288 research outputs found
Noncommutative geometry inspired black holes in higher dimensions at the LHC
When embedding models of noncommutative geometry inspired black holes into
the peridium of large extra dimensions, it is natural to relate the
noncommutativity scale to the higher-dimensional Planck scale. If the Planck
scale is of the order of a TeV, noncommutative geometry inspired black holes
could become accessible to experiments. In this paper, we present a detailed
phenomenological study of the production and decay of these black holes at the
Large Hadron Collider (LHC). Noncommutative inspired black holes are relatively
cold and can be well described by the microcanonical ensemble during their
entire decay. One of the main consequences of the model is the existence of a
black hole remnant. The mass of the black hole remnant increases with
decreasing mass scale associated with noncommutative and decreasing number of
dimensions. The experimental signatures could be quite different from previous
studies of black holes and remnants at the LHC since the mass of the remnant
could be well above the Planck scale. Although the black hole remnant can be
very heavy, and perhaps even charged, it could result in very little activity
in the central detectors of the LHC experiments, when compared to the usual
anticipated black hole signatures. If this type of noncommutative inspired
black hole can be produced and detected, it would result in an additional mass
threshold above the Planck scale at which new physics occurs.Comment: 21 pages, 7 figure
Recent developments of the Hierarchical Reference Theory of Fluids and its relation to the Renormalization Group
The Hierarchical Reference Theory (HRT) of fluids is a general framework for
the description of phase transitions in microscopic models of classical and
quantum statistical physics. The foundations of HRT are briefly reviewed in a
self-consistent formulation which includes both the original sharp cut-off
procedure and the smooth cut-off implementation, which has been recently
investigated. The critical properties of HRT are summarized, together with the
behavior of the theory at first order phase transitions. However, the emphasis
of this presentation is on the close relationship between HRT and non
perturbative renormalization group methods, as well as on recent
generalizations of HRT to microscopic models of interest in soft matter and
quantum many body physics.Comment: 17 pages, 5 figures. Review paper to appear in Molecular Physic
Hawking emission from quantum gravity black holes
We address the issue of modelling quantum gravity effects in the evaporation
of higher dimensional black holes in order to go beyond the usual
semi-classical approximation. After reviewing the existing six families of
quantum gravity corrected black hole geometries, we focus our work on
non-commutative geometry inspired black holes, which encode model independent
characteristics, are unaffected by the quantum back reaction and have an
analytical form compact enough for numerical simulations. We consider the
higher dimensional, spherically symmetric case and we proceed with a complete
analysis of the brane/bulk emission for scalar fields. The key feature which
makes the evaporation of non-commutative black holes so peculiar is the
possibility of having a maximum temperature. Contrary to what happens with
classical Schwarzschild black holes, the emission is dominated by low frequency
field modes on the brane. This is a distinctive and potentially testable
signature which might disclose further features about the nature of quantum
gravity.Comment: 36 pages, 18 figures, v2: updated reference list, minor corrections,
version matching that published on JHE
An anatomically-based masking protocol for the assessment of in-shoe plantar pressure measurement of the forefoot
Background
The area beneath the metatarsal heads is a common location of foot pain, which is often associated with high plantar pressures. Current plantar pressure assessment protocols focus mainly on the gross area of the forefoot with minimal attention paid to specific areas such as the metatarsal heads. The aim of this study was to develop and assess a new anatomically-based masking protocol that is clinically relevant to measure forefoot plantar pressure during shod conditions based on the anatomical positions of the metatarsal heads.
Methods
Initially, we developed a masking protocol to measure forefoot plantar pressure during shod conditions based on the anatomical positions of the metatarsal heads. This new masking protocol divided the forefoot into three sub-areas (proximal, beneath, and distal to the metatarsal heads) as determined by the position of each metatarsal head. Following development of the new masking protocol, we compared the new protocol against a traditional protocol, which defines the forefoot as between 51 and 81% of the foot length. To compare the two masking protocols, we tested two experimental conditions: (i) a control condition (i.e. no metatarsal pad), and (ii) a metatarsal pad condition. We then compared plantar pressure differences between the two experimental conditions for the two masking protocols. Participants for this component of the study included 36 community dwelling older adults (mean age 75.6 years ±5.4) with a history of forefoot pain. Forefoot plantar pressure data were measured while walking using the pedar®-X in-shoe system. Peak pressure, maximum force and contact area at the time of peak pressure were determined and results were compared between the two masking protocols.
Results
The traditional masking protocol showed that the metatarsal pad significantly decreased peak pressure and increased contact area in the forefoot area (i.e. within the entire mask area), but maximum force was not significantly different between the two conditions. In contrast, the newly developed anatomically-based masking protocol indicated that the metatarsal pad decreased peak plantar pressures distal to and beneath the metatarsal heads by increasing force and contact area proximal to the metatarsal heads.
Conclusions
An anatomically-based masking protocol that is clinically relevant was developed to assess forefoot plantar pressure during shod conditions based on the anatomical positions of metatarsal heads. We propose that the new forefoot masking protocol will provide greater interpretability of forefoot plantar pressure data, which will aid clinicians and researchers for diagnostic, prognostic and therapeutic purposes
Mothers' accounts of their stillbirth experiences and of their subsequent relationships with their living infant:an interpretative phenomenological analysis
BACKGROUND: Due to contradictory findings regarding the effects of seeing and holding stillborn infants on women's worsening mental health symptoms, there is a lack of clear of guidance in stillbirth bereavement care. Although some current research examines this phenomenon we are still not certain of the meaning of such experiences to women and what effects there may be on her subsequent parenting. Thus the present study focuses on the meaning of the stillbirth experience to women and its influence on the subsequent pregnancy and subsequent parenting from the mothers' own experiences. METHODS: A purposive sample of six women who experienced a stillbirth during their first pregnancy and who then went on to give birth to a living child after a further pregnancy, took part in email interviews, providing rich and detailed experiential narratives about both the stillbirth itself, and their relationship with their living child. An Interpretive Phenomenological Analysis was carried out in order to focus on mothers making sense of such experiences. RESULTS: Analysis of written accounts led to the development of three overarching themes. In 'Broken Canopy', 'How This Happened' and 'Continuing Bonds', their accounts revealed an ongoing process where women accepted a new 'unsafe' view of the world, re-evaluated their view of self and others, and established relationships with both the deceased and the living infant. CONCLUSIONS: This study provided an insight into the stillbirth experience of mothers and its meaning to them with an existential focus. Typically the mother struggled with the contradictory process of accepting the existence of her deceased baby (this baby once lived) while being aware of the nonexistence (this baby). Meeting the dead baby was a crucial point at which the mother started processing her grief. The importance of individual differences in dealing with stressful situations was highlighted in terms of attachment strategies. Subsequent parenting experiences of mothers were very much influenced by their own previous experiences. Although some mothers managed to integrate this trauma into their life some remained very concerned and anxious about future and this anxiety then translated into their parenting experiences
Resilience in the Face of Disaster: Prevalence and Longitudinal Course of Mental Disorders following Hurricane Ike
Objectives: Natural disasters may increase risk for a broad range of psychiatric disorders, both in the short- and in the medium-term. We sought to determine the prevalence and longitudinal course of posttraumatic stress disorder (PTSD), generalized anxiety disorder (GAD), panic disorder (PD), depression, and suicidality in the first 18 months after Hurricane Ike.
Methods: Six hundred fifty-eight adults representative of Galveston and Chambers Counties, Texas participated in a random, population-based survey. The initial assessment was conducted 2 to 5 months after Hurricane Ike struck Galveston Bay on September 13, 2008. Follow-up assessments were conducted at 5 to 9 and 14 to 18 months after Hurricane Ike. Results: Past-month prevalence of any mental disorder (20.6% to 10.9%) and hurricane-related PTSD (6.9% to 2.5%) decreased over time. Past-month prevalence of PTSD related to a non-disaster traumatic event (5.8% to 7.1%), GAD (3.1% to 1.8%), PD (0.8% to 0.7%), depression (5.0% to 5.6%), and suicidality (2.6% to 4.2%) remained relatively stable over time.
Conclusions: PTSD, both due to the hurricane and due to other traumatic events, was the most prevalent psychiatric disorder 2 to 5 months after Hurricane Ike. Prevalence of psychiatric disorders declined rapidly over time, suggesting that the vast majority of individuals exposed to this natural disaster ‘bounced back’ and were resilient to long-term mental health consequences of this large-scale traumatic event
Identifying bereaved subjects at risk of complicated grief: Predictive value of questionnaire items in a cohort study
<p>Abstract</p> <p>Background</p> <p>Bereavement is a condition which most people experience several times during their lives. A small but noteworthy proportion of bereaved individuals experience a syndrome of prolonged psychological distress in relation to bereavement. The aim of the study was to develop a clinical tool to identify bereaved individuals who had a prognosis of complicated grief and to propose a model for a screening tool to identify those at risk of complicated grief applicable among bereaved patients in general practice and palliative care.</p> <p>Methods</p> <p>We examined the responses of 276 newly bereaved individuals to a variety of standardised and ad hoc questionnaire items eight weeks post loss. Inventory of Complicated Grief (ICG-R) was used as a gold standard of distress at six months after bereavement. Receiver operating characteristic (ROC) curves analysis was performed for all scales and items regarding ICG-R score. Sensitivity, specificity and area under curve (AUC) were calculated for scales and items with the most promising ROC curve analyses.</p> <p>Results</p> <p>Beck's Depression Inventory (BDI) was the scale with the highest AUC (0.83) and adding a single item question ('Even while my relative was dying, I felt a sense of purpose in my life') gave a sensitivity of 80% and specificity of 75%. The positive/negative predictive values for this combination of questions were 70% and 85%, respectively. With this screening tool bereaved people could be categorized into three groups where group 1 had 7%, group 2 had 23% and group 3 had 64% propensity of suffering from complicated grief six months post loss.</p> <p>Conclusions</p> <p>This study shows that the BDI in combination with a single item question eight weeks post loss may be used for clinical screening for risk of developing complicated grief after six months. The feasibility and clinical implications of the screening tool has to be tested in a clinical setting.</p
Minimum length effects in black hole physics
We review the main consequences of the possible existence of a minimum
measurable length, of the order of the Planck scale, on quantum effects
occurring in black hole physics. In particular, we focus on the ensuing minimum
mass for black holes and how modified dispersion relations affect the Hawking
decay, both in four space-time dimensions and in models with extra spatial
dimensions. In the latter case, we briefly discuss possible phenomenological
signatures.Comment: 29 pages, 12 figures. To be published in "Quantum Aspects of Black
Holes", ed. X. Calmet (Springer, 2014
Impact of resilience enhancing programs on youth surviving the Beslan school siege
The objective of this study was to evaluate a resilience-enhancing program for youth (mean age = 13.32 years) from Beslan, North Ossetia, in the Russian Federation. The program, offered in the summer of 2006, combined recreation, sport, and psychosocial rehabilitation activities for 94 participants, 46 of who were taken hostage in the 2004 school tragedy and experienced those events first hand. Self-reported resilience, as measured by the CD-RISC, was compared within subjects at the study baseline and at two follow-up assessments: immediately after the program and 6 months later. We also compared changes in resilience levels across groups that differed in their traumatic experiences. The results indicate a significant intra-participant mean increase in resilience at both follow-up assessments, and greater self-reported improvements in resilience processes for participants who experienced more trauma events
Target selection and annotation for the structural genomics of the amidohydrolase and enolase superfamilies
To study the substrate specificity of enzymes, we use the amidohydrolase and enolase superfamilies as model systems; members of these superfamilies share a common TIM barrel fold and catalyze a wide range of chemical reactions. Here, we describe a collaboration between the Enzyme Specificity Consortium (ENSPEC) and the New York SGX Research Center for Structural Genomics (NYSGXRC) that aims to maximize the structural coverage of the amidohydrolase and enolase superfamilies. Using sequence- and structure-based protein comparisons, we first selected 535 target proteins from a variety of genomes for high-throughput structure determination by X-ray crystallography; 63 of these targets were not previously annotated as superfamily members. To date, 20 unique amidohydrolase and 41 unique enolase structures have been determined, increasing the fraction of sequences in the two superfamilies that can be modeled based on at least 30% sequence identity from 45% to 73%. We present case studies of proteins related to uronate isomerase (an amidohydrolase superfamily member) and mandelate racemase (an enolase superfamily member), to illustrate how this structure-focused approach can be used to generate hypotheses about sequence–structure–function relationships
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