2,864 research outputs found
Projective Normality and Ehrhart Unimodality for Weighted Projective Space Simplices
Within the intersection of Ehrhart theory, commutative algebra, and algebraic
geometry lie lattice polytopes. Ehrhart theory is concerned with lattice point
enumeration in dilates of polytopes; lattice polytopes provide a sandbox in
which to test many conjectures in commutative algebra; and many properties of
projectively normal toric varieties in algebraic geometry are encoded through
corresponding lattice polytopes. In this article we focus on reflexive
simplices and work to identify when these have the integer decomposition
property (IDP), or equivalently, when certain weighted projective spaces are
projectively normal. We characterize the reflexive, IDP simplices whose
associated weighted projective spaces have one projective coordinate with
weight fixed to unity and for which the remaining coordinates can assume one of
three distinct weights. We show that several subfamilies of such reflexive
simplices have unimodal -polynomials, thereby making progress towards
conjectures and questions of Stanley, Hibi-Ohsugi, and others regarding the
unimodality of their -polynomials. We also provide computational
results and introduce the notion of reflexive stabilizations to explore the
(non-)ubiquity of reflexive simplices that are simultaneously IDP and
-unimodal
Cold Dust in Kepler's Supernova Remnant
The timescales to replenish dust from the cool, dense winds of Asymptotic
Giant Branch stars are believed to be greater than the timescales for dust
destruction. In high redshift galaxies, this problem is further compounded as
the stars take longer than the age of the Universe to evolve into the dust
production stages. To explain these discrepancies, dust formation in supernovae
(SNe) is required to be an important process but until very recently dust in
supernova remnants has only been detected in very small quantities. We present
the first submillimeter observations of cold dust in Kepler's supernova remnant
(SNR) using SCUBA. A two component dust temperature model is required to fit
the Spectral Energy Distribution (SED) with K and K. The total mass of dust implied for Kepler is -
1000 times greater than previous estimates. Thus SNe, or their progenitors may
be important dust formation sites.Comment: 12 pages, 2 figures, accepted to ApJL, corrected proof
Genetic Analyses and Annotations of Two Newly Discovered C1 Mycobacteriophages
Poster presentation abstract
Homeless people's access to primary care physiotherapy services : an exploratory, mixed-method investigation using a follow-up qualitative extension to core quantitative research
Objectives: The purpose of this study was to appraise referrals of homeless patients to physiotherapy services and explore perceptions of barriers to access. // Design: This exploratory mixed-method study used a follow-up qualitative extension to core quantitative research design. Over 9 months, quantitative data were gathered from the healthcare records of homeless patients referred to physiotherapy by a general practitioner (GP) practice, including the number of referrals and demographic data of all homeless patients referred. Corresponding physiotherapy records of those people referred to physiotherapy were searched for the outcome of their care. Qualitative semi-structured telephone interviews, based on the quantitative findings, were carried out with staff involved with patient care from the referring GP practice and were used to expand insight into the quantitative findings.
Setting Two primary care sites provided data for this study: a GP practice dedicated exclusively to homeless people and the physiotherapy department receiving their referrals. //
Participants: Quantitative data from the healthcare records of 34 homeless patient referrals to physiotherapy were collected and analysed. In addition, five staff involved in patient care were interviewed. // Results: 34 referrals of homeless people were made to physiotherapy in a 9-month period. It was possible to match 25 of these to records from the physiotherapy department. Nine (36%) patients did not attend their first appointment; seven (28%) attended an initial appointment, but did not attend a subsequent appointment and were discharged from the service; five (20%) completed treatment and four patients (16%) had ongoing treatment. Semi-structured interviews revealed potential barriers preventing homeless people from accessing physiotherapy services, the complex factors being faced by those making referrals and possible ways to improve physiotherapy access. // Conclusions: Homeless people with musculoskeletal problems may fail to access physiotherapy treatment, but opportunities exist to make access to physiotherapy easier
Desorption of alkali atoms from 4He nanodroplets
The dynamics following the photoexcitation of Na and Li atoms located on the
surface of helium nanodroplets has been investigated in a joint experimental
and theoretical study. Photoelectron spectroscopy has revealed that excitation
of the alkali atoms via the (n+1) -> ns transition leads to the desorption of
these atoms. The mean kinetic energy of the desorbed atoms, as determined by
ion imaging, shows a linear dependence on excitation frequency. These
experimental findings are analyzed within a three-dimensional, time-dependent
density functional approach for the helium droplet combined with a Bohmian
dynamics description of the desorbing atom. This hybrid method reproduces well
the key experimental observables. The dependence of the observables on the
impurity mass is discussed by comparing the results obtained for the 6Li and
7Li isotopes. The calculations show that the desorption of the excited alkali
atom is accompanied by the creation of highly non-linear density waves in the
helium droplet that propagate at supersonic velocities
The shifting nature of women’s experiences and perceptions of ductal carcinoma in situ
Aim: This paper is a report of a descriptive qualitative study of the evolution of women’s perceptions and experiences of ductal carcinoma in situ from the period near to diagnosis to one year later.
Background: Ductal carcinoma in situ is a non-invasive breast condition where cancer cells are detected but confined to the ducts of the breast. With treatment, the condition has a positive prognosis but ironically patients undergo treatment similar to that for invasive breast cancer. There is a lack of longitudinal qualitative research studying women’s experiences of ductal carcinoma in situ, especially amongst newly diagnosed patients and how experiences change over time.
Methods: Forty-five women took part in an initial interview following a diagnosis of ductal carcinoma in situ and twenty-seven took part in a follow-up interview 9-13 months later. Data were collected between January 2007 and October 2008. Transcripts were analysed using a hybrid approach to thematic analysis.
Findings: Women’s early perceptions of ductal carcinoma in situ merged and sometimes conflicted with their lay beliefs of breast cancer. Perceptions and experiences of the condition shifted over time. These overriding aspects were evident within four themes identified across the interviews: 1) perceptions of DCIS versus breast cancer, 2) from paradox to acceptance, 3) personal impact, and 4) support and interactions with others.
Conclusion: This study represents one of the few longitudinal qualitative studies with newly diagnosed patients, capturing women’s initial and shifting experiences and perceptions of the condition. The issues identified need to be recognised in clinical practice and supported appropriately
Neuromuscular responses to mild-muscle damaging eccentric exercise in a low glycogen state.
The aim of this study was to examine the effect of low muscle glycogen on the neuromuscular responses to maximal eccentric contractions. Fourteen healthy men (22±3years) performed single-leg cycling (20min at ∼75% maximal oxygen uptake (V̇O2 max); eight 90 s sprints at a 1:1 work-to-rest ratio (5% decrements from 90% to 55% V̇O2 max until exhaustion) the evening before 100 eccentric (1.57rads(-1)) with reduced (RED) and normal glycogen (NORM). Neuromuscular responses were measured during and up to 48h after with maximal voluntary and involuntary (twitch, 20Hz and 50Hz) isometric contractions. During eccentric contractions, peak torque decreased (RED: -16.1±2.5%; NORM: -6.2±5.1%) and EMG frequency increased according to muscle length. EMG activity decreased for RED only. After eccentric contractions, maximal isometric force was reduced up to 24h for NORM (-13.5±5.8%) and 48h for RED (-7.4±10.9%). Twelve hours after eccentric contractions, twitch force and the 20:50Hz ratio were decreased for RED but not for NORM. Immediate involuntary with prolonged voluntary force loss suggests that reduced glycogen is associated with increased susceptibility to mild muscle-damaging eccentric exercise with contributions of peripheral and central mechanisms to be different during recovery
Defining and characterizing team resilience in elite sport
Objectives: The objectives of this study were to develop a definition of team resilience and to identify the resilient characteristics of elite sport teams.
Design and Method: Focus groups consisting of a total of 31 participants were conducted with five elite teams from a range of sports. An interpretive thematic analysis using inductive and deductive reasoning was employed to analyze the data.
Results and Conclusions: Team resilience was defined as a dynamic, psychosocial process which protects a group of individuals from the potential negative effect of the stressors they collectively encounter. It comprises of processes whereby team members use their individual and combined resources to positively adapt when experiencing adversity. Findings revealed four main resilient characteristics of elite sport teams: group structure, mastery approaches, social capital, and collective efficacy. This study extends resilience research in sport psychology by providing greater conceptual clarity of resilience at a team level. The implications of the findings for those conducting research in this area and for those consulting with elite sport teams are discussed
What doesn’t kill me ... : adversity-related experiences are vital in the development of superior Olympic performance
Objectives: Recent research suggests that experiencing some adversity can have beneficial outcomes for human growth and development. The purpose of this paper was to explore the adversities that the world’s best athletes encounter and the perceived role that these experiences play in their psychological and performance development.
Design: A qualitative design was employed because detailed information of rich quality was required to better understand adversity-related experiences in the world’s best athletes.
Method: Semi-structured interviews were conducted with 10 Olympic gold medalists from a variety of sports. Inductive thematic analysis was used to analyze the data.
Results: The findings indicate that the participants encountered a range of sport- and non-sport adversities that they considered were essential for winning their gold medals, including repeated non-selection, significant sporting failure, serious injury, political unrest, and the death of a family member. The participants described the role that these experiences played in their psychological and performance development, specifically focusing on their resultant trauma, motivation, and learning.
Conclusions: Adversity-related experiences were deemed to be vital in the psychological and performance development of Olympic champions. In the future, researchers should conduct more in-depth comparative studies of Olympic athletes’ adversity- and growth-related experiences, and draw on existing and alternative theoretical explanations of the growth-performance relationship. For professional practitioners, adversity-related experiences offer potential developmental opportunities if they are carefully and purposely harnessed
Enhanced Spin Dependent Shot Noise in Magnetic Tunnel Barriers
We report the observation of enhanced spin dependent shot noise in magnetic
tunnel barriers, suggesting transport through localized states within the
barrier. This is supported by the existence of negative magnetoresistance and
structure in the differential conductance curves. A simple model of tunneling
through two interacting localized states with spin dependent tunneling rates is
used to explain our observations.Comment: 8 pages, 8 figures, submitted to Physica E (proceedings of the
seminar on Quantum Coherence, Noise and Decoherence in Nanostructures
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