Intermodal competition changes with changes in technology, economics, and environmental concerns. Trucks and airships are generally considered not to be competitors, but this depends on the distance of haul. The tonne...Intermodal competition changes with changes in technology, economics, and environmental concerns. Trucks and airships are generally considered not to be competitors, but this depends on the distance of haul. The tonne-kilometer cost of trucking rises much more quickly with distance than it does the cost of a cargo airship. At some distance, the two modes are direct substitutes. The costs of the Mexico-Canada refrigerated truck supply chain are compared with the costs of a 100t-lift, electrically-powered airship. The flight characteristics of the Hindenburg Zeppelin are used as a model for a modern cargo airship. The supply chain cost of trucking tomatoes is used to test the theorical proposition. The cost difference works out to about US10￠/kg (5￠/lb) advantage for trucking Mexican tomatoes to Canada. However, this cost disadvantage of the airship could be made up by their vibrationless ride, better air circulation and one-day service versus four days by truck. This alternative form of transportation could have a positive impact on worldwide north-south distribution of food. Airships can overcome trade barriers and distance to open new markets for perishable food exports. In addition, they would reduce the carbon emissions of transport. Canada imports 160,000 refrigerated truckloads of fruits and vegetables by from the southern US and Mexico. With an average driving distance of 3,000 km, these trucks emit 606,000 MT of CO<sub>2</sub> annually. Airships powered by hydrogen fuel cells would have zero-carbon emissions. Markets are not yet incorporating the environmental advantage of airships in any freight comparison, but inevitably this will be important.展开更多
Context: The hypothesis that a low- fat dietary pattern can reduce breast cancer risk has existed for decades but has never been tested in a controlled intervention trial. Objective: To assess the effects of undertaki...Context: The hypothesis that a low- fat dietary pattern can reduce breast cancer risk has existed for decades but has never been tested in a controlled intervention trial. Objective: To assess the effects of undertaking a low- fat dietary pattern on breast cancer incidence. Design and Setting: A randomized, controlled, primary prevention trial conducted at 40 US clinical centers from 1993 to 2005. Participants: A total of 48 835 postmenopausal women, aged 50 to 79 years, without prior breast cancer, including 18.6% of minority race/ethnicity, were enrolled. Interventions: Women were randomly assigned to the dietary modification intervention group (40% [n = 19 541]) or the comparison group (60% [n = 29 294]). The intervention was designed to promote dietary change with the goals of reducing intake of total fat to 20% of energy and increasing consumption of vegetables and fruit to at least 5 servings daily and grains to at least 6 servings daily. Comparison group participants were not asked to make dietary changes. Main Outcome Measure: Invasive breast cancer incidence. Results: Dietary fat intake was significantly lower in the dietary modification intervention group compared with the comparison group. The difference between groups in change from baseline for percentage of energy from fat varied from 10.7% at year 1 to 8.1% at year 6. Vegetable and fruit consumption was higher in the intervention group by at least 1 serving per day and a smaller, more transient difference was found for grain consumption. The number of women who developed invasive breast cancer (annualized incidence rate) over the 8.1- year average follow- up period was 655 (0.42% ) in the intervention group and 1072 (0.45% ) in the comparison group (hazard ratio, 0.91; 95% confidence interval, 0.83- 1.01 for the comparison between the 2 groups). Secondary analyses suggest a lower hazard ratio among adherent women, provide greater evidence of risk reduction among women having a high- fat diet at baseline, and suggest a dietary effect that varies by 展开更多
Biomization provides an important way to assign pollen taxa to biomes and to simulate palaeo-vegetation patterns, so that pollen data can be mapped to reconstruct biogeography and climate. The authors have tested the ...Biomization provides an important way to assign pollen taxa to biomes and to simulate palaeo-vegetation patterns, so that pollen data can be mapped to reconstruct biogeography and climate. The authors have tested the applicability of this procedure to assign modern pollen surface samples from China to biomes. The procedure successfully delineated the major vegetation types of China. When the same procedure was applied to 6 ka B.P. fossil pollen samples, the reconstructions showed that the forest zones were systematically shifted northwards ca. 300\500 km beyond their present northern limits in eastern China; the area of desert and steppe vegetation was reduced compared to the present in northwestern China; the area of tundra was reduced largely on the Tibetan Plateau. This research is a contribution to the project of BIOME 6000 in Pacific-Asian regions.展开更多
BACKGROUND:The use of ultrasound(US)within healthcare has inspired the development of new US technology.There have been few studies comparing the use of handheld US to standard US for medical education.This research a...BACKGROUND:The use of ultrasound(US)within healthcare has inspired the development of new US technology.There have been few studies comparing the use of handheld US to standard US for medical education.This research aims to determine whether a handheld US device can provide a comparable primary learning experience to that of a standard US machine.METHODS:Over two days of instruction,participants were taught and evaluated on core US fundamentals.The standard group received instruction on standard US machines,while the handheld group received instruction on handheld US devices.Participants completed a qualitative survey regarding their experience.Six hundred and four images were obtained and graded by two emergency medicine physicians.RESULTS:A total of 119 Swiss medical students were enrolled in our study.There was no statistically significant difference in the US assessment measurements,except for faster endpoint septal separation(EPSS)vascular setup time in the handheld group(P=0.001).There was no statistically significant difference in participants’perceived difficulty of US learning(P=0.198),comfort level(P=0.188),or self-estimated capability to perform US in the future(P=0.442).There was no statistically significant difference in the percentage of correctly obtained images(P=0.211)or images that were clinically useful(P=0.256).The median quality score of images obtained by the standard group was eight compared to seven in handheld group(P<0.01).CONCLUSION:Our data suggest a handheld US machine can perform as well as a standard US machine as an educational tool despite sacrifices in image quality.展开更多
The containerized shipment of freight continues to grow rapidly. This development can be traced to a transformation of bulk and break-bulk service to containerization. Demand has been driven by opportunities to broade...The containerized shipment of freight continues to grow rapidly. This development can be traced to a transformation of bulk and break-bulk service to containerization. Demand has been driven by opportunities to broaden logistical options as well as advantageous freight rates. Logisticians and policy makers are unsure how much more bulk traffic can be converted to containerization, but the trends are evident. Of particular interest is grain. Bulk grain handlers have successfully resisted the conversion of grain shipping to containerization, except on the North American-Asian traffic lanes and the Australian-Asian traffic lanes where growth has been significant. This paper reviews the theoretical case for grain containerization from a logistics perspective, followed by an examination of the current trends in the United States and Canada. Subsequently, the analysis considers the restrictions and resistance to the conversion of grain from bulk shipping to containerization.展开更多
Objective: To demonstrate the impact of inadequate standardization and population coverage on the ability to measure and improve maternal mortality in the United States. Data Sources: The CDC Wonder system for the yea...Objective: To demonstrate the impact of inadequate standardization and population coverage on the ability to measure and improve maternal mortality in the United States. Data Sources: The CDC Wonder system for the years 2000-2015 using the following definitions of maternal mortality and associated ICD-CM-10 codes: 1) Maternal deaths up to 42 days after delivery (A34, O00-O99, except O96-O97);2) Maternal deaths within one year after delivery (A34, O00-O99, except O97);3) All maternal deaths (A34, O00-O99). Study Design: For each year between 2000-2015, we provided maternal deaths, live births, and calculated maternal mortality ratios (MDR). For deaths within 42 days, we also calculated adjusted mortality ratios (ADR). Principal Findings: Maternal mortality comparisons which utilize inconsistent definitions and apply non-validated statistical adjustments produce specious results. Conclusions: Variation and inconsistency in definitions, coding, and other reporting anomalies render the current aggregated vital statistics on maternal mortality inadequate for accurate trending and service impact studies. The definition of maternal mortality must be expanded to all outcomes of pregnancy: births, induced abortions, and natural fetal losses.展开更多
BACKGROUND There are approximately 25% of women in the United States suffering from pelvic floor disorders (PFDs) and this number is predicted to rise. The potential complications and increasing healthcare costs that ...BACKGROUND There are approximately 25% of women in the United States suffering from pelvic floor disorders (PFDs) and this number is predicted to rise. The potential complications and increasing healthcare costs that exist with an operation indicate the importance of conservative treatment options prior to attempting surgery. Considering the prevalence of PFDs, it is important for primary care physician and specialists (obstetricians and gynecologists) to be familiar with the initial work-up and the available conservative treatment options prior to subspecialist (urogynecologist) referral. AIM To assess the types of treatments that specialists attempted prior to subspecialty referral and determine the differences in referral patterns. METHODS This is a retrospective cohort study of 234 patients from a community teaching hospital referred to a single female pelvic medicine and reconstructive surgery (FPMRS) provider for PFD. Specialist vs primary care provider (PCP) referrals were compared. Number, length and treatment types were studied using descriptive statistics. RESULTS There were 184 referrals (78.6%) by specialists and 50 (21.4%) by PCP. Treatment (with Kegel exercises, pessary placements, and anticholinergic medications) was attempted on 51%(n = 26) of the PCP compared to 48%(n = 88) of the specialist referrals prior to FPMRS referral (P = 0.6). There was no significant difference in length of treatment prior to referral for PCPs vs specialists (14 mo vs 16 mo, respectively, P = 0.88). However, there was a significant difference in the patient’s average time with the condition prior to referral (35 mo vs 58 mo for PCP compared to specialist referrals)(P = 0.02). CONCLUSION One half of the patients referred to FPMRS clinic received treatment prior to referral. Thus, specialists and generalists can benefit from education regarding therapies for PFD before subspecialty referral.展开更多
Objective: To investigate the possibility that response to cholinesterase inhi bitor therapy could be predicted by easily measurable variables that are known t o change as a result of treatment (such as the Mini Menta...Objective: To investigate the possibility that response to cholinesterase inhi bitor therapy could be predicted by easily measurable variables that are known t o change as a result of treatment (such as the Mini Mental State Examination), m easures of function (such as the instrumental activities of daily living and the social behaviour subscales of the Nurse’s Observation Scale for Geriatric Pati ents), and measures of attention(such as the Digit Symbol Substitution Test; DSS T), or that might influence response through structural (for example, age,cerebr ovascular disease, medial temporal lobe (MTL) atrophy,hypertension) or chemical (for example, smoking) mechanisms.Method: This was a cohort study of 160 consecu tive outpatients with probable Alzheimer’s disease who commenced cholinestera- se inhibitor treatment over a 3 year period in a semi-rural area of Scotland. Results: The overall response rate was 42.1%.Stratification of response betwee n good and poor responders was possible using baseline DSST and a measure of MTL thickness using CT. Among the patients, 60.4%of those above the cut off point for both DSST and MTL thickness (29/48 subjects)were classified as good responde rs, compared with 6.3%of subjects below the cut off point for both (1/16 subjec ts).Subjects above the cut off point for both measures were morelikely to be cla ssified as good responders than subjects with only one or no values above the re spective cut off points (χ2=10.61, df=1, p=0.001) Conclusions: The DSST and a m easure of MTL thickness derived from CT scanning may be useful in improving the prediction of response to cholinesterase inhibitors in subjects with AD. Subject s with low DSST scores and more severe MTL atrophy are unlikely to respond to tr eatment.These preliminary data justify a prospective trial of the usefulness of our suggested predictive measures.展开更多
死亡大多发生在医院。因此，照顾临终病人对医院的医疗是一大挑战。利物浦医疗照顾路径（Liverpool care pathway，LCP）作为一个范本，指导医务人员如何正确医疗照顾临终病人，并将安宁病房临终关怀理念引入医院。医院在临终关怀方面...死亡大多发生在医院。因此，照顾临终病人对医院的医疗是一大挑战。利物浦医疗照顾路径（Liverpool care pathway，LCP）作为一个范本，指导医务人员如何正确医疗照顾临终病人，并将安宁病房临终关怀理念引入医院。医院在临终关怀方面的医疗质量做得并不太好。展开更多
We present an algorithm for determining the stepsize in an explicit Runge-Kutta method that is suitable when solving moderately stiff differential equations. The algorithm has a geometric character, and is based on a ...We present an algorithm for determining the stepsize in an explicit Runge-Kutta method that is suitable when solving moderately stiff differential equations. The algorithm has a geometric character, and is based on a pair of semicircles that enclose the boundary of the stability region in the left half of the complex plane. The algorithm includes an error control device. We describe a vectorized form of the algorithm, and present a corresponding MATLAB code. Numerical examples for Runge-Kutta methods of third and fourth order demonstrate the properties and capabilities of the algorithm.展开更多
文摘Intermodal competition changes with changes in technology, economics, and environmental concerns. Trucks and airships are generally considered not to be competitors, but this depends on the distance of haul. The tonne-kilometer cost of trucking rises much more quickly with distance than it does the cost of a cargo airship. At some distance, the two modes are direct substitutes. The costs of the Mexico-Canada refrigerated truck supply chain are compared with the costs of a 100t-lift, electrically-powered airship. The flight characteristics of the Hindenburg Zeppelin are used as a model for a modern cargo airship. The supply chain cost of trucking tomatoes is used to test the theorical proposition. The cost difference works out to about US10￠/kg (5￠/lb) advantage for trucking Mexican tomatoes to Canada. However, this cost disadvantage of the airship could be made up by their vibrationless ride, better air circulation and one-day service versus four days by truck. This alternative form of transportation could have a positive impact on worldwide north-south distribution of food. Airships can overcome trade barriers and distance to open new markets for perishable food exports. In addition, they would reduce the carbon emissions of transport. Canada imports 160,000 refrigerated truckloads of fruits and vegetables by from the southern US and Mexico. With an average driving distance of 3,000 km, these trucks emit 606,000 MT of CO<sub>2</sub> annually. Airships powered by hydrogen fuel cells would have zero-carbon emissions. Markets are not yet incorporating the environmental advantage of airships in any freight comparison, but inevitably this will be important.
文摘Context: The hypothesis that a low- fat dietary pattern can reduce breast cancer risk has existed for decades but has never been tested in a controlled intervention trial. Objective: To assess the effects of undertaking a low- fat dietary pattern on breast cancer incidence. Design and Setting: A randomized, controlled, primary prevention trial conducted at 40 US clinical centers from 1993 to 2005. Participants: A total of 48 835 postmenopausal women, aged 50 to 79 years, without prior breast cancer, including 18.6% of minority race/ethnicity, were enrolled. Interventions: Women were randomly assigned to the dietary modification intervention group (40% [n = 19 541]) or the comparison group (60% [n = 29 294]). The intervention was designed to promote dietary change with the goals of reducing intake of total fat to 20% of energy and increasing consumption of vegetables and fruit to at least 5 servings daily and grains to at least 6 servings daily. Comparison group participants were not asked to make dietary changes. Main Outcome Measure: Invasive breast cancer incidence. Results: Dietary fat intake was significantly lower in the dietary modification intervention group compared with the comparison group. The difference between groups in change from baseline for percentage of energy from fat varied from 10.7% at year 1 to 8.1% at year 6. Vegetable and fruit consumption was higher in the intervention group by at least 1 serving per day and a smaller, more transient difference was found for grain consumption. The number of women who developed invasive breast cancer (annualized incidence rate) over the 8.1- year average follow- up period was 655 (0.42% ) in the intervention group and 1072 (0.45% ) in the comparison group (hazard ratio, 0.91; 95% confidence interval, 0.83- 1.01 for the comparison between the 2 groups). Secondary analyses suggest a lower hazard ratio among adherent women, provide greater evidence of risk reduction among women having a high- fat diet at baseline, and suggest a dietary effect that varies by
文摘Biomization provides an important way to assign pollen taxa to biomes and to simulate palaeo-vegetation patterns, so that pollen data can be mapped to reconstruct biogeography and climate. The authors have tested the applicability of this procedure to assign modern pollen surface samples from China to biomes. The procedure successfully delineated the major vegetation types of China. When the same procedure was applied to 6 ka B.P. fossil pollen samples, the reconstructions showed that the forest zones were systematically shifted northwards ca. 300\500 km beyond their present northern limits in eastern China; the area of desert and steppe vegetation was reduced compared to the present in northwestern China; the area of tundra was reduced largely on the Tibetan Plateau. This research is a contribution to the project of BIOME 6000 in Pacific-Asian regions.
文摘BACKGROUND:The use of ultrasound(US)within healthcare has inspired the development of new US technology.There have been few studies comparing the use of handheld US to standard US for medical education.This research aims to determine whether a handheld US device can provide a comparable primary learning experience to that of a standard US machine.METHODS:Over two days of instruction,participants were taught and evaluated on core US fundamentals.The standard group received instruction on standard US machines,while the handheld group received instruction on handheld US devices.Participants completed a qualitative survey regarding their experience.Six hundred and four images were obtained and graded by two emergency medicine physicians.RESULTS:A total of 119 Swiss medical students were enrolled in our study.There was no statistically significant difference in the US assessment measurements,except for faster endpoint septal separation(EPSS)vascular setup time in the handheld group(P=0.001).There was no statistically significant difference in participants’perceived difficulty of US learning(P=0.198),comfort level(P=0.188),or self-estimated capability to perform US in the future(P=0.442).There was no statistically significant difference in the percentage of correctly obtained images(P=0.211)or images that were clinically useful(P=0.256).The median quality score of images obtained by the standard group was eight compared to seven in handheld group(P<0.01).CONCLUSION:Our data suggest a handheld US machine can perform as well as a standard US machine as an educational tool despite sacrifices in image quality.
文摘The containerized shipment of freight continues to grow rapidly. This development can be traced to a transformation of bulk and break-bulk service to containerization. Demand has been driven by opportunities to broaden logistical options as well as advantageous freight rates. Logisticians and policy makers are unsure how much more bulk traffic can be converted to containerization, but the trends are evident. Of particular interest is grain. Bulk grain handlers have successfully resisted the conversion of grain shipping to containerization, except on the North American-Asian traffic lanes and the Australian-Asian traffic lanes where growth has been significant. This paper reviews the theoretical case for grain containerization from a logistics perspective, followed by an examination of the current trends in the United States and Canada. Subsequently, the analysis considers the restrictions and resistance to the conversion of grain from bulk shipping to containerization.
文摘Objective: To demonstrate the impact of inadequate standardization and population coverage on the ability to measure and improve maternal mortality in the United States. Data Sources: The CDC Wonder system for the years 2000-2015 using the following definitions of maternal mortality and associated ICD-CM-10 codes: 1) Maternal deaths up to 42 days after delivery (A34, O00-O99, except O96-O97);2) Maternal deaths within one year after delivery (A34, O00-O99, except O97);3) All maternal deaths (A34, O00-O99). Study Design: For each year between 2000-2015, we provided maternal deaths, live births, and calculated maternal mortality ratios (MDR). For deaths within 42 days, we also calculated adjusted mortality ratios (ADR). Principal Findings: Maternal mortality comparisons which utilize inconsistent definitions and apply non-validated statistical adjustments produce specious results. Conclusions: Variation and inconsistency in definitions, coding, and other reporting anomalies render the current aggregated vital statistics on maternal mortality inadequate for accurate trending and service impact studies. The definition of maternal mortality must be expanded to all outcomes of pregnancy: births, induced abortions, and natural fetal losses.
文摘BACKGROUND There are approximately 25% of women in the United States suffering from pelvic floor disorders (PFDs) and this number is predicted to rise. The potential complications and increasing healthcare costs that exist with an operation indicate the importance of conservative treatment options prior to attempting surgery. Considering the prevalence of PFDs, it is important for primary care physician and specialists (obstetricians and gynecologists) to be familiar with the initial work-up and the available conservative treatment options prior to subspecialist (urogynecologist) referral. AIM To assess the types of treatments that specialists attempted prior to subspecialty referral and determine the differences in referral patterns. METHODS This is a retrospective cohort study of 234 patients from a community teaching hospital referred to a single female pelvic medicine and reconstructive surgery (FPMRS) provider for PFD. Specialist vs primary care provider (PCP) referrals were compared. Number, length and treatment types were studied using descriptive statistics. RESULTS There were 184 referrals (78.6%) by specialists and 50 (21.4%) by PCP. Treatment (with Kegel exercises, pessary placements, and anticholinergic medications) was attempted on 51%(n = 26) of the PCP compared to 48%(n = 88) of the specialist referrals prior to FPMRS referral (P = 0.6). There was no significant difference in length of treatment prior to referral for PCPs vs specialists (14 mo vs 16 mo, respectively, P = 0.88). However, there was a significant difference in the patient’s average time with the condition prior to referral (35 mo vs 58 mo for PCP compared to specialist referrals)(P = 0.02). CONCLUSION One half of the patients referred to FPMRS clinic received treatment prior to referral. Thus, specialists and generalists can benefit from education regarding therapies for PFD before subspecialty referral.
文摘Objective: To investigate the possibility that response to cholinesterase inhi bitor therapy could be predicted by easily measurable variables that are known t o change as a result of treatment (such as the Mini Mental State Examination), m easures of function (such as the instrumental activities of daily living and the social behaviour subscales of the Nurse’s Observation Scale for Geriatric Pati ents), and measures of attention(such as the Digit Symbol Substitution Test; DSS T), or that might influence response through structural (for example, age,cerebr ovascular disease, medial temporal lobe (MTL) atrophy,hypertension) or chemical (for example, smoking) mechanisms.Method: This was a cohort study of 160 consecu tive outpatients with probable Alzheimer’s disease who commenced cholinestera- se inhibitor treatment over a 3 year period in a semi-rural area of Scotland. Results: The overall response rate was 42.1%.Stratification of response betwee n good and poor responders was possible using baseline DSST and a measure of MTL thickness using CT. Among the patients, 60.4%of those above the cut off point for both DSST and MTL thickness (29/48 subjects)were classified as good responde rs, compared with 6.3%of subjects below the cut off point for both (1/16 subjec ts).Subjects above the cut off point for both measures were morelikely to be cla ssified as good responders than subjects with only one or no values above the re spective cut off points (χ2=10.61, df=1, p=0.001) Conclusions: The DSST and a m easure of MTL thickness derived from CT scanning may be useful in improving the prediction of response to cholinesterase inhibitors in subjects with AD. Subject s with low DSST scores and more severe MTL atrophy are unlikely to respond to tr eatment.These preliminary data justify a prospective trial of the usefulness of our suggested predictive measures.
文摘We present an algorithm for determining the stepsize in an explicit Runge-Kutta method that is suitable when solving moderately stiff differential equations. The algorithm has a geometric character, and is based on a pair of semicircles that enclose the boundary of the stability region in the left half of the complex plane. The algorithm includes an error control device. We describe a vectorized form of the algorithm, and present a corresponding MATLAB code. Numerical examples for Runge-Kutta methods of third and fourth order demonstrate the properties and capabilities of the algorithm.
