709 research outputs found
Relationship Between Supervisors\u27 Servant Leadership and Police Officers Job Satisfaction
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 studyās 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
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
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
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
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 2012ā2013 and 2013ā2014 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 useāyield relationship was not significantly different for
wheat following the mixture (11.80 kg haā1 mmā1) than for wheat
following single-species plantings (12.32ā13.57 kg haā1 mmā1).
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
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 ĪE FWHM/Eā15 %. 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
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
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
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
, where is the mass, while the typical cluster mass grows with
time as . In aggregation-condensation, we consider the process with a
growth rate for clusters of mass , , which is: (i) independent of ,
(ii) proportional to , and (iii) proportional to , with . In
the first case, the mass distribution attains a conventional scaling form, but
with the typical cluster mass growing as . When , the
typical mass grows exponentially in time, while the mass distribution again
scales. In the intermediate case of , scaling generally
applies, with the typical mass growing as . We also give an
exact solution for the linear growth model, , in one dimension.Comment: plain TeX, 17 pages, no figures, macro file prepende
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Los Alamos National Laboratory`s Mobile Real Time Radiography System
A 450-KeV Mobile Real Time Radiography (RTR) System was delivered to Los Alamos National Laboratory (LANL) in January 1996. It was purchased to inspect containers of radioactive waste produced at (LANL). Since its delivery it has been used to radiograph greater than 600 drums of radioactive waste at various LANL sites. It has the capability of inspecting waste containers of various sizes. It has three independent X-Ray acquisition formats. The primary system used is a 12 in. image intensifier, the second is a 36 in. linear diode array (LDA) and the last is an open system. It is fully self contained with on board generator, HVAC and a fire suppression system. It is on a 53 ft long X 8 ft. wide X 14 ft. high trailer that can be moved over any highway requiring only a easily obtainable overweight permit because it weighs approximately 38 tons. It was built to conform to industry standards for a cabinet system which does not require an exclusion zone. The fact that this unit is mobile has allowed us to operate where the waste is stored, rather than having to move the waste to a fixed facility
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