1,236 research outputs found
Structure of d(TGCGCA)(2) and a comparison with other DNA Hexamers
The X-ray crystal structure of d(TGCGCA)(2) has been determined at 120 K to a resolution of 1.3 Angstrom. Hexamer duplexes, in the Z-DNA conformation, pack in an arrangement similar to the 'pure spermine form' [Egli et al. (1991). Biochemistry, 30, 11388-11402] but with significantly different cell dimensions. The phosphate backbone exists in two equally populated discrete conformations at one nucleotide step, around phosphate 11. The structure contains two ordered cobalt hexammine molecules which have roles in stabilization of both the Z-DNA conformation of the duplex and in crystal packing. A comparison of d(TGCGCA)(2) with other Z-DNA hexamer structures available in the Nucleic Acid Database illustrates the elusive nature of crystal packing. A review of the interactions with the metal cations Na+, Mg2+ and Co3+ reveals a relatively small proportion of phosphate binding and that close contacts between metal ions are common. A prediction of the water structure is compared with the observed pattern in the reported structure
Parenting stress, maternal depression and child mental health in a Melbourne cohort before and during the COVIDâ19 pandemic
Aim
This paper aims to examine the maternal and child mental health and parenting outcomes in the context of COVID-19 pandemic conditions using a sample from Melbourne, Australia â a city exposed to one of the longest lockdowns world-wide in response to the pandemic.
Methods
This study utilises observational data from a prospective, pregnancy cohort, Mercy Pregnancy Emotional Wellbeing Study and includes 468 women and their children followed up in Melbourne to 3â4âyears postpartum pre-COVID pandemic and compared to those followed up during the COVID-19 pandemic.
Results
When compared to mothers followed up at 3â4âyears postpartum pre-pandemic, those followed up during the COVID-19 pandemic showed higher depressive symptoms with a steep incline in their symptom trajectory (EMMdifference = 1.72, Bonferroni-corrected Pâ<â0.01, d = 0.35) and had a three times higher risk of scoring 13 or above on the EPDS (aRR = 3.22, Bonferroni-corrected Pâ<â0.01). Although this increase was not associated with the variation in the duration of exposure to pandemic conditions, the steep increase in depressive symptoms was more pronounced in those with pre-existing depressive disorders. There was no difference in parenting stress or adjusted childhood mental health symptoms or disorder.
Conclusions
Our findings highlight the vulnerability of those with pre-existing clinical mental health disorders and the need for adequate clinical care for this vulnerable group. Equally, our study indicates the possibility that parenting and early childhood mental health outcomes, at least in the short term, may be resilient
Are Antiprotons Forever?
Up to one million antiprotons from a single LEAR spill have been captured in
a large Penning trap. Surprisingly, when the antiprotons are cooled to energies
significantly below 1 eV, the annihilation rate falls below background. Thus,
very long storage times for antiprotons have been demonstrated in the trap,
even at the compromised vacuum conditions imposed by the experimental set up.
The significance for future ultra-low energy experiments, including portable
antiproton traps, is discussed.Comment: 12 pages, latex; 4 figures, uufiled. Slightly expanded discussion of
expected energy dependence of annihilation cross section and rate, and of
estimates of trap pressure, plus minor text improvement
Wear and damage transitions of wheel and rail materials under various contact conditions
This study discusses a TÎł/A method of plotting wear data from a twin-disc machine for identifying the wear and damage transitions of wheel and rail materials. As found in previous work, three wear regimes (mild wear, severe wear and catastrophic wear) of U71Mn rail material were identified in dry rolling-sliding contact tests. It was determined that the damage mechanism transforms in the different wear regimes. Here earlier studies were extended to establish wear behavior for the presence of a number of third body materials (oil, water, friction enhancers) and a rail cladding process designed to make wheels and rails more durable. This has provided much needed data for Multi-Body Dynamics (MBD) simulations, and will allow better predictions of profile evolution of wheel and rail over a wider range of conditions
Constraining Warm Inflation with the Cosmic Microwave Background
We discuss the spectrum of scalar density perturbations from warm inflation
when the friction coefficient in the inflaton equation is dependent on
the inflaton field. The spectral index of scalar fluctuations depends on a new
slow-roll parameter constructed from . A numerical integration of the
perturbation equations is performed for a model of warm inflation and gives a
good fit to the WMAP data for reasonable values of the model's parameters.Comment: 6 pages, 2 figures, RevTeX
Face Detection on Embedded Systems
Over recent years automated face detection and recognition (FDR) have gained significant attention from the commercial and research sectors. This paper presents an embedded face detection solution aimed at addressing the real-time image processing requirements within a wide range of applications. As face detection is a computationally intensive task, an embedded solution would give rise to opportunities for discrete economical devices that could be applied and integrated into a vast majority of applications. This work focuses on the use of FPGAs as the embedded prototyping technology where the thread of execution is carried out on an embedded soft-core processor. Custom instructions have been utilized as a means of applying software/hardware partitioning through which the computational bottlenecks are moved to hardware. A speedup by a factor of 110 was achieved from employing custom instructions and software optimizations
Asymmetric Dark Matter and Dark Radiation
Asymmetric Dark Matter (ADM) models invoke a particle-antiparticle asymmetry,
similar to the one observed in the Baryon sector, to account for the Dark
Matter (DM) abundance. Both asymmetries are usually generated by the same
mechanism and generally related, thus predicting DM masses around 5 GeV in
order to obtain the correct density. The main challenge for successful models
is to ensure efficient annihilation of the thermally produced symmetric
component of such a light DM candidate without violating constraints from
collider or direct searches. A common way to overcome this involves a light
mediator, into which DM can efficiently annihilate and which subsequently
decays into Standard Model particles. Here we explore the scenario where the
light mediator decays instead into lighter degrees of freedom in the dark
sector that act as radiation in the early Universe. While this assumption makes
indirect DM searches challenging, it leads to signals of extra radiation at BBN
and CMB. Under certain conditions, precise measurements of the number of
relativistic species, such as those expected from the Planck satellite, can
provide information on the structure of the dark sector. We also discuss the
constraints of the interactions between DM and Dark Radiation from their
imprint in the matter power spectrum.Comment: 22 pages, 5 figures, to be published in JCAP, minor changes to match
version to be publishe
- âŠ