1,171 research outputs found

    Petiole nutrient concentrations of upland cotton, Gossypium hirsutum L

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    Experiments were conducted at seven locations in 1969 and 1970 to determine the effects of growth stage, location differences, and cultivars on the Ca, Mg, K, and P concentrations of cotton petioles. In general, nutrient content of cotton petioles was affected more by growth stage and location than by cultivar difference. Calcium and K concentration usually decreased as the cotton plants approached maturity while Mg and P varied with location. Acala 1517D was generally higher in Ca and P concentrations than were any of the other nine cultivars tested. Coker 417 was high in Mg while the Stoneville cultivars were high in K. The high yielding Stoneville 213 was consistently low in Ca and Mg. Acala 1517D was the lowest yielding of all cultivars tested. When using plant analysis to diagnose nutrient levels in cotton, particular consideration should be given to the cultivars sampled. In this experiment more differences were found among cultivars at mid bloom than at any other physiological growth stage investigated

    International policy experience: short-term international travel courses in structured degree programs

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    This descriptive quantitative research examined 7 years of data to find what are the benefits, challenges, and outcomes of short-term international travel courses in a structured degree program in the organizational leadership, doctoral program at Pepperdine University Graduate School of Education and Psychology from 2007 to 2014. While there is currently a plethora of study abroad research, most of the existing research explores semester or academic-year programs. Very few studies have investigated shorter durations or students’ perceptions and experiences during these programs or their experiences with, self-identified encounters during these courses. This study aimed to alleviate the dearth of information. The main purpose of the study was to determine what were: ‱ the personal characteristics of students who participated in short-term, course-based, international travels in structured degree programs? ‱ the perceived benefits experienced by students who participated in short-term, course-based, international travels in structured degree programs? ‱ the perceived shortcomings experienced by students who participated in short-term, course-based, international travels in structured degree programs? ‱ the perceived challenges faced by students who participated in short-term, course-based, international travels in structured degree program. ‱ the major areas of perceived learning by students who participated in short-term, course-based, international travels in structured degree programs? ‱ the changes recommended for improving these programs? The study found that 91% of the participants favored the logistical components of the trips; 91% were very satisfied with the trip selected; 93% felt that the lead faculty member’s level of academic experience was high; 93% indicated that they felt safe and hotel accommodations were good; and 100% felt that overall the program was effective. Weaknesses were post -trip debriefing of important learning during the trip scored (20%), reading materials about the trip scored 14%, evaluation of assignments and supplemental material including, handout and videos about the trip scored 26%, and 46% of the participants said academic demands were weak. This study provides useful information that can help determine whether or not international trips in structured degree programs are meeting their intended goals and objectives; whether or not there are areas of improvement with the EDOL short-term study-abroad programs from the student’s point of view

    Pulsatile Hormonal Signaling to Extracellular Signal-Regulated Kinase: Exploring System Sensitivity to Gonadotropin-Releasing Hormone Pulse Frequency and Width

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    Gonadotropin-releasing hormone (GnRH) is secreted in brief pulses that stimulate synthesis and secretion of pituitary gonadotropin hormones and thereby mediate control of reproduction. It acts via G-protein-coupled receptors to stimulate effectors, including ERK. Information could be encoded in GnRH pulse frequency, width, amplitude, or other features of pulse shape, but the relative importance of these features is unknown. Here we examine this using automated fluorescence microscopy and mathematical modeling, focusing on ERK signaling. The simplest scenario is one in which the system is linear, and response dynamics are relatively fast (compared with the signal dynamics). In this case integrated system output (ERK activation or ERK-driven transcription) will be roughly proportional to integrated input, but we find that this is not the case. Notably, we find that relatively slow response kinetics lead to ERK activity beyond the GnRH pulse, and this reduces sensitivity to pulse width. More generally, we show that the slowing of response kinetics through the signaling cascade creates a system that is robust to pulse width. We, therefore, show how various levels of response kinetics synergize to dictate system sensitivity to different features of pulsatile hormone input. We reveal the mathematical and biochemical basis of a dynamic GnRH signaling system that is robust to changes in pulse amplitude and width but is sensitive to changes in receptor occupancy and frequency, precisely the features that are tightly regulated and exploited to exert physiological control in vivo

    Generalized Logistic Models and its orthant tail dependence

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    The Multivariate Extreme Value distributions have shown their usefulness in environmental studies, financial and insurance mathematics. The Logistic or Gumbel-Hougaard distribution is one of the oldest multivariate extreme value models and it has been extended to asymmetric models. In this paper we introduce generalized logistic multivariate distributions. Our tools are mixtures of copulas and stable mixing variables, extending approaches in Tawn (1990), Joe and Hu (1996) and Foug\`eres et al. (2009). The parametric family of multivariate extreme value distributions considered presents a flexible dependence structure and we compute for it the multivariate tail dependence coefficients considered in Li (2009)

    Customers as decision-makers: strategic environmental assessment in the private sector

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    Despite its diversification and global spread, strategic environmental assessment (SEA) remains limited mainly to activities characterised by well-defined planning processes, typically within the public sector. This article explores the possible application of SEA within certain private-sector contexts where higher-level strategy-making itself is inherently weaker and development is often piecemeal and reactive. The possible adaptation of SEA to the preparation of a strategic document by a particular industrial concern in the UK is examined: this draws attention to the multi-actor nature of development processes within the industry. This leads to the suggestion that SEA in this setting should be thought of as a form of environmental advocacy oriented towards industrial customers, who are understood as sharing a decision-making role in infrastructure development.</p

    Viscous placebo and carbohydrate breakfasts similarly decrease appetite and increase resistance exercise performance compared to a control breakfast in trained males

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    Given the common view that pre-exercise nutrition/breakfast is important for performance, the present study investigated whether breakfast influences resistance exercise performance via a physiological or psychological effect. Twenty-two resistance trained, breakfast-consuming men completed three experimental trials, consuming water-only (WAT), or semi-solid breakfasts containing 0 g/kg (PLA) or 1.5 g/kg (CHO) maltodextrin. PLA and CHO meals contained xanthan gum and low-energy flavouring (~29 kcal) and subjects were told both ‘contained energy’. Two hours post-meal, subjects completed 4 sets of back squat and bench press to failure at 90% 10 repetition maximum. Blood samples were taken pre-meal, 45 min and 105 min post-meal to measure serum/plasma glucose, insulin, ghrelin, GLP-1 and PYY concentrations. Subjective hunger/fullness were also measured. Total back squat repetitions were greater in CHO (44 (SD 10) repetitions) and PLA (43 ± 10 repetitions) than WAT (38 (SD 10) repetitions; P < 0.001). Total bench press repetitions were similar between trials (WAT 37 (SD 7) repetitions; CHO 39 ± 7 repetitions; PLA 38 (SD 7) repetitions; P = 0.130). Performance was similar between CHO and PLA trials. Hunger was suppressed and fullness increased similarly in PLA and CHO, relative to WAT (P < 0.001). During CHO, plasma glucose was elevated at 45 min (P < 0.05), whilst serum insulin was elevated (P < 0.05) and plasma ghrelin supressed at 45 and 105 min (P < 0.05). These results suggest that breakfast/pre-exercise nutrition enhances resistance exercise performance via a psychological effect, although a potential mediating role of hunger cannot be discounted

    ISG20L1 is a p53 family target gene that modulates genotoxic stress-induced autophagy

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    <p>Abstract</p> <p>Background</p> <p>Autophagy is characterized by the sequestration of cytoplasm and organelles into multimembrane vesicles and subsequent degradation by the cell's lysosomal system. It is linked to many physiological functions in human cells including stress response, protein degradation, organelle turnover, caspase-independent cell death and tumor suppression. Malignant transformation is frequently associated with deregulation of autophagy and several tumor suppressors can modulate autophagic processes. The tumor suppressor p53 can induce autophagy after metabolic or genotoxic stress through transcriptionally-dependent and -independent mechanisms. In this study we expand on the former mechanism by functionally characterizing a p53 family target gene, ISG20L1 under conditions of genotoxic stress.</p> <p>Results</p> <p>We identified a p53 target gene, ISG20L1, and show that transcription of the gene can be regulated by all three p53 family members (p53, p63, and p73). We generated an antibody to ISG20L1 and found that it localizes to the nucleolar and perinucleolar regions of the nucleus and its protein levels increase in a p53- and p73-dependent manner after various forms of genotoxic stress. When ectopically expressed in epithelial cancer-derived cell lines, ISG20L1 expression decreased clonogenic survival without a concomitant elevation in apoptosis and this effect was partially rescued in cells that were ATG5 deficient. Knockdown of ISG20L1 did not alter 5-FU induced apoptosis as assessed by PARP and caspase-3 cleavage, sub-G<sub>1 </sub>content, and DNA laddering. Thus, we investigated the role of ISG20L1 in autophagy, a process commonly associated with type II cell death, and found that ISG20L1 knockdown decreased levels of autophagic vacuoles and LC3-II after genotoxic stress as assessed by electron microscopy, biochemical, and immunohistochemical measurements of LC3-II.</p> <p>Conclusions</p> <p>Our identification of ISG20L1 as a p53 family target and discovery that modulation of this target can regulate autophagic processes further strengthens the connection between p53 signaling and autophagy. Given the keen interest in targeting autophagy as an anticancer therapeutic approach in tumor cells that are defective in apoptosis, investigation of genes and signaling pathways involved in cell death associated with autophagy is critical.</p
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