1,490 research outputs found
On the effect of pressure, oxygen concentration, air flow and gravity on simulated pool fires
The initial development of a fire is characterized by the establishment of a diffusion flame over the surface of a the condensed fuel and is particularly influenced by gravity, with most of the gaseous flow induced by natural convection. Low initial momentum of the fuel vapor, strong buoyant flows induced by the hot post-combustion gases and consequently low values of the Froude number (inertia-gravity forces ratio) are typical of this kind of scenario. An experimental study is conducted by using a porous burner to simulate the burning of a horizontal combustible surface. Ethane is used as fuel and different mixtures of oxygen and nitrogen as oxidizer. The magnitude of the fuel injection velocities is restricted to values that will keep the Froude number on the order of 10-5, when calculated at normal gravity and pressure, which are characteristic of condensed fuel burning. Two different burners are used, a circular burner (62 mm diameter) placed inside a cylindrical chamber (0.3 m diameter and 1.0 m height) and a rectangular burner (50 mm wide by 200 mm long) placed in a wind tunnel (350 mm long) of rectangular cross section (120 mm wide and 90 mm height). The first burner is used to study the effect of pressure and gravity in the absence of a forced flow parallel to the surface. The second burner is used to study the effect of a forced flow parallel to the burner surface as well as the effect of oxygen concentration in the oxidizer flow. In this case experiments are also conducted at different gravity levels (micro-gravity, 0.2 g(sub 0), g(sub 0) and 1.8 g(sub 0)) to quantify the relative importance of buoyancy
Multifocal Langerhans Cell Histiocytosis in an Adult
Eosinophilic granuloma (EG) is the most common and benign form of the spectrum of disorders referred to as Langerhans cell histiocytosis (LCH). Langerhans cell histiocytosis is primarily regarded as a pediatric disease, with few adult cases of multifocal EG of bone reported. We report a case of multifocal EG in a 48-year-old woman, who presented with right knee pain. Radiographs showed a small lytic lesion in the medial femoral condyle. Diagnosis was confirmed by ultrasound-guided biopsy. She had had a previous EG lesion excised from her skull. Whole-body bone scan demonstrated a new skull lesion in the right diploic space, which was confirmed by magnetic resonance imaging. The patient underwent curettage, bone grafting, and prophylactic internal fixation of the right distal femur lesion. The skull lesion was treated with repeat craniectomy. Two years later, she developed a new lesion in the right distal femoral metaphysis, which was treated with intralesional corticosteroid injections. Now, more than 1 year later, the patient is pain-free with no evidence of new or recurrent disease. Because multifocal EG is a rare diagnosis in adults, appropriate clinical suspicion, in combination with radiographic findings and histologic examination, is essential for correct diagnosis and treatment
No Woman is an Island -- Access to Care and Extreme Measures for Cancer Pain and Lymphedema: A Case Report
Background: Cancer rehabilitation is a rapidly growing diverse field in physiatry. This case provides an example where rehabilitation physiatrists played a crucial role in the pain management, education, and rehabilitation before and after a palliative amputation. Due to her limited resources, both in her home country and in her local community, she could not access appropriate care that may have prevented the need for amputation. Though amputation is not generally accepted as the first line of treatment for pain, there have been several reports of palliative amputation in metastatic cancer patients. In particular, fore quarter amputations have been reported in metastatic breast cancer patients to manage pain and recurrent fractures
GWASinspector:comprehensive quality control of genome-wide association study results
Quality control (QC) of genome wide association study (GWAS) result files has become increasingly difficult due to advances in genomic technology. The main challenges include continuous increases in the number of polymorphic genetic variants contained in recent GWASs and reference panels, the rising number of cohorts participating in a GWAS consortium, and inclusion of new variant types. Here, we present GWASinspector, a flexible R package for comprehensive QC of GWAS results. This package is compatible with recent imputation reference panels, handles insertion/deletion and multi-allelic variants, provides extensive QC reports and efficiently processes big data files. Reference panels covering three human genome builds (NCBI36, GRCh37 and GRCh38) are available. GWASinspector has a user friendly design and allows easy set-up of the QC pipeline through a configuration file. In addition to checking and reporting on individual files, it can be used in preparation of a meta-analysis by testing for systemic differences between studies and generating cleaned, harmonized GWAS files. Comparison with existing GWAS QC tools shows that the main advantages of GWASinspector are its ability to more effectively deal with insertion/deletion and multi-allelic variants and its relatively low memory use
Non-Abelian toplogical superconductors from topological semimetals and related systems under superconducting proximity effect
Non-Abelian toplogical superconductors are characterized by the existence of
{zero-energy} Majorana fermions bound in the quantized vortices. This is a
consequence of the nontrivial bulk topology characterized by an {\em odd} Chern
number. It is found that in topological semimetals with a single two-bands
crossing point all the gapped superconductors are non-Abelian ones. Such a
property is generalized to related but more generic systems which will be
useful in the search of non-Abelian superconductors and Majorana fermions
Genetic Risk Scores for Complex Disease Traits in Youth
Background: For most disease-related traits the magnitude of the contribution of genetic factors in adolescents remains unclear. Methods: Twenty continuous traits related to anthropometry, cardiovascular and renal function, metabolism, and inflammation were selected from the ongoing prospective Tracking Adolescents' Individual Lives Survey cohort in the Netherlands with measurements of up to 5 waves from age 11 to 22 years (n=1354, 47.6% males) and all traits available at the third wave (mean age [SD]=16.22 [0.66]). For each trait, unweighted and weighted genetic risk scores (GRSs) were generated based on significantly associated single nucleotide polymorphisms identified from literature. The variance explained by the GRSs in adolescents were estimated by linear regression after adjustment for covariates. Results: Except for ALT (alanine transaminase), all GRSs were significantly associated with their traits. The trait variance explained by the GRSs was highest for lipoprotein[a] (39.59%) and varied between 0.09% (ALT) and 18.49% (LDL [low-density lipoprotein]) for the other traits. For most traits, the variances explained in adolescents were comparable with or slightly smaller than those in adults. Significant increases of trait levels (except ALT) and increased risks for overweight/obesity (odds ratio, 6.41 [95% CI, 2.95-15.56]) and hypertension (odds ratio, 2.86 [95% CI, 1.39-6.17]) were found in individuals in the top GRS decile compared with those at the bottom decile. Conclusions: Variances explained by adult-based GRSs for disease-related traits in adolescents, although still relatively modest, were comparable with or slightly smaller than in adults offering promise for improved risk prediction at early ages
Ecology of the Invasive Red Alga Gracilaria salicornia (Rhodophyta) on O'ahu, Hawai'i
The red alga Gracilaria salicornia (C. Agardh) E. Y. Dawson was introduced
intentionally to two reefs on O'ahu, Hawai'i, in the 1970s for experimental
aquaculture for the agar industry. Some 30 yr later, this species has
spread from the initial sites of introduction and is now competing with native
marine flora and fauna. The goals of this study were to quantify various aspects
of G. salicornia ecology in Hawai'i in an effort to develop control or eradication
tools. Experimental plots were established to determine cover and biomass of G.
salicornia per square meter and to determine the amount of time and person
hours needed to remove G. salicornia from these plots. Substantial amounts of G.
salicornia become dislodged from the reef during large wave events and periodically
become deposited onto the beach in front of the Waikiki Aquarium. Algal
beach wash biomass was quantified and positive relationships were established
between swell height and the amount of algae that washed up onto the beach in
this location. We then quantified the ability of G. salicornia vegetative fragments
to regrow after desiccation to determine if algal biomass stranded on shore survives
the tidal cycle until being washed back out on the reef at high tide. Gracilaria
salicornia was remarkably resistant to temperature, salinity, and chemical
treatments examined as possible in situ control options. Herbivore preference
tests showed that a native Gracilaria species is consumed far more frequently
than the alien congener. Finally, large-scale community volunteer efforts were
organized to remove drifting G. salicornia fragments from the reef area in front
of the Waikiki Aquarium. Over 20,000 kg of alien algal fragments were removed
from this location in five 4-hr cleanup events. However, based on G. salicornia
growth rates, ability to fragment, physical tolerance, and low herbivory, it is
clear that a large-scale dedicated effort will be needed to control this invasive
species on Waikiki's reefs
The Longitudinal Polarimeter at HERA
The design, construction and operation of a Compton back-scattering laser
polarimeter at the HERA storage ring at DESY are described. The device measures
the longitudinal polarization of the electron beam between the spin rotators at
the HERMES experiment with a fractional systematic uncertainty of 1.6%. A
measurement of the beam polarization to an absolute statistical precision of
0.01 requires typically one minute when the device is operated in the
multi-photon mode. The polarimeter also measures the polarization of each
individual electron bunch to an absolute statistical precision of 0.06 in
approximately five minutes. It was found that colliding and non-colliding
bunches can have substantially different polarizations. This information is
important to the collider experiments H1 and ZEUS for their future
longitudinally polarized electron program because those experiments use the
colliding bunches only.Comment: 21 pages (Latex), 14 figures (EPS
Introduction to topological superconductivity and Majorana fermions
This short review article provides a pedagogical introduction to the rapidly
growing research field of Majorana fermions in topological superconductors. We
first discuss in some details the simplest "toy model" in which Majoranas
appear, namely a one-dimensional tight-binding representation of a p-wave
superconductor, introduced more than ten years ago by Kitaev. We then give a
general introduction to the remarkable properties of Majorana fermions in
condensed matter systems, such as their intrinsically non-local nature and
exotic exchange statistics, and explain why these quasiparticles are suspected
to be especially well suited for low-decoherence quantum information
processing. We also discuss the experimentally promising (and perhaps already
successfully realized) possibility of creating topological superconductors
using semiconductors with strong spin-orbit coupling, proximity-coupled to
standard s-wave superconductors and exposed to a magnetic field. The goal is to
provide an introduction to the subject for experimentalists or theorists who
are new to the field, focusing on the aspects which are most important for
understanding the basic physics. The text should be accessible for readers with
a basic understanding of quantum mechanics and second quantization, and does
not require knowledge of quantum field theory or topological states of matter.Comment: 21 pages, 5 figure
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