2,398 research outputs found
The origin of defects induced in ultra-pure germanium by Electron Beam Deposition
The creation of point defects in the crystal lattices of various
semiconductors by subthreshold events has been reported on by a number of
groups. These observations have been made in great detail using sensitive
electrical techniques but there is still much that needs to be clarified.
Experiments using Ge and Si were performed that demonstrate that energetic
particles, the products of collisions in the electron beam, were responsible
for the majority of electron-beam deposition (EBD) induced defects in a
two-step energy transfer process. Lowering the number of collisions of these
energetic particles with the semiconductor during metal deposition was
accomplished using a combination of static shields and superior vacuum
resulting in devices with defect concentrations lower than cm, the measurement limit of our deep level transient
spectroscopy (DLTS) system. High energy electrons and photons that samples are
typically exposed to were not influenced by the shields as most of these
particles originate at the metal target thus eliminating these particles as
possible damage causing agents. It remains unclear how packets of energy that
can sometimes be as small of 2eV travel up to a m into the material while
still retaining enough energy, that is, in the order of 1eV, to cause changes
in the crystal. The manipulation of this defect causing phenomenon may hold the
key to developing defect free material for future applications.Comment: 18 pages, 9 figure
Pulsar Results with the Fermi Large Area Telescope
The launch of the Fermi Gamma-ray Space Telescope has heralded a new era in
the study of gamma-ray pulsars. The population of confirmed gamma-ray pulsars
has gone from 6-7 to more than 60, and the superb sensitivity of the Large Area
Telescope (LAT) on Fermi has allowed the detailed study of their spectra and
light curves. Twenty-four of these pulsars were discovered in blind searches of
the gamma-ray data, and twenty-one of these are, at present, radio quiet,
despite deep radio follow-up observations. In addition, millisecond pulsars
have been confirmed as a class of gamma-ray emitters, both individually and
collectively in globular clusters. Recently, radio searches in the direction of
LAT sources with no likely counterparts have been highly productive, leading to
the discovery of a large number of new millisecond pulsars. Taken together,
these discoveries promise a great improvement in the understanding of the
gamma-ray emission properties and Galactic population of pulsars. We summarize
some of the results stemming from these newly-detected pulsars and their timing
and multi-wavelength follow-up observations.Comment: 21 pages, 9 figures, to appear in Proceedings of ICREA Workshop on
The High-Energy Emission from Pulsars and their Systems, Sant Cugat, Spain,
2010 April 12-16 (Springer
Response to novel objects and foraging tasks by common marmoset (Callithrix Jacchus) female Pairs
Many studies have shown that environmental enrichment can significantly improve the psychological well-being of captive primates, increasing the occurrence of explorative behavior and thus reducing boredom. The response of primates to enrichment devices may be affected by many factors such as species, sex, age, personality and social context. Environmental enrichment is particularly important for social primates living in unnatural social groupings (i.e. same-sex pairs or singly housed animals), who have very few, or no, benefits from the presence of social companions in addition to all the problems related to captivity (e.g. increased inactivity). This study analyses the effects of enrichment devices (i.e. novel objects and foraging tasks) on the behavior of common marmoset (Callithrix jacchus) female pairs, a species that usually lives in family groups. It aims to determine which aspects of an enrichment device are more likely to elicit explorative behaviors, and how aggressive and stress-related behaviors are affected by its presence. Overall, the marmosets explored foraging tasks significantly longer than novel objects. The type of object, which varied in size, shape and aural responsiveness (i.e. they made a noise when the monkey touched them), did not affect the response of the monkeys, but they explored objects that were placed higher in the enclosure more than those placed lower down.Younger monkeys were more attracted to the enrichment devices than the older ones. Finally, stress-related behavior (i.e. scratching) significantly decreased when the monkeys were presented with the objects; aggressive behavior as unaffected. This study supports the importance of environmental enrichment for captive primates and shows that in marmosets its effectiveness strongly depends upon the height of the device in the enclosure and the presence of hidden food. The findings can be explained ifone considers the foraging behavior of wild common marmosets. Broader applications for the research findings are suggested in relation to enrichment
Properties of monocytes generated from haematopoietic CD34+ stem cells from bone marrow of colon cancer patients
Monocytes exhibit direct and indirect antitumour activities and may be potentially useful for various forms of adoptive cellular immunotherapy of cancer. However, blood is a limited source of them. This study explored whether monocytes can be obtained from bone marrow haematopoietic CD34(+) stem cells of colon cancer patients, using previously described protocol of expansion and differentiation to monocytes of cord blood-derived CD34(+) haematopoietic progenitors. Data show that in two-step cultures, the yield of cells was increased approximately 200-fold, and among these cells, up to 60 % of CD14(+) monocytes were found. They consisted of two subpopulations: CD14(++)CD16(+) and CD14(+)CD16(−), at approximately 1:1 ratio, that differed in HLA-DR expression, being higher on the former. No differences in expression of costimulatory molecules were observed, as CD80 was not detected, while CD86 expression was comparable. These CD14(+) monocytes showed the ability to present recall antigens (PPD, Candida albicans) and neoantigens expressed on tumour cells and tumour-derived microvesicles (TMV) to autologous CD3(+) T cells isolated from the peripheral blood. Monocytes also efficiently presented the immunodominant HER-2/neu(369–377) peptide (KIFGSLAFL), resulting in the generation of specific cytotoxic CD8(+) T lymphocytes (CTL). The CD14(++)CD16(+) subset exhibited enhanced cytotoxicity, though nonsignificant, towards tumour cells in vitro. These observations indicate that generation of monocytes from CD34(+) stem cells of cancer patients is feasible. To our knowledge, it is the first demonstration of such approach that may open a way to obtain autologous monocytes for alternative forms of adaptive and adoptive cellular immunotherapy of cancer
Building Babies - Chapter 16
In contrast to birds, male mammals rarely help to raise the offspring. Of all mammals, only among rodents, carnivores, and primates, males are sometimes intensively engaged in providing infant care (Kleiman and Malcolm 1981). Male caretaking of infants has long been recognized in nonhuman primates (Itani 1959). Given that infant care behavior can have a positive effect on the infant’s development, growth, well-being, or survival, why are male mammals not more frequently involved in “building babies”? We begin the chapter defining a few relevant terms and introducing the theory and hypotheses that have historically addressed the evolution of paternal care. We then review empirical findings on male care among primate taxa, before focusing, in the final section, on our own work on paternal care in South American owl monkeys (Aotus spp.). We conclude the chapter with some suggestions for future studies.Deutsche Forschungsgemeinschaft (HU 1746/2-1)
Wenner-Gren Foundation, the L.S.B. Leakey Foundation, the National Geographic Society, the National Science Foundation (BCS-0621020), the University of Pennsylvania Research Foundation, the Zoological Society of San Dieg
Parasite infection is associated with Kaposi's sarcoma associated herpesvirus (KSHV) in Ugandan women
Background:
Immune modulation by parasites may influence susceptibility to bacteria and viruses. We examined the association between current parasite infections, HIV and syphilis (measured in blood or stool samples using standard methods) and antibodies against Kaposi's sarcoma herpesvirus (KSHV), measured by ELISA, in 1915 stored plasma samples from pregnant women in Entebbe, Uganda.<p></p>
Results:
Seroprevalence of KSHV was higher in women with malaria parasitaemia (73% vs 60% p = 0.01), hookworm (67% vs 56% p = 0.001) and Mansonella perstans (69% vs 59% p = 0.05); seroprevalence increased with increasing intensity of hookworm infection (p < 0.001[trend]). No associations were found for HIV, five other parasites or active syphilis. These effects were not explained by socioeconomic status or education.<p></p>
Conclusions:
Specific parasite infections are associated with presence of antibodies against KSHV, perhaps mediated via their effect on immune function.<p></p>
Interactions among mitochondrial proteins altered in glioblastoma
Mitochondrial dysfunction is putatively central to glioblastoma (GBM) pathophysiology but there has been no systematic analysis in GBM of the proteins which are integral to mitochondrial function. Alterations in proteins in mitochondrial enriched fractions from patients with GBM were defined with label-free liquid chromatography mass spectrometry. 256 mitochondrially-associated proteins were identified in mitochondrial enriched fractions and 117 of these mitochondrial proteins were markedly (fold-change ≥2) and significantly altered in GBM (p ≤ 0.05). Proteins associated with oxidative damage (including catalase, superoxide dismutase 2, peroxiredoxin 1 and peroxiredoxin 4) were increased in GBM. Protein–protein interaction analysis highlighted a reduction in multiple proteins coupled to energy metabolism (in particular respiratory chain proteins, including 23 complex-I proteins). Qualitative ultrastructural analysis in GBM with electron microscopy showed a notably higher prevalence of mitochondria with cristolysis in GBM. This study highlights the complex mitochondrial proteomic adjustments which occur in GBM pathophysiology
Quantum value indefiniteness
The indeterministic outcome of a measurement of an individual quantum is
certified by the impossibility of the simultaneous, definite, deterministic
pre-existence of all conceivable observables from physical conditions of that
quantum alone. We discuss possible interpretations and consequences for quantum
oracles.Comment: 19 pages, 2 tables, 2 figures; contribution to PC0
- …