349 research outputs found
Poissonian tunneling through an extended impurity in the quantum Hall effect
We consider transport in the Poissonian regime between edge states in the
quantum Hall effect. The backscattering potential is assumed to be arbitrary,
as it allows for multiple tunneling paths. We show that the Schottky relation
between the backscattering current and noise can be established in full
generality: the Fano factor corresponds to the electron charge (the
quasiparticle charge) in the integer (fractional) quantum Hall effect, as in
the case of purely local tunneling. We derive an analytical expression for the
backscattering current, which can be written as that of a local tunneling
current, albeit with a renormalized tunneling amplitude which depends on the
voltage bias. We apply our results to a separable tunneling amplitude which can
represent an extended point contact in the integer or in the fractional quantum
Hall effect. We show that the differential conductance of an extended quantum
point contact is suppressed by the interference between tunneling paths, and it
has an anomalous dependence with respect to the bias voltage
IceCube3--a new window on the Universe
This paper gives an overview of the scientific goals of IceCube with an
emphasis on the importance of atmospheric neutrinos. Status and schedule for
completing the detector are presented.Comment: 13 pages, 6 figures, to appear in A.I.P. Conf. Proceedings, 3rd Latin
American School on Cosmic Rays, Arequipa, Peru, September, 200
Younger Than Ever? Subjective Age Is Becoming Younger and Remains More Stable in Middle-Age and Older Adults Today
Little is known about historical shifts in subjective age (i.e., how old individuals feel). Moving beyond the very few time-lagged cross-sectional cohort comparisons, we examined historical shifts in within-person trajectories of subjective age from midlife to advanced old age. We used cohort-comparative longitudinal data from middle-age and older adults in the German Ageing Survey (N = 14,928; ~50% female) who lived in Germany and were between 40 and 85 years old when entering the study. They provided up to seven observations over 24 years. Results revealed that being born later in historical time is associated with feeling younger by 2% every birth-year decade and with less intraindividual change toward an older subjective age. Women reported feeling younger than men; this gender gap widened across cohorts. The association of higher education with younger subjective age became weaker across cohorts. Potential reasons for the subjective-rejuvenation effect across cohorts are discussed.Bundesministerin fĂĽr Frauen, Familien und Jugend
https://doi.org/10.13039/501100011090Peer Reviewe
Awareness of age-related change in the context of major life events
Although gains and losses are an integral part of human development, the experience of change and readjustment that often comes with major life events may be particularly influential for an individual's subjective aging experience and awareness of age-related change (AARC). Thus, this study focused on the role of life events in the domains of family and health for an individual's awareness of age-related gains and losses. Specifically, we differentiated between the experience of specific life events (e.g., entering a new romantic relationship; hospital stay) and the cumulative experience of multiple life events. Furthermore, we differentiated between life events experienced at an expected time in life and life events experienced relatively early or relatively late compared to established social norms. Data came from the Innovation Sample of the German Socio-Economic Panel (SOEP-IS) and consisted of 1,612 participants aged 16 to 93 years (M = 54.1; SD = 18.2). Life events were assessed annually and retrospectively for the last 2 years. Propensity score matching provided evidence for an association of specific family life events and a higher awareness of age-related gains, as well as specific health life events and a higher awareness of age-related losses. Results furthermore indicated that the cumulative experience of family life events was associated with a higher awareness of age-related gains. Conversely, the cumulative experience of health events was associated with higher awareness of both age-related losses and age-related gains. Moreover, it was not only life events happening at an expected age, but also those happening relatively early and particularly those happening late in life, which were associated with AARC. In summary, life events and the change they may bring seem to be reflected in individuals' awareness of age-related losses and awareness of age-related gains.Peer Reviewe
Positive and negative affect are associated with salivary cortisol in the everyday life of older adults: A quantitative synthesis of four aging studies
Research on time-fluctuating links between positive affect and cortisol is inconsistent and mostly based on young to middle-aged samples. The current project investigated how moment-to-moment changes in positive and negative affect are associated with moment-to-moment changes in cortisol levels in older adults’ daily lives and whether those associations are moderated by differences in health status (as indicated by the number of comorbidities). Affect and cortisol data collected in four separately conducted momentary assessment studies with parallel protocols were pooled to obtain a sample of N=476 individuals aged 56–88 years (Mage=71.9, SD=6.6; 52% female). Participants provided affect reports and collected salivary cortisol 5–7 times a day for a 7-day period and reported the presence of 13 different health conditions. Data were analyzed using multilevel models, with time since waking, daily behaviors associated with cortisol secretion, age, and sex controlled. Feeling more positive affect than usual was associated with lower momentary cortisol. In contrast, feeling more negative affect than usual was associated with higher momentary cortisol. Associations of momentary positive and negative affect with cortisol were weaker among participants in worse as compared to those in better health. Trait positive affectivity was associated with more curvature of waking cortisol profiles and trait negative affectivity was associated with smaller cortisol awakening responses. Findings suggest that HPA axis responses fluctuate with everyday changes in positive and negative affect in older adults, and that higher HPA reactivity may indicate preserved health in this age group
Detection of anti-cardiolipin and anti-β2glycoprotein I antibodies differs between platforms without influence on association with clinical symptoms
Background: The anti-phospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy morbidity with persistent presence of anti-phospholipid antibodies (aPL). Laboratory criteria include aPL detection by coagulation tests for lupus anticoagulant (LAC) or solid phase assays measuring anti-beta 2 glycoprotein I (a beta 2GPI) or anticardiolipin (aCL) immunoglobulin (Ig) G/IgM antibodies. External quality control programs illustrate that commercially available aPL assays produce variable results.
Objective: We aimed to investigate the agreement and diagnostic accuracy of solid phase assays.
Materials and Methods: In thismulti-centre study, 1,168 patient samples were tested on one site for aCL and a beta 2GPI IgG/IgM antibodies by four solid phase test systems. Samples included APS patients, controls and monoclonal antibodies (MoAB) against different epitopes of beta 2GPI. LAC was determined by the local centre.
Results: aCL IgM assays resulted in the most discrepancies (60%), while aCL IgG and a beta 2GPI IgM assays resulted in lower discrepancies (36%), suggesting better agreement. Discrepant samples displayed lower median aPL titers. Dependent on the solid phase test system, odds ratios (ORs) for thrombosis and pregnancy morbidity ranged from 1.98 to 2.56 and 3.42 to 4.78, respectively. Three platforms showed lower sensitivity for MoAB directed against the glycine (Gly) 40-arginine (Arg) 43 epitope of domain I of beta 2GPI.
Conclusion: Poor agreement was observed between different commercially available aCL and a beta 2GPI IgG/IgM assays, hampering uniformity in the identification of aPL-positive patients. Clinical association was globally concordant between solid phase test systems considering results of the four aPL together. An assay sensitive in detecting the MoAB against Gly40-Arg43 of domain I of beta 2GPI reached the highest OR for thrombosis
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