709 research outputs found

    Relationship Between Supervisors\u27 Servant Leadership and Police Officers Job Satisfaction

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    Recent police killings of unarmed African Americans in the United States and the subsequent protests and demonstrations against police brutality have resulted in more focus on the importance of collaborative relationships between law enforcement agencies and their communities. This quantitative correlational research study was conducted in one southern United States police department that incorporated a servant leadership philosophy, including its leaders being publicly heralded for their servant leadership practices that positively impacted its relationship with its community. The study examined if a relationship existed between perceived servant leadership of law enforcement leaders and line police officersā€™ job satisfaction. The studyā€™s participants n=31 completed the Servant Leadership Scale to measure servant leadership characteristics and Job Descriptive Index to measure employee job satisfaction. Results indicated a statistically significant relationship between servant leadership and employee job satisfaction of the police officers in the department

    Percolation and jamming in random sequential adsorption of linear segments on square lattice

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    We present the results of study of random sequential adsorption of linear segments (needles) on sites of a square lattice. We show that the percolation threshold is a nonmonotonic function of the length of the adsorbed needle, showing a minimum for a certain length of the needles, while the jamming threshold decreases to a constant with a power law. The ratio of the two thresholds is also nonmonotonic and it remains constant only in a restricted range of the needles length. We determine the values of the correlation length exponent for percolation, jamming and their ratio

    Temperature-modulated solution-based synthesis of copper oxide nanostructures for glucose sensing

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    Glucose sensors are widely applied in society as an effective way to diagnose and control diabetes by monitoring the blood glucose level. With advantages in stability and efficiency in glucose detection, non-enzymatic glucose sensors are gradually replacing their enzymatic counterparts and copper(ii) oxide (CuO) is a leading material. However, previous work extensively shows that even if the synthesis of CuO nanostructures is performed under nominally similar conditions, entirely different nanostructured products are obtained, resulting in varying physical and chemical properties of the final product, thereby leading to a differing performance in glucose detection. This work investigates the temperature dependence of a wet chemical precipitation synthesis for CuO nanostructures with the resulting samples showing selectivity for glucose in electrochemical tests. X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) demonstrate that all products are predominantly CuO, with some contribution from Cu(OH)2 and other surface species varying across synthesis temperatures. The most important change with increasing synthesis temperature is that the overall nanostructure size changes and the morphology shifts from nanoneedles to nanoparticles between 65 and 70 Ā°C. This work helps to understand the critical relationship between synthesis temperature and final nanostructure and can explain the seemingly random nanostructures observed in the literature. The variations are key to controlling sensor performance and ultimately offering further development in copper oxide-based glucose sensors

    Coagulation and fragmentation processes with evolving size and shape profiles : a semigroup approach

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    We investigate a class of bivariate coagulation-fragmentation equations. These equations describe the evolution of a system of particles that are characterised not only by a discrete size variable but also by a shape variable which can be either discrete or continuous. Existence and uniqueness of strong solutions to the associated abstract Cauchy problems are established by using the theory of substochastic semigroups of operators

    Cover Crop Effect on Subsequent Wheat Yield in the Central Great Plains

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    Crop production systems in the water-limited environment of the semiarid central Great Plains may not have potential to profitably use cover crops because of lowered subsequent wheat (Triticum asestivum L.) yields following the cover crop. Mixtures have reportedly shown less yield-reducing effects on subsequent crops than single-species plantings. This study was conducted to determine winter wheat yields following both mixtures and single-species plantings of spring-planted cover crops. The study was conducted at Akron, CO, and Sidney, NE, during the 2012ā€“2013 and 2013ā€“2014 wheat growing seasons under both rainfed and irrigated conditions. Precipitation storage efficiency before wheat planting, wheat water use, biomass, and yield were measured and water use efficiency and harvest index were calculated for wheat following four single-species cover crops (flax [Linum usitatissimum L.], oat [Avena sativa L.], pea [Pisum sativum ssp. arvense L. Poir], rapeseed [Brassica napus L.]), a 10-species mixture, and a fallow treatment with proso millet (Panicum miliaceum L.) residue. There was an average 10% reduction in wheat yield following a cover crop compared with following fallow, regardless of whether the cover crop was grown in a mixture or in a single-species planting. Yield reductions were greater under drier conditions. The slope of the wheat water useā€“yield relationship was not significantly different for wheat following the mixture (11.80 kg haā€“1 mmā€“1) than for wheat following single-species plantings (12.32ā€“13.57 kg haā€“1 mmā€“1). The greater expense associated with a cover crop mixture compared with a single species is not justified

    Helium, Oxygen, Proton, and Electron (HOPE) Mass Spectrometer for the Radiation Belt Storm Probes Mission

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    The HOPE mass spectrometer of the Radiation Belt Storm Probes (RBSP) mission (renamed the Van Allen Probes) is designed to measure the in situ plasma ion and electron fluxes over 4Ļ€ sr at each RBSP spacecraft within the terrestrial radiation belts. The scientific goal is to understand the underlying physical processes that govern the radiation belt structure and dynamics. Spectral measurements for both ions and electrons are acquired over 1 eV to 50 keV in 36 log-spaced steps at an energy resolution Ī”E FWHM/Eā‰ˆ15 %. The dominant ion species (H+, He+, and O+) of the magnetosphere are identified using foil-based time-of-flight (TOF) mass spectrometry with channel electron multiplier (CEM) detectors. Angular measurements are derived using five polar pixels coplanar with the spacecraft spin axis, and up to 16 azimuthal bins are acquired for each polar pixel over time as the spacecraft spins. Ion and electron measurements are acquired on alternate spacecraft spins. HOPE incorporates several new methods to minimize and monitor the background induced by penetrating particles in the harsh environment of the radiation belts. The absolute efficiencies of detection are continuously monitored, enabling precise, quantitative measurements of electron and ion fluxes and ion species abundances throughout the mission. We describe the engineering approaches for plasma measurements in the radiation belts and present summaries of HOPE measurement strategy and performance

    Role of DLC-1, a tumor suppressor protein with RhoGAP activity, in regulation of the cytoskeleton and cell motility

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    DLC-1 was originally identified as a potential tumor suppressor. One of the key biochemical functions of DLC-1 is to serve as a GTPase activating protein (GAP) for members of the Rho family of GTPases, particularly Rho A-C and Cdc 42. Since these GTPases are critically involved in regulation of the cytoskeleton and cell migration, it seems clear that DLC-1 will also influence these processes. In this review we examine basic aspects of the actin cyoskeleton and how it relates to cell motility. We then delineate the characteristics of DLC-1 and other members of its family, and describe how they may have multiple effects on the regulation of cell polarity, actin organization, and cell migration

    p120Ras-GAP binds the DLC1 Rho-GAP tumor suppressor protein and inhibits its RhoA GTPase and growth-suppressing activities

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    DLC1, which encodes a Rho GTPase activating protein (Rho-GAP), is a potent tumor suppressor gene that is frequently inactivated in several human cancers. DLC-1 is a multidomain protein that has been shown previously to bind members of the tensin gene family. Here we show that p120Ras-GAP (Ras-GAP; also known as RASA1) interacts and extensively colocalizes with DLC1 in focal adhesions. The binding was mapped to the SH3 domain located in the N-terminus of Ras-GAP and to the RhoGAP catalytic domain, located in the C-terminus of the DLC1. In vitro analyses with purified proteins determined that the isolated Ras-GAP SH3 domain inhibits DLC1 RhoGAP activity, suggesting that Ras-GAP is a negative regulator of DLC1 RhoGAP activity. Consistent with this possibility, we found that ectopic overexpression of Ras-GAP in a Ras-GAP-insensitive tumor line impaired the growth suppressing activity of DLC1 and increased RhoA activity in vivo. Our observations expand the complexity of proteins that regulate DLC1 function and define a novel mechanism of the cross-talk between Ras and Rho GTPases

    Borderline Aggregation Kinetics in ``Dry'' and ``Wet'' Environments

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    We investigate the kinetics of constant-kernel aggregation which is augmented by either: (a) evaporation of monomers from finite-mass clusters, or (b) continuous cluster growth -- \ie, condensation. The rate equations for these two processes are analyzed using both exact and asymptotic methods. In aggregation-evaporation, if the evaporation is mass conserving, \ie, the monomers which evaporate remain in the system and continue to be reactive, the competition between evaporation and aggregation leads to several asymptotic outcomes. For weak evaporation, the kinetics is similar to that of aggregation with no evaporation, while equilibrium is quickly reached in the opposite case. At a critical evaporation rate, the cluster mass distribution decays as kāˆ’5/2k^{-5/2}, where kk is the mass, while the typical cluster mass grows with time as t2/3t^{2/3}. In aggregation-condensation, we consider the process with a growth rate for clusters of mass kk, LkL_k, which is: (i) independent of kk, (ii) proportional to kk, and (iii) proportional to kĪ¼k^\mu, with 0<Ī¼<10<\mu<1. In the first case, the mass distribution attains a conventional scaling form, but with the typical cluster mass growing as tlnā”tt\ln t. When LkāˆkL_k\propto k, the typical mass grows exponentially in time, while the mass distribution again scales. In the intermediate case of LkāˆkĪ¼L_k\propto k^\mu, scaling generally applies, with the typical mass growing as t1/(1āˆ’Ī¼)t^{1/(1-\mu)}. We also give an exact solution for the linear growth model, LkāˆkL_k\propto k, in one dimension.Comment: plain TeX, 17 pages, no figures, macro file prepende
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