In spintronics, the two main approaches to actively control the electrons' spin involve static magnetic or electric fields. An alternative avenue relies on the use of optical fields to generate spin ...currents, which can bolster spin-device performance, allowing for faster and more efficient logic. To date, research has mainly focused on the optical injection of spin currents through the photogalvanic effect, and little is known about the direct optical control of the intrinsic spin-splitting. To explore the optical manipulation of a material's spin properties, we consider the Rashba effect. Using time- and angle-resolved photoemission spectroscopy (TR-ARPES), we demonstrate that an optical excitation can tune the Rashba-induced spin splitting of a two-dimensional electron gas at the surface of Bi
Se
. We establish that light-induced photovoltage and charge carrier redistribution - which in concert modulate the Rashba spin-orbit coupling strength on a sub-picosecond timescale - can offer an unprecedented platform for achieving optically-driven spin logic devices.
Protein misfolding underlies the pathology of a large number of human disorders, many of which are age-related. An exception to this is preeclampsia, a leading cause of pregnancy-associated morbidity ...and mortality in which misfolded proteins accumulate in body fluids and the placenta. We demonstrate that pregnancy zone protein (PZP), which is dramatically elevated in maternal plasma during pregnancy, efficiently inhibits in vitro the aggregation of misfolded proteins, including the amyloid beta peptide (Aβ) that is implicated in preeclampsia as well as with Alzheimer’s disease. The mechanism by which this inhibition occurs involves the formation of stable complexes between PZP and monomeric Aβ or small soluble Aβ oligomers formed early in the aggregation pathway. The chaperone activity of PZP is more efficient than that of the closely related protein alpha-2-macroglobulin (α₂M), although the chaperone activity of α₂M is enhanced by inducing its dissociation into PZP-like dimers. By immunohistochemistry analysis, PZP is found primarily in extravillous trophoblasts in the placenta. In severe preeclampsia, PZP-positive extravillous trophoblasts are adjacent to extracellular plaques containing Aβ, but PZP is not abundant within extracellular plaques. Our data support the conclusion that the up-regulation of PZP during pregnancy represents a major maternal adaptation that helps to maintain extracellular proteostasis during gestation in humans. We propose that overwhelming or disrupting the chaperone function of PZP could underlie the accumulation of misfolded proteins in vivo. Attempts to characterize extracellular proteostasis in pregnancy will potentially have broad-reaching significance for understanding disease-related protein misfolding.
Aging is characterized by compromised organ and tissue function. A decrease in stem cell number and/or activity could lead to the aging-related decline in tissue homeostasis. We have analyzed how the ...process of aging affects germ line stem cell (GSC) behavior in the Drosophila testis and report that significant changes within the stem cell microenvironment, or niche, occur that contribute to a decline in stem cell number over time. Specifically, somatic niche cells in testes from older males display reduced expression of the cell adhesion molecule DE-cadherin and a key self-renewal signal unpaired (upd). Loss of upd correlates with an overall decrease in stem cells residing within the niche. Conversely, forced expression of upd within niche cells maintains GSCs in older males. Therefore, our data indicate that age-related changes within stem cell niches may be a significant contributing factor to reduced tissue homeostasis and regeneration in older individuals.
Understanding how the emergence of the anthropogenic warming signal from the noise of internal variability translates to changes in extreme event occurrence is of crucial societal importance. By ...utilising simulations of cumulative carbon dioxide (CO2) emissions and temperature changes from eleven earth system models, we demonstrate that the inherently lower internal variability found at tropical latitudes results in large increases in the frequency of extreme daily temperatures (exceedances of the 99.9th percentile derived from pre-industrial climate simulations) occurring much earlier than for mid-to-high latitude regions. Most of the world's poorest people live at low latitudes, when considering 2010 GDP-PPP per capita; conversely the wealthiest population quintile disproportionately inhabit more variable mid-latitude climates. Consequently, the fraction of the global population in the lowest socio-economic quintile is exposed to substantially more frequent daily temperature extremes after much lower increases in both mean global warming and cumulative CO2 emissions.
As a social determinant of health, poverty has been medicalised in such a way that interventions to address it have fallen on the shoulders of healthcare systems and healthcare professionals to ...reduce health inequities as opposed to creating and investing in a strong social safety net. In our current fee-for-service model of healthcare delivery, the cost of delivering secondary or even tertiary interventions to mitigate the poor health effects of poverty in the clinic is much more costly than preventive measures taken by communities. In addition, this leads to increasing burnout among the healthcare workforce, which may ultimately result in a healthcare worker shortage. To mitigate, physicians and other healthcare workers with power and privilege in communities systematically disenfranchised may take action by being outspoken on the development and implementation of policies known to result in health inequities. Developing strong advocacy skills is essential to being an effective patient advocate in and outside of the exam room.
Adult mesenchymal stem cells (MSCs) are a population of multipotent
cells found primarily in the bone marrow. They have long been known to
be capable of osteogenic, adipogenic and chondrogenic ...differentiation
and are currently the subject of a number of trials to assess their
potential use in the clinic. Recently, the plasticity of these cells
has come under close scrutiny as it has been suggested that they may
have a differentiation potential beyond the mesenchymal lineage.
Myogenic and in particular cardiomyogenic potential has been shown in
vitro . MSCs have also been shown to have the ability to form neural
cells both in vitro and in vivo , although the molecular mechanisms
underlying these apparent transdifferentiation events are yet to be
elucidated. We describe here the cellular characteristics and
differentiation potential of MSCs, which represent a promising stem
cell population for future applications in regenerative medicine.
Tumor cells secrete factors that modulate macrophage activation and polarization into M2 type tumor-associated macrophages, which promote tumor growth, progression, and metastasis. The mechanisms ...that mediate this polarization are not clear. Macrophages are phagocytic cells that participate in the clearance of apoptotic cells, a process known as efferocytosis. Milk fat globule- EGF factor 8 (MFG-E8) is a bridge protein that facilitates efferocytosis and is associated with suppression of proinflammatory responses. This study investigated the hypothesis that MFG-E8-mediated efferocytosis promotes M2 polarization. Tissue and serum exosomes from prostate cancer patients presented higher levels of MFG-E8 compared with controls, a novel finding in human prostate cancer. Coculture of macrophages with apoptotic cancer cells increased efferocytosis, elevated MFG-E8 protein expression levels, and induced macrophage polarization into an alternatively activated M2 phenotype. Administration of antibody against MFG-E8 significantly attenuated the increase in M2 polarization. Inhibition of STAT3 phosphorylation using the inhibitor Stattic decreased efferocytosis and M2 macrophage polarization in vitro, with a correlating increase in SOCS3 protein expression. Moreover, MFG-E8 knockdown tumor cells cultured with wild-type or MFG-E8-deficient macrophages resulted in increased SOCS3 expression with decreased STAT3 activation. This suggests that SOCS3 and phospho-STAT3 act in an inversely dependent manner when stimulated by MFG-E8 and efferocytosis. These results uncover a unique role of efferocytosis via MFG-E8 as a mechanism for macrophage polarization into tumor-promoting M2 cells.
The rhizosphere is the zone of soil immediately surrounding plant roots that is modified by root activity. In this critical zone, plants perceive and respond to their environment. As a consequence of ...normal growth and development, a large range of organic and inorganic substances are exchanged between the root and soil, which inevitably leads to changes in the biochemical and physical properties of the rhizosphere. Plants also modify their rhizosphere in response to certain environmental signals and stresses. Organic anions are commonly detected in this region, and their exudation from plant roots has now been associated with nutrient deficiencies and inorganic ion stresses. This review summarizes recent developments in the understanding of the function, mechanism, and regulation of organic anion exudation from roots. The benefits that plants derive from the presence of organic anions in the rhizosphere are described and the potential for biotechnology to increase organic anion exudation is highlighted.
Recent Changes in Surface Humidity Willett, Katharine M.; Jones, Philip D.; Gillett, Nathan P. ...
Journal of climate,
10/2008, Letnik:
21, Številka:
20
Journal Article
Recenzirano
Odprti dostop
Water vapor constitutes the most significant greenhouse gas, is a key driver of many atmospheric processes, and hence, is fundamental to understanding the climate system. It is a major factor in ...human “heat stress,” whereby increasing humidity reduces the ability to stay cool. Until now no truly global homogenized surface humidity dataset has existed with which to assess recent changes. The Met Office Hadley Centre and Climatic Research Unit Global Surface Humidity dataset (HadCRUH), described herein, provides a homogenized quality controlled near-global 5° by 5° gridded monthly mean anomaly dataset in surface specific and relative humidity from 1973 to 2003. It consists of land and marine data, and is geographically quasicomplete over the region 60°N–40°S.
Between 1973 and 2003 surface specific humidity has increased significantly over the globe, tropics, and Northern Hemisphere. Global trends are 0.11 and 0.07 g kg-1(10 yr)-1for land and marine components, respectively. Trends are consistently larger in the tropics and in the Northern Hemisphere during summer, as expected: warmer regions exhibit larger increases in specific humidity for a given temperature change under conditions of constant relative humidity, based on the Clausius–Clapeyron equation. Relative humidity trends are not significant when averaged over the landmass of the globe, tropics, and Northern Hemisphere, although some seasonal changes are significant.
A strong positive bias is apparent in marine humidity data prior to 1982, likely owing to a known change in reporting practice for dewpoint temperature at this time. Consequently, trends in both specific and relative humidity are likely underestimated over the oceans.
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