Determinación de la correlación de resistencia a la compresión mediante el método de madurez e índice de rebote en concretos convencionales, Trujillo

La presente investigación fue realizada en la ciudad de Trujillo, teniendo como objetivo general determinar la correlación de resistencia a la compresión mediante el método de madurez e índice de rebote en concretos convencionales; asimismo, la metodología empleada según su propósito fue de tipo aplicada, según el diseño de tipo experimental, pre-experimental. El muestreo fue no probabilístico por juicio de experto, contando con una muestra de 17 probetas por cada tipo de concreto. En primer lugar se obtuvo las propiedades de los agregados a través de ensayos de laboratorio, luego se realizó un diseño de mezcla para cada relación a/c de 0.50, 0.55 y 0.60; determinando la resistencia a la compresión del concreto mediante el método de madurez a edades de 1, 3, 5, 7 y 9 días; seguido a ello, se calculó los índices de rebote para probetas de cada tipo de concreto a la edad de 7 días de curado; para luego determinar la correlación entre estas dos variables considerando los resultados obtenidos de los ensayos. Finalmente, las correlaciones que se establecieron entre la resistencia a la compresión, mediante el método de madurez, y el índice de rebotes en concretos convencionales, fueron de tipo lineal y de tipo potencial a la edad de 7 días; resultando la primera: f’c = 23.75*IR - 50.5 y la segunda: f’c = 12.721*IR1.1736, ambas con una confiabilidad (R2) mayor a 99%

Effects of post-transcriptional regulation on phenotypic noise

ABSTRACT Cell-to-cell variations in protein abundance, called noise, give rise to phenotypic variability between isogenic cells. Studies of noise have focused on stochasticity introduced at transcription, yet the effects of post-transcriptional regulatory processes on noise remain unknown. We study the effects of RyhB, a small-RNA of Escherichia coli produced on iron stress, on the phenotypic variability of two of its downregulated target proteins, using dual chromosomal fusions to fluorescent reporters and measurements in live individual cells. The total noise of each of the target proteins is remarkably constant over a wide range of RyhB production rates despite cells being in stress. In fact, coordinate downregulation of the two target proteins by RyhB reduces the correlation between their levels. Hence, an increase in phenotypic variability under stress is achieved by decoupling the expression of different target proteins in the same cell, rather than by an increase in the total noise of each. Extrinsic noise provides the dominant contribution to the total protein noise over the total range of RyhB production rates. Stochastic simulations reproduce qualitatively key features of our observations and show that a feed-forward loop formed by transcriptional extrinsic noise, an sRNA and its target genes exhibits strong noise filtration capabilities

Characterization of a Bacillus anthracis spore coat-surface protein that influences coat-surface morphology

Bacterial spores are encased in a multilayered proteinaceous shell, called the coat. In many Bacillus spp., the coat protects against environmental assault and facilitates germination. In Bacillus anthracis , the spore is the etiological agent of anthrax, and the functions of the coat likely contribute to virulence. Here, we characterize a B. anthracis spore protein, called CotΒ, which is encoded only in the genomes of the Bacillus cereus group. We found that CotΒ is synthesized specifically during sporulation and is assembled onto the spore coat surface. Our analysis of a cotΒ null mutant in the Sterne strain reveals that CotΒ has a role in determining coat-surface morphology but does not detectably affect germination. In the fully virulent Ames strain, a cotΒ null mutation has no effect on virulence in a murine model of B. anthracis infection.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72138/1/j.1574-6968.2008.01380.x.pd

Structure and Functions of Pediatric Aerodigestive Programs: A Consensus Statement

Aerodigestive programs provide coordinated interdisciplinary care to pediatric patients with complex congenital or acquired conditions affecting breathing, swallowing, and growth. Although there has been a proliferation of programs, as well as national meetings, interest groups and early research activity, there is, as of yet, no consensus definition of an aerodigestive patient, standardized structure, and functions of an aerodigestive program or a blueprint for research prioritization. The Delphi method was used by a multidisciplinary and multi-institutional panel of aerodigestive providers to obtain consensus on 4 broad content areas related to aerodigestive care: (1) definition of an aerodigestive patient, (2) essential construct and functions of an aerodigestive program, (3) identification of aerodigestive research priorities, and (4) evaluation and recognition of aerodigestive programs and future directions. After 3 iterations of survey, consensus was obtained by either a supermajority of 75% or stability in median ranking on 33 of 36 items. This included a standard definition of an aerodigestive patient, level of participation of specific pediatric disciplines in a program, essential components of the care cycle and functions of the program, feeding and swallowing assessment and therapy, procedural scope and volume, research priorities and outcome measures, certification, coding, and funding. We propose the first consensus definition of the aerodigestive care model with specific recommendations regarding associated personnel, infrastructure, research, and outcome measures. We hope that this may provide an initial framework to further standardize care, develop clinical guidelines, and improve outcomes for aerodigestive patients

A multi-ancestry genome-wide study incorporating gene-smoking interactions identifies multiple new loci for pulse pressure and mean arterial pressure

Elevated blood pressure (BP), a leading cause of global morbidity and mortality, is influenced by both genetic and lifestyle factors. Cigarette smoking is one such lifestyle factor. Across five ancestries, we performed a genome-wide gene-smoking interaction study of mean arterial pressure (MAP) and pulse pressure (PP) in 129 913 individuals in stage 1 and follow-up analysis in 480 178 additional individuals in stage 2. We report here 136 loci significantly associated with MAP and/or PP. Of these, 61 were previously published through main-effect analysis of BP traits, 37 were recently reported by us for systolic BP and/or diastolic BP through gene-smoking interaction analysis and 38 were newly identified (P <5 x 10(-8), false discovery rate <0.05). We also identified nine new signals near known loci. Of the 136 loci, 8 showed significant interaction with smoking status. They include CSMD1 previously reported for insulin resistance and BP in the spontaneously hypertensive rats. Many of the 38 new loci show biologic plausibility for a role in BP regulation. SLC26A7 encodes a chloride/bicarbonate exchanger expressed in the renal outer medullary collecting duct. AVPR1A is widely expressed, including in vascular smooth muscle cells, kidney, myocardium and brain. FHAD1 is a long non-coding RNA overexpressed in heart failure. TMEM51 was associated with contractile function in cardiomyocytes. CASP9 plays a central role in cardiomyocyte apoptosis. Identified only in African ancestry were 30 novel loci. Our findings highlight the value of multi-ancestry investigations, particularly in studies of interaction with lifestyle factors, where genomic and lifestyle differences may contribute to novel findings.Peer reviewe

Preemptive analgesia. Clinical evidence of neuroplasticity contributing to postoperative pain.

Recent evidence suggests that surgical incision and other noxious perioperative events may induce prolonged changes in central neural function that later contribute to postoperative pain. The present study tested the hypothesis that patients receiving epidural fentanyl before incision would have less pain and need fewer analgesics post-operatively than patients receiving the same dose of epidural fentanyl after incision. Thirty patients (ASA physical status 2) scheduled for elective thoracic surgery through a posterolateral thoracotomy incision were randomized to one of two groups of equal size and prospectively studied in a double-blind manner. Epidural catheters were placed via the L2-L3 or L3-L4 interspaces preoperatively, and the position was confirmed with lidocaine. Group 1 received epidural fentanyl (4 micrograms/kg, in 20 ml normal saline) before surgical incision, followed by epidural normal saline (20 ml) infused 15 min after incision. Group 2 received epidural normal saline (20 ml) before surgical incision, followed by epidural fentanyl (4 micrograms/kg, in 20 ml normal saline) infused 15 min after incision. No additional analgesics were used before or during the operation. Anesthesia was induced with thiopental (3-5 mg/kg) and maintained with N2O/O2 and isoflurane. Paralysis was achieved with pancuronium (0.1 mg/kg). Postoperative analgesia consisted of patient-controlled intravenous morphine. Visual analogue scale pain scores were significantly less in group 1 (2.6 +/- 0.44) than in group 2 (4.7 +/- 0.58) 6 h after surgery (P less than 0.05), by which time plasma fentanyl concentrations had decreased to subtherapeutic levels (less than 0.15 ng/ml) in both groups

A Randomized, Double-blind Comparison of Lumbar Epidural and Intravenous Fentanyl Infusions for Postthoracotomy Pain Relief: Analgesic, Pharmacokinetic, and Respiratory Effects

Although epidural opioids frequently are used to provide postoperative analgesia, several articles have suggested that the analgesia after epidural fentanyl is similar to that after an equal dose of fentanyl given intravenously. To address this issue further, 29 postthoracotomy patients were studied in a randomized, double-blinded trial comparing a lumbar epidural fentanyl infusion with an intravenous fentanyl infusion for analgesia, plasma fentanyl pharmacokinetics, and respiratory effects for 20 h postoperatively. In all patients in both groups, good analgesia was achieved (pain score < 3, maximum 10) over a similar time course, although the patients receiving epidural infusion required a significantly larger fentanyl infusion dose than did the patients receiving intravenous infusion (group receiving epidural fentanyl infusion: 1.95 +/- 0.45 [micro]g [middle dot] kg-1 [middle dot] h-1; group receiving intravenous fentanyl infusion: 1.56 +/- 0.36 [micro]g [middle dot] kg-1 [middle dot] h-1; P = 0.0002). The time course for the plasma fentanyl concentrations was similar in the two groups, and plasma fentanyl concentrations were not significantly different at any sampling period (T7-T20; group receiving epidural fentanyl infusion:1.8 +/- 0.5 ng/ml; group receiving intravenous fentanyl infusion: 1.6 +/- 0.6 ng/ml; P = 0.06). Similarly, calculated clearance values for the two groups were not significantly different (group receiving epidural fentanyl infusion: 0.95 +/- 0.26 l [middle dot] kg-1 [middle dot] h-1; group receiving intravenous fentanyl infusion: 0.87 +/- 0.25 l [middle dot] kg-1 [middle dot] h-1; P = 0.3). Both groups demonstrated a similar degree of mild to moderate respiratory depression postoperatively, which was assessed with continuous respiratory inductance plethysmography and sequential arterial blood gas analysis. Side effects (nausea, vomiting, pruritus) were mild and did not differ between groups. The authors conclude that lumbar epidural fentanyl infusions are equivalent to intravenous fentanyl infusions for postthoracotomy analgesia and that the mode of action of a lumbar epidural fentanyl infusion is primarily through systemic absorption