7,216 research outputs found
Tau Clearance Mechanisms and Their Possible Role in the Pathogenesis of Alzheimer Disease
One of the defining pathological features of Alzheimer disease (AD) is the intraneuronal accumulation of tau. The tau that forms these accumulations is altered both posttranslationally and conformationally, and there is now significant evidence that soluble forms of these modified tau species are the toxic entities rather than the insoluble neurofibrillary tangles. However there is still noteworthy debate concerning which specific pathological forms of tau are the contributors to neuronal dysfunction and death in AD. Given that increases in aberrant forms of tau play a role in the neurodegeneration process in AD, there is growing interest in understanding the degradative pathways that remove tau from the cell, and the selectivity of these different pathways for various forms of tau. Indeed, one can speculate that deficits in a pathway that selectively removes certain pathological forms of tau could play a pivotal role in AD. In this review we will discuss the different proteolytic and degradative machineries that may be involved in removing tau from the cell. How deficits in these different degradative pathways may contribute to abnormal accumulation of tau in AD will also be considered. In addition, the issue of the selective targeting of specific tau species to a given degradative pathway for clearance from the cell will be addressed
Multi-Wavelength Properties of the Type IIb SN 2008ax
We present the UV, optical, X-ray, and radio properties of the Type IIb SN
2008ax discovered in NGC 4490. The observations in the UV are one of the
earliest of a Type IIb supernova (SN). On approximately day four after the
explosion, a dramatic upturn in the u and uvw1 (lambda_c = 2600 Angstroms)
light curves occurred after an initial rapid decline which is attributed to
adiabatic cooling after the initial shock breakout. This rapid decline and
upturn is reminiscent of the Type IIb SN 1993J on day six after the explosion.
Optical/near-IR spectra taken around the peak reveal prominent H-alpha, HeI,
and CaII absorption lines. A fading X-ray source is also located at the
position of SN 2008ax, implying an interaction of the SN shock with the
surrounding circumstellar material and a mass-loss rate of the progenitor of
M_dot = (9+/-3)x10^-6 solar masses per year. The unusual time evolution (14
days) of the 6 cm peak radio luminosity provides further evidence that the
mass-loss rate is low. Combining the UV, optical, X-ray, and radio data with
models of helium exploding stars implies the progenitor of SN 2008ax was an
unmixed star in an interacting-binary. Modeling of the SN light curve suggests
a kinetic energy (E_k) of 0.5x10^51 ergs, an ejecta mass (M_ej) of 2.9 solar
masses, and a nickel mass (M_Ni) of 0.06 solar masses.Comment: Accepted to ApJ Letters, 14 pages, 3 figures, 2 table
Night MattersâWhy the Interdisciplinary Field of âNight Studiesâ Is Needed
The night has historically been neglected in both disciplinary and interdisciplinary research. To some extent, this is not surprising, given the diurnal bias of human researchers and the difficulty of performing work at night. The night is, however, a critical element of biological, chemical, physical, and social systems on Earth. Moreover, research into social issues such as inequality, demographic changes, and the transition to a sustainable economy will be compromised if the night is not considered. Recent years, however, have seen a surge in research into the night. We argue that ânight studiesâ is on the cusp of coming into its own as an interdisciplinary field, and that when it does, the field will consider questions that disciplinary researchers have not yet thought to ask
Long Phase Coherence Time and Number Squeezing of two Bose-Einstein Condensates on an Atom Chip
We measured the relative phase of two Bose-Einstein condensates confined in
an radio frequency induced double well potential on an atom chip. We observed
phase coherence between the separated condensates for times up to 200 ms after
splitting, a factor of 10 beyond the phase diffusion limit expected for a
coherent state in our experimental conditions (20 ms). The enhanced coherence
time is attributed to number squeezing of the initial state by a factor of 10.
In addition, we demonstrated a rotationally sensitive (Sagnac) geometry for a
guided atom interferometer by propagating the split condensates.Comment: 5 pages, 5 figure
Transport of Bose-Einstein Condensates with Optical Tweezers
We have transported gaseous Bose-Einstein condensates over distances up to 44
cm. This was accomplished by trapping the condensate in the focus of an
infrared laser and translating the location of the laser focus with controlled
acceleration. Condensates of order 1 million atoms were moved into an auxiliary
chamber and loaded into a magnetic trap formed by a Z-shaped wire. This
transport technique avoids the optical and mechanical access constraints of
conventional condensate experiments and creates many new scientific
opportunities.Comment: 5 pages, 3 figure
Child-Abuse-Related-Deaths, Child Mortality (0-4) & Income Inequality in America and Other Developed Nations 1989-91 v 2012-14: Speaking Truth to Power.
The major concern for social work, namely child abuseârelated deaths (CARD), involves parental neglect. Societal neglect, when measured by child mortality rates (CMR), is considered by bodies such as UNICEF to be indicative of how a nation meets the needs of its children. This populationâbased study analyses CARD and CMR for children aged from newborn to four years old between 1989â91 and 2013â15 to identify any relative child neglect in the USA and 20 other developed nations (ODN).
World Health Organization data were used for CARD, CMR and undetermined deaths (UnD), a possible source of unreported CARD, juxtaposed against World Bank income inequality data.
The USA had the highest number of CARD, the highest CMR and the worst income inequality. Five countries reduced their CARD significantly more than the USA, and 14 countries reduced their CMR more than the USA. Income inequality and CMR were correlated.
Had the USA matched the CMR of Japan, where income inequality was narrowest, there would have been on average 16 745 fewer child deaths annually.
CARD and UnD correlated, suggesting that UnD may contain unreported CARD. US CMR data indicate that services in the USA are less effective than those in ODN, possibly due to income inequality. These results will be unwelcome but child protection services must dare to speak truth to power.
âThis populationâbased study analyses CARD and CMR for children aged from newborn to four years old between 1989â91 and 2013â15 to identify any relative child neglect in the USA and 20 other developed nationsâ
Key Practitioner Messages
The richest country in the world, the USA, has the highest rates of child abuse and total child mortality in the Western world.
The USA has the highest income inequality in the West, highlighting the statistical link between child mortality and poverty.
Children's services should lead the call for the necessary changes and âspeak truth to powerâ
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