30,908 research outputs found
The N N -> NN pi+ Reaction near Threshold in a Chiral Power Counting Approach
Power-counting arguments are used to organize the interactions contributing
to the N N -> d pi, p n pi reactions near threshold. We estimate the
contributions from the three formally leading mechanisms: the Weinberg-Tomozawa
(WT) term, the impulse term, and the -excitation mechanism. Sub-leading
but potentially large mechanisms, including -wave pion-rescattering, the
Galilean correction to the WT term, and short-ranged contributions are also
examined. The WT term is shown to be numerically the largest, and the other
contributions are found to approximately cancel. Similarly to the reaction p p
-> p p pi0, the computed cross sections are considerably smaller than the data.
We discuss possible origins of this discrepancy.Comment: 31 pages, 17 figure
Poincare's Recurrence Theorem and the Unitarity of the S matrix
A scattering process can be described by suitably closing the system and
considering the first return map from the entrance onto itself. This scattering
map may be singular and discontinuous, but it will be measure preserving as a
consequence of the recurrence theorem applied to any region of a simpler map.
In the case of a billiard this is the Birkhoff map. The semiclassical
quantization of the Birkhoff map can be subdivided into an entrance and a
repeller. The construction of a scattering operator then follows in exact
analogy to the classical process. Generically, the approximate unitarity of the
semiclassical Birkhoff map is inherited by the S-matrix, even for highly
resonant scattering where direct quantization of the scattering map breaks
down.Comment: 4 latex pages, 5 ps figure
Co-constructing a new framework for evaluating social innovation in marginalized rural areas
The EU funded H2020 project \u2018Social Innovation in Marginalised Rural Areas\u2019 (SIMRA; www.simra-h2020.eu) has the overall objective of advancing the state-of-the-art in social innovation. This paper outlines the process for co- developing an evaluation framework with stakeholders, drawn from across Europe and the Mediterranean area, in the fields of agriculture, forestry and rural development. Preliminary results show the importance of integrating process and outcome-oriented evaluations, and implementing participatory approaches in evaluation practice. They also raise critical issues related to the comparability of primary data in diverse regional contexts and highlight the need for mixed methods approaches in evaluation
Simultaneous complementary idiotypic responses: absence of reciprocal regulation
Complementary antibodies, i.e. antibodies having combining site structures which are at least partially directed against each other, were induced in A/He mice by immunization with phosphorylcholine (Pc) coupled to keyhole limpet hemocyanin or with the Pc-binding IgA myeloma protein, HOPC-8 (H8). Both responses were monitored by enumerating plaque-forming cells and assaying serum antibody levels to Pc and H8. Prior immunization with H8 markedly suppressed subsequent immunization with Pc and vice versa; neither plaque-forming cell response was diminished, however, when mice were immunized simultaneously with Pc and H8. Experiments were designed to determine if the absence of reciprocal regulation was due to change in idiotypes. This was determined by measuring inhibition of plaque formation using complementary antibody. Plaque formation by cells was equally inhibited by high dilutions of the appropriate complementary antibody whether cells were from mice immunized with one, the other, or both antigens. Thus, the absence of regulation could not be accounted for by emergence of different idiotypes. Interestingly, sera from mice immunized to have high responses to both antigens were relatively ineffective in inhibiting plaque formation or suppressing immunization to Pc. However, such sera contained complexes of the complementary antibodies; apparently antibody to Pc in such sera quenches or neutralizes the activity of anti-H8 antibody. But the formation of complexes, at least measurable levels of circulating complexes, must be a result rather than the cause for the absence of reciprocal regulation, since regulation was also absent when immunization to Pc was manipulated so that responses were too low to result in detectable levels of circulating antibody to Pc. It is proposed that simultaneous complementary responses may occur in nature to other antigens and antibodies, and that such simultaneous responses may cause pathologic changes
A Psychotic Reaction in a Sex-Chromatin Negative Female
Neuropsychiatric disorders found in association with Turner's syndrome (gonadal agenesis) are unusual. The case report describes a patient with Turner's syndrome who suffered an acute psychotic reaction. A brief review of the literature concerning this association is surveyed.S. Afr. Med. J., 47, 146 (1973
Public expenditures on health and pensions in OECD countries : their simultaneous estimation
This dissertation aims to explore the simultaneous determination of public expenditures on health and old-age pensions regarding 31 high-income OECD countries during the period 1990-2011. To take into account that each country and year can´t be treated as homogenous, the thesis uses a panel data model with country and year fixed effects. Regarding pensions and health individual determination, it was verified through an OLS regression with Dummy Variables, that GDP is the most important determinant of health expenditures and that it also has a strong impact on old-age pensions expenditures. Given that old-age pensions expenditures have a statistically significant impact on health expenditures and vice versa, a 2SLS model was used in order to estimate this simultaneous determination. Per capita pensions expenditures have a positive and robust impact on health expenditure per capita mainly because pensions expenditures will redistribute income for those that have a larger propensity to spend on health. Additionally the expectations of the future pensions payments serve as an incentive to invest in living longer. (Yonghong An 2015) The impact on pensions expenditures of expenditures on health was not so clear. The impact is positive and significant, but the instruments for health used in the pensions 2SLS equation, though relevant, seem not to be strong enough to totally validate this causality relation. If true, this relation would indicate that when the Government invests in health, invests in a higher life expectancy which means that also it will have to pay for pensions during a longer period.Esta dissertação tem como objetivo explorar a determinação simultânea dos gastos públicos com pensões de velhice e saúde em 31 países da OCDE durante o período 1990 - 2011. Como os países e períodos de tempo não podem ser tratados de forma homogénea, um modelo de dados de painel com efeitos fixos por país e ano é utilizado. No que se refere à determinação individual dos gastos, verificou-se através de regressões OLS com Dummy Variables que o é a variável com maior impacto na despesa em saúde e que também tem um forte impacto nas despesas com pensões. Dado que as despesas com pensões de velhice tiveram um impacto nas despesas de saúde e vice-versa, um modelo 2SLS foi utilizado. A despesa com as pensões tem um impacto positivo e robusto nas despesas em saúde, devido ao facto das despesas com pensões redistribuírem o rendimento por aqueles que têm maior propensão para gastar em saúde. (Yonghong An 2015). Por outro lado as expectativas dos pagamentos futuros das pensões servem como um incentivo para se investir em viver mais tempo. O impacto nas despesas com pensões das despesas em saúde não é tão claro. Apesar do impacto ser significativo, os instrumentos utilizados para a saúde na equação de 2SLS das pensões, apesar de relevantes, não parecem ser suficientemente fortes para validar totalmente esta relação. Se verdadeira ela indicará que quando o Governo investe em saúde, investe na esperança de vida o que implicará pagamentos de pensões durante períodos mais longos
Homozygous in-frame deletion in CATSPERE in a man producing spermatozoa with loss of CatSper function and compromised fertilizing capacity
STUDY QUESTIONDoes a man (patient 1) with a previously described deficiency in principle cation channel of sperm (CatSper) function have a mutation in the CatSper-epsilon (CATSPERE) and/or CatSper-zeta (CATSPERZ) gene?SUMMARY ANSWERPatient 1 has a homozygous in-frame 6-bp deletion in exon 18 (c.2393_2398delCTATGG, rs761237686) of CATSPERE.WHAT IS KNOWN ALREADYCatSper is the principal calcium channel of mammalian spermatozoa. Spermatozoa from patient 1 had a specific loss of CatSper function and were unable to fertilize at IVF. Loss of CatSper function could not be attributed to genetic abnormalities in coding regions of seven CatSper subunits. Two additional subunits (CatSper-epsilon (CATPSERE) and CatSper-zeta (CATSPERZ)) were recently identified, and are now proposed to contribute to the formation of the mature channel complex.STUDY DESIGN, SIZE, DURATIONThis was a basic medical research study analysing genomic data from a single patient (patient 1) for defects in CATSPERE and CATSPERZ.PARTICIPANTS/MATERIALS, SETTING, METHODSThe original exome sequencing data for patient 1 were analysed for mutations in CATSPERE and CATSPERZ. Sanger sequencing was conducted to confirm the presence of a rare variant.MAIN RESULTS AND THE ROLE OF CHANCEPatient 1 is homozygous for an in-frame 6-bp deletion in exon 18 (c.2393_2398delCTATGG, rs761237686) of CATSPERE that is predicted to be highly deleterious.LIMITATIONS, REASONS FOR CAUTIONThe nature of the molecular deficit caused by the rs761237686 variant and whether it is exclusively responsible for the loss of CatSper function remain to be elucidated.WIDER IMPLICATIONS OF THE FINDINGSPopulation genetics are available for a significant number of predicted deleterious variants of CatSper subunits. The consequence of homozygous and compound heterozygous forms on sperm fertilization potential could be significant. Selective targeting of CatSper subunit expression maybe a feasible strategy for the development of novel contraceptives.STUDY FUNDING/COMPETING INTEREST(S)This study was funded by project grants from the MRC (MR/K013343/1 and MR/012492/1), Chief Scientist Office/NHS research Scotland. This work was also supported by NIH R01GM111802, Pew Biomedical Scholars Award 00028642 and Packer Wentz Endowment Will to P.V.L. C.L.R.B is the editor-in-chief of Molecular Human Reproduction, has received lecturing fees from Merck and Ferring, and is on the Scientific Advisory Panel for Ohana BioSciences. C.L.R.B was chair of the World Health Organization Expert Synthesis Group on Diagnosis of Male infertility (2012–2016)
A Comparative Study of the Formation of Aromatics in Rich Methane Flames Doped by Unsaturated Compounds
For a better modeling of the importance of the different channels leading to
the first aromatic ring, we have compared the structures of laminar rich
premixed methane flames doped with several unsaturated hydrocarbons: allene and
propyne, because they are precursors of propargyl radicals which are well known
as having an important role in forming benzene, 1,3-butadiene to put in
evidence a possible production of benzene due to reactions of C4 compounds,
and, finally, cyclopentene which is a source of cyclopentadienylmethylene
radicals which in turn are expected to easily isomerizes to give benzene. These
flames have been stabilized on a burner at a pressure of 6.7 kPa (50 Torr)
using argon as dilutant, for equivalence ratios (?) from 1.55 to 1.79. A unique
mechanism, including the formation and decomposition of benzene and toluene,
has been used to model the oxidation of allene, propyne, 1,3 butadiene and
cyclopentene. The main reaction pathways of aromatics formation have been
derived from reaction rate and sensitivity analyses and have been compared for
the three types of additives. These combined analyses and comparisons can only
been performed when a unique mechanism is available for all the studied
additives
Effects of bovine lipid extract surfactant administration in preterm infants treated for respiratory distress syndrome
Aim: To review the initial effectiveness of bovine lipid extract surfactant (BLES) for the treatment of respiratory distress syndrome in preterm infants. Methods and results: A retrospective review of data collected from infants born \u3c37-week gestation with respiratory distress syndrome treated with BLES between February 1, 2015 and March 1, 2016. Data were analyzed to determine the timing of initial dose, the length of time to wean the fraction of inspired oxygen (FiO2) concentration to 0.21 following initial dose, and the number of repeated doses given during hospital admission. Infants were subgrouped by gestational age stratum, 230 to 276 weeks (group 1), 280 to 316 weeks (group 2), and 320 to 366 weeks (group 3). Ninety-eight infants received the surfactant during the study period. After applying exclusion criteria, 77 infants were analyzed. Mean (SD) gestational age was 28 (4) weeks, and mean (SD) birth weight was 1250 (602) g. Initial dose of BLES was given at a median (interquartile range) time of 29 (19-43) minutes in group 1, 150 (20-615) minutes in group 2, and 990 (53-2025) minutes in group 3. Median (interquartile range) length of time to wean the FiO2 concentration to 0.21 was 14 (5-56) minutes, 10 (5-53) minutes, and 10 (5-38) minutes in groups 1, 2, and 3, respectively. Ten infants required repeated doses. Conclusion: Given the rapid response of BLES in all the groups, careful monitoring of ventilator parameters is paramount to allow for rapid weaning and early extubation to avoid lung injury associated with mechanical ventilation
Evidence for an accretion origin for the outer halo globular cluster system of M31
We use a sample of newly-discovered globular clusters from the Pan-Andromeda
Archaeological Survey (PAndAS) in combination with previously-catalogued
objects to map the spatial distribution of globular clusters in the M31 halo.
At projected radii beyond ~30 kpc, where large coherent stellar streams are
readily distinguished in the field, there is a striking correlation between
these features and the positions of the globular clusters. Adopting a simple
Monte Carlo approach, we test the significance of this association by computing
the probability that it could be due to the chance alignment of globular
clusters smoothly distributed in the M31 halo. We find the likelihood of this
possibility is low, below 1%, and conclude that the observed spatial
coincidence between globular clusters and multiple tidal debris streams in the
outer halo of M31 reflects a genuine physical association. Our results imply
that the majority of the remote globular cluster system of M31 has been
assembled as a consequence of the accretion of cluster-bearing satellite
galaxies. This constitutes the most direct evidence to date that the outer halo
globular cluster populations in some galaxies are largely accreted.Comment: Accepted for publication in ApJ Letter
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