Diverticular disease(DD) is an age-related disorder of the large bowel which may affect half of the population over the age of 65 in the UK.This high prevalence ranks it as one of the most common bowel disorders in we...Diverticular disease(DD) is an age-related disorder of the large bowel which may affect half of the population over the age of 65 in the UK.This high prevalence ranks it as one of the most common bowel disorders in western nations.The majority of patients remain asymptomatic but there are associated life-threatening co-morbidities, which, given the large numbers of people with DD, translates into a considerable number of deaths per annum.Despite this public health burden, relatively little seems to be known about either the mechanisms of development or causality.In the 1970s, a model of DD formulated the concept that diverticula occur as a consequence of pressureinduced damage to the colon wall amongst those with a low intake of dietary fiber.In this review, we have examined the evidence regarding the influence of ageing, diet, inflammation and genetics on DD development.We argue that the evidence supporting the barotrauma hypothesis is largely anecdotal.We have also identified several gaps in the knowledge base which need to be filled before we can complete a model for the etiology of diverticular disease.展开更多
Understanding the nature of cell surface markers on exfoliated colonic cells is a crucial step in establishing criteria for a normally functioning mucosa. We have found that colonic cells isolated from stool samples (...Understanding the nature of cell surface markers on exfoliated colonic cells is a crucial step in establishing criteria for a normally functioning mucosa. We have found that colonic cells isolated from stool samples (SCSR-010 Fecal Cell Isolation Kit, NonInvasive Technologies, Elkridge, MD), preserved at room temperature for up to one week, with viability of >85% and low levels of apoptosis (8% - 10%) exhibit two distinct cell size subpopulations, in the 2.5 μM - 5.0 μM and 5.0 μM - 8.0 μM range. In addition to IgA, about 60% of the cells expressed a novel heterodimeric IgA/IgG immunoglobulin that conferred a broad-spectrum cell mediated cytotoxicity against tumor cells. In a cohort of 58 subjects the exclusive absence of this immunoglobulin in two African-Americans was suggestive of a germline deletion. Serial cultures in stem cell medium retained the expression of this heterodimer. Since a majority of the cystic cells expressed the stem cell markers Lgr5 and Musashi-1 we termed these cells as gastrointestinal progenitor stem cells (GIP-C**). CXCR-4, the cytokine co-receptor for HIV was markedly expressed. These cells also expressed CD20, IgA, IgG, CD45, and COX-2. We assume that they originated from mature columnar epithelium by dedifferentiation. Our observations indicate that we have a robust noninvasive method to study mucosal pathophysiology and a direct method to create a database for applications in regenerative medicine.展开更多
Background: Retention in clinical trials is critical for the accumulation of data over time and retaining enough power for comprehensive analysis. We document for the first time the retention rates and factors associa...Background: Retention in clinical trials is critical for the accumulation of data over time and retaining enough power for comprehensive analysis. We document for the first time the retention rates and factors associated with retention among a cohort of HIV exposed seronegative (HESN) person in a discordant relationship. Understanding these factors will provide valuable cues for maintaining high retention rates in future HIV biomedical prevention studies in this cohort. Aim: We aimed to document retention rates and associated factors relevant in conducting future HIV prevention studies using a cohort of HIV exposed sero-negative individuals. Method: We conducted a prospective cohort study to enroll HESN persons in discordant relationship based on established inclusion criteria that includes: Established sero-discordance with at least 3 months in the relationship;above 18 years and willingness to be followed up. Relevant ethical approvals were obtained. Following informed consent at enrollment, standardized questionnaires on risk behavior and factors that may affect retention were administered at enrollment and during the 2 years follow-up. This was spread over 10 follow-up visits to mimic phase a 2b HIV vaccine clinical trial follow up and duration. In addition, clinical examinations were done and samples collected for safety lab during the follow up visits. Estimation of CD4 and viral load was also done for the HIV+ partners of HESN study participants. Results: Six hundred and sixty HESN persons were screened and 534 (81%) enrolled (i.e. month 0) and followed up. There was a decline in retention from 96% at month 1 (visit 1) to 78% at month 24 (Visit 10). Sharpest drop out from the study occurred at month 1 (20%) and month 15 (14%) follow-up visits. Inability to reach study participants, unwillingness of study participants to continue study, and mortality of the HIV+ partners of HESN participants were the commonest reasons for participant study termination. Furthermore, no or low level of formal education, (AOR 2.79;95% CI 1.29 - 6.02, p = 0.06), being unemployed (AOR 1.96;95% CI 1.18 - 3.29, p < 0.01) and inconsistent use of condoms (AOR 1.83;95% CI 1.16 - 2.91, p Conclusion: Retention rates decline especially during month 1 (visit 1) and month 15 (visit 7) mainly due to participants’ inability to locate study participants and death of HIV+ partners of HESN enrollees. One unexpected finding from our study is that those who were more consistent in their use of condom were more likely to stay in the study. This is a possible indication of commitment or an incentive for giving free condoms at study visits. This is encouraging for combined biomedical prevention strategies where consistent condoms use is desired. On the other hand, factors such as unemployment, poor formal education and never/occasional condom use were predictors of study drop out. Retention strategies should consider these barriers and predictors of drop out as exclusion criteria in preparation for future HIV biomedical prevention trial.展开更多
The burden and viral diversity of HIV in Nigeria makes it suitable to evaluate biomedical prevention strategies including HIV vaccines. We document baseline clinical characteristics of a cohort of HIV Exposed Sero-Neg...The burden and viral diversity of HIV in Nigeria makes it suitable to evaluate biomedical prevention strategies including HIV vaccines. We document baseline clinical characteristics of a cohort of HIV Exposed Sero-Negative (HESN) partners to highlight background morbidities that might impact the interpretation of research findings especially in low income countries where “normal control” is based on physical appearance and self-reporting. We established a 2-year prospective cohort of HESN, and obtained, at baseline medical history, general physical examination findings and safety laboratory tests results. Among 534 participants with a mean age of 37 ± 9 years, the commonest symptoms were headache (25.5%) and fever (20%), which occurred more among females. Also, 13% reported a history of urethral/vaginal discharge and genital ulcer. High blood pressure (HBP) (i.e. blood pressure ≥ 140/90 mmhg) was a major abnormal examination finding, which occurred more among males (53.2% vs 26.2%, p < 0.01). More female participants had abnormal laboratory results with 31% having low hemoglobin concentration (<12 g/dl, p = 0.021);30% with elevated alanine transaminase level (p = 0.019) and 28% with abnormal blood urea nitrogen level (p = 0.093). HBP and abnormal safety laboratory are significant findings among so called “normal population” that could affect interpretation of research findings of HIV biomedical prevention studies in Nigeria.展开更多
The right to data portability is an essential part of personal data protection in the booming era of big data,which is closely related to our work and lives,as it may play a crucial role in safeguarding self-determina...The right to data portability is an essential part of personal data protection in the booming era of big data,which is closely related to our work and lives,as it may play a crucial role in safeguarding self-determination right of the data subject and foster a favorable environment for the players in a fair competition market.However,the implementation of the right to data portability in China is still in its infancy,fraught with complexities and uncertainties.This paper studies the right to data portability in China based on the Personal Information Protection Law,and explores its development,current status and potential impact in China.Moreover,it conducts a comparative analysis of the EU and US experience,mostly from the legislative perspective,to better understand practices in the world.In addition,this paper puts forward some specific suggestions on implementing the right to data portability,hoping that the right to data portability can be fully guaranteed in our real life.展开更多
Purpose:To consolidate and evaluate meta-analyses reporting the effects of blood flow restricted exercise(BFRE)on measures of health and physical fitness across all populations.Methods:This preregistered umbrella revi...Purpose:To consolidate and evaluate meta-analyses reporting the effects of blood flow restricted exercise(BFRE)on measures of health and physical fitness across all populations.Methods:This preregistered umbrella review followed PRISMA guidelines.A comprehensive search of five databases identified meta-analyses evaluating the effects of BFRE interventions(aerobic,resistance,combined)compared to exercising and non-exercising control conditions on measures of health and performance.A multilevel meta-analysis of standardised mean differences(SMDs)was conducted to examine the effects of BFRE.Subgroup analyses were conducted for the participant and intervention characteristics.Risk of bias was assessed using the AMSTAR-2.Results:47 meta-analyses comprised of 265 unique studies were included.All reviews were rated as low-moderate quality.BFRE had a small effect on hypertrophy(SMD=0.39,p<0.001)and a moderate effect on strength(SMD=0.61,p<0.001)when compared to low load,but not high load resistance training(hypertrophy,SMD=-0.13,p=0.142;strength,SMD=-0.28,p<0.001).BFRE had small-to-moderate effects on aerobic fitness(SMD=0.50,p<0.001),vascular health(SMD=0.45,p<0.001),blood pressure(SMD=0.46,p<0.001),and muscular power(SMD=0.56,p<0.001).BFRE had no effect on physical function(SMD=0.16,p=0.096),pain(SMD=0.00,p=0.996),and speed(SMD=0.22,p=0.213).Conclusions:BFRE is a viable option to improve hypertrophy,strength,aerobic fitness,and vascular health across various populations,though its effects on hypertrophy and strength are smaller when compared to traditional high load resistance training.It doesn't appear to offer any additional benefits than other training methods for physical function,pain,or speed,although sub-analyses suggest further research is warranted in select areas of application.展开更多
Heterogeneous template-induced nucleation is a promising way to regulate protein crystallization events and could be employed for purification processes and crystallographic studies.Protein crystallization process wit...Heterogeneous template-induced nucleation is a promising way to regulate protein crystallization events and could be employed for purification processes and crystallographic studies.Protein crystallization process with graphite and graphene oxide,as heterogeneous templates,were investigated.More than 640 hanging drops with different concentrations of Lysozyme(30,50,70,100 mg/mL)and NaCl(0.7,0.9,1.1,1.3,1.5 M)were crystallised at 4 ℃ with or without graphite/graphene oxide templates.The induction times and crystallization process were observed under the microscope.The lysozyme in the solutions with graphite flakes nucleated faster under all the conditions than the lysozyme with equal experimental conditions without templates.The crystals preferred to grow around the edge of graphite flakes than on the flat surfaces.In the droplets with monolayer graphene oxide,more crystals appeared around gra-phene oxide particles,and the faster or slower nucleation processes with templates were dependent on the lysozyme and NaCl concentrations.Graphene oxide templates strongly inhibited nucleation at high lysozyme concentrations but promoted nucleation at low lysozyme concentrations.Both heterogeneous templates changed the crystal morphology and the crystallization kinetics.More crystals were observed in the solution with graphite templatesthan with graphene oxide templates and without any template.展开更多
Using the multi-product dual revenue function framework,this paper examines the nature and extent of technical and economic interactions among five demersal species of Al-Batinah demersal fishery,Oman during the 2010-...Using the multi-product dual revenue function framework,this paper examines the nature and extent of technical and economic interactions among five demersal species of Al-Batinah demersal fishery,Oman during the 2010-2016 period.The parameters of the system of output supply functions are estimated using Zellner’s seemingly unrelated regressions(SUR)technique.The likelihood ratio test in relation to the structure of the multi-output production technology rejects the null-hypothesis of input-output separability and non-jointness in inputs.These results suggest that the underlying production technology is non-separable between the outputs and the quasi-fixed input,and the harvesting level of one species is likely to have spill-over economic effects on the harvesting levels of others.The own-price elasticities of output supply are found to be positive,inelastic,and statistically significant in four out of five cases suggesting that,other things being equal,fishers’supply decisions are influenced by the prevailing market prices of outputs.The estimated values of the cross-price elasticity of supply are negative,inelastic and statistically significant at the 5%level for eight output pairs.The calculated values of the Morishima elasticity of substitution(MES)indicate the presence of substitutability between ten output pairs.The cross-price elasticity estimates are in the range of0.001(between Emperor and Catfish)to0.275(between Seabream and Grouper)which is lower(in absolute value)than that of the MES estimates.The magnitudes of the cross-price elasticity and the MES estimates indicate the extent of spill-over effects of one species on the other and signal the extent of species targeting by fishers.A statistically significant spatial,seasonal,and inter-annual variability is observed in all species cases.Finally,the implications of the findings are discussed from the perspective of developing effective management approaches,achieving sustainability of fisheries resources and improving fishers’socio-economic conditions stipulated in the Five-Year development plans for the sector.展开更多
Jose Ordovas及其同事认为,根据个体特征和行为进行个体化营养干预具有前景,但在实施之前还需要做更多的工作。膳食因素公认是导致心脏病、卒中、2型糖尿病、癌症等常见疾病的主要因素之一1-3。尽管已知疾病与膳食模式相关联.试图改变...Jose Ordovas及其同事认为,根据个体特征和行为进行个体化营养干预具有前景,但在实施之前还需要做更多的工作。膳食因素公认是导致心脏病、卒中、2型糖尿病、癌症等常见疾病的主要因素之一1-3。尽管已知疾病与膳食模式相关联.试图改变膳食习惯进而影响公众健康和福祉的干预措施仍收效甚微。对于能够影响健康结果的行为,将干预措施个体化可能更凑效4-5,在本文中我们考量了个体化营养的相关证据。展开更多
Elite athletes will compete in extreme heat more frequently as global land and sea temperatures increase,alongside more intense,frequent and longer duration heatwaves.Best practices to protect athlete health and perfo...Elite athletes will compete in extreme heat more frequently as global land and sea temperatures increase,alongside more intense,frequent and longer duration heatwaves.Best practices to protect athlete health and performance during competition include heat acclimation/acclimatisation[(HA);i.e.,long-term pre-competition preparation]complemented by pre-planned and practised cooling and hydration strategies(i.e.,short-term interventions immediately before or during competition).This review explores elite athletes’current behaviours and practices when preparing for competition in the heat and assesses the level of knowledge that has been exhibited by athletes and their practitioners in this space.Recommendations for future research,discussions of current best practices,and methods to improve translation of research into practice are provided.Available research focuses on small samples of elite endurance athletes during a selection of World Championship/Olympic/Paralympic events(~6%of competing athletes).While generally an increase in the adoption of evidence-based HA is seen chronologically from 2015 onwards,universal adoption is not seen.HA adoption is lowest in those who live/train in cold/temperate environments with cost and access to facilities/equipment being the most commonly reported barriers.Further research is required across the sporting landscape to fully characterise elite athlete behaviours and practices in these spaces.International federations and national governing bodies should continue their efforts to educate athletes and focus on regularly updated and reinvigorated release of evidence-based guidelines(in multiple germane languages)for competing in the heat,to increase the adoption of HA and other heat related best practice.展开更多
Purpose This study aimed to determine whether a series of repeated maximal voluntary apnoeas is effective in improving subsequent time trial performance in competitive level track and field athletes.Methods Seventeen ...Purpose This study aimed to determine whether a series of repeated maximal voluntary apnoeas is effective in improving subsequent time trial performance in competitive level track and field athletes.Methods Seventeen competitive runners volunteered for this study and based on their preferred competitive distance they were placed either in the 200 m(5 male,4 female)or 1000 m group(3 male,5 female).On two separate occasions(≤7 days apart),the participants performed a running time-trial that was preceded either by:(i)a standardised warm up(WO)or(ii)a standardised warm up succeeded by five repeated maximal dry static apnoeas(WA).Splenic volume,haematology and cardiovascular parameters were monitor at rest,before and after each time-trial.Results WA resulted in a significantly faster performance(27.51±3.49 s;P=0.009)compared with WO(27.96±3.34 s)in the 200 m group,whereas no differences were observed in the 1000 m group(WA,211.10±26.18 s;WO,215.82±25.13 s,P=0.120).No differences were noted in splenic volume between WO and WA in either group(P≥0.081).Haemoglobin was significantly elevated after breath-holding in the 200 m(+7 g/dL,P=0.041)but not 1000 m group.Conclusion This study demonstrates that five repeated maximal apnoeas are capable of significantly improving a 200 m but not a 1000 m time-trial performance in competitive track and field athletes.展开更多
基金Supported by Food Standards Agency, N12105Northumbria Colorectal Research Funds
文摘Diverticular disease(DD) is an age-related disorder of the large bowel which may affect half of the population over the age of 65 in the UK.This high prevalence ranks it as one of the most common bowel disorders in western nations.The majority of patients remain asymptomatic but there are associated life-threatening co-morbidities, which, given the large numbers of people with DD, translates into a considerable number of deaths per annum.Despite this public health burden, relatively little seems to be known about either the mechanisms of development or causality.In the 1970s, a model of DD formulated the concept that diverticula occur as a consequence of pressureinduced damage to the colon wall amongst those with a low intake of dietary fiber.In this review, we have examined the evidence regarding the influence of ageing, diet, inflammation and genetics on DD development.We argue that the evidence supporting the barotrauma hypothesis is largely anecdotal.We have also identified several gaps in the knowledge base which need to be filled before we can complete a model for the etiology of diverticular disease.
文摘Understanding the nature of cell surface markers on exfoliated colonic cells is a crucial step in establishing criteria for a normally functioning mucosa. We have found that colonic cells isolated from stool samples (SCSR-010 Fecal Cell Isolation Kit, NonInvasive Technologies, Elkridge, MD), preserved at room temperature for up to one week, with viability of >85% and low levels of apoptosis (8% - 10%) exhibit two distinct cell size subpopulations, in the 2.5 μM - 5.0 μM and 5.0 μM - 8.0 μM range. In addition to IgA, about 60% of the cells expressed a novel heterodimeric IgA/IgG immunoglobulin that conferred a broad-spectrum cell mediated cytotoxicity against tumor cells. In a cohort of 58 subjects the exclusive absence of this immunoglobulin in two African-Americans was suggestive of a germline deletion. Serial cultures in stem cell medium retained the expression of this heterodimer. Since a majority of the cystic cells expressed the stem cell markers Lgr5 and Musashi-1 we termed these cells as gastrointestinal progenitor stem cells (GIP-C**). CXCR-4, the cytokine co-receptor for HIV was markedly expressed. These cells also expressed CD20, IgA, IgG, CD45, and COX-2. We assume that they originated from mature columnar epithelium by dedifferentiation. Our observations indicate that we have a robust noninvasive method to study mucosal pathophysiology and a direct method to create a database for applications in regenerative medicine.
文摘Background: Retention in clinical trials is critical for the accumulation of data over time and retaining enough power for comprehensive analysis. We document for the first time the retention rates and factors associated with retention among a cohort of HIV exposed seronegative (HESN) person in a discordant relationship. Understanding these factors will provide valuable cues for maintaining high retention rates in future HIV biomedical prevention studies in this cohort. Aim: We aimed to document retention rates and associated factors relevant in conducting future HIV prevention studies using a cohort of HIV exposed sero-negative individuals. Method: We conducted a prospective cohort study to enroll HESN persons in discordant relationship based on established inclusion criteria that includes: Established sero-discordance with at least 3 months in the relationship;above 18 years and willingness to be followed up. Relevant ethical approvals were obtained. Following informed consent at enrollment, standardized questionnaires on risk behavior and factors that may affect retention were administered at enrollment and during the 2 years follow-up. This was spread over 10 follow-up visits to mimic phase a 2b HIV vaccine clinical trial follow up and duration. In addition, clinical examinations were done and samples collected for safety lab during the follow up visits. Estimation of CD4 and viral load was also done for the HIV+ partners of HESN study participants. Results: Six hundred and sixty HESN persons were screened and 534 (81%) enrolled (i.e. month 0) and followed up. There was a decline in retention from 96% at month 1 (visit 1) to 78% at month 24 (Visit 10). Sharpest drop out from the study occurred at month 1 (20%) and month 15 (14%) follow-up visits. Inability to reach study participants, unwillingness of study participants to continue study, and mortality of the HIV+ partners of HESN participants were the commonest reasons for participant study termination. Furthermore, no or low level of formal education, (AOR 2.79;95% CI 1.29 - 6.02, p = 0.06), being unemployed (AOR 1.96;95% CI 1.18 - 3.29, p < 0.01) and inconsistent use of condoms (AOR 1.83;95% CI 1.16 - 2.91, p Conclusion: Retention rates decline especially during month 1 (visit 1) and month 15 (visit 7) mainly due to participants’ inability to locate study participants and death of HIV+ partners of HESN enrollees. One unexpected finding from our study is that those who were more consistent in their use of condom were more likely to stay in the study. This is a possible indication of commitment or an incentive for giving free condoms at study visits. This is encouraging for combined biomedical prevention strategies where consistent condoms use is desired. On the other hand, factors such as unemployment, poor formal education and never/occasional condom use were predictors of study drop out. Retention strategies should consider these barriers and predictors of drop out as exclusion criteria in preparation for future HIV biomedical prevention trial.
文摘The burden and viral diversity of HIV in Nigeria makes it suitable to evaluate biomedical prevention strategies including HIV vaccines. We document baseline clinical characteristics of a cohort of HIV Exposed Sero-Negative (HESN) partners to highlight background morbidities that might impact the interpretation of research findings especially in low income countries where “normal control” is based on physical appearance and self-reporting. We established a 2-year prospective cohort of HESN, and obtained, at baseline medical history, general physical examination findings and safety laboratory tests results. Among 534 participants with a mean age of 37 ± 9 years, the commonest symptoms were headache (25.5%) and fever (20%), which occurred more among females. Also, 13% reported a history of urethral/vaginal discharge and genital ulcer. High blood pressure (HBP) (i.e. blood pressure ≥ 140/90 mmhg) was a major abnormal examination finding, which occurred more among males (53.2% vs 26.2%, p < 0.01). More female participants had abnormal laboratory results with 31% having low hemoglobin concentration (<12 g/dl, p = 0.021);30% with elevated alanine transaminase level (p = 0.019) and 28% with abnormal blood urea nitrogen level (p = 0.093). HBP and abnormal safety laboratory are significant findings among so called “normal population” that could affect interpretation of research findings of HIV biomedical prevention studies in Nigeria.
文摘The right to data portability is an essential part of personal data protection in the booming era of big data,which is closely related to our work and lives,as it may play a crucial role in safeguarding self-determination right of the data subject and foster a favorable environment for the players in a fair competition market.However,the implementation of the right to data portability in China is still in its infancy,fraught with complexities and uncertainties.This paper studies the right to data portability in China based on the Personal Information Protection Law,and explores its development,current status and potential impact in China.Moreover,it conducts a comparative analysis of the EU and US experience,mostly from the legislative perspective,to better understand practices in the world.In addition,this paper puts forward some specific suggestions on implementing the right to data portability,hoping that the right to data portability can be fully guaranteed in our real life.
文摘Purpose:To consolidate and evaluate meta-analyses reporting the effects of blood flow restricted exercise(BFRE)on measures of health and physical fitness across all populations.Methods:This preregistered umbrella review followed PRISMA guidelines.A comprehensive search of five databases identified meta-analyses evaluating the effects of BFRE interventions(aerobic,resistance,combined)compared to exercising and non-exercising control conditions on measures of health and performance.A multilevel meta-analysis of standardised mean differences(SMDs)was conducted to examine the effects of BFRE.Subgroup analyses were conducted for the participant and intervention characteristics.Risk of bias was assessed using the AMSTAR-2.Results:47 meta-analyses comprised of 265 unique studies were included.All reviews were rated as low-moderate quality.BFRE had a small effect on hypertrophy(SMD=0.39,p<0.001)and a moderate effect on strength(SMD=0.61,p<0.001)when compared to low load,but not high load resistance training(hypertrophy,SMD=-0.13,p=0.142;strength,SMD=-0.28,p<0.001).BFRE had small-to-moderate effects on aerobic fitness(SMD=0.50,p<0.001),vascular health(SMD=0.45,p<0.001),blood pressure(SMD=0.46,p<0.001),and muscular power(SMD=0.56,p<0.001).BFRE had no effect on physical function(SMD=0.16,p=0.096),pain(SMD=0.00,p=0.996),and speed(SMD=0.22,p=0.213).Conclusions:BFRE is a viable option to improve hypertrophy,strength,aerobic fitness,and vascular health across various populations,though its effects on hypertrophy and strength are smaller when compared to traditional high load resistance training.It doesn't appear to offer any additional benefits than other training methods for physical function,pain,or speed,although sub-analyses suggest further research is warranted in select areas of application.
基金grateful to the UK EPSRC(Engineering and Physical Sciences Research Council)for support(EP/T005378/1).
文摘Heterogeneous template-induced nucleation is a promising way to regulate protein crystallization events and could be employed for purification processes and crystallographic studies.Protein crystallization process with graphite and graphene oxide,as heterogeneous templates,were investigated.More than 640 hanging drops with different concentrations of Lysozyme(30,50,70,100 mg/mL)and NaCl(0.7,0.9,1.1,1.3,1.5 M)were crystallised at 4 ℃ with or without graphite/graphene oxide templates.The induction times and crystallization process were observed under the microscope.The lysozyme in the solutions with graphite flakes nucleated faster under all the conditions than the lysozyme with equal experimental conditions without templates.The crystals preferred to grow around the edge of graphite flakes than on the flat surfaces.In the droplets with monolayer graphene oxide,more crystals appeared around gra-phene oxide particles,and the faster or slower nucleation processes with templates were dependent on the lysozyme and NaCl concentrations.Graphene oxide templates strongly inhibited nucleation at high lysozyme concentrations but promoted nucleation at low lysozyme concentrations.Both heterogeneous templates changed the crystal morphology and the crystallization kinetics.More crystals were observed in the solution with graphite templatesthan with graphene oxide templates and without any template.
文摘Using the multi-product dual revenue function framework,this paper examines the nature and extent of technical and economic interactions among five demersal species of Al-Batinah demersal fishery,Oman during the 2010-2016 period.The parameters of the system of output supply functions are estimated using Zellner’s seemingly unrelated regressions(SUR)technique.The likelihood ratio test in relation to the structure of the multi-output production technology rejects the null-hypothesis of input-output separability and non-jointness in inputs.These results suggest that the underlying production technology is non-separable between the outputs and the quasi-fixed input,and the harvesting level of one species is likely to have spill-over economic effects on the harvesting levels of others.The own-price elasticities of output supply are found to be positive,inelastic,and statistically significant in four out of five cases suggesting that,other things being equal,fishers’supply decisions are influenced by the prevailing market prices of outputs.The estimated values of the cross-price elasticity of supply are negative,inelastic and statistically significant at the 5%level for eight output pairs.The calculated values of the Morishima elasticity of substitution(MES)indicate the presence of substitutability between ten output pairs.The cross-price elasticity estimates are in the range of0.001(between Emperor and Catfish)to0.275(between Seabream and Grouper)which is lower(in absolute value)than that of the MES estimates.The magnitudes of the cross-price elasticity and the MES estimates indicate the extent of spill-over effects of one species on the other and signal the extent of species targeting by fishers.A statistically significant spatial,seasonal,and inter-annual variability is observed in all species cases.Finally,the implications of the findings are discussed from the perspective of developing effective management approaches,achieving sustainability of fisheries resources and improving fishers’socio-economic conditions stipulated in the Five-Year development plans for the sector.
文摘Elite athletes will compete in extreme heat more frequently as global land and sea temperatures increase,alongside more intense,frequent and longer duration heatwaves.Best practices to protect athlete health and performance during competition include heat acclimation/acclimatisation[(HA);i.e.,long-term pre-competition preparation]complemented by pre-planned and practised cooling and hydration strategies(i.e.,short-term interventions immediately before or during competition).This review explores elite athletes’current behaviours and practices when preparing for competition in the heat and assesses the level of knowledge that has been exhibited by athletes and their practitioners in this space.Recommendations for future research,discussions of current best practices,and methods to improve translation of research into practice are provided.Available research focuses on small samples of elite endurance athletes during a selection of World Championship/Olympic/Paralympic events(~6%of competing athletes).While generally an increase in the adoption of evidence-based HA is seen chronologically from 2015 onwards,universal adoption is not seen.HA adoption is lowest in those who live/train in cold/temperate environments with cost and access to facilities/equipment being the most commonly reported barriers.Further research is required across the sporting landscape to fully characterise elite athlete behaviours and practices in these spaces.International federations and national governing bodies should continue their efforts to educate athletes and focus on regularly updated and reinvigorated release of evidence-based guidelines(in multiple germane languages)for competing in the heat,to increase the adoption of HA and other heat related best practice.
文摘Purpose This study aimed to determine whether a series of repeated maximal voluntary apnoeas is effective in improving subsequent time trial performance in competitive level track and field athletes.Methods Seventeen competitive runners volunteered for this study and based on their preferred competitive distance they were placed either in the 200 m(5 male,4 female)or 1000 m group(3 male,5 female).On two separate occasions(≤7 days apart),the participants performed a running time-trial that was preceded either by:(i)a standardised warm up(WO)or(ii)a standardised warm up succeeded by five repeated maximal dry static apnoeas(WA).Splenic volume,haematology and cardiovascular parameters were monitor at rest,before and after each time-trial.Results WA resulted in a significantly faster performance(27.51±3.49 s;P=0.009)compared with WO(27.96±3.34 s)in the 200 m group,whereas no differences were observed in the 1000 m group(WA,211.10±26.18 s;WO,215.82±25.13 s,P=0.120).No differences were noted in splenic volume between WO and WA in either group(P≥0.081).Haemoglobin was significantly elevated after breath-holding in the 200 m(+7 g/dL,P=0.041)but not 1000 m group.Conclusion This study demonstrates that five repeated maximal apnoeas are capable of significantly improving a 200 m but not a 1000 m time-trial performance in competitive track and field athletes.
