Internal bores and gravity currents in a two-fluid system

In this paper, a unified theory of internal bores and gravity currents is presented within the framework of the one-dimensional two-layer shallow-water equations. The equations represent four basic physical laws: the theory is developed on the basis of these laws. Though the first three of the four basic laws are apparent, the forth basic law has been uncertain. This paper shows first that this forth basic law can be deduced from the law which is called in this paper the conservation law of circulation. It is then demonstrated that, within the framework of the equations, an internal bore is represented by a shock satisfying the shock conditions that follow from the four basic laws. A gravity current can also be treated within the framework of the equations if the front conditions, i.e. the boundary conditions to be imposed at the front of the current, are known. Basically, the front conditions for a gravity current also follow from the four basic laws. When the gravity current is advancing along a no-slip boundary, however, it is necessary to take into account the influence of the thin boundary layer formed on the boundary; this paper describes how this influence can be evaluated. It is verified that the theory can satisfactorily explain the behaviour of internal bores advancing into two stationary layers of fluid. The theory also provides a formula for the rate of advance of a gravity current along a no-slip lower boundary; this formula proves to be consistent with some empirical formulae. In addition, some well-known theoretical formulae on gravity currents turn out to be obtainable on the basis of the theory.Comment: 47 pages, 5 figure

Importance of Milk Expression for Preterm Infants

Mothers of preterm infants may find it difficult to express breast milk. There is a low breast milk rate among preterm infants at discharge at our hospital, and here we tested the hypothesis that milk expression factors were the cause of the low rate. The study subjects were born before 33 gestational weeks at our hospital between March 2005 and June 2014. Nutritional evaluation was performed at discharge and noted whether breast milk, infant formula, or a mix of the 2 was being given. We compared the group given breast milk or the mix versus the group given formula. Of the 337 infants, 40 cases were excluded. Data from 297 infants were analyzed. The mean (SD) gestational age and birth weight were 29.5 (2.4) weeks and 1,230 (391) g, respectively. At discharge, 26 (8.8%), 102 (33.3%), and 174 (57.9%) infants were given breast milk, formula, and the mix, respectively. A multivariate logistic regression analysis showed that the first milk expression (h) was the risk factor for the formula group: adjusted odds ratio (95% confidence interval) 1.06 (1.02-1.09) and p=0.002. Delayed first milk expression could affect the low breast milk rate at discharge. Improvement of milk expression should be achieved to promote breastfeeding

Survival and Neurodevelopmental Outcomes of Very Low Birth Weight Infants in a Regional Core Hospital in Kochi, Japan

We sought to clarify the survival and neurodevelopmental outcomes of very low birth weight infants (VLBWIs) and to identify risk factors for death or neurodevelopmental impairment (NDI) in VLBWIs at our hospital. The total study population was 217 infants born in 2005-2012 weighing ≤1,500 g. We compared their outcomes with those from previous reports analyzed the causes of death. Risk factors for death after discharge or NDI were evaluated by a multivariate logistic regression analysis. The incidences of death or NDI reported revealed in this study and the database of Neonatal Research Network of Japan were 25.3% and 19.6% (p＝0.039), respectively. The main causes of death before discharge were intraventricular hemorrhage, sepsis, and persistent pulmonary hypertension of the newborn. The significant risk factors for death after discharge or NDI were early gestational age (weeks) and periventricular leukomalacia (adjusted odds ratio [95% confidence interval, p-value], 0.72 [0.54-0.94, 0.017] and 6.90 [1.35-38.25, 0.021], respectively). These factors must be addressed in order to improve treatment strategies for VLBWIs

Vacant rooms? The secondary use of stem-galls by ants in Eremanthus erythropappus (Asteraceae)

Galls are atypical proliferations of plant tissue induced by highly specialized herbivores, such as some insect groups. Although gall inducers create these structures for their own purpose (food, habitat, protection against natural enemies, and harsh weather), many other organisms can use galls as secondary inhabitants. The creation of new and better habitats with ameliorated micro-environmental conditions allows for the use of many other organisms, and as such, some galling insects are considered "micro" ecosystem engineers. This study characterized the occurrence of ants in microhabitats created by a gall-inducing cecidomyiidae associated with Eremanthus erythropappus (DC.) Mac. Leish (Asteraceae). It was 153 individuals of ants belonging to three species in 19 galls (9.5%) from the 200 galls sampled. The most common ant species found was Myrmelachista gallicola Mayr (Formicinae), including a single queen and larvae individuals. Galls occupied by these ants were 11.5% larger compared to unoccupied galls (gall diameter: occupied galls - 10.00 ± 2.09 mm; unoccupied galls - 8.97 ± 1.90 mm). Abandoned galls might promote the diversity of other organisms, especially for opportunistic dwellers such as ants

Potential of the Angiotensin Receptor Blockers (ARBs) Telmisartan, Irbesartan, and Candesartan for Inhibiting the HMGB1/RAGE Axis in Prevention and Acute Treatment of Stroke

Abstract: Stroke is a major cause of mortality and disability worldwide. The main cause of stroke is atherosclerosis, and the most common risk factor for atherosclerosis is hypertension. Int. J. Mol. Sci. 2013, 14 18900 Therefore, antihypertensive treatments are recommended for the prevention of stroke. Thre

Relationship between physical activity and cerebral white matter hyperintensity volumes in older adults with depressive symptoms and mild memory impairment: a cross-sectional study

IntroductionCerebral white matter hyperintensities (WMHs) are commonly found in the aging brain and have been implicated in the initiation and severity of many central nervous system diseases. Furthermore, an increased WMH volume indicates reduced brain health in older adults. This study investigated the association between WMH volume and physical activity in older adults with depressive symptoms (DS) and mild memory impairment (MMI). Factors associated with the WMH volume were also investigated.MethodsA total of 57 individuals aged over 65 years with DS and MMI were included in this study. The participants underwent magnetic resonance imaging to quantify WMH volumes. After WMH volume was accumulated, normalized to the total intracranial volume (TIV), the percentage of WMH volume was calculated. In addition, all participants wore a triaxial accelerometer for 2 weeks, and the average daily physical activity and number of steps were measured. The levels of blood biomarkers including cortisol, interleukin-6 (IL-6), brain-derived insulin-like growth factor-1, and brain-derived neurotrophic factor were measured. Motor and cognitive functions were also assessed.ResultsFaster maximum walking speed and longer time spent engaged in moderate physical activity were associated with a smaller percent of WMH volume, whereas higher serum IL-6 levels were associated with a larger percent of WMH volume. The number of steps per day, time spent engaged in low levels of physical activity, cognitive function, and all other measured biomarkers were not significantly associated with percent of WMH volume.DiscussionHigher blood inflammatory cytokine levels, shorter duration of moderate physical activity, and lower maximum walking speed were associated with a higher percent of WMH volume. Our results provide useful information for maintaining brain health in older adults at a high risk of developing dementia and may contribute to the development of preventive medicine for brain health

Changes in the Features of Invasive Pneumococcal Disease after Introduction of the Seven-valent Pneumococcal Conjugate Vaccine in a Regional Core Hospital of Kochi, Japan

Since the introduction of the seven-valent pneumococcal conjugate vaccine (PCV7) in 2007, invasive pneumococcal disease has declined, but the incidence of Streptococcus pneumoniae serotype 19A has risen worldwide. The present study examined changes in the features of invasive pneumococcal disease since the introduction of the PCV7 in Kochi, Japan. Pediatric cases of invasive pneumococcal disease were investigated before and after vaccine introduction (January 2008 to December 2013). Cases of invasive pneumococcal disease tended to decrease after PCV7 introduction. In addition, before introduction of the vaccine, most serotypes causing invasive pneumococcal disease were those included in the vaccine. However, after the introduction, we found cases infected by serotypes not covered by vaccine. Penicillin-resistant S. pneumoniae was the predominant serotype causing invasive pneumococcal disease before introduction of the PCV7, and the susceptibility of this serotype to antibiotics improved after vaccine introduction. Serotype isolates identified after vaccine introduction were also relatively susceptible to antibiotic therapy, but decreased susceptibility is expected