensive research suggests that the underlying etiology is multifactorial. In the acute and early sub-acute stages, the pathophysiology of mTBI is likely to be dominated by complex physiological alterations including cellular injury, inflammation, and the acute stress response, which could lead to neural network dysfunction. In this stage, patients often report symptoms such as fatigue, headache, unstable mood and poor concentration. When time passes, psychological processes, such as coping styles, personality and emotion regulation, become increasingly influential. Disadvantageous, maladaptive, psychological mechanisms likely result in chronic stress which facilitates the development of long-lasting symptoms, possibly via persistent neural network dysfunction. So far, a systemic understanding of the coupling between these physiological and psychological factors that in concert define outcome after mTBI is lacking. The purpose of this narrative review article is to address how psychophysiological interactions may lead to poor outcome after mTBI. In addition, a framework is presented that may serve as a template for future studies on this subject
Effects of GPR139 agonism on effort expenditure for food reward in rodent models: Evidence for pro-motivational actions
Apathy, deficiency of motivation including willingness to exert effort for reward, is a common symptom in many psychiatric and neurological disorders, including depression and schizophrenia. Despite improved understanding of the neurocircuitry and neurochemistry underlying normal and deficient motivation, there is still no approved pharmacological treatment for such a deficiency. GPR139 is an orphan G protein-coupled receptor expressed in brain regions which contribute to the neural circuitry that controls motivation including effortful responding for reward, typically sweet gustatory reward. The GPR139 agonist TAK-041 is currently under development for treatment of negative symptoms in schizophrenia which include apathy. To date, however, there are no published preclinical data regarding its potential effect on reward motivation or deficiencies thereof. Here we report in vitro evidence confirming that TAK-041 increases intracellular Ca2+ mobilization and has high selectivity for GPR139. In vivo, TAK-041 was brain penetrant and showed a favorable pharmacokinetic profile. It was without effect on extracellular dopamine concentration in the nucleus accumbens. In addition, TAK-041 did not alter the effort exerted to obtain sweet gustatory reward in rats that were moderately food deprived. By contrast, TAK-041 increased the effort exerted to obtain sweet gustatory reward in mice that were only minimally food deprived; furthermore, this effect of TAK-041 occurred both in control mice and in mice in which deficient effortful responding was induced by chronic social stress. Overall, this study provides preclinical evidence in support of GPR139 agonism as a molecular target mechanism for treatment of apathy
Interpreting the Evolution of the Size - Luminosity Relation for Disk Galaxies from Redshift 1 to the Present
A sample of very high resolution cosmological disk galaxy simulations is used
to investigate the evolution of galaxy disk sizes back to redshift 1 within the
Lambda CDM cosmology. Artificial images in the rest frame B band are generated,
allowing for a measurement of disk scale lengths using surface brightness
profiles as observations would, and avoiding any assumption that light must
follow mass as previous models have assumed. We demonstrate that these
simulated disks are an excellent match to the observed magnitude - size
relation for both local disks, and for disks at z=1 in the magnitude/mass range
of overlap. We disentangle the evolution seen in the population as a whole from
the evolution of individual disk galaxies. In agreement with observations, our
simulated disks undergo roughly 1.5 magnitudes/arcsec^2 of surface brightness
dimming since z=1. We find evidence that evolution in the magnitude - size
plane varies by mass, such that galaxies with M* > 10^9 M_sun undergo more
evolution in size than luminosity, while dwarf galaxies tend to evolve
potentially more in luminosity. The disks grow in such a way as to stay on
roughly the same stellar mass - size relation with time. Finally, due to an
evolving stellar mass - SFR relation, a galaxy at a given stellar mass (or
size) at z=1 will reside in a more massive halo and have a higher SFR, and thus
a higher luminosity, than a counterpart of the same stellar mass at z=0.Comment: Version resubmitted to ApJ, after referee's comment
High-Redshift Star-Forming Galaxies: Angular Momentum and Baryon Fraction, Turbulent Pressure Effects and the Origin of Turbulence
The structure of a sample of high-redshift (z=2), rotating galaxies with high
star formation rates and turbulent gas velocities of sigma=40-80 km/s is
investigated. Fitting the observed disk rotational velocities and radii with a
Mo, Mao, White (1998) (MMW) model requires unusually large disk spin parameters
lambda_d>0.1 and disk-to-dark halo mass fraction m_d=0.2, close to the cosmic
baryon fraction. The galaxies segregate into dispersion-dominated systems with
1<vmax/sigma<3, maximum rotational velocities vmax<200 km/s and disk half-light
radii rd=1-3 kpc and rotation-dominated systems with vmax>200 km/s,
vmax/sigma>3 and rd=4-8 kpc. For the dispersion-dominated sample, radial
pressure gradients partly compensate the gravitational force, reducing the
rotational velocities. Including this pressure effect in the MMW model,
dispersion-dominated galaxies can be fitted well with spin parameters lf
lambda_d=0.03-0.05 for high disk mass fractions of m_d=0.2 and with
lambda_d=0.01-0.03 for m_d=0.05. These values are in good agreement with
cosmological expectations. For the rotation-dominated sample however pressure
effects are small and better agreement with theoretically expected disk spin
parameters can only be achieved if the dark halo mass contribution in the
visible disk regime (2-3*rd) is smaller than predicted by the MMW model. We
argue that these galaxies can still be embedded in standard cold dark matter
halos if the halos did not contract adiabatically in response to disk
formation. It is shown that the observed high turbulent gas motions of the
galaxies are consistent with a Toomre instability parameter Q=1 which is equal
to the critical value, expected for gravitational disk instability to be the
major driver of turbulence. The dominant energy source of turbulence is then
the potential energy of the gas in the disk.Comment: 23 pages, 4 figures, ApJ, in pres
Computational archaeology of the Pristionchus pacificus genome reveals evidence of horizontal gene transfers from insects
<p>Abstract</p> <p>Background</p> <p>The recent sequencing of nematode genomes has laid the basis for comparative genomics approaches to study the impact of horizontal gene transfer (HGT) on the adaptation to new environments and the evolution of parasitism. In the beetle associated nematode <it>Pristionchus pacificus </it>HGT events were found to involve cellulase genes of microbial origin and Diapausin genes that are known from beetles, but not from other nematodes. The insect-to-nematode horizontal transfer is of special interest given that <it>P. pacificus </it>shows a tight association with insects.</p> <p>Results</p> <p>In this study we utilized the observation that horizontally transferred genes often exhibit codon usage patterns more similar to that of the donor than that of the acceptor genome. We introduced GC-normalized relative codon frequencies as a measure to detect characteristic features of <it>P. pacificus </it>orphan genes that show no homology to other nematode genes. We found that atypical codon usage is particularly prevalent in <it>P. pacificus </it>orphans. By comparing codon usage profiles of 71 species, we detected the most significant enrichment in insect-like codon usage profiles. In cross-species comparisons, we identified 509 HGT candidates that show a significantly higher similarity to insect-like profiles than genes with nematode homologs. The most abundant gene family among these genes are non-LTR retrotransposons. Speculating that retrotransposons might have served as carriers of foreign genetic material, we found a significant local clustering tendency of orphan genes in the vicinity of retrotransposons.</p> <p>Conclusions</p> <p>Our study combined codon usage bias, phylogenetic analysis, and genomic colocalization into a general picture of the computational archaeology of the <it>P. pacificus </it>genome and suggests that a substantial fraction of the gene repertoire is of insect origin. We propose that the <it>Pristionchus</it>-beetle association has facilitated HGT and discuss potential vectors of these events.</p
The Star Formation History in The Far Outer Disc of M33
The outer regions of disc galaxies are becoming increasingly recognized as
key testing sites for models of disc assembly and evolution. Important issues
are the epoch at which the bulk of the stars in these regions formed and how
discs grow radially over time. To address these issues, we use Hubble Space
Telescope Advanced Camera for Surveys imaging to study the star formation
history (SFH) of two fields at 9.1 and 11.6 kpc along M33's northern major
axis. These fields lie at ~ 4 and 5 V-band disc scale-lengths and straddle the
break in M33's surface brightness profile. The colour-magnitude diagrams (CMDs)
reach the ancient main sequence turnoff with a signal-to-noise ratio of ~ 5.
From detailed modelling of the CMDs, we find that the majority of stars in both
fields combined formed at z < 1. The mean age in the inner field, S1, is ~ 3
+/- 1 Gyr and the mean metallicity is [M/H] ~ -0.5 +/- 0.2 dex. The star
formation history of S1 unambiguously reveals how the inside-out growth
previously measured for M33's inner disc out to ~ 6 kpc extends out to the disc
edge at ~ 9 kpc. In comparison, the outer field, S2, is older (mean age ~ 7 +/-
2 Gyr), more metal-poor (mean [M/H] ~ -0.8 +/- 0.3 dex), and contains ~ 30
times less stellar mass. These results provide the most compelling evidence yet
that M33's age gradient reverses at large radii near the disc break and that
this reversal is accompanied by a break in stellar mass surface density. We
discuss several possible interpretations of this behaviour including radial
stellar mixing, warping of the gaseous disc, a change in star formation
efficiency, and a transition to another structural component. These results
offer one of the most detailed views yet of the peripheral regions of any disc
galaxy and provide a much-needed observational constraint on the last major
epoch of star formation in the outer disc.Comment: 15 pages, 9 figures, accepted to MNRAS, hi-res version available at
http://www.roe.ac.uk/~mkb/astroph/m33hires.pd
Cosmological neutrinos
The current status of neutrino cosmology is reviewed, from the question of
neutrino decoupling and the presence of sterile neutrinos to the effects of
neutrinos on the cosmic microwave background and large scale structure.
Particular emphasis is put on cosmological neutrino mass measurements.Comment: 21 pages, 4 figures, review for NJP focus issue on neutrino
Horizontal gene transfer of microbial cellulases into nematode genomes is associated with functional assimilation and gene turnover
<p>Abstract</p> <p>Background</p> <p>Natural acquisition of novel genes from other organisms by horizontal or lateral gene transfer is well established for microorganisms. There is now growing evidence that horizontal gene transfer also plays important roles in the evolution of eukaryotes. Genome-sequencing and EST projects of plant and animal associated nematodes such as <it>Brugia</it>, <it>Meloidogyne</it>, <it>Bursaphelenchus </it>and <it>Pristionchus </it>indicate horizontal gene transfer as a key adaptation towards parasitism and pathogenicity. However, little is known about the functional activity and evolutionary longevity of genes acquired by horizontal gene transfer and the mechanisms favoring such processes.</p> <p>Results</p> <p>We examine the transfer of cellulase genes to the free-living and beetle-associated nematode <it>Pristionchus pacificus</it>, for which detailed phylogenetic knowledge is available, to address predictions by evolutionary theory for successful gene transfer. We used transcriptomics in seven <it>Pristionchus </it>species and three other related diplogastrid nematodes with a well-defined phylogenetic framework to study the evolution of ancestral cellulase genes acquired by horizontal gene transfer. We performed intra-species, inter-species and inter-genic analysis by comparing the transcriptomes of these ten species and tested for cellulase activity in each species. Species with cellulase genes in their transcriptome always exhibited cellulase activity indicating functional integration into the host's genome and biology. The phylogenetic profile of cellulase genes was congruent with the species phylogeny demonstrating gene longevity. Cellulase genes show notable turnover with elevated birth and death rates. Comparison by sequencing of three selected cellulase genes in 24 natural isolates of <it>Pristionchus pacificus </it>suggests these high evolutionary dynamics to be associated with copy number variations and positive selection.</p> <p>Conclusion</p> <p>We could demonstrate functional integration of acquired cellulase genes into the nematode's biology as predicted by theory. Thus, functional assimilation, remarkable gene turnover and selection might represent key features of horizontal gene transfer events in nematodes.</p
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