Perforated Wall Breakwater with Internal Horizontal Plate

The hydrodynamic performance of a perforated wall breakwater with an internal horizontal plate is studied. It is suggested that a horizontally submerged plate be installed inside the wave chamber to enhance the stability of the structure. Based on the linear wave theory, the 2D problem is formulated to analyze the wave reflection with different porosity, physical dimensions, and wave conditions. The method of matched eigenfunction expansions is used to obtain the solution. Generally, the hydrodynamic performance of a wave chamber is similar with or without an internal horizontal plate. However, the minimum reflection occurs at some particular ratios of the length of the wave chamber to the wavelength, which are less than the corresponding ratios for a wave chamber without the plate, because the waves become shorter over the submerged plate. Thus, the size of the wave chamber can be reduced. It is also found that a moderate porosity is optimal to dissipate the wave energy. By investigating the wave-induced force and moment, such breakwaters with an internal horizontal plate can be designed and constructed with a higher degree of confidence and reliability.     

How far droplets can move in indoor environments--revisiting the Wells evaporation-falling curve

A large number of infectious diseases are believed to be transmitted between people via large droplets and by airborne routes. An understanding of evaporation and dispersion of droplets and droplet nuclei is not only significant for developing effective engineering control methods for infectious diseases but also for exploring the basic transmission mechanisms of the infectious diseases. How far droplets can move is related to how far droplet-borne diseases can transmit. A simple physical model is developed and used here to investigate the evaporation and movement of droplets expelled during respiratory activities; in particular, the well-known Wells evaporation-falling curve of droplets is revisited considering the effect of relative humidity, air speed, and respiratory jets. Our simple model considers the movement of exhaled air, as well as the evaporation and movement of a single droplet. Exhaled air is treated as a steady-state non-isothermal (warm) jet horizontally issuing into stagnant surrounding air. A droplet is assumed to evaporate and move in this non-isothermal jet. Calculations are performed for both pure water droplets and droplets of sodium chloride (physiological saline) solution (0.9% w/v). We calculate the droplet lifetimes and how droplet size changes, as well as how far the droplets travel in different relative humidities. Our results indicate that a droplet's size predominately dictates its evaporation and movement after being expelled. The sizes of the largest droplets that would totally evaporate before falling 2 m away are determined under different conditions. The maximum horizontal distances that droplets can reach during different respiratory activities are also obtained. Our study is useful for developing effective prevention measures for controlling infectious diseases in hospitals and in the community at large. PRACTICAL IMPLICATIONS: Our study reveals that for respiratory exhalation flows, the sizes of the largest droplets that would totally evaporate before falling 2 m away are between 60 and 100 microm, and these expelled large droplets are carried more than 6 m away by exhaled air at a velocity of 50 m/s (sneezing), more than 2 m away at a velocity of 10 m/s (coughing) and less than 1 m away at a velocity of 1 m/s (breathing). These findings are useful for developing effective engineering control methods for infectious diseases, and also for exploring the basic transmission mechanisms of the infectious diseases. There is a need to examine the air distribution systems in hospital wards for controlling both airborne and droplet-borne transmitted diseases.     

Orchestration of neutrophil movement by intestinal epithelial cells in response to Salmonella typhimurium can be uncoupled from bacterial internalization

Intestinal epithelial cells respond to Salmonella typhimurium by internalizing this pathogen and secreting, in a polarized manner, an array of chemokines which direct polymorphonuclear leukocyte (PMN) movement. Notably, interleukin-8 (IL-8) is secreted basolaterally and directs PMN through the lamina propria, whereas pathogen-elicited epithelial chemoattractant (PEEC) is secreted apically and directs PMN migration across the epithelial monolayer to the intestinal lumen. While most studies of S. typhimurium pathogenicity have focused on the mechanism by which this bacterium invades its host, the enteritis characteristically associated with salmonellosis appears to be more directly attributable to the PMN movement that occurs in response to this pathogen. Therefore, we sought to better understand the relationship between S. typhimurium invasion and epithelial promotion of PMN movement. First, we investigated whether S. typhimurium becoming intracellular was necessary or sufficient to induce epithelial promotion of PMN movement. Blocking S. typhimurium invasion by preventing, with cytochalasin D, the epithelial cytoskeletal rearrangements which mediate internalization did not reduce the epithelial promotion of PMN movement. Conversely, bacterial attainment of an intracellular position was not sufficient to induce model epithelia to direct PMN transmigration, since neither basolateral invasion by S. typhimurium nor apical internalization of an invasion-deficient mutant (achieved by inducing membrane ruffling with epidermal growth factor) induced this epithelial cell response. These results indicate that specific interactions between the apical surface of epithelial cells and S. typhimurium, rather than simply bacterial invasion, mediate the epithelial direction of PMN transmigration. To further investigate the means by which S. typhimurium induces epithelia to direct PMN movement, we investigated whether the same signaling pathways regulate secretion of IL-8 and PEEC. IL-8 secretion, but not PEEC secretion, was activated by phorbol myristate acetate and blocked by an inhibitor (mg-132) of the proteosome which mediates NF-kappabeta activation. Further, secretion of IL-8, but not PEEC, was activated by an entry-deficient (HilDelta) S. typhimurium mutant or by basolateral invasion of a wild-type strain. Together, these results indicate that distinct signaling pathways mediate S. typhimurium invasion, induction of IL-8 secretion, and induction of PEEC secretion in model intestinal epithelia.     

Unusual case of tracheal agenesis

We describe the clinical presentation and pathological features of an unusual case of tracheal agenesis. The axial derivatives of the primitive foregut between the larynx and stomach were represented by a single structure featuring sequential segmentation into regions showing exclusively tracheal or esophageal differentiation in a pattern that is not easily classified by existing nosologic systems nor explained by the conventional hypothesis of dysontogenesis.     

It is time to move from the nursing process to critical thinking

As we reflect on the concept of critical thinking in perioperative nursing practice, we should ask ourselves whether we think critically. If not, we must learn the principles of critical thinking and apply them in our clinical practice settings. Our perioperative nurse managers and directors must demonstrate critical thinking in leading other nurses in the delivery of quality, cost-effective, service-oriented patient care. They also must identify peers who use critical thinking skills to support and sustain them in their quest.     

Cloning and functional expression of a human liver organic cation transporter

OBJECTIVE: The triglyceride-lowering effects of omega-3 fats and HDL cholesterol-raising effects of exercise may be appropriate management for dyslipidemia in NIDDM. However, fish oil may impair glycemic control in NIDDM. The present study examined the effects of moderate aerobic exercise and the incorporation of fish into a low-fat (30% total energy) diet on serum lipids and glycemic control in dyslipidemic NIDDM patients. RESEARCH DESIGN AND METHODS: In a controlled, 8-week intervention, 55 sedentary NIDDM subjects with serum triglycerides > 1.8 mmol/l and/or HDL cholesterol < 1.0 mmol/l were randomly assigned to a low-fat diet (30% daily energy intake) with or without one fish meal daily (3.6 g omega-3/day) and further randomized to a moderate (55-65% VO2max) or light (heart rate < 100 bpm) exercise program. An oral glucose tolerance test (75 g), fasting serum glucose, insulin, lipids, and GHb were measured before and after intervention. Self-monitoring of blood glucose was performed throughout. RESULTS: In the 49 subjects who completed the study, moderate exercise improved aerobic fitness (VO2max) by 12% (from 1.87 to 2.07 l/min, P = 0.0001). Fish consumption reduced triglycerides (0.80 mmol/l, P = 0.03) and HDL3 cholesterol (0.05 mmol/l, P = 0.02) and increased HDL2 cholesterol (0.06 mmol/l, P = 0.01). After adjustment for age, sex, and changes in body weight, fish diets were associated with increases in GHb (0.50%, P = 0.05) and self-monitored glucose (0.57 mmol/l, P = 0.0002), which were prevented by moderate exercise. CONCLUSIONS: A reduced fat diet incorporating one daily fish meal reduces serum triglycerides and increases HDL2 cholesterol in dyslipidemic NIDDM patients. Associated deterioration in glycemic control can be prevented by a concomitant program of moderate exercise.     

Tension pneumothorax precluding laparoscopic repair of diaphragmatic hernia

BACKGROUND: Central Europe and the Czech Republic are specific in the prevalence of obesity which has increased by 10-40% during the last 10 years. METHODS: In the Czech republic there is 30 years of experience of a comprehensive approach to obesity treatment which includes: dietary treatment; exercise; behavioral modification; drug treatment; and bariatric surgery. Each of these approaches has its place in complex obesity management. Since 1983 bariatric surgery has been established in the Czech Republic for the treatment of morbid obesity. Vertical banded gastroplasty (VBG), gastric banding, laparoscopic nonadjustable and adjustable gastric bandings have been used over the years. Since 1993 laparoscopic gastric banding has been the only method used in our department. RESULTS: The comprehensive approach for obesity treatment in the Czech Republic has resulted in the development of obesity management and research centers, regional obesity units, obesity out-patients clinics and weight reduction clubs. The surgical treatment is a well-established part of this system and the long-term results of surgical treatment are acceptable both in terms of weight loss and complication rate. There has been no statistical difference in weight loss results following VBG and laparoscopic gastric banding, but there is a significant decrease in morbidity, and shorter hospital stay associated with laparoscopic gastric banding. CONCLUSIONS: The surgical approach in obesity treatment has an important place in the comprehensive care of obese patients. Laparoscopic gastric banding in the hands of an experienced surgeon is a method with low morbidity, short hospital stay and long-term weight loss results which are fully comparable with the results of other surgical approaches.