69 research outputs found
Investigating solid N as a new source of ultra-cold neutrons
The dynamical structure factor of solid N in the phase
(K) is measured at the IN4 time-of-flight spectrometer at the Institut
Laue Langevin, and the potential performance of this substance as a UCN
converter is assessed. The cross-section to down-scatter neutrons to ultra-cold
neutron energies is determined as a function of incident energy, as well as the
up-scattering mean free path. The UCN production cross-section is found to be
approximately 20% of that of deuterium. However, UCN with energy 181 neV have
an up-scattering mean free path of 46 cm at K, which is times
larger than deuterium. Therefore, a large volume N source
may produce an improved UCN density if sufficient isotopic purity can be
achieved.Comment: 7 pages, 6 figure
New Understanding of Ultra-Cold Neutron Production in Solid Deuterium
Our recent neutron scattering measurements of phonons and other
quasi-particle excitations in solid deuterium (sD) and the extraction of
the density of states for phonons and rotational transitions in sD2 have led us
to a new understanding of the production of ultra-cold neutrons (UCN) in sD2.
This new picture is somehow different to earlier published results for sD2. The
cross section for UCN production in sD2 has been determined by using the
density of states G1(E) in combination with the incoherent approximation and by
a direct calibration of our measured neutron cross sections with the known
cross section of the J=1 -> 0 rotational transition in deuterium. Both methods
deliver new data on this cross section and agree quite well with direct
measurements of this energy averaged UCN production cross section.Comment: 4 pages, 6 figure
β-cell metabolic alterations under chronic nutrient overload in rat and human islets
The aim of this study was to assess multifactorial β-cell responses to metabolic perturbations in primary rat and human islets. Treatment of dispersed rat islet cells with elevated glucose and free fatty acids (FFAs, oleate:palmitate = 1:1 v/v) resulted in increases in the size and the number of lipid droplets in β-cells in a time- and concentration-dependent manner. Glucose and FFAs synergistically stimulated the nutrient sensor mammalian target of rapamycin complex 1 (mTORC1). A potent mTORC1 inhibitor, rapamycin (25 nM), significantly reduced triglyceride accumulation in rat islets. Importantly, lipid droplets accumulated only in β-cells but not in α-cells in an mTORC1-dependent manner. Nutrient activation of mTORC1 upregulated the expression of adipose differentiation related protein (ADRP), known to stabilize lipid droplets. Rat islet size and new DNA synthesis also increased under nutrient overload. Insulin secretion into the culture medium increased steadily over a 4-day period without any significant difference between glucose (10 mM) alone and the combination of glucose (10 mM) and FFAs (240 μM). Insulin content and insulin biosynthesis, however, were significantly reduced under the combination of nutrients compared with glucose alone. Elevated nutrients also stimulated lipid droplet formation in human islets in an mTORC1-dependent manner. Unlike rat islets, however, human islets did not increase in size under nutrient overload despite a normal response to nutrients in releasing insulin. The different responses of islet cell growth under nutrient overload appear to impact insulin biosynthesis and storage differently in rat and human islets
Production of Ultra-Cold-Neutrons in Solid \alpha-Oxygen
Our recent neutron scattering measurements of phonons and magnons in solid
\alpha-oxygen have led us to a new understanding of the production mechanismen
of ultra-cold-neutrons (UCN) in this super-thermal converter. The UCN
production in solid \alpha-oxygen is dominated by the excitation of phonons.
The contribution of magnons to UCN production becomes only slightly important
above E >10 meV and at E >4 meV. Solid \alpha-oxygen is in comparison to solid
deuterium less effcient in the down-scattering of thermal or cold neutrons into
the UCN energy regime.Comment: 4 pages, 5 figuer
Multicultural Interdisciplinary Handbook: tools for learning history and geography in a multicultural perspective (MIH)
[ES] MIH project (Multicultural Interdisciplinary Handbook: tools for learning History and Geography in a multicultural perspective) is a Comenius Multilateral Project funded with support from the European Commission that has been
developed from 2009 to 2011.Conceived from the idea of educating lower and upper Secondary School pupils in a process of construction of a European identity by involving them in the culture of other countries, MIH project meets this need by providing new methodological and ICT tools that could help teachers and pupils to plunge deeper into both cultures and languages of another nations via their History and Geography, and opens the way to introduce a European perspective in History and Geography school curricula and classroom activities
Magnetic Field Amplification in Galaxy Clusters and its Simulation
We review the present theoretical and numerical understanding of magnetic
field amplification in cosmic large-scale structure, on length scales of galaxy
clusters and beyond. Structure formation drives compression and turbulence,
which amplify tiny magnetic seed fields to the microGauss values that are
observed in the intracluster medium. This process is intimately connected to
the properties of turbulence and the microphysics of the intra-cluster medium.
Additional roles are played by merger induced shocks that sweep through the
intra-cluster medium and motions induced by sloshing cool cores. The accurate
simulation of magnetic field amplification in clusters still poses a serious
challenge for simulations of cosmological structure formation. We review the
current literature on cosmological simulations that include magnetic fields and
outline theoretical as well as numerical challenges.Comment: 60 pages, 19 Figure
Comprehensive Analysis of 5-Aminolevulinic Acid Dehydrogenase (ALAD) Variants and Renal Cell Carcinoma Risk among Individuals Exposed to Lead
BACKGROUND: Epidemiologic studies are reporting associations between lead exposure and human cancers. A polymorphism in the 5-aminolevulinic acid dehydratase (ALAD) gene affects lead toxicokinetics and may modify the adverse effects of lead. METHODS: The objective of this study was to evaluate single-nucleotide polymorphisms (SNPs) tagging the ALAD region among renal cancer cases and controls to determine whether genetic variation alters the relationship between lead and renal cancer. Occupational exposure to lead and risk of cancer was examined in a case-control study of renal cell carcinoma (RCC). Comprehensive analysis of variation across the ALAD gene was assessed using a tagging SNP approach among 987 cases and 1298 controls. Occupational lead exposure was estimated using questionnaire-based exposure assessment and expert review. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression. RESULTS: The adjusted risk associated with the ALAD variant rs8177796(CT/TT) was increased (OR = 1.35, 95%CI = 1.05-1.73, p-value = 0.02) when compared to the major allele, regardless of lead exposure. Joint effects of lead and ALAD rs2761016 suggest an increased RCC risk for the homozygous wild-type and heterozygous alleles ((GG)OR = 2.68, 95%CI = 1.17-6.12, p = 0.01; (GA)OR = 1.79, 95%CI = 1.06-3.04 with an interaction approaching significance (p(int) = 0.06). No significant modification in RCC risk was observed for the functional variant rs1800435(K68N). Haplotype analysis identified a region associated with risk supporting tagging SNP results. CONCLUSION: A common genetic variation in ALAD may alter the risk of RCC overall, and among individuals occupationally exposed to lead. Further work in larger exposed populations is warranted to determine if ALAD modifies RCC risk associated with lead exposure
Hospital service areas – a new tool for health care planning in Switzerland
BACKGROUND: The description of patient travel patterns and variations in health care utilization may guide a sound health care planning process. In order to accurately describe these differences across regions with homogeneous populations, small area analysis (SAA) has proved as a valuable tool to create appropriate area models. This paper presents the methodology to create and characterize population-based hospital service areas (HSAs) for Switzerland. METHODS: We employed federal hospital discharge data to perform a patient origin study using small area analysis. Each of 605 residential regions was assigned to one of 215 hospital provider regions where the most frequent number of discharges took place. HSAs were characterized geographically, demographically, and through health utilization indices and rates that describe hospital use. We introduced novel planning variables extracted from the patient origin study and investigated relationships among health utilization indices and rates to understand patient travel patterns for hospital use. Results were visualized as maps in a geographic information system (GIS). RESULTS: We obtained 100 HSAs using a patient origin matrix containing over four million discharges. HSAs had diverse demographic and geographic characteristics. Urban HSAs had above average population sizes, while mountainous HSAs were scarcely populated but larger in size. We found higher localization of care in urban HSAs and in mountainous HSAs. Half of the Swiss population lives in service areas where 65% of hospital care is provided by local hospitals. CONCLUSION: Health utilization indices and rates demonstrated patient travel patterns that merit more detailed analyses in light of political, infrastructural and developmental determinants. HSAs and health utilization indices provide valuable information for health care planning. They will be used to study variation phenomena in Swiss health care
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