1,346 research outputs found
Functional co-monotony of processes with applications to peacocks and barrier options
We show that several general classes of stochastic processes satisfy a
functional co-monotony principle, including processes with independent
increments, Brownian diffusions, Liouville processes. As a first application,
we recover some recent results about peacock processes obtained by Hirsch et
al. which were themselves motivated by a former work of Carr et al. about the
sensitivity of Asian Call options with respect to their volatility and residual
maturity (seniority). We also derive semi-universal bounds for various barrier
options.Comment: 27 page
The Representation of Texture in Cold-Rolled Copper Sheet by an Advanced X-Ray Diffraction Technique
The influence of texture on forming properties of metals has widely been recognized [l–4]. Preferred orientation of the crystallites (grains) in polycrystalline aggregates results in anisotropy of the mechanical properties. The desired degree of, or absence of, anisotropy depends on the particular process of forming, and any subsequent manufacturing process requires certain material properties for satisfactory performance. For example, the type of texture desired in deep drawing is quite different from the one necessary for simple stamping or multiaxial bending. Thus, in-process texture monitoring is receiving increased interest, both from manufacturers and researchers [4,5].</p
The connection between superconducting phase correlations and spin excitations in YBaCuO: A magnetic field study
One of the most striking universal properties of the
high-transition-temperature (high-) superconductors is that they are all
derived from the hole-doping of their insulating antiferromagnetic (AF) parent
compounds. From the outset, the intimate relationship between magnetism and
superconductivity in these copper-oxides has intrigued researchers. Evidence
for this link comes from neutron scattering experiments that show the
unambiguous presence of short-range AF correlations (excitations) in cuprate
superconductors. Even so, the role of such excitations in the pairing mechanism
and superconductivity is still a subject of controversy. For
YBaCuO, where controls the hole-doping level, the most
prominent feature in the magnetic excitations spectra is the ``resonance''.
Here we show that for underdoped YBaCuO, where and
are below the optimal values, modest magnetic fields suppress the resonance
significantly, much more so for fields approximately perpendicular rather than
parallel to the CuO planes. Our results indicate that the resonance
measures pairing and phase coherence, suggesting that magnetism plays an
important role in the superconductivity of cuprates. The persistence of a field
effect above favors mechanisms with preformed pairs in the normal state
of underdoped cuprates.Comment: 12 pages, 4 figures, Nature (in press
The Epstein-Barr Virus G-Protein-Coupled Receptor Contributes to Immune Evasion by Targeting MHC Class I Molecules for Degradation
Epstein-Barr virus (EBV) is a human herpesvirus that persists as a largely subclinical infection in the vast majority of adults worldwide. Recent evidence indicates that an important component of the persistence strategy involves active interference with the MHC class I antigen processing pathway during the lytic replication cycle. We have now identified a novel role for the lytic cycle gene, BILF1, which encodes a glycoprotein with the properties of a constitutive signaling G-protein-coupled receptor (GPCR). BILF1 reduced the levels of MHC class I at the cell surface and inhibited CD8+ T cell recognition of
endogenous target antigens. The underlying mechanism involves physical association of BILF1 with MHC class I molecules, an increased turnover from the cell surface, and enhanced degradation via lysosomal proteases. The BILF1 protein of the closely related CeHV15 c1-herpesvirus of the Rhesus Old World primate (80% amino acid sequence identity) downregulated surface MHC class I similarly to EBV BILF1. Amongst the human herpesviruses, the GPCR encoded by the ORF74 of the KSHV c2-herpesvirus is most closely related to EBV BILF1 (15% amino acid sequence identity) but did not affect levels of surface MHC class I. An engineered mutant of BILF1 that was unable to activate G protein signaling pathways retained the ability to downregulate MHC class I, indicating that the immune-modulating and GPCR-signaling properties are two distinct functions of BILF1. These findings extend our understanding of the normal biology of an important human pathogen. The discovery of a third EBV lytic cycle gene that cooperates to interfere with MHC class I antigen processing underscores the importance of the need for EBV to be able to evade CD8+ T cell responses during the lytic replication cycle, at a time when such a large number of potential viral targets are expressed
Appropriate age range for introduction of complementary feeding into an infant's diet
Following a request from the European Commission, the Panel on Nutrition, Novel Foods and Food
Allergens (NDA) revised its 2009 Opinion on the appropriate age for introduction of complementary
feeding of infants. This age has been evaluated considering the effects on health outcomes, nutritional
aspects and infant development, and depends on the individual’s characteristics and development. As
long as foods have an age-appropriate texture, are nutritionally appropriate and prepared following good
hygiene practices, there is no convincing evidence that at any age investigated in the included studies
(< 1 to < 6 months), the introduction of complementary foods (CFs) is associated with adverse health
effects or benefits (except for infants at risk of iron depletion). For nutritional reasons, the majority of
infants need CFs from around 6 months of age. Infants at risk of iron depletion (exclusively breastfed
infants born to mothers with low iron status, or with early umbilical cord clamping (< 1 min after birth),
or born preterm, or born small-for-gestational age or with high growth velocity) may benefit from earlier
introduction of CFs that are a source of iron. The earliest developmental skills relevant for consuming
pureed CFs can be observed between 3 and 4 months of age. Skills for consuming finger foods can be
observed in some infants at 4 months, but more commonly at 5–7 months. The fact that an infant may
be ready from a neurodevelopmental perspective to progress to a more diversified diet before 6 months
of age does not imply that there is a need to introduce CFs. There is no reason to postpone the
introduction of potentially allergenic foods (egg, cereals, fish and peanut) to a later age than that of
other CFs as far as the risk of developing atopic diseases is concerned. Regarding the risk of coeliac
disease, gluten can be introduced with other CFs
Scientific opinion on the tolerable upper intake level for vitamin D, including the derivation of a conversion factor for calcidiol monohydrate
A fixed carbohydrate: protein ratio <= 1.8 on an energy basis consumed in the context of an energy-restricted diet and reduction of body weight: evaluation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006.
Following an application from Marks and Spencer PLC, submitted for authorisation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of the United Kingdom, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion on the scientific substantiation of a health claim related to a CHO:P ratio <= 1.8 on an energy basis in the context of an energy-restricted diet and body weight. The Panel considers that the food/constituent that is the subject of the health claim is sufficiently characterised. The Panel also considers that reduction of body weight in the context of an energy-restricted diet is a beneficial physiological effect. The target population proposed by the applicant is 'adults between the ages of 18 and 70 years with excess body weight'. No conclusions could be drawn from two unpublished studies investigating the effect of ready-to-eat meals with a CHO: P ratio <= 1.8 on body weight. The remaining 14 human intervention studies investigated the effect of diets targeting a CHO: P ratio <= 1.8 as compared to diets targeting a CHO: P ratio >= 3.0 on overweight and obese adults in the context of energy restriction. Four out of seven studies lasting < 12 weeks reported an effect of a CHO: P ratio <= 1.8 on body weight in overweight/obese subjects, whereas no significant effect was observed in six out of the seven studies lasting 12 weeks or more. The Panel considers that these studies do not provide evidence for a sustained effect of the food/constituent on body weight. The Panel concludes that a cause and effect relationship has not been established between the consumption of a fixed CHO: P ratio <= 1.8 on an energy basis consumed in the context of an energy-restricted diet and reduction of body weight. (C) 2017 European Food Safety Authority
One-year follow-up after sacrospinous hysteropexy and vaginal hysterectomy for uterine descent: a randomized study
Safety of betaine as a novel food pursuant to Regulation (EC) No 258/97
Following a request from the European Commission, the EFSA Panelon Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion on betaine as a novel food (NF) pursuant to Regulation (EC) No 258/97. The information provided on the composition, the specifications, the batch-to-batch variability, stability and production process of the NF is sufficient and does not raise concerns about the safety of the NF. The NF is proposed to be used in foods intended to meet additional requirements for intense muscular effort with a maximum intake of 2.5 g/day of betaine for sports people above 10 years of age. Based on the lowest BMDL05, which was derived from a chronic toxicity study in rats in which a dose-related increase in platelet counts was observed, and the anticipated daily intake of the NF in the target population, the Margins of Exposure are 3.6 and 5, which are generally regarded as not sufficient. However, the total exposure to betaine from the diet (about 830 mg/day) is not known to be associated with adverse effects. Moreover, no adverse effects on platelet counts were noted in human intervention studies with exposure levels of 4 g/day of betaine for up to 6 months. A significant increase in total and low-density lipoprotein (LDL)-cholesterol concentrations was noted at intakes of 4 g/day of betaine in overweight subjects with metabolic syndrome but not in healthy subjects, nor at intakes of 3 g/day. Thus, considering 4 g/day of betaine as a reference point and applying an uncertainty factor of 10 to account for interindividual variability, an amount of 400 mg/day of betaine in addition to the background exposure is considered as safe. The Panelconsiders that the NF is safe to be used at maximum intake of 400 mg/day in the target population
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