1,744 research outputs found
The Formation of the Double Pulsar PSR J0737-3039A/B
Recent timing observations of the double pulsar J0737-3039A/B have shown that
its transverse velocity is extremely low, only 10 km/s, and nearly in the Plane
of the Galaxy. With this new information, we rigorously re-examine the history
and formation of this system, determining estimates of the pre-supernova
companion mass, supernova kick and misalignment angle between the pre- and
post-supernova orbital planes. We find that the progenitor to the recently
formed `B' pulsar was probably less than 2 MSun, lending credence to
suggestions that this object may not have formed in a normal supernova
involving the collapse of an iron core. At the same time, the supernova kick
was likely non-zero. A comparison to the history of the double-neutron-star
binary B1534+12 suggests a range of possible parameters for the progenitors of
these systems, which should be taken into account in future binary population
syntheses and in predictions of the rate and spatial distribution of short
gamma-ray burst events.Comment: To appear in MNRAS Letters. Title typo fix only; no change to pape
Mapping With the Land: Co-developing a Cumulative Impact Monitoring and Land Stewardship Framework with Sambaa Kâe First Nation, Northwest Territories, Canada
Across the Northwest Territories (NWT), Canada, Indigenous populations are striving to achieve effective environmental protection, whilst navigating complex methods, policies, and research relationships within co-management contexts. This thesis seeks to identify how differing cultural systems, environmental change, and fractured partnerships may be unified to align with the needs of the Sambaa Kâe First Nation (SKFN), a remote Dehcho Dene community. Indigenous methodologies guided co-development of research questions with SKFN leadership which yielded objectives a) develop a GIS-based method to manage, organize and mobilize cultural and environmental data; b) develop a new stewardship monitoring procedure so that users can apply the former while âWith The Landâ (WTL), and c) test new methods developed in (a) and (b). A mapping rubric developed by the NWT Geologic Surveyâs Thermokarst Collective (TKC) working group was expanded to include themes related to biological, cultural, and socio-political change. Interviews, focus groups, and participant observation directed the collection of 195 GPS-link observations which centered Dene perspectives of space and place. This thesis provides SKFN with an improved operational procedure for data collection as well as a functional social framework adapted for the organization of grassroots, community based, intergenerational knowledge exchange. This produced the praxis, âMapping with the Land,â where youth and Elders are united through cumulative impact monitoring and cultural revitalization, with the assistance of GIS. This aims to increase communication and understanding between local, institutional, and government actors by bridging gaps in research capabilities, local capacity, and recognition of Dene Law
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HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM
The objective of this project is to improve the productivity and lower the expense of existing vacuum blasting technology. This technology is used to remove radioactive contamination, PCBs, and lead-based paint and provides worker protection by continuously recycling the material and dust for the decontamination tasks. The proposed work would increase the cleaning rate and provide safe and cost-effective decontamination of the DOE sites. This work focuses on redesigning and improving existing vacuum blasting technology including blast head nozzles, ergonomic handling of the blast head by reducing its weight; brush-ring design, vacuum level regulator, efficiency of the dust separator, and operational control sensors. The redesign is expected to enhance the productivity and economy of the vacuum blasting system by at least 50% over current vacuum blasting systems. There are three phases in the project. Phase I consists of developing and testing mathematical models. Phase II consists of pre-prototype design and fabrication and pre-prototype unit testing. Phase III consists of prototype design and field verification testing. In phase I, mathematical models are developed and analyzed for the nozzle, blast head, wind curtain, and dust separator, first as individual devices and then combined as an integrated model. This allows study of respective airflow and design parameters. The Contractor shall, based on the results of the mathematical modeling studies, design experimental models of the components and test these models. In addition, the Contractor shall develop sensors to detect the relationship of the blast head to the blast surfaces and controls to minimize the dependency on an operator's skill and judgment to obtain optimum positioning, as well as real-time characterization sensors to determine as the blast head is moving the depth to which coatings must be removed, thereby improving production and minimizing waste. In phase II, the Contractor shall design and construct a pre-prototype of the nozzle, blast head with wind curtain, sensors, and dust separator and test this system to assess the performance of the new design under controlled conditions at the contractor's facility. In phase III, the Contractor shall design and construct a prototype of the High Productivity Vacuum Blasting System, based on the results of the pre-prototype design and testing performed. This unit will be a full-scale prototype and will be tested at a designated Department of Energy (DOE) facility. Based on the results, the system performance, the productivity, and the economy of the improved vacuum blasting system will be evaluated
Comparison of MRI and DXA to measure muscle size and age-related atrophy in thigh muscles.
OBJECTIVES
Magnetic resonance imaging (MRI) and dual-energy x-ray absorptiometry (DXA) were used to examine the thigh lean mass in young and old men and women.
METHODS
A whole-body DXA scan was used to estimate thigh lean mass in young (20 men; 22.4±3.1y; 18 women; 22.1±2.0y) and older adults (25 men; 72.3±4.9y; 28 women; 72.0±4.5y). Thigh lean mass determined with a thigh scan on the DXA or full thigh MRI scans were compared.
RESULTS
Although the thigh lean mass quantified by DXA and MRI in young and older participants were correlated (R(2)=0.88; p<0.001) the magnitude of the differences in thigh lean mass between young and old was smaller with DXA than MRI (old vs. young men 79.5±13.1% and 73.4±11.2%; old vs. young women 88.6±11.8% and 79.4±12.3%, respectively). Detailed analysis of MRI revealed 30% smaller quadriceps muscles in the older than young individuals, while the other thigh muscles were only 18% smaller.
CONCLUSIONS
DXA underestimates the age-related loss of thigh muscle mass in comparison to MRI. The quadriceps muscles were more susceptible to age-related atrophy compared with other thigh muscles
Comparison of Hip and Knee Biomechanics during Sidestep Cutting in Male Basketball Athletes with and without Anterior Cruciate Ligament Reconstruction
This study aimed to compare hip and knee biomechanics during sidestep cutting on the operated and non-operated sides in individuals with anterior cruciate ligament reconstruction (ACLR), and in an uninjured control group. Twenty male basketball athletes, 10 individuals with ACLR and 10 controls, were recruited. Hip and knee joint angles and angular velocities were investigated with a three-dimensional motion analysis system, and ground reaction forces (GRF) along with moments were collected during the deceleration phase of the stance limb during sidestep cutting maneuvers. We found significantly higher peak hip flexion, hip internal rotation angular velocities, and peak thigh angular velocity in the sagittal plane in the ACLR group. In addition, the peak vertical GRF and peak posterior GRF of the ACLR group were significantly higher than those of the control group. Univariate analyses indicated that the posterior GRF of the non-operated side was significantly higher than in the matched operated side in the control group. The operated and non-operated sides in male basketball athletes with ACLR showed alterations in hip and knee biomechanics compared with a control group, especially in the sagittal plane. Therefore, the emphasis of neuromuscular control training for the hip and the knee in basketball players with ACLR is required
Inhibition of release of inflammatory in primary and cultured cells by a Chinese herbal medicine formula for allergic rhinitis
BACKGROUND - We demonstrated that a Chinese herbal formula, which we refer to as RCM-101, developed from a traditional Chinese medicine formula, reduced nasal and non-nasal symptoms of seasonal allergic rhinitis (SAR). The present study in primary and cultured cells was undertaken to investigate the effects of RCM-101 on the production/release of inflammatory mediators known to be involved in SAR. METHODS - Compound 48/80-induced histamine release was studied in rat peritoneal mast cells. Production of leukotriene B4 induced by the calcium ionophore A23187 was studied in porcine neutrophils using an HPLC assay and lipopolysaccharide-stimulated prostaglandin E2 production was studied in murine macrophage (Raw 264.7) cells by immune-enzyme assay. Expression of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) was determined in Raw 264.7 cells, using western blotting techniques. RESULTS - RCM-101 (1-100 microg/mL) produced concentration-dependent inhibition of compound 48/80-induced histamine release from rat peritoneal mast cells and of lipopolysaccharide-stimulated prostaglandin E2 release from Raw 264.7 cells. Over the range 1 - 10 microg/mL, it inhibited A23187-induced leukotriene B4 production in porcine neutrophils. In addition, RCM-101 (100 microg/mL) inhibited the expression of COX-2 protein but did not affect that of COX-1. CONCLUSION - The findings indicate that RCM-101 inhibits the release and/or synthesis of histamine, leukotriene B4 and prostaglandin E2 in cultured cells. These interactions of RCM-101 with multiple inflammatory mediators are likely to be related to its ability to reduce symptoms of allergic rhinitis
Discordance of physiological and biochemical response to smoking and to psychological stress
Both smoking and psychological stress produce marked effects upon cardiovascular function, and several studies have demonstrated that in combination they produce additive or potentiating effects. More recently, it has been reported that individuals strongly reactive to psychological stress are also strongly reactive to nicotine. In an attempt to replicate and extend those findings, we examined reactivity to smoking and competitive mental arithmetic across several physiological and biochemical variables. Despite stable responding across mental arithmetic trials, we were unable to demonstrate significant correlations between reactivity to smoking and to a psychological stressor. We further observed that anxiety level, when low, was a poor predictor of desire to smoke and of withdrawal, whereas higher anxiety levels were more tightly linked to these measures. These findings have implications for the iDentification of individuals at risk of cardiovascular disease as well as for the design of smoking treatment and relapse prevention programs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72030/1/j.1360-0443.1990.tb01607.x.pd
Risk factors for wound infection in surgery for spinal metastasis
Wound infection rates are generally higher in patients undergoing surgery for spinal metastasis. Risk factors of wound infection in these patients are poorly understood.
Purpose
To identify demographic and clinical variables that may be associated with patients experiencing a higher wound infection rate.
Study design
Retrospective study with prospectively collected data of spinal metastasis patients operated consecutively at a University Teaching Hospital, adult spine division which is a tertiary referral centre for complex spinal surgery.
Patient sample
Ninety-eight patients were all surgically treated, consecutively from January 2009 to September 2011. Three patients had to be excluded due to inadequate data.
Outcome measures
Physiological measures, with presence or absence of microbiologically proven infection.
Methods
Various demographic and clinical data were recorded, including age, serum albumin level, blood total lymphocyte count, corticosteroid intake, Malnutrition Universal Screening Tool (MUST) score, neurological disability, skin closure material used, levels of surgery and administration of peri-operative corticosteroids. No funding was received from any sources for this study and as far as we are aware, there are no potential conflict of interest-associated biases in this study.
Results
Higher probabilities of infection were associated with low albumin level, seven or more levels of surgery, use of delayed/non-absorbable skin closure material and presence of neurological disability. Of these factors, levels of surgery were found to be statistically significant at the 5 % significance level.
Conclusion
Risk of infection is high (17.9 %) in patients undergoing surgery for spinal metastasis. Seven or more vertebral levels of surgery increase the risk of infection significantly (p < 0.05). Low albumin level and presence of neurological disability appear to show a trend towards increased risk of infection. Use of absorbable skin closure material, age, low lymphocyte count, peri-operative administration of corticosteroids and MUST score do not appear to influence the risk of infection
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