127 research outputs found
Phase Structure and Compactness
In order to study the influence of compactness on low-energy properties, we
compare the phase structures of the compact and non-compact two-dimensional
multi-frequency sine-Gordon models. It is shown that the high-energy scaling of
the compact and non-compact models coincides, but their low-energy behaviors
differ. The critical frequency at which the sine-Gordon model
undergoes a topological phase transition is found to be unaffected by the
compactness of the field since it is determined by high-energy scaling laws.
However, the compact two-frequency sine-Gordon model has first and second order
phase transitions determined by the low-energy scaling: we show that these are
absent in the non-compact model.Comment: 21 pages, 5 figures, minor changes, final version, accepted for
publication in JHE
Physics, Astrophysics and Cosmology with Gravitational Waves
Gravitational wave detectors are already operating at interesting sensitivity
levels, and they have an upgrade path that should result in secure detections
by 2014. We review the physics of gravitational waves, how they interact with
detectors (bars and interferometers), and how these detectors operate. We study
the most likely sources of gravitational waves and review the data analysis
methods that are used to extract their signals from detector noise. Then we
consider the consequences of gravitational wave detections and observations for
physics, astrophysics, and cosmology.Comment: 137 pages, 16 figures, Published version
<http://www.livingreviews.org/lrr-2009-2
Canadian infants' nutrient intakes from complementary foods during the first year of life
<p>Abstract</p> <p>Background</p> <p>Complementary feeding is currently recommended after six months of age, when the nutrients in breast milk alone are no longer adequate to support growth. Few studies have examined macro- and micro-nutrient intakes from complementary foods (CF) only. Our purpose was to assess the sources and nutritional contribution of CF over the first year of life.</p> <p>Methods</p> <p>In July 2003, a cross-sectional survey was conducted on a nationally representative sample of mothers with infants aged three to 12 months. The survey was administered evenly across all regions of the country and included a four-day dietary record to assess infants' CF intakes in household (tablespoon) measures (breast milk and formula intakes excluded). Records from 2,663 infants were analyzed for nutrient and CF food intake according to 12 categories. Mean daily intakes for infants at each month of age from CF were pooled and compared to the Dietary Reference Intakes for the respective age range.</p> <p>Results</p> <p>At three months of age, 83% of infants were already consuming infant cereals. Fruits and vegetables were among the most common foods consumed by infants at all ages, while meats were least common at all ages except 12 months. Macro- and micro-nutrient intakes from CF generally increased with age. All mean nutrient intakes, except vitamin D and iron, met CF recommendations at seven to 12 months.</p> <p>Conclusions</p> <p>Complementary foods were introduced earlier than recommended. Although mean nutrient intakes from CF at six to 12 months appear to be adequate among Canadian infants, further attention to iron and vitamin D intakes and sources may be warranted.</p
Lower Bounds for Multi-Server Oblivious RAMs
In this work, we consider the construction of oblivious RAMs (ORAM) in a setting
with multiple servers and the adversary may corrupt a subset of the servers.
We present an overhead lower bound for any -server
ORAM that limits any PPT adversary to distinguishing advantage at most when
only one server is corrupted. In other words, if one insists on
negligible distinguishing advantage, then multi-server ORAMs cannot
be faster than single-server ORAMs even with polynomially many servers
of which only one unknown server is corrupted.
Our results apply to ORAMs that may err with probability at most
as well as scenarios where the adversary corrupts larger subsets of servers.
We also extend our lower bounds to other important data structures
including oblivious stacks, queues, deques, priority queues and search trees
The broad spectrum of unbearable suffering in end of life cancer studied in dutch primary care
<p>Abstract</p> <p>Background</p> <p>Unbearable suffering most frequently is reported in end-of-life cancer patients in primary care. However, research seldom addresses unbearable suffering. The aim of this study was to comprehensively investigate the various aspects of unbearable suffering in end-of-life cancer patients cared for in primary care.</p> <p>Methods</p> <p>Forty four general practitioners recruited end-of-life cancer patients with an estimated life expectancy of half a year or shorter. The inclusion period was three years, follow-up lasted one additional year. Practices were monitored bimonthly to identify new cases. Unbearable aspects in five domains and overall unbearable suffering were quantitatively assessed (5-point scale) through patient interviews every two months with a comprehensive instrument. Scores of 4 (serious) or 5 (hardly can be worse) were defined unbearable. The last interviews before death were analyzed. Sources providing strength to bear suffering were identified through additional open-ended questions.</p> <p>Results</p> <p>Seventy six out of 148 patients (51%) requested to participate consented; the attrition rate was 8%, while 8% were alive at the end of follow-up. Sixty four patients were followed up until death; in 60 patients interviews were complete. Overall unbearable suffering occurred in 28%. A mean of 18 unbearable aspects was present in patients with serious (score 4) overall unbearable suffering. Overall, half of the unbearable aspects involved the domain of traditional medical symptoms. The most frequent unbearable aspects were weakness, general discomfort, tiredness, pain, loss of appetite and not sleeping well (25%-57%). The other half of the unbearable aspects involved the domains of function, personhood, environment, and nature and prognosis of disease. The most frequent unbearable aspects were impaired activities, feeling dependent, help needed with housekeeping, not being able to do important things, trouble accepting the situation, being bedridden and loss of control (27%-55%). The combination of love and support was the most frequent source (67%) providing strength to bear suffering.</p> <p>Conclusions</p> <p>Overall unbearable suffering occurred in one in every four end-of-life cancer patients. Half of the unbearable aspects involved medical symptoms, the other half concerned psychological, social and existential dimensions. Physicians need to comprehensively assess suffering and provide psychosocial interventions alongside physical symptom management.</p
The Mass Distribution and Rotation Curve in the Galaxy
The mass distribution in the Galaxy is determined by dynamical and
photometric methods. Rotation curves are the major tool for determining the
dynamical mass distribution in the Milky Way and spiral galaxies. The
photometric (statistical) method utilizes luminosity profiles from optical and
infrared observations, and assumes empirical values of the mass-to-luminosity
(M/L) ratio to convert the luminosity to mass. In this chapter the dynamical
method is described in detail, and rotation curves and mass distribution in the
Milky Way and nearby spiral galaxies are presented. The dynamical method is
categorized into two methods: the decomposition method and direct method. The
former fits the rotation curve by calculated curve assuming several mass
components such as a bulge, disk and halo, and adjust the dynamical parameters
of each component. Explanations are given of the mass profiles as the de
Vaucouleurs law, exponential disk, and dark halo profiles inferred from
numerical simulations. Another method is the direct method, with which the mass
distribution can be directly calculated from the data of rotation velocities
without employing any mass models. Some results from both methods are
presented, and the Galactic structure is discussed in terms of the mass.
Rotation curves and mass distributions in external galaxies are also discussed,
and the fundamental mass structures are shown to be universal.Comment: 54 pages, 25 figures, in 'Planets, Stars and Stellar Systems',
Springer, Vol. 5, ed. G. Gilmore, Chap. 19. Note: Preprint with full figures
is available from http://www.ioa.s.u-tokyo.ac.jp/~sofue/htdocs/2013psss
Painful and painless mutations of SCN9A and SCN11A voltage-gated sodium channels
Chronic pain is a global problem affecting up to 20% of the world’s population and has a significant economic, social and personal cost to society. Sensory neurons of the dorsal root ganglia (DRG) detect noxious stimuli and transmit this sensory information to regions of the central nervous system (CNS) where activity is perceived as pain. DRG neurons express multiple voltage-gated sodium channels that underlie their excitability. Research over the last 20 years has provided valuable insights into the critical roles that two channels, NaV1.7 and NaV1.9, play in pain signalling in man. Gain of function mutations in NaV1.7 cause painful conditions while loss of function mutations cause complete insensitivity to pain. Only gain of function mutations have been reported for NaV1.9. However, while most NaV1.9 mutations lead to painful conditions, a few are reported to cause insensitivity to pain. The critical roles these channels play in pain along with their low expression in the CNS and heart muscle suggest they are valid targets for novel analgesic drugs
A Genome-Wide Metabolic QTL Analysis in Europeans Implicates Two Loci Shaped by Recent Positive Selection
We have performed a metabolite quantitative trait locus (mQTL) study of the 1H nuclear magnetic resonance spectroscopy (1H NMR) metabolome in humans, building on recent targeted knowledge of genetic drivers of metabolic regulation. Urine and plasma samples were collected from two cohorts of individuals of European descent, with one cohort comprised of female twins donating samples longitudinally. Sample metabolite concentrations were quantified by 1H NMR and tested for association with genome-wide single-nucleotide polymorphisms (SNPs). Four metabolites' concentrations exhibited significant, replicable association with SNP variation (8.6×10−11<p<2.8×10−23). Three of these—trimethylamine, 3-amino-isobutyrate, and an N-acetylated compound—were measured in urine. The other—dimethylamine—was measured in plasma. Trimethylamine and dimethylamine mapped to a single genetic region (hence we report a total of three implicated genomic regions). Two of the three hit regions lie within haplotype blocks (at 2p13.1 and 10q24.2) that carry the genetic signature of strong, recent, positive selection in European populations. Genes NAT8 and PYROXD2, both with relatively uncharacterized functional roles, are good candidates for mediating the corresponding mQTL associations. The study's longitudinal twin design allowed detailed variance-components analysis of the sources of population variation in metabolite levels. The mQTLs explained 40%–64% of biological population variation in the corresponding metabolites' concentrations. These effect sizes are stronger than those reported in a recent, targeted mQTL study of metabolites in serum using the targeted-metabolomics Biocrates platform. By re-analysing our plasma samples using the Biocrates platform, we replicated the mQTL findings of the previous study and discovered a previously uncharacterized yet substantial familial component of variation in metabolite levels in addition to the heritability contribution from the corresponding mQTL effects
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