The recently deployed Transition Region Explorer(TREx)-RGB(red-green-blue)all-sky imager(ASI)is designed to capture“true color”images of the aurora and airglow.Because the 557.7 nm green line is usually the brightes...The recently deployed Transition Region Explorer(TREx)-RGB(red-green-blue)all-sky imager(ASI)is designed to capture“true color”images of the aurora and airglow.Because the 557.7 nm green line is usually the brightest emission line in visible auroras,the green channel of a TREx-RGB camera is usually dominated by the 557.7 nm emission.Under this rationale,the TREx mission does not include a specific 557.7 nm imager and is designed to use the RGB green-channel data as a proxy for the 557.7 nm aurora.In this study,we present an initial effort to establish the conversion ratio or formula linking the RGB green-channel data to the absolute intensity of 557.7 nm auroras,which is crucial for quantitative uses of the RGB data.We illustrate two approaches:(1)through a comparison with the collocated measurement of green-line auroras from the TREx spectrograph,and(2)through a comparison with the modeled green-line intensity according to realistic electron precipitation flux measurements from low-Earth-orbit satellites,with the aid of an auroral transport model.We demonstrate the procedures and provide initial results for the TREx-RGB ASIs at the Rabbit Lake and Lucky Lake stations.The RGB response is found to be nonlinear.Empirical conversion ratios or formulas between RGB green-channel data and the green-line auroral intensity are given and can be applied immediately by TREx-RGB data users.The methodology established in this study will also be applicable to the upcoming SMILE ASI mission,which will adopt a similar RGB camera system in its deployment.展开更多
Storylines of Family Medicine is a 12-part series of thematically linked essays with accompanying illustrations that explore the many dimensions of family medicine,as interpreted by individual family physicians and me...Storylines of Family Medicine is a 12-part series of thematically linked essays with accompanying illustrations that explore the many dimensions of family medicine,as interpreted by individual family physicians and medical educators in the USA and elsewhere around the world.In‘Ⅴ:ways of thinking—honing the therapeutic self’,authors present the following sections:‘Reflective practice in action’,‘The doctor as drug—Balint groups’,‘Cultivating compassion’,‘Towards a humanistic approach to doctoring’,‘Intimacy in family medicine’,‘The many faces of suffering’,‘Transcending suffering’and‘The power of listening to stories.’May readers feel a deeper sense of their own therapeutic agency by reflecting on these essays.展开更多
BACKGROUND Retinal organoids serve as excellent human-specific disease models for conditions affecting otherwise inaccessible retinal tissue from patients.They permit the isolation of key cell types affected in variou...BACKGROUND Retinal organoids serve as excellent human-specific disease models for conditions affecting otherwise inaccessible retinal tissue from patients.They permit the isolation of key cell types affected in various eye diseases including retinal ganglion cells(RGCs)and Müller glia.AIM To refine human-induced pluripotent stem cells(hiPSCs)differentiated into threedimensional(3D)retinal organoids to generate sufficient numbers of RGCs and Müller glia progenitors for downstream analyses.METHODS In this study we described,evaluated,and refined methods with which to generate Müller glia and RGC progenitors,isolated them via magnetic-activated cell sorting,and assessed their lineage stability after prolonged 2D culture.Putative progenitor populations were characterized via quantitative PCR and immunocytochemistry,and the ultrastructural composition of retinal organoid cells was investigated.RESULTS Our study confirms the feasibility of generating marker-characterized Müller glia and RGC progenitors within retinal organoids.Such retinal organoids can be dissociated and the Müller glia and RGC progenitor-like cells isolated via magnetic-activated cell sorting and propagated as monolayers.CONCLUSION Enrichment of Müller glia and RGC progenitors from retinal organoids is a feasible method with which to study cell type-specific disease phenotypes and to potentially generate specific retinal populations for cell replacement therapies.展开更多
To investigate the association between elevated intraocular pressure (IOP) and accelerated cataract formation in patients treated with intravitreal triamcinol one. Analysis of longitudinal data from a randomized, doub...To investigate the association between elevated intraocular pressure (IOP) and accelerated cataract formation in patients treated with intravitreal triamcinol one. Analysis of longitudinal data from a randomized, double-masked, placebo-c ontrolled trial of intravitreal triamcinolone for age-related macular degenerat ion (the Intravitreal Triamcinolone Study). Patients with phakic eyes who partic ipated in a randomized clinical trial of intravitreal triamcinolone for age-rel ated macular degeneration were studied. There were 57 phakic eyes in the treatme nt group and 54 phakic eyes in the control group. One eye per patient was studie d. Four milligrams of intravitreal triamcinolone or 1 ml subconjunctival saline. Intraocular pressure rise of at least 5 mmHg (IOP responders) and progression o f posterior subcapsular cataract by 2 or more grades using photographic standard s from the Age Related Eye Disease Study. Progression of posterior subcapsular c ataract (PSC) by 2 or more grades in the treatment group was significantly highe r among 16 IOP responders (51%after 2 years) than among 37 nonresponders (3%; P < 0.0001, log-rank test). There was no significant progression of PSC in the placebo group or the opposite eye of the treatment group. Progression of cortica l cataracts also was significantly higher among responders than nonresponders (1 5%vs. 3%; P=0.015, log-rank test). The progression of nuclear cataracts (13% vs. 3%) was not significantly different between IOP responders and nonresponders (P=0.3, log-rank test). Although steroid-relate d cataracts are unlikely to develop in eyes that do not experience elevated IOP after intravitreal triamcinolone, those eyes that do also have a very high risk of rapidly experiencing posterior subcapsular lens opacification. This strong as sociation suggests that the mechanism responsible for the development of steroid -induced PSC cataract and raised IOP may be similar.展开更多
This study presents experimental results of the change in threshold friction velocity and dust emission strength as a function of soil moisture content. The dust and soil moisture data were obtained from irrigated plo...This study presents experimental results of the change in threshold friction velocity and dust emission strength as a function of soil moisture content. The dust and soil moisture data were obtained from irrigated plots of a bare, sandy soil （no vegetation） situated in the Mongolian steppe. Dust flux was measured using the PI-SWERL^（R） device, while soil moisture was measured using gravimetric methods. Our results demonstrate the strong controlling effects of soil moisture on both the threshold friction velocity and dust emission strengths. Threshold friction velocity increased from 0.44 m/s for dry soil （0.002 g/g） to 0.67 m/s for wet soil （0.06 g/g）, confirming the importance of soil moisture for controlling dust events. Dust emission strength was significantly depressed for wet soils, starting at a soil moisture value of 0.02 g/g. From these results, we developed a simple dust diagram that may be useful as part of a warning system to identify initial sensitivity to threshold conditions as well as conditions that could lead to potentially significant dust emissions. Overall, the research findings in this study could be used to provide foreknowledge of conditions that would be conducive to high dust emissions for this area of Mongolia.展开更多
Antiviral therapy consisting of interferon-alpha and ribavirin for chronic hepatitis C infection is associated with multi-system side-effects.Ophthalmologic complications are common and can be classified into two grou...Antiviral therapy consisting of interferon-alpha and ribavirin for chronic hepatitis C infection is associated with multi-system side-effects.Ophthalmologic complications are common and can be classified into two groups:interferon-associated retinopathy and atypical adverse events.Interferon-associated retinopathy has been investigated by multiple observational studies that have found widely divergent results.The clinical importance of this complication is,consequently,controversial.This review examines the literature with the specific goal of identifying the most important ophthalmologic issues facing the hepatologist prescribing antiviral therapy.Accordingly,it assesses the incidence of interferon-associated retinopathy,as well as its risk factors,pathogenesis,clinical manifestations and options for management using data from the observational studies.The likely benefit of a screening program,especially one targeting patients with the highest risk of developing interferon-associated retinopathy,is analysed.Atypical ophthalmologic adverse events occur less frequently than interferon-associated retinopathy during antiviral therapy for chronic hepatitis C infection.They often,however,lead to irreversible vision loss.We examine the reports of these adverse events-in individual case reports or case series and in the observational studies investigating interferon-associated retinopathy-to describe the spectrum of these adverse events,the likely outcome for patients and to highlight the most important areas of future clinical research.展开更多
A booster fan is an underground main fan which is installed in series with a main surface fan and used to boost the air pressure of the ventilation to overcome mine resistance.Currently booster fans are used in severa...A booster fan is an underground main fan which is installed in series with a main surface fan and used to boost the air pressure of the ventilation to overcome mine resistance.Currently booster fans are used in several major coal mining countries including the United Kingdom,Australia,Poland and China.In the United States booster fans are prohibited in coal mines although they are used in several metal and non-metal mines.A study has been undertaken to examine alternatives for ventilating an underground room and pillar coal mine system.A feasibility study of a hypothetical situation has shown that current ventilation facilities are incapable of fulfilling mine air requirements in the future due to increased seam methane levels.A current ventilation network model has been prepared and projected to a mine five years plan."Ventsim visual" software simulations of different possible ventilation options have been conducted in which varying methane levels are found at working faces.The software can also undertake financial simulations and project present value total costs for the options under study.Several scenarios for improving the ventilation situation such as improving main surface fans,adding intake shafts,adding exhaust shafts and utilizing booster fans have been examined.After taking into account the total capital and operating costs for the five years mine plan the booster fan scenarios are recommended as being the best alternatives for further serious consideration by the mine.The optimum option is a properly sized and installed booster fan system that can be used to create safe work conditions,maintain adequate air quantity with lowest cost,generate a reduction in energy consumption and decrease mine system air leakage.展开更多
Classical electrodynamics foresees that the effective interaction force between a moving charge and a magnetic dipole is modified by the time-varying total momentum of the interaction fields. We derive the equations o...Classical electrodynamics foresees that the effective interaction force between a moving charge and a magnetic dipole is modified by the time-varying total momentum of the interaction fields. We derive the equations of motion of the particles from the total stress-energy tensor, assuming the validity of Maxwell’s equations and the total momentum conservation law. Applications to the effects of Aharonov–Bohm type show that the observed phase shift may be due to the relative lag between interfering particles caused by the effective local force.展开更多
A real-time Diesel Particulate Matter （DPM） monitor has been developed on the base of the successful National In- stitute of Occupational Health and Safety （NIOSH） designed Personal Dust Monitor （PDM） unit. The ...A real-time Diesel Particulate Matter （DPM） monitor has been developed on the base of the successful National In- stitute of Occupational Health and Safety （NIOSH） designed Personal Dust Monitor （PDM） unit. The objectives of a recently completed Australian Coal Association Research Program （ACARP） study was to modify the PDM to measure the submicrometre fraction of the aerosol in a real-time monitoring underground instrument. Mine testing focused on use of the monitor in engineering evaluations of Longwall （LW） moves demonstrated how DPM concentrations from vehicles fluctuate under varying ventilation and operational conditions. The strong influence of mine ventilation systems is reviewed. Correlation between the current SKC DPM measurement system and real-time DPM monitors were conducted and results from eight mines show a correlation between elemental carbon （EC） and the new monitor DPM mass ranging from 0.45 to 0.82 with R2〉0.86 in all but two cases. This differences in suspected to be due to variations from mine to mine in aspects such as mine atmospheric contamination, vehicle fleet variations, fuel type, engine maintenance, engine combustion efficiency, engine behavior or interference from other submicrometre aerosol. Real-time monitoring clearly reflects the movement of individual diesel vehicles and allows pin-pointing of high exposure zones such as those encountered where various vehicles engage in intense work in areas of constrained or difficult ventilation. DPM shift average monitoring approaches do not readily allow successful engineering evaluation exercises to determine acceptability of pollution levels. Identification of high DPM concentration zones allows efficient modification of mine ventilation, operator positioning and other work practices to reduce miners＇ exposures without waiting for laboratory analysis results.展开更多
To determine whether an intravitreal injection of triamcinolone acetonide for persistent diabetic macular edema after adequate laser treatment improves visual acuity. Prospective, double masked, placebo controlled, ra...To determine whether an intravitreal injection of triamcinolone acetonide for persistent diabetic macular edema after adequate laser treatment improves visual acuity. Prospective, double masked, placebo controlled, randomized clinical t rial. Sixty nine eyes of 43 patients were entered into the study, with 34 eyes randomized to receive active treatment and 35 randomized to receive a placebo in jection. Sixty five of 69 eyes (94%) completed the 3 month study visit. Using a 27 gauge needle, 0.1 ml of triamcinolone acetonide was injected through the pars plana. The procedure was performed in a minor procedures area in the outpat ient clinic under sterile conditions and using topical and subconjunctival anest hesia. Eyes randomized to placebo received a subconjunctival saline injection us ing the identical procedure for preparation. The main outcome measures were impr ovement of best corrected logarithm of the minimum angle of resolution visual a cuity by 5 or more letters and incidence of moderate or severe adverse events. E ighteen of 33 eyes (55%) treated with triamcinolone gained 5 or more letters of best corrected visual acuity compared with 5 of 32 eyes (16%) treated with pl acebo (P=0.002). Macular edema was reduced by 1 or more grades as determined by masked semiquantitative contact lens examination in 25 of 33 treated eyes (75%) versus 5 of 32 untreated eyes (16%; P < 0.0001). Optical coherence tomography showed a mean reduction of central retinal thickness of 152 μm in the 21 treate d eyes that were examined compared with a reduction of 36 μm in 20 placebo tre ated eyes. Infectious endophthalmitis developed in 1 triamcinolone treated eye that was treated adequately without loss of visual acuity. In the short term, in travitreal triamcinolone is an effective and relatively safe treatment for eyes with diabetic macular edema that have failed laser treatment. Although it will b e essential to study longer term outcomes, the use of intravitreal triamcinolon e may be considered in 1 eye of patients who continu展开更多
In this study, the phenotype of psoriatic keratinocytes and fibroblasts in reconstructed skin models was compared to those constructed from normal cells. Characterization of this model by immunohistochemistry showed t...In this study, the phenotype of psoriatic keratinocytes and fibroblasts in reconstructed skin models was compared to those constructed from normal cells. Characterization of this model by immunohistochemistry showed that classical markers of keratinocyte differentiation exhibited similar patterns of distribution in the psoriatic models to those derived from normal cells and generally reflected in vivo observations. Some crucial differences, however, were observed between normal and psoriatic models when pro-inflammatory gene expression and keratinocyte proliferation were investigated. Notably, the chemokine receptor CXCR2 was overexpressed in the psoriatic models, and, moreover, was localized to the granular layer of keratinocytes as seen in psoriasis in vivo. Pro-inflammatory genes(tumor necrosis factor alpha[TNF-α], interferon gamma[IFN-γ], and interleukin 8[IL-8]) were expressed at high levels in the psoriatic models, but were only minimally expressed in the normal models. Models derived from uninvolved psoriatic skin showed the same gene expression profile as those derived from involved skinalong with an increased proliferation rate when compared to normal models. These results suggest that psoriatic individuals possess an inherent predisposition to develop the disease phenotype even in the absence of T cells. This study represents a comprehensive characterization of psoriatic human skin reconstructed in vitro, and demonstrates the potential of this model as a valuable tool in drug discovery.展开更多
新一代短柄髋关节植入物的设计理念是通过促进与生理相似的加载方式将应力一应变遮挡和植人物远期松动率降至最低。至今仍缺乏远期临床研究来证明短柄植人物的优点。由于缺乏临床数据，因此可以使用数字模拟来预测其远期性能。通过有限...新一代短柄髋关节植入物的设计理念是通过促进与生理相似的加载方式将应力一应变遮挡和植人物远期松动率降至最低。至今仍缺乏远期临床研究来证明短柄植人物的优点。由于缺乏临床数据，因此可以使用数字模拟来预测其远期性能。通过有限元研究预测短柄植入物的初始和远期稳定性，从界面微动方面对植入物的初始稳定性进行评价。结果发现，初始稳定性在允许骨整合出现的极限内。使用应变适应性骨重建法则对远期稳定性进行评估，进而在骨密度（bone mineral density，BMD）变化方面对骨的远期行为进行预测。在经典的Gruen1区和Gruen7区内未发现BMD降低，且骨重建模式与文献中髋关节表面置换的结果相似。展开更多
This paper summarizes research related to the 2012 record the NEWS （NASA （National Aeronautics and Space Administration） drought in the central United States conducted by members of Energy and Water cycle Study） W...This paper summarizes research related to the 2012 record the NEWS （NASA （National Aeronautics and Space Administration） drought in the central United States conducted by members of Energy and Water cycle Study） Working Group. Past drought patterns were analyzed for signal coherency with latest drought and the contribution of long-term trends in the Great Plains low-level jet, an important regional circulation feature of the spring rainy season in the Great Plains. Long-term changes in the seasonal transition from rainy spring into dry summer were also examined. Potential external forcing from radiative processes, soil-air interactions, and ocean teleconnections were assessed as contributors to the intensity of the drought. The atmospheric Rossby wave activity was found to be a potential source of predictability for the onset of drought. A probabilistic model was introduced and evaluated for its performance in predicting drought recovery in the Great Plains.展开更多
基金jointly funded by the Canada Foundation for Innovationthe Alberta Economic Development and Trade organization+1 种基金the University of Calgarysupported by the Canadian Space Agency。
文摘The recently deployed Transition Region Explorer(TREx)-RGB(red-green-blue)all-sky imager(ASI)is designed to capture“true color”images of the aurora and airglow.Because the 557.7 nm green line is usually the brightest emission line in visible auroras,the green channel of a TREx-RGB camera is usually dominated by the 557.7 nm emission.Under this rationale,the TREx mission does not include a specific 557.7 nm imager and is designed to use the RGB green-channel data as a proxy for the 557.7 nm aurora.In this study,we present an initial effort to establish the conversion ratio or formula linking the RGB green-channel data to the absolute intensity of 557.7 nm auroras,which is crucial for quantitative uses of the RGB data.We illustrate two approaches:(1)through a comparison with the collocated measurement of green-line auroras from the TREx spectrograph,and(2)through a comparison with the modeled green-line intensity according to realistic electron precipitation flux measurements from low-Earth-orbit satellites,with the aid of an auroral transport model.We demonstrate the procedures and provide initial results for the TREx-RGB ASIs at the Rabbit Lake and Lucky Lake stations.The RGB response is found to be nonlinear.Empirical conversion ratios or formulas between RGB green-channel data and the green-line auroral intensity are given and can be applied immediately by TREx-RGB data users.The methodology established in this study will also be applicable to the upcoming SMILE ASI mission,which will adopt a similar RGB camera system in its deployment.
文摘Storylines of Family Medicine is a 12-part series of thematically linked essays with accompanying illustrations that explore the many dimensions of family medicine,as interpreted by individual family physicians and medical educators in the USA and elsewhere around the world.In‘Ⅴ:ways of thinking—honing the therapeutic self’,authors present the following sections:‘Reflective practice in action’,‘The doctor as drug—Balint groups’,‘Cultivating compassion’,‘Towards a humanistic approach to doctoring’,‘Intimacy in family medicine’,‘The many faces of suffering’,‘Transcending suffering’and‘The power of listening to stories.’May readers feel a deeper sense of their own therapeutic agency by reflecting on these essays.
基金Innovation Fund Denmark,No.4108-00008BThe Bagenkop NielsensØjen-Fond,No.115227+2 种基金Hørslev-Fonden,No.116967Beckett Fonden,No.116936Velux Foundation,No.1179261001/2.
文摘BACKGROUND Retinal organoids serve as excellent human-specific disease models for conditions affecting otherwise inaccessible retinal tissue from patients.They permit the isolation of key cell types affected in various eye diseases including retinal ganglion cells(RGCs)and Müller glia.AIM To refine human-induced pluripotent stem cells(hiPSCs)differentiated into threedimensional(3D)retinal organoids to generate sufficient numbers of RGCs and Müller glia progenitors for downstream analyses.METHODS In this study we described,evaluated,and refined methods with which to generate Müller glia and RGC progenitors,isolated them via magnetic-activated cell sorting,and assessed their lineage stability after prolonged 2D culture.Putative progenitor populations were characterized via quantitative PCR and immunocytochemistry,and the ultrastructural composition of retinal organoid cells was investigated.RESULTS Our study confirms the feasibility of generating marker-characterized Müller glia and RGC progenitors within retinal organoids.Such retinal organoids can be dissociated and the Müller glia and RGC progenitor-like cells isolated via magnetic-activated cell sorting and propagated as monolayers.CONCLUSION Enrichment of Müller glia and RGC progenitors from retinal organoids is a feasible method with which to study cell type-specific disease phenotypes and to potentially generate specific retinal populations for cell replacement therapies.
文摘To investigate the association between elevated intraocular pressure (IOP) and accelerated cataract formation in patients treated with intravitreal triamcinol one. Analysis of longitudinal data from a randomized, double-masked, placebo-c ontrolled trial of intravitreal triamcinolone for age-related macular degenerat ion (the Intravitreal Triamcinolone Study). Patients with phakic eyes who partic ipated in a randomized clinical trial of intravitreal triamcinolone for age-rel ated macular degeneration were studied. There were 57 phakic eyes in the treatme nt group and 54 phakic eyes in the control group. One eye per patient was studie d. Four milligrams of intravitreal triamcinolone or 1 ml subconjunctival saline. Intraocular pressure rise of at least 5 mmHg (IOP responders) and progression o f posterior subcapsular cataract by 2 or more grades using photographic standard s from the Age Related Eye Disease Study. Progression of posterior subcapsular c ataract (PSC) by 2 or more grades in the treatment group was significantly highe r among 16 IOP responders (51%after 2 years) than among 37 nonresponders (3%; P < 0.0001, log-rank test). There was no significant progression of PSC in the placebo group or the opposite eye of the treatment group. Progression of cortica l cataracts also was significantly higher among responders than nonresponders (1 5%vs. 3%; P=0.015, log-rank test). The progression of nuclear cataracts (13% vs. 3%) was not significantly different between IOP responders and nonresponders (P=0.3, log-rank test). Although steroid-relate d cataracts are unlikely to develop in eyes that do not experience elevated IOP after intravitreal triamcinolone, those eyes that do also have a very high risk of rapidly experiencing posterior subcapsular lens opacification. This strong as sociation suggests that the mechanism responsible for the development of steroid -induced PSC cataract and raised IOP may be similar.
文摘This study presents experimental results of the change in threshold friction velocity and dust emission strength as a function of soil moisture content. The dust and soil moisture data were obtained from irrigated plots of a bare, sandy soil （no vegetation） situated in the Mongolian steppe. Dust flux was measured using the PI-SWERL^（R） device, while soil moisture was measured using gravimetric methods. Our results demonstrate the strong controlling effects of soil moisture on both the threshold friction velocity and dust emission strengths. Threshold friction velocity increased from 0.44 m/s for dry soil （0.002 g/g） to 0.67 m/s for wet soil （0.06 g/g）, confirming the importance of soil moisture for controlling dust events. Dust emission strength was significantly depressed for wet soils, starting at a soil moisture value of 0.02 g/g. From these results, we developed a simple dust diagram that may be useful as part of a warning system to identify initial sensitivity to threshold conditions as well as conditions that could lead to potentially significant dust emissions. Overall, the research findings in this study could be used to provide foreknowledge of conditions that would be conducive to high dust emissions for this area of Mongolia.
基金Supported by National Health and Medical Research Council Project Grant,No.APP1006759 and the Robert W.Storr Bequest to the Sydney Medical Foundation of the University of Sydney to Ahlenstiel G
文摘Antiviral therapy consisting of interferon-alpha and ribavirin for chronic hepatitis C infection is associated with multi-system side-effects.Ophthalmologic complications are common and can be classified into two groups:interferon-associated retinopathy and atypical adverse events.Interferon-associated retinopathy has been investigated by multiple observational studies that have found widely divergent results.The clinical importance of this complication is,consequently,controversial.This review examines the literature with the specific goal of identifying the most important ophthalmologic issues facing the hepatologist prescribing antiviral therapy.Accordingly,it assesses the incidence of interferon-associated retinopathy,as well as its risk factors,pathogenesis,clinical manifestations and options for management using data from the observational studies.The likely benefit of a screening program,especially one targeting patients with the highest risk of developing interferon-associated retinopathy,is analysed.Atypical ophthalmologic adverse events occur less frequently than interferon-associated retinopathy during antiviral therapy for chronic hepatitis C infection.They often,however,lead to irreversible vision loss.We examine the reports of these adverse events-in individual case reports or case series and in the observational studies investigating interferon-associated retinopathy-to describe the spectrum of these adverse events,the likely outcome for patients and to highlight the most important areas of future clinical research.
基金Supported by National Institute for Occupational Safety and Health (NIOSH) of USA(200-2009-30328)
文摘A booster fan is an underground main fan which is installed in series with a main surface fan and used to boost the air pressure of the ventilation to overcome mine resistance.Currently booster fans are used in several major coal mining countries including the United Kingdom,Australia,Poland and China.In the United States booster fans are prohibited in coal mines although they are used in several metal and non-metal mines.A study has been undertaken to examine alternatives for ventilating an underground room and pillar coal mine system.A feasibility study of a hypothetical situation has shown that current ventilation facilities are incapable of fulfilling mine air requirements in the future due to increased seam methane levels.A current ventilation network model has been prepared and projected to a mine five years plan."Ventsim visual" software simulations of different possible ventilation options have been conducted in which varying methane levels are found at working faces.The software can also undertake financial simulations and project present value total costs for the options under study.Several scenarios for improving the ventilation situation such as improving main surface fans,adding intake shafts,adding exhaust shafts and utilizing booster fans have been examined.After taking into account the total capital and operating costs for the five years mine plan the booster fan scenarios are recommended as being the best alternatives for further serious consideration by the mine.The optimum option is a properly sized and installed booster fan system that can be used to create safe work conditions,maintain adequate air quantity with lowest cost,generate a reduction in energy consumption and decrease mine system air leakage.
基金Supported partially by the CDCHT(ULA,Mérida,Venezuela)。
文摘Classical electrodynamics foresees that the effective interaction force between a moving charge and a magnetic dipole is modified by the time-varying total momentum of the interaction fields. We derive the equations of motion of the particles from the total stress-energy tensor, assuming the validity of Maxwell’s equations and the total momentum conservation law. Applications to the effects of Aharonov–Bohm type show that the observed phase shift may be due to the relative lag between interfering particles caused by the effective local force.
文摘A real-time Diesel Particulate Matter （DPM） monitor has been developed on the base of the successful National In- stitute of Occupational Health and Safety （NIOSH） designed Personal Dust Monitor （PDM） unit. The objectives of a recently completed Australian Coal Association Research Program （ACARP） study was to modify the PDM to measure the submicrometre fraction of the aerosol in a real-time monitoring underground instrument. Mine testing focused on use of the monitor in engineering evaluations of Longwall （LW） moves demonstrated how DPM concentrations from vehicles fluctuate under varying ventilation and operational conditions. The strong influence of mine ventilation systems is reviewed. Correlation between the current SKC DPM measurement system and real-time DPM monitors were conducted and results from eight mines show a correlation between elemental carbon （EC） and the new monitor DPM mass ranging from 0.45 to 0.82 with R2〉0.86 in all but two cases. This differences in suspected to be due to variations from mine to mine in aspects such as mine atmospheric contamination, vehicle fleet variations, fuel type, engine maintenance, engine combustion efficiency, engine behavior or interference from other submicrometre aerosol. Real-time monitoring clearly reflects the movement of individual diesel vehicles and allows pin-pointing of high exposure zones such as those encountered where various vehicles engage in intense work in areas of constrained or difficult ventilation. DPM shift average monitoring approaches do not readily allow successful engineering evaluation exercises to determine acceptability of pollution levels. Identification of high DPM concentration zones allows efficient modification of mine ventilation, operator positioning and other work practices to reduce miners＇ exposures without waiting for laboratory analysis results.
文摘To determine whether an intravitreal injection of triamcinolone acetonide for persistent diabetic macular edema after adequate laser treatment improves visual acuity. Prospective, double masked, placebo controlled, randomized clinical t rial. Sixty nine eyes of 43 patients were entered into the study, with 34 eyes randomized to receive active treatment and 35 randomized to receive a placebo in jection. Sixty five of 69 eyes (94%) completed the 3 month study visit. Using a 27 gauge needle, 0.1 ml of triamcinolone acetonide was injected through the pars plana. The procedure was performed in a minor procedures area in the outpat ient clinic under sterile conditions and using topical and subconjunctival anest hesia. Eyes randomized to placebo received a subconjunctival saline injection us ing the identical procedure for preparation. The main outcome measures were impr ovement of best corrected logarithm of the minimum angle of resolution visual a cuity by 5 or more letters and incidence of moderate or severe adverse events. E ighteen of 33 eyes (55%) treated with triamcinolone gained 5 or more letters of best corrected visual acuity compared with 5 of 32 eyes (16%) treated with pl acebo (P=0.002). Macular edema was reduced by 1 or more grades as determined by masked semiquantitative contact lens examination in 25 of 33 treated eyes (75%) versus 5 of 32 untreated eyes (16%; P < 0.0001). Optical coherence tomography showed a mean reduction of central retinal thickness of 152 μm in the 21 treate d eyes that were examined compared with a reduction of 36 μm in 20 placebo tre ated eyes. Infectious endophthalmitis developed in 1 triamcinolone treated eye that was treated adequately without loss of visual acuity. In the short term, in travitreal triamcinolone is an effective and relatively safe treatment for eyes with diabetic macular edema that have failed laser treatment. Although it will b e essential to study longer term outcomes, the use of intravitreal triamcinolon e may be considered in 1 eye of patients who continu
文摘In this study, the phenotype of psoriatic keratinocytes and fibroblasts in reconstructed skin models was compared to those constructed from normal cells. Characterization of this model by immunohistochemistry showed that classical markers of keratinocyte differentiation exhibited similar patterns of distribution in the psoriatic models to those derived from normal cells and generally reflected in vivo observations. Some crucial differences, however, were observed between normal and psoriatic models when pro-inflammatory gene expression and keratinocyte proliferation were investigated. Notably, the chemokine receptor CXCR2 was overexpressed in the psoriatic models, and, moreover, was localized to the granular layer of keratinocytes as seen in psoriasis in vivo. Pro-inflammatory genes(tumor necrosis factor alpha[TNF-α], interferon gamma[IFN-γ], and interleukin 8[IL-8]) were expressed at high levels in the psoriatic models, but were only minimally expressed in the normal models. Models derived from uninvolved psoriatic skin showed the same gene expression profile as those derived from involved skinalong with an increased proliferation rate when compared to normal models. These results suggest that psoriatic individuals possess an inherent predisposition to develop the disease phenotype even in the absence of T cells. This study represents a comprehensive characterization of psoriatic human skin reconstructed in vitro, and demonstrates the potential of this model as a valuable tool in drug discovery.
文摘新一代短柄髋关节植入物的设计理念是通过促进与生理相似的加载方式将应力一应变遮挡和植人物远期松动率降至最低。至今仍缺乏远期临床研究来证明短柄植人物的优点。由于缺乏临床数据，因此可以使用数字模拟来预测其远期性能。通过有限元研究预测短柄植入物的初始和远期稳定性，从界面微动方面对植入物的初始稳定性进行评价。结果发现，初始稳定性在允许骨整合出现的极限内。使用应变适应性骨重建法则对远期稳定性进行评估，进而在骨密度（bone mineral density，BMD）变化方面对骨的远期行为进行预测。在经典的Gruen1区和Gruen7区内未发现BMD降低，且骨重建模式与文献中髋关节表面置换的结果相似。
文摘This paper summarizes research related to the 2012 record the NEWS （NASA （National Aeronautics and Space Administration） drought in the central United States conducted by members of Energy and Water cycle Study） Working Group. Past drought patterns were analyzed for signal coherency with latest drought and the contribution of long-term trends in the Great Plains low-level jet, an important regional circulation feature of the spring rainy season in the Great Plains. Long-term changes in the seasonal transition from rainy spring into dry summer were also examined. Potential external forcing from radiative processes, soil-air interactions, and ocean teleconnections were assessed as contributors to the intensity of the drought. The atmospheric Rossby wave activity was found to be a potential source of predictability for the onset of drought. A probabilistic model was introduced and evaluated for its performance in predicting drought recovery in the Great Plains.
