Injury rate, mechanism, and risk factors of hamstring strain injuries in sports: A review of the literature

Hamstring strains are one of most common sports injuries. The purpose of this literature review is to summarize studies on hamstring strain injury rate, mechanism, and risk factors in the last several decades with a focus on the prevention and rehabilitation of this injury. Hamstring injury commonly occurs in sporting events in which high speed sprinting and kicking are frequently performed, such as Australian football, English rugby, American football, and soccer. Basic science studies have demonstrated that a muscle strain injury occurs due to excessive strain in eccentric contraction instead of force, and that elongation speed and duration of activation before eccentric contraction affect the severity of the injury. Hamstring strain injury is likely to occur during the late swing phase and late stance phase of sprint running. Shortened optimum muscle length, lack of muscle flexibility, strength imbalance, insufficient warm-up, fatigue, lower back injury, poor lumbar posture, and increased muscle neural tension have been identified as modifiable risk factors while muscle compositions, age, race, and previous injuries are non-modifiable risk factors. The theoretical basis of some of these risk factors, however, is lacking, and the results of clinical studies on these risk factors are inconsistent. Future studies are needed to establish the cause-and-effect relationships between those proposed risk factors and the injury

Analysis of Negative Revisions to Natural Gas Reserves in Texas

Early problems in overestimating effective porosity in some deep Delaware Basin carbonate reservoirs in the Permian Basin, particularly in District 8, resulted in noticeable negative revisions once these issues were resolved. However, the net negative volume of revisions for the Permian Basin (Districts 8, SA, and parts of 7B and 7C) was nearly an order of magnitude less than that for the Gulf Coast Basin. The largest negative revisions of total natural gas reserves were concentrated in the Gulf Coast within Texas Railroad Commission Districts 2, 3, and 4. District 4, with the largest volume of negative revisions, accounted for 56 percent of all negative revisions in Texas for the period 1966-1979. The total for the three districts equaled that of the whole state for the same period. Negative revisions of non-associated gas reserves in Districts 2, 3, and 4 accounted for more than two-thirds of the total gas negative revisions for the entire state from 1966 through 1979. Large negative revisions were mainly due to a combination of interrelated factors. Among these, the original overestimation of natural gas reserves in the Texas Gulf Coast, fueled by optimism from market-related incentives, was significant. These estimates underwent insufficient critical review and reassessment, as supplies greatly exceeded demand. Continued high Reserves to Production (R/P) ratios into the 1960s further delayed reassessment. Technical variables such as water saturation, reservoir heterogeneity, and recovery factors, as well as non-technical variables including economic climate and regulatory controls, were analyzed. Concern should be raised regarding the quality of reserve estimates declared during times of excess supply, as these reserves would not have undergone the test of extended maximum demand. However, there have been more frequent reviews of actual recoverable reserves over the last five years. Continued careful review of technical factors and awareness of the impacts of economic and regulatory environment changes suggest that extensive negative revisions over the next 10 to 20 years can be avoided.Bureau of Economic Geolog

Analysis of Negative Revisions to Natural Gas Reserves in Texas

The role of negative revisions in the large-scale decline in natural gas reserves in Texas during the late 1960s and through the 1970s was examined. Analysis of the factors that contributed to the negative revisions determined that no single element was responsible. However, (1) continued high levels of production, (2) original optimistic estimates of gas in place and recovery factors, (3) market-related factors that encouraged overestimation of reserves, and (4) unusually high reserves-to-production ratios (> 15) that obscured the underlying weakness in reserves combined in the Texas Gulf Coast to drastically reduce booked reserves of natural gas. Negative revisions totaling more than 20 trillion cubic feet during the period were found to have resulted mainly from ambiguities in the degree of reservoir heterogeneity, in calculation of water saturations, and in drive mechanism, along with the overestimation of reserves due to optimism encouraged by market-related incentives. The much-reduced reserves-to-production ratios that now exist, along with continued closer monitoring of technical, economic, and regulatory factors that affect gas reserves, indicate that a return of extensive negative revisions over the next 10 to 20 years is avoidable.Bureau of Economic Geolog

Opportunities for Additional Recovery in University Lands Reservoirs -- Characterization of University Lands Reservoirs, Final Report

In 1984, The University of Texas System funded a Bureau of Economic Geology project, "Characterization of University Lands Reservoirs," to assess in detail the potential for incremental recovery of oil from University Lands reservoirs by extended conventional methods. The objectives of the 5-year project were to quantify the volumes of unrecovered mobile oil remaining in reservoirs on University Lands, to determine whether the specific location of the unrecovered mobile oil could be delineated through integrated geoscience characterization of individual reservoirs, and to develop strategies to optimize recovery of this resource. Unrecovered mobile oil is mobile at reservoir conditions but is prevented from migrating to the wellbore by geologic complexities or heterogeneities. This final report describes results of the 5 years of research conducted on University Lands reservoirs. One hundred and one reservoirs, each of which has produced more than 1 million stock tank barrels (MMSTB) of oil, were included in a resource assessment and play analysis undertaken (1) to determine the volumes and distribution of all components of the University Lands resource base and (2) to select reservoirs for detailed analysis. These reservoirs collectively contained 7.25 billion barrels (BSTB) of oil at discovery, have produced 1.5 BSTB, and contain 200 MMSTB of reserves. Ultimate recovery at implemented technology is projected to be 24 percent of the original oil in place; thus, 5.5 BSTB of oil will remain after recovery of existing reserves. Unrecovered mobile oil (exclusive of reserves) amounts to 2.2 BSTB, and immobile, or residual, oil totals 3.3 BSTB.Bureau of Economic Geolog

Thickness dependence of the magnetic hysteresis of NiFe-31% films as a function of an applied isotropic in-plane stress

The magnetic hysteresis of dc magnetron-sputtered Ni69Fe31 films that were sandwiched between titanium layers was investigated as a function of an externally applied isotropic in-plane strain. The hysteresis curves were measured with a Kerr magnetometer that monitored the longitudinal Kerr ellipticity as a function of the in-plane magnetic field. The strain was created by bending the samples in two dimensions using a pressure cell. Measurements were performed on films with different thicknesses. The magnetoelastic properties appeared to be much smaller for films with a thickness of 100 nm than for films with a thickness of 288 or 500 nm. This might be due to a change of the domain wall pinning, or a change of the domain wall density as a function of the film thickness. Measurements under compressive isotropic in-plane stress were shown to be possible by flipping the sample in the pressure holder and measuring through the glass substrate. The Faraday effect and stress-induced birefringence in the glass substrate did not hinder the accumulation of noiseless hysteresis data. The magnetoelastic effects appeared to be different for positive and negative values of the applied stress

Positional identification of variants of Adamts16 linked to inherited hypertension

A previously reported blood pressure (BP) quantitative trait locus on rat Chromosome 1 was isolated in a short congenic segment spanning 804.6 kb. The 804.6 kb region contained only two genes, LOC306664 and LOC306665. LOC306664 is predicted to translate into A Disintegrin-like and Metalloproteinase with Thrombospondin Motifs-16 (Adamts16). LOC306665 is a novel gene. All predicted exons of both LOC306664 and LOC306665 were sequenced. Non-synonymous variants were identified in only one of these genes, LOC306664. These variants were naturally existing polymorphisms among inbred, outbred and wild rats. The full-length rat transcript of Adamts16 was detected in multiple tissues. Similar to ADAMTS16 in humans, expression of Adamts16 was prominent in the kidney. Renal transcriptome analysis suggested that a network of genes related to BP was differential between congenic and S rats. These genes were also differentially expressed between kidney cell lines with or without knock-down of Adamts16. Adamts16 is conserved between rats and humans. It is a candidate gene within the homologous region on human Chromosome 5, which is linked to systolic and diastolic BP in the Quebec Family Study. Multiple variants, including an Ala to Pro variant in codon 90 (rs2086310) of human ADAMTS16, were associated with human resting systolic BP (SBP). Replication study in GenNet confirmed the association of two variants of ADAMTS16 with SBP, including rs2086310. Overall, our report represents a high resolution positional cloning and translational study for Adamts16 as a candidate gene controlling BP

Perspective and priorities for improvement of parathyroid hormone (PTH) measurement – A view from the IFCC Working Group for PTH

Parathyroid hormone (PTH) measurement in serum or plasma is a necessary tool for the exploration of calcium/phosphate disorders, and is widely used as a surrogate marker to assess skeletal and mineral disorders associated with chronic kidney disease (CKD), referred to as CKD-bone mineral disorders (CKD-MBD). CKD currently affects >10% of the adult population in the United States and represents a major health issue worldwide. Disturbances in mineral metabolism and fractures in CKD patients are associated with increased morbidity and mortality. Appropriate identification and management of CKD-MBD is therefore critical to improving clinical outcome. Recent increases in understanding of the complex pathophysiology of CKD, which involves calcium, phosphate and magnesium balance, and is also influenced by vitamin D status and fibroblast growth factor (FGF)-23 production, should facilitate such improvement. Development of evidence-based recommendations about how best to use PTH is limited by considerable method-related variation in results, of up to 5-fold, as well as by lack of clarity about which PTH metabolites these methods recognise. This makes it difficult to compare PTH results from different studies and to develop common reference intervals and/or decision levels for treatment. The implications of these method-related differences for current clinical practice are reviewed here. Work being undertaken by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) to improve the comparability of PTH measurements worldwide is also described

Residual and Dynamic Range of Retinal Nerve Fiber Layer Thickness in Glaucoma: Comparison of Three OCT Platforms

To estimate visual field (VF) sensitivity at which retinal nerve fiber layer (RNFL) thinning reaches the measurement floor and at which RNFL stops thinning (change points), the dynamic range of RNFL thickness, and the number of steps from normal to RNFL floor among three optical coherence tomography (OCT) devices

Positional identification of variants of Adamts16 linked to inherited hypertension

A previously reported blood pressure (BP) quantitative trait locus on rat Chromosome 1 was isolated in a short congenic segment spanning 804.6 kb. The 804.6 kb region contained only two genes, LOC306664 and LOC306665. LOC306664 is predicted to translate into A Disintegrin-like and Metalloproteinase with Thrombospondin Motifs-16 (Adamts16). LOC306665 is a novel gene. All predicted exons of both LOC306664 and LOC306665 were sequenced. Non-synonymous variants were identified in only one of these genes, LOC306664. These variants were naturally existing polymorphisms among inbred, outbred and wild rats. The full-length rat transcript of Adamts16 was detected in multiple tissues. Similar to ADAMTS16 in humans, expression of Adamts16 was prominent in the kidney. Renal transcriptome analysis suggested that a network of genes related to BP was differential between congenic and S rats. These genes were also differentially expressed between kidney cell lines with or without knock-down of Adamts16. Adamts16 is conserved between rats and humans. It is a candidate gene within the homologous region on human Chromosome 5, which is linked to systolic and diastolic BP in the Quebec Family Study. Multiple variants, including an Ala to Pro variant in codon 90 (rs2086310) of human ADAMTS16, were associated with human resting systolic BP (SBP). Replication study in GenNet confirmed the association of two variants of ADAMTS16 with SBP, including rs2086310. Overall, our report represents a high resolution positional cloning and translational study for Adamts16 as a candidate gene controlling B