The status of the Virginia high school assistant principal

Early secondary schools were relatively small and made few demands on the principal\u27s time. With the growth of the schools the responsibilities of the principal have grown proportionately. As these responsibilities increased, it became necessary for him to share these duties with an assistant. This assistant began taking over routine activities mostly those of a clerical nature. As the schools continued to grow he began assuming duties in the realm of supervision and administration. To be effective he needed to be as dedicated, as perceptive and as well trained as the principal himself

Management of Tobacco Budworm, Heliothis Virescens (F.) and Bollworm, Helicoverpa Zea (Boddie) in Cotton: Host Plant Resistance and Ovicidal Approaches.

Growth, development and survival of pyrethroid-resistant (PY-R) and -susceptible (PY-S and FIELD-88) tobacco budworm, Heliothis virescens (F.), and bollworm (CORN-BW), Helicoverpa zea (Boddie), were compared on four cotton lines (\u27Deltapine 41\u27, La. HG-660, La. HG-063 and PD-0804) and artificial diet. The FIELD-88 and CORN-BW strains had significantly higher 5 and 9 day larval weights compared to the PY-R and PY-S laboratory strains. Larvae fed squares of La. HG-660 and La. HG-063 had significantly lower larval and pupal weights, required significantly more days to pupate and had higher cumulative mortality compared to those reared on squares of a commercial cultivar, Deltapine 41. In a field trial conducted during 1988 to evaluate advanced cotton lines and insecticide treatments against tobacco budworm and bollworm, no significant interaction was observed. However, La. HG-660 reduced larval infestations and damage, matured earlier and had comparable yields to DPL 41. Lint turnout and boll weight was lower for La. HG-660 than that for Deltapine 41. No significant differences were found among treatments in fiber length, micronaire and fiber strength of cotton samples. The toxicity of insecticides to eggs of PY-R, PY-S and field (FIELD-89) tobacco budworm strains was determined in laboratory tests. LC\sb{50}\u27s for all insecticides except profenofos on eggs of the PY-R strain were significantly higher than LC\sb{50}\u27s for the same insecticide on eggs of the PY-S strain. All insecticides except profenofos and methomyl were significantly more toxic to eggs of the PY-S strain compared to their respective toxicity to eggs of the FIELD-89 strain. Eggs of the PY-R strain exhibited resistance to esfenvalerate, lambda-cyhalothrin, and chlordimeform while eggs of the FIELD-89 strain possessed resistance to lambda-cyhalothrin, chlordimeform and SN 49844. In field tests conducted during 1987-1989, all insecticide treatments except methomyl (0.0071 kg (AI) /ha) and profenofos (0.56 kg (AI) /ha) exhibited initial ovicidal activity in one or more trials. The formamidines (amitraz and SN 49844) and a carbamate (thiodicarb) at 0.28 kg (AI) /ha generally exhibited residual ovicidal activity comparable to that of chlordimeform at 0.28 kg (AI) /ha

Canonical and Noncanonical Mechanisms of Resistance to Arginine Starvation in Cancer

The enzyme argininosuccinate synthetase 1 (ASS1) catalyzes the condensation of citrulline and aspartate into argininosuccinate as part of the urea cycle and citrulline-nitric oxide cycle. This reaction is essential for mammals to synthesize the amino acid arginine, which is required for all cells. Nearly all human tissues express at least some ASS1, but they import most of their arginine from the extracellular space after it is produced and released by the kidneys. Most solid tumors lack a functional level of ASS1, including over 85% of sarcomas, which are cancers of connective tissues. Published evidence suggests that this provides a proliferation advantage by reducing the consumption of aspartate by ASS1, resulting in a larger supply of aspartate to be used in the production of pyrimidines for nucleic acid synthesis. However, ASS1 deficiency causes these cancers to rely on extracellular arginine for survival and growth, which can be targeted through arginine deprivation therapy. PEGylated arginine deiminase (ADI-PEG20), an enzymatic drug that degrades extracellular arginine to citrulline, is the most widely used arginine deprivation therapy, currently being tested in many clinical trials.While often effective at slowing growth, many cancers, especially sarcomas, gain resistance to ADI-PEG20 in the long term by upregulating their expression of ASS1 and gaining the ability to synthesize arginine from the now abundant citrulline. This is so common because the ASS1 gene is almost always transcriptionally repressed rather than being deleted or mutated. However, it takes time to increase ASS1 expression sufficiently. In the short term, cells also upregulate autophagy to provide a temporary source of arginine for protein translation and survival. These canonical mechanisms have been studied extensively, and ASS1 re-expression is the only published pathway of long-term resistance to arginine deprivation therapy. Many other pathways could theoretically provide long-term resistance to ADI-PEG20, but none have yet been shown to do so. To determine whether ASS1 deficiency truly provides an advantage to sarcomas in vivo, a murine model of spontaneous sarcomas was developed with Ass1 knocked out (KO). Conditional Ass1 KO mice did not develop tumors sooner than control mice, nor did their tumors grow faster. In fact, tumors that expressed high levels of ASS1 initiated earlier and grew faster. These data cast doubt on the importance of previous findings explaining the advantages of ASS1 silencing; they suggest that the main reason for a lack of ASS1 in sarcomas may be inheritance from their tissues of origin. The apparent advantage conferred by ASS1 overexpression in these tumors remains unexplained but is a good target for future study. To characterize the kinetics and heterogeneity of the development of resistance to ADI-PEG20 in ASS1-deficient cancers, a sensor system was developed to monitor the availability of intracellular arginine for protein translation. The sensor consists principally of a genomically integrated gene encoding a reporter protein downstream of an arginine-rich region. Sensor expression is thereby regulated at the translational level, as ribosomes stall or move more slowly at the arginine-rich region, causing reporter protein expression to decrease when arginine supplies are low. Nuclear localization of the reporter and automated imaging allowed tracking of resistance to arginine deprivation in individual live cells. It was found that all ASS1-deficient cancer cells reduced their expression of the sensor when treated with ADI-PEG20 in vitro, followed by a period of heterogeneous recovery of expression. The timing and magnitude of resistance varied widely among individual cells. However, the sensor expression profile was quite different in vivo, as ADI-PEG20 unexpectedly had no impact on the expression of the arginine sensor even while tumor growth was slowed. Ass1 KO tumor cell lines generated from the mouse model described above also did not decrease their expression of the arginine sensor when grafted into syngeneic mice and treated with ADI-PEG20. Unexpectedly, these tumors grew robustly through arginine deprivation therapy in vivo, where they were expected to die as they do in vitro. This suggested that the tumor microenvironment lent strong growth support to the tumors by supplying arginine. This hypothesis was further supported with in vitro experiments showing that ASS1-competent fibroblasts could support growth of Ass1 KO tumor cells during ADI-PEG20 treatment. This growth support effect was found to likely be mediated through the uptake of fibroblast-derived extracellular vesicles (EVs) by macropinocytosis into cancer cells, followed by degradation and recycling of the EV components by autophagy/lysosomal degradation to yield free arginine for the cancer cells to use. Inhibition of this growth support phenomenon was shown to be possible by targeting either EV production and macropinocytosis or autophagy both in vitro and in vivo. These experiments uncovered a novel mechanism of resistance to arginine deprivation therapy, completely independent of intrinsic ASS1 expression, which was previously thought necessary. Further, these results highlight the importance and previously unknown magnitude of the ability of the tumor microenvironment to metabolically support tumors. Finally, this work has opened multiple promising avenues for future research that deserve to be explored

Bioassays for Monitoring Insecticide Resistance

Pest resistance to pesticides is an increasing problem because pesticides are an integral part of high-yielding production agriculture. When few products are labeled for an individual pest within a particular crop system, chemical control options are limited. Therefore, the same product(s) are used repeatedly and continual selection pressure is placed on the target pest. There are both financial and environmental costs associated with the development of resistant populations. The cost of pesticide resistance has been estimated at approximately $ 1.5 billion annually in the United States. This paper will describe protocols, currently used to monitor arthropod (specifically insects) populations for the development of resistance. The adult vial test is used to measure the toxicity to contact insecticides and a modification of this test is used for plant-systemic insecticides. In these bioassays, insects are exposed to technical grade insecticide and responses (mortality) recorded at a specific post-exposure interval. The mortality data are subjected to Log Dose probit analysis to generate estimates of a lethal concentration that provides mortality to 50% (LC50) of the target populations and a series of confidence limits (CL's) as estimates of data variability. When these data are collected for a range of insecticide-susceptible populations, the LC50 can be used as baseline data for future monitoring purposes. After populations have been exposed to products, the results can be compared to a previously determined LC50 using the same methodology

Late-season Insect Pests of Soybean in Louisiana: Preventive Management and Yield Enhancement (Bulletin #880)

The velvetbean caterpillar and the soybean looper are important pests of soybeans in Louisiana. These late-season soybean insect pests create the need for the continuous development of insecticide programs that are cost effective, maintain profitable yields and conserve natural enemies.https://digitalcommons.lsu.edu/agcenter_bulletins/1020/thumbnail.jp

The baroclinic secondary instability of the two-dimensional shear layer

The focus of this study is on the numerical investigation of two-dimensional, isovolume, high Reynolds and Froude numbers, variable-density mixing layers. Lagrangian simulations, of both the temporal and the spatial models, are performed. They reveal the breaking-up of the strained vorticity and density-gradient braids, connecting two neighboring primary structures. The secondary instability arises where the vorticity has been intensified by the baroclinic torque. A simplified model of the braid of the variable-density mixing layer, consisting of a strained vorticity and density-gradient filament, is analyzed. It is concluded that the physical mechanism responsible for the secondary instability is the forcing of the vorticity field by the baroclinic torque, itself sensitive to perturbations. This mechanism suggests a rapid route to turbulence for the variable-density mixing layer

Microglial responses to amyloid β peptide opsonization and indomethacin treatment

BACKGROUND: Recent studies have suggested that passive or active immunization with anti-amyloid β peptide (Aβ) antibodies may enhance microglial clearance of Aβ deposits from the brain. However, in a human clinical trial, several patients developed secondary inflammatory responses in brain that were sufficient to halt the study. METHODS: We have used an in vitro culture system to model the responses of microglia, derived from rapid autopsies of Alzheimer's disease patients, to Aβ deposits. RESULTS: Opsonization of the deposits with anti-Aβ IgG 6E10 enhanced microglial chemotaxis to and phagocytosis of Aβ, as well as exacerbated microglial secretion of the pro-inflammatory cytokines TNF-α and IL-6. Indomethacin, a common nonsteroidal anti-inflammatory drug (NSAID), had no effect on microglial chemotaxis or phagocytosis, but did significantly inhibit the enhanced production of IL-6 after Aβ opsonization. CONCLUSION: These results are consistent with well known, differential NSAID actions on immune cell functions, and suggest that concurrent NSAID administration might serve as a useful adjunct to Aβ immunization, permitting unfettered clearance of Aβ while dampening secondary, inflammation-related adverse events

Seasonal Abudance of Arthropod Populations on Selected Soybean Variteties Grown in Early Season Production Systems in Louisiana (Bulletin #860)

The data presented in this report were collected by entomologists to provide Louisiana soybean producers with information on insect management practices that may be required as they select the soybean maturity group that best fits their production systems.https://digitalcommons.lsu.edu/agcenter_bulletins/1044/thumbnail.jp

Low voltage local strain enhanced switching of magnetic tunnel junctions

Strain-controlled modulation of the magnetic switching behavior in magnetic tunnel junctions (MTJs) could provide the energy efficiency needed to accelerate the use of MTJs in memory, logic, and neuromorphic computing, as well as an additional way to tune MTJ properties for these applications. State-of-the-art CoFeB-MgO based MTJs still require too high voltages to alter their magnetic switching behavior with strain. In this study, we demonstrate strain-enhanced field switching of nanoscale MTJs through electric field control via voltage applied across local gates. The results show that record-low voltage down to 200 mV can be used to control the switching field of the MTJ through enhancing the magnetic anisotropy, and that tunnel magnetoresistance is linearly enhanced with voltage through straining the crystal structure of the tunnel barrier. These findings underscore the potential of electric field manipulation and strain engineering as effective strategies for tailoring the properties and functionality of nanoscale MTJs