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Search Results: 1 - 10 of 367592 matches for " T. W. R. Briggs "
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Nancay blind 21cm line survey of the Canes Venatici group region
R. C. Kraan-Korteweg,W. van Driel,F. Briggs,B. Binggeli,T. I. Mostefaoui
Physics , 1998, DOI: 10.1051/aas:1999175
Abstract: A radio spectroscopic driftscan survey in the 21cm line with the Nancay Radio Telescope of 0.08 steradians of sky in the direction of the constellation Canes Venatici covering a heliocentric velocity range of -350 < V_hel < 2350 km/s produced 53 spectral features, which was further reduced to a sample of 33 reliably detected galaxies by extensive follow-up observations. With a typical noise level of rms = 10 mJy after Hanning smoothing, the survey is -- depending on where the detections are located with regard to the center of the beam -- sensitive to M(HI)=1-2x10^8 Msun at 23 Mpc and to M(HI)=4-8x10^7 Msun throughout the CVn Groups (Ho=100). The survey region had been previously examined on deep optical plates by Binggeli et al. 1990 and contains loose groups with many gas-rich galaxies as well as voids. No galaxies that had not been previously identified in these deep optical surveys were uncovered in our HI survey, neither in the groups nor the voids. The implication is that no substantial quantity of neutral hydrogen contained in gas-rich galaxies has been missed in these well-studied groups. All late-type members of our sample are listed in the Fisher and Tully (1981b) optically selected sample of nearby late-type galaxies; the only system not contained in Fisher and Tullys' Catalog is the S0 galaxy NGC 4203. Within the well--sampled CVn group volume with distances corrected for flow motions, the HI mass function is best fitted with the Zwaan et al. (1997) HI mass function (alpha=-1.2) scaled by a factor of f=4.5 in account of the locally overdense region.
Myolipoma Affecting the Erector Spinae: A Case Report in a Child
M. T. R. Parratt,K. Gokaraju,B. G. I. Spiegelberg,J. Miles,S. R. Cannon,T. W. R. Briggs
Case Reports in Medicine , 2009, DOI: 10.1155/2009/520126
Abstract: Myolipoma is a rare, benign, lipomatous tumour which most commonly occurs in the retroperitoneum, pelvis, and abdomen. A 4-year-old boy presented with a painless enlarging mass in the left paraspinal region. Magnetic Resonance Imaging (MRI) revealed a soft tissue lesion with high fat content and areas of calcification. Excision and histopathological analysis revealed a tumour composed of lobules of mature adipose tissue and broad septa of well-differentiated smooth muscle tissue. The smooth muscle nature of the nonfatty component was demonstrated by a diffuse and strong immunoreactivity for smooth muscle actin and desmin. The mass was reported as a myolipoma. The patient made an unremarkable recovery from surgery and remains healthy with no signs of recurrence at seven years. This paper represents the youngest patient diagnosed with this rare soft tissue tumour which is normally confined to the adult population. A newly reported site of the tumour is also highlighted.
The Use of Massive Endoprostheses for the Treatment of Bone Metastases
D. H. Park,P. K. Jaiswal,W. Al-Hakim,W. J. S. Aston,R. C. Pollock,J. A. Skinner,S. R. Cannon,T. W. R. Briggs
Sarcoma , 2007, DOI: 10.1155/2007/62151
Abstract: Purpose. We report a series of 58 patients with metastatic bone disease treated with resection and endoprosthetic reconstruction over a five-year period at our institution. Introduction. The recent advances in adjuvant and neoadjuvant therapy in cancer treatment have resulted in improved prognosis of patients with bone metastases. Most patients who have either an actual or impending pathological fracture should have operative stabilisation or reconstruction. Endoprosthetic reconstructions are indicated in patients with extensive bone loss, failed conventional reconstructions, and selected isolated metastases. Methods and Results. We identified all patients who were diagnosed with metastatic disease to bone between 1999 and 2003. One hundred and seventy-one patients were diagnosed with bone metastases. Metastatic breast and renal cancer accounted for 84 lesions (49%). Fifty-eight patients with isolated bone metastasis to the appendicular skeleton had an endoprosthetic reconstruction. There were 28 males and 30 females. Twelve patients had an endoprosthesis in the upper extremity and 46 patients had an endoprosthesis in the lower extremity. The mean age at presentation was 62 years (24 to 88). At the time of writing, 19 patients are still alive, 34 patients have died, and 5 have been lost to follow up. Patients were followed up and evaluated using the musculoskeletal society tumour score (MSTS) and the Toronto extremity salvage score (TESS). The mean MSTS was 73% (57% to 90%) and TESS was 71% (46% to 95%). Mean follow-up was 48.2 months (range 27 to 82 months) and patients died of disease at a mean of 22 months (2 to 51 months) from surgery. Complications included 5 superficial wound infections, 1 aseptic loosening, 4 dislocations, 1 subluxation, and 1 case, where the tibial component of a prosthesis rotated requiring open repositioning. Conclusions. We conclude that endoprosthetic replacement for the treatment of isolated bone metastases is a reliable method of limb reconstruction in selected cases. It is associated with low complication and failure rates in our series, and achieves the aims of restoring function, allowing early weight bearing and alleviating pain.
Use of a Distal Radius Endoprosthesis Following Resection of a Bone Tumour: A Case Report
Kishan Gokaraju,Kesavan Sri-Ram,James Donaldson,Michael T. R. Parratt,Gordon W. Blunn,Steve R. Cannon,Timothy W. R. Briggs
Sarcoma , 2009, DOI: 10.1155/2009/938295
Abstract: Limited literature is available on the reconstruction of the distal radius using prosthetic replacement following resection of a bone tumour. We present the first reported case, in the English literature, of the use of an entirely metal endoprosthesis for the reconstruction of the distal radius. This case involves a 66-year-old male who was treated for giant cell tumour of the distal radius with surgical excision of the lesion and replacement of the defect using a predominantly titanium endoprosthesis. He was followed-up for 56 months following surgery and had a good functional outcome with no associated pain or complications. We propose that the use of a primarily titanium endoprosthesis for the reconstruction of a bone defect of the distal radius is a suitable alternative, providing good function of the forearm with satisfactory range of movement at the wrist and adequate pain relief.
Extended Power-Law Decays in BATSE Gamma-Ray Bursts: Signatures of External Shocks?
T. W. Giblin,V. Connaughton,J. van Paradijs,R. D. Preece,M. S. Briggs,C. Kouveliotou,R. A. M. J. Wijers,G. J. Fishman
Physics , 2002, DOI: 10.1063/1.1579356
Abstract: The connection between Gamma-Ray Bursts (GRBs) and their afterglows is currently not well understood. Afterglow models of synchrotron emission generated by external shocks in the GRB fireball model predict emission detectable in the gamma-ray regime ($\gax 25$ keV). In this paper, we present a temporal and spectral analysis of a subset of BATSE GRBs with smooth extended emission tails to search for signatures of the ``early high-energy afterglow'', i.e., afterglow emission that initially begins in the gamma-ray phase and subsequently evolves into X-Ray, uv, optical, and radio emission as the blast wave is decelerated by the ambient medium. From a sample of 40 GRBs we find that the temporal decays are best described with a power-law $\sim t^{\beta}$, rather than an exponential, with a mean index $<\beta > \approx -2$. Spectral analysis shows that $\sim 20%$ of these events are consistent with fast-cooling synchrotron emission for an adiabatic blast wave; three of which are consistent with the blast wave evolution of a jet, with $F_{\nu} \sim t^{-p}$. This behavior suggests that, in some cases, the emission may originate from a narrow jet, possibly consisting of ``nuggets'' whose angular size are less than $1 / \Gamma$, where $\Gamma$ is the bulk Lorentz factor.
Evidence for an Early High-Energy Afterglow Observed with BATSE from GRB980923
T. W. Giblin,J. van Paradijs,C. Kouveliotou,V. Connaughton,R. A. M. J. Wijers,M. S. Briggs,R. D. Preece,G. J. Fishman
Physics , 1999, DOI: 10.1086/312285
Abstract: In this Letter, we present the first evidence in the BATSE data for a prompt high-energy (25-300 keV) afterglow component from a gamma-ray burst (GRB), GRB980923. The event consists of rapid variabilty lasting ~40 s followed by a smooth power law emission tail lasting ~400 s. An abrupt change in spectral shape is found when the tail becomes noticeable. Our analysis reveals that the spectral evolution in the tail of the burst mimics that of a cooling synchrotron spectrum, similar to the spectral evolution of the low-energy afterglows for GRBs. This evidence for a separate emission component is consistent with the internal-external shock scenario in the relativistic fireball picture. In particular, it illustrates that the external shocks can be generated during the gamma-ray emission phase, as in the case of GRB990123.
Hyperfine structure of Sc@C82 from ESR and DFT
G. W. Morley,B. J. Herbert,S. M. Lee,K. Porfyrakis,T. J. S. Dennis,D. Nguyen-Manh,R. Scipioni,J. van Tol,A. P. Horsfield,A. Ardavan,D. G. Pettifor,J. C. Green,G. A. D. Briggs
Physics , 2008, DOI: 10.1088/0957-4484/16/11/001
Abstract: The electron spin g- and hyperfine tensors of the endohedral metallofullerene Sc@C82 are anisotropic. Using electron spin resonance (ESR) and density functional theory (DFT), we can relate their principal axes to the coordinate frame of the molecule, finding that the g-tensor is not axially symmetric. The Sc bond with the cage is partly covalent and partly ionic. Most of the electron spin density is distributed around the carbon cage, but 5% is associated with the scandium d_yz orbital, and this drives the observed anisotropy.
The Fourth BATSE Gamma-Ray Burst Catalog (Revised)
W. S. Paciesas,C. A. Meegan,G. N. Pendleton,M. S. Briggs,C. Kouveliotou,T. M. Koshut,J. P. Lestrade,M. L. McCollough,J. J. Brainerd,J. Hakkila,W. Henze,R. D. Preece,V. Connaughton,R. M. Kippen,R. S. Mallozzi,G. J. Fishman,G. A. Richardson,M. Sahi
Physics , 1999, DOI: 10.1086/313224
Abstract: The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (CGRO) has triggered on 1637 cosmic gamma-ray bursts between 1991 April 19 and 1996 August 29. These events constitute the Fourth BATSE burst catalog. The current version (4Br) has been revised from the version first circulated on CD-ROM in September 1997 (4B) to include improved locations for a subset of bursts that have been reprocssed using additional data. A significant difference from previous BATSE catalogs is the inclusion of bursts from periods when the trigger energy range differed from the nominal 50-300 keV. We present tables of the burst occurrence times, locations, peak fluxes, fluences, and durations. In general, results from previous BATSE catalogs are confirmed here with greater statistical significance.
Cold Object Identification in the Java Virtual Machine
Kim T. Briggs,Baoguo Zhou,Gerhard W. Dueck
Computer Science , 2015,
Abstract: Many Java applications instantiate objects within the Java heap that are persistent but seldom if ever referenced by the application. Examples include strings, such as error messages, and collections of value objects that are preloaded for fast access but they may include objects that are seldom referenced. This paper describes a stack-based framework for detecting these "cold" objects at runtime, with a view to marshaling and sequestering them in designated regions of the heap where they may be preferentially paged out to a backing store, thereby freeing physical memory pages for occupation by more active objects. Furthermore, we evaluate the correctness and efficiency of stack-based approach with an Access Barrier. The experimental results from a series of SPECjvm2008 benchmarks are presented.
A simple ecohydrological model captures essentials of seasonal leaf dynamics in semi-arid tropical grasslands
P. Choler, W. Sea, P. Briggs, M. Raupach,R. Leuning
Biogeosciences (BG) & Discussions (BGD) , 2010,
Abstract: Modelling leaf phenology in water-controlled ecosystems remains a difficult task because of high spatial and temporal variability in the interaction of plant growth and soil moisture. Here, we move beyond widely used linear models to examine the performance of low-dimensional, nonlinear ecohydrological models that couple the dynamics of plant cover and soil moisture. The study area encompasses 400 000 km2 of semi-arid perennial tropical grasslands, dominated by C4 grasses, in the Northern Territory and Queensland (Australia). We prepared 8-year time series (2001–2008) of climatic variables and estimates of fractional vegetation cover derived from MODIS Normalized Difference Vegetation Index (NDVI) for 400 randomly chosen sites, of which 25% were used for model calibration and 75% for model validation. We found that the mean absolute error of linear and nonlinear models did not markedly differ. However, nonlinear models presented key advantages: (1) they exhibited far less systematic error than their linear counterparts; (2) their error magnitude was consistent throughout a precipitation gradient while the performance of linear models deteriorated at the driest sites, and (3) they better captured the sharp transitions in leaf cover that are observed under high seasonality of precipitation. Our results showed that low-dimensional models including feedbacks between soil water balance and plant growth adequately predict leaf dynamics in semi-arid perennial grasslands. Because these models attempt to capture fundamental ecohydrological processes, they should be the favoured approach for prognostic models of phenology.
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