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101.
In Vehicle-to-Infrastructure (V2I) communication networks, mobile users are able to access Internet services, such as video stre- aming, digital map downloading, database acc- ess, online gaming, and even safety services like accident alarm, traffic condition broadcast, etc., through fixed roadside units. However, the dynamics of communication environment and frequent changing topology critically challe- nge the design of an efficient transport layer protocol, which makes it difficult to guarantee diverse Quality of Service (QoS) requirements for various applications. In this paper, we pre- sent a novel transport layer scheme in infra- structure based vehicular networks, and aim to resolve some challenging issues such as sou- rce transfer rate adjustment, congestion avoid- ance, and fairness. By precisely detecting pac- ket losses and identifying various causes of th- ese losses (for example, link disconnection, cha- nnel error, packet collision, buffer overflow), the proposed scheme adopts different reacting mechanisms to deal with each of the losses. Moreover, it timely monitors the buffer size of the bottleneck Road-Side Unit (RSU), and dyn- amically makes transfer rate feedbacks to sou- rce nodes to avoid buffer overflow or vacancy. Finally, analysis and simulation results show that the proposed scheme not only successfully reduces packet losses because of buffer over- flow and link disconnection but also improves the utilization efficiency of channel resource. 相似文献
102.
An eye monitor whose design is inspired by the human visual system is presented. The monitor incorporates an internal representation or model of what the eye looks like to a video camera. The system can measure the position of the eyes and the size of the pupil in the presence of interfering noise and in patients wearing eyeglasses or contact lenses, and it tolerates defocusing due to small movements in depth by the patient. The system makes real-time correction for head and eye movements while measuring pupillary responses to controlled light stimuli. The design and software and hardware components are described, and some applications are noted. Its use for early clinical detection of visual diseases by objectively measuring pupillary responses to carefully controlled light stimuli is examined as an example. Some general observations about using computers in medical measurements are made 相似文献
103.
Chassin Laurie; Presson Clark C.; Todd Michael; Rose Jennifer S.; Sherman Steven J. 《Canadian Metallurgical Quarterly》1998,34(6):1189
A longitudinal multigenerational design was used to examine the intergenerational transmission of smoking and the correlated transmission of parental support and control. Whether maternal socialization of adolescent smoking (both general parenting practices and smoking-specific strategies) would predict adolescent smoking both directly and indirectly by affecting peer affiliations was tested. There was strong evidence for the intergenerational transmission of cigarette smoking and for the relation between peer smoking and adolescent smoking. Both general parenting practices and smoking-specific discussion and punishment were significantly related to adolescents' smoking, especially for adolescent-reported parenting. Support for the intergenerational transmission of parenting practices emerged only in mothers' reports of support. Results suggest expanding current peer-focused prevention efforts to include parental socialization strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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MP Sande-Lemos Azcue R Shaoul E Cutz PM Sherman 《Canadian Metallurgical Quarterly》1998,27(4):452-456
We studied mortality related to peptic ulcer bleed in a well defined cohort of patients in the month after the episode of peptic ulcer bleed. Our objective was to assess the contribution of peptic ulcer antecedents and other predictive factors on the risk of dying. The study cohort comprised 1,020 patients hospitalized for an episode of peptic ulcer bleed between January 1991 and March 1994 and identified in the General Practice Research Database in the United Kingdom. Six hundred twenty-three patients had no prior episode of peptic ulcer disease, and 384 had peptic ulcer antecedents; for 13 patients, information was not available. Forty-five patients died (mortality rate = 4.4 per 100 person-months; 95% confidence interval = 3.3-5.9) within 1 month of the peptic ulcer bleed. Patients with no peptic ulcer antecedent faced a greater risk of dying than patients with antecedents (relative risk = 3.0; 95% confidence interval = 1.2-7.1). Elderly patients, those undergoing surgery, and current users of acid-suppressing drugs or nonsteroidal antiinflammatory drugs all had an increased mortality risk. Patients presenting with their first-ever episode of peptic ulcer bleed have a higher case fatality rate than those with previous episodes of peptic ulcer. 相似文献
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VA Convertino LE Armstrong EF Coyle GW Mack MN Sawka LC Senay WM Sherman 《Canadian Metallurgical Quarterly》1996,28(1):i-vii
It is the position of the American College of Sports Medicine that adequate fluid replacement helps maintain hydration and, therefore, promotes the health, safety, and optimal physical performance of individuals participating in regular physical activity. This position statement is based on a comprehensive review and interpretation of scientific literature concerning the influence of fluid replacement on exercise performance and the risk of thermal injury associated with dehydration and hyperthermia. Based on available evidence, the American College of Sports Medicine makes the following general recommendations on the amount and composition of fluid that should be ingested in preparation for, during, and after exercise or athletic competition: 1) It is recommended that individuals consume a nutritionally balanced diet and drink adequate fluids during the 24-hr period before an event, especially during the period that includes the meal prior to exercise, to promote proper hydration before exercise or competition. 2) It is recommended that individuals drink about 500 ml (about 17 ounces) of fluid about 2 h before exercise to promote adequate hydration and allow time for excretion of excess ingested water. 3) During exercise, athletes should start drinking early and at regular intervals in an attempt to consume fluids at a rate sufficient to replace all the water lost through sweating (i.e., body weight loss), or consume the maximal amount that can be tolerated. 4) It is recommended that ingested fluids be cooler than ambient temperature [between 15 degrees and 22 degrees C (59 degrees and 72 degrees F])] and flavored to enhance palatability and promote fluid replacement. Fluids should be readily available and served in containers that allow adequate volumes to be ingested with ease and with minimal interruption of exercise. 5) Addition of proper amounts of carbohydrates and/or electrolytes to a fluid replacement solution is recommended for exercise events of duration greater than 1 h since it does not significantly impair water delivery to the body and may enhance performance. During exercise lasting less than 1 h, there is little evidence of physiological or physical performance differences between consuming a carbohydrate-electrolyte drink and plain water. 6) During intense exercise lasting longer than 1 h, it is recommended that carbohydrates be ingested at a rate of 30-60 g.h(-1) to maintain oxidation of carbohydrates and delay fatigue. This rate of carbohydrate intake can be achieved without compromising fluid delivery by drinking 600-1200 ml.h(-1) of solutions containing 4%-8% carbohydrates (g.100 ml(-1)). The carbohydrates can be sugars (glucose or sucrose) or starch (e.g., maltodextrin). 7) Inclusion of sodium (0.5-0.7 g.1(-1) of water) in the rehydration solution ingested during exercise lasting longer than 1 h is recommended since it may be advantageous in enhancing palatability, promoting fluid retention, and possibly preventing hyponatremia in certain individuals who drink excessive quantities of fluid. There is little physiological basis for the presence of sodium in n oral rehydration solution for enhancing intestinal water absorption as long as sodium is sufficiently available from the previous meal. 相似文献
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V. D. Gol'dina D. N. Nabotov S. I. Prokhorenko S. M. Sherman 《Power Technology and Engineering (formerly Hydrotechnical Construction)》1990,24(8):490-496
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 8, pp. 9–13, August, 1990. 相似文献
110.