Equations for the Drag Force and Aerodynamic Roughness Length of Urban Areas with Random Building Heights

We use a conceptual model to investigate how randomly varying building heights within a city affect the atmospheric drag forces and the aerodynamic roughness length of the city. The model is based on the assumptions regarding wake spreading and mutual sheltering effects proposed by Raupach (Boundary-Layer Meteorol 60:375-395, 1992). It is applied both to canopies having uniform building heights and to those having the same building density and mean height, but with variability about the mean. For each simulated urban area, a correction is determined, due to height variability, to the shear stress predicted for the uniform building height case. It is found that u (*)/u (*R) , where u (*) is the friction velocity and u (*R) is the friction velocity from the uniform building height case, is expressed well as an algebraic function of lambda and sigma (h) /h (m) , where lambda is the frontal area index, sigma (h) is the standard deviation of the building height, and h (m) is the mean building height. The simulations also resulted in a simple algebraic relation for z (0)/z (0R) as a function of lambda and sigma (h) /h (m) , where z (0) is the aerodynamic roughness length and z (0R) is z (0) found from the original Raupach formulation for a uniform canopy. Model results are in keeping with those of several previous studies.

Effect of treatment delay on disease severity and need for resuscitation in porcine fecal peritonitis.

Early treatment in sepsis may improve outcome. The aim of this study was to evaluate how the delay in starting resuscitation influences the severity of sepsis and the treatment needed to achieve hemodynamic stability.

Clinical presentation and diagnostic delay in bullous pemphigoid: a prospective nationwide cohort

Prospective systematic analyses of the clinical presentation of bullous pemphigoid (BP) are lacking. Little is known about the time required for its diagnosis. Knowledge of the disease spectrum is important for diagnosis, management and inclusion of patients in therapeutic trials.

Brown Capuchins (Cebus apella) Exhibit Self-Control on a Delay of Gratification Food Exchange Task When Food Options Differ Qualitatively

Self-control allows an individual to obtain a more preferred outcome by forgoing an immediate interest. Self-control is an advanced cognitive process because it involves the ability to weigh the costs and benefits of impulsive versus restrained behavior, determine the consequences of such behavior, and make decisions based on the most advantageous course of action. Self-control has been thoroughly explored in Old World primates, but less so in New World monkeys. There are many ways to test self-control abilities in non-human primates, including exchange tasks in which an animal must forgo an immediate, less preferred reward to receive a delayed, more preferred reward. I examined the self-control abilities of six capuchin monkeys using a task in which a monkey was given a less preferred food and was required to wait a delay interval to trade the fully intact less preferred food for a qualitatively higher, more preferred food. Partially eaten pieces of the less preferred food were not rewarded, and delay intervals increased on an individual basis based on performance. All six monkeys were successful in inhibiting impulsivity and trading a less preferred food for a more preferred food at the end of a delay interval. The maximum duration each subject postponed gratification instead of responding impulsively was considered their delay tolerance. This study was the first to show that monkeys could inhibit impulsivity in a delay of gratification food exchange task in which the immediate and delayed food options differed qualitatively and a partially eaten less preferred food was not rewarded with the more preferred food at the end of a delay interval. These results show that New World monkeys possess advanced cognitive abilities similar to those of Old World primates.

Executive functions of children born very preterm--deficit or delay?

This cross-sectional study examined the performance of children born very preterm and/or at very low birth weight (VPT/VLBW) and same-aged term-born controls in three core executive functions: inhibition, working memory, and shifting. Children were divided into two age groups according to the median (young, 8.00-9.86 years; old, 9.87-12.99 years). The aims of the study were to investigate whether (a) VPT/VLBW children of both age groups performed poorer than controls (deficit hypothesis) or caught up with increasing age (delay hypothesis) and (b) whether VPT/VLBW children displayed a similar pattern of performance increase in executive functions with advancing age compared with the controls. Fifty-six VPT/VLBW children born in the cohort of 1998-2003 and 41 healthy-term-born controls were recruited. All children completed tests of inhibition (Color-Word Interference Task, Delis-Kaplan Executive Function System (D-KEFS)), working memory (Digit Span Backwards, HAWIK-IV), and shifting (Trail Making Test, Number-Letter Sequencing, D-KEFS). Results revealed that young VPT/VLBW children performed significantly poorer than the young controls in inhibition, working memory, and shifting, whereas old VPT/VLBW children performed similar to the old controls across all three executive functions. Furthermore, the frequencies of impairment in inhibition, working memory and shifting were higher in the young VPT/VLBW group compared with the young control group, whereas frequencies of impairment were equal in the old groups. In both VPT/VLBW children and controls, the highest increase in executive performance across the ages of 8 to 12 years was observed in shifting, followed by working memory, and inhibition.

GH mutant (R77C) in a pedigree presenting with the delay of growth and pubertal development: structural analysis of the mutant and evaluation of the biological activity

A heterozygous missense mutation in the GH-1 gene converting codon 77 from arginine (R) to cysteine (C), which was previously reported to have some GH antagonistic effect, was identified in a Syrian family. The index patient, a boy, was referred for assessment of his short stature (-2.5 SDS) at the age of 6 years. His mother and grandfather were also carrying the same mutation, but did not differ in adult height from the other unaffected family members. Hormonal examination in all affected subjects revealed increased basal GH, low IGF-I concentrations, and subnormal IGF-I response in generation test leading to the diagnosis of partial GH insensitivity. However, GH receptor gene (GHR) sequencing demonstrated no abnormalities. As other family members carrying the GH-R77C form showed similar alterations at the hormonal level, but presented with normal final height, no GH therapy was given to the boy, but he was followed through his pubertal development which was delayed. At the age of 20 years he reached his final height, which was normal within his parental target height. Functional characterization of the GH-R77C, assessed through activation of Jak2/Stat5 pathway, revealed no differences in the bioactivity between wild-type-GH (wt-GH) and GH-R77C. Detailed structural analysis indicated that the structure of GH-R77C, in terms of disulfide bond formation, is almost identical to that of the wt-GH despite the introduced mutation (Cys77). Previous studies from our group demonstrated a reduced capability of GH-R77C to induce GHR/GH-binding protein (GHBP) gene transcription rate when compared with wt-GH. Therefore, reduced GHR/GHBP expression might well be the possible cause for the partial GH insensitivity found in our patients. In addition, this group of patients deserve further attention because they could represent a distinct clinical entity underlining that an altered GH peptide may also have a direct impact on GHR/GHBP gene expression causing partial GH insensitivity. This might be responsible for the delay of growth and pubertal development. Finally, we clearly demonstrate that GH-R77C is not invariably associated with short stature, but that great care needs to be taken in ascribing growth failure to various heterozygous mutations affecting the GH-IGF axis and that careful functional studies are mandatory.

Does diagnostic delay result in decreased survival in paediatric brain tumours?

To study the hypothesis that a delay in the diagnosis of paediatric brain tumours results in decreased survival outcome probability, we compared the prediagnostic period of 315 brain tumour patients (median age 6.7 years, range, 0 to 16 years) with progression-free and overall survival. The median prediagnostic symptomatic interval was 60 days (range, 0 to 3,480 days), with a median parental delay of 14 days (range, 0 to 1,835 days) and a median doctor's delay of 14 days (range, 0 to 3,480 days). The prediagnostic symptomatic interval correlated significantly with the patient age, tumour histology, tumour location and year of diagnosis, but not with gender. We then grouped the patients according to histology (low-grade glioma [n=77], medulloblastoma [n=57], high-grade glioma [n=40], craniopharyngioma [n=27], ependymoma [n=20] and germ cell tumours [n=18]). Contrary to common belief, long prediagnostic symptomatic interval or long doctor's delay did not result in decreased survival outcome probability in any of these groups. The effect of tumour biology on survival seems to be dominant and overwhelms any possible opposing effect on survival of a delay in diagnosis.

Estimation of the flammability zone boundaries with thermodynamic and empirical equations

The flammability zone boundaries are very important properties to prevent explosions in the process industries. Within the boundaries, a flame or explosion can occur so it is important to understand these boundaries to prevent fires and explosions. Very little work has been reported in the literature to model the flammability zone boundaries. Two boundaries are defined and studied: the upper flammability zone boundary and the lower flammability zone boundary. Three methods are presented to predict the upper and lower flammability zone boundaries: The linear model The extended linear model, and An empirical model The linear model is a thermodynamic model that uses the upper flammability limit (UFL) and lower flammability limit (LFL) to calculate two adiabatic flame temperatures. When the proper assumptions are applied, the linear model can be reduced to the well-known equation yLOC = zyLFL for estimation of the limiting oxygen concentration. The extended linear model attempts to account for the changes in the reactions along the UFL boundary. Finally, the empirical method fits the boundaries with linear equations between the UFL or LFL and the intercept with the oxygen axis. xx Comparison of the models to experimental data of the flammability zone shows that the best model for estimating the flammability zone boundaries is the empirical method. It is shown that is fits the limiting oxygen concentration (LOC), upper oxygen limit (UOL), and the lower oxygen limit (LOL) quite well. The regression coefficient values for the fits to the LOC, UOL, and LOL are 0.672, 0.968, and 0.959, respectively. This is better than the fit of the "zyLFL" method for the LOC in which the regression coefficient’s value is 0.416.