Stochastic Data Clustering

In 1961 Herbert Simon and Albert Ando published the theory behind the long-term behavior of a dynamical system that can be described by a nearly uncoupled matrix. Over the past fifty years this theory has been used in a variety of contexts, including queueing theory, brain organization, and ecology. In all these applications, the structure of the system is known and the point of interest is the various stages the system passes through on its way to some long-term equilibrium. This paper looks at this problem from the other direction. That is, we develop a technique for using the evolution of the system to tell us about its initial structure, and we use this technique to develop a new algorithm for data clustering.Comment: 23 page

Performance of a turbojet engine with adjustable first-stage turbine stator and variable-area exhaust nozzle

The performance of a turbojet engine with a two-stage turbine, an adjustable first-stage turbine stator, and a variable-area exhaust nozzle was investigated at selected constant engine speeds and two simulated flight conditions. For the particular component characteristics of the engine investigated, little improvement in thrust levels of interest by use of an adjustable rather than an optimum fixed first-stage turbine stator

A stand-alone tree demography and landscape structure module for Earth system models

We propose and demonstrate a new approach for the simulation of woody ecosystem stand dynamics, demography, and disturbance-mediated heterogeneity suitable for continental to global applications and designed for coupling to the terrestrial ecosystem component of any earth system model. The approach is encoded in a model called Populations-Order-Physiology (POP). We demonstrate the behavior and performance of POP coupled to the Community Atmosphere Biosphere Land Exchange model (CABLE) applied along the Northern Australian Tropical Transect, featuring gradients in rainfall and fire disturbance. The model is able to simultaneously reproduce observation-based estimates of key functional and structural variables along the transect, namely gross primary production, tree foliage projective cover, basal area, and maximum tree height. Prospects for the use of POP to address current vegetation dynamic deficiencies in earth system modeling are discussed

A search for new particles in proton‐nucleus collisions at 400 GeV/c

We report preliminary results from a search for new particles produced in proton‐nucleus collisions at 400 GeV/c. A double‐arm spectrometer is used to detect two‐body final states where each spectrometer arm has the capability of uniquely identifying Π±, K±, p, ?, μ±, and ϕ. The Jψ is measured in the μ+μ− mode.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87398/2/30_1.pd

Granite–a new telescope for TeV gamma ray astronomy

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87435/2/253_1.pd

Observations of TeV photons at the Whipple Observatory

The Whipple Observatory 10 m gamma‐ray telescope has been used to search for TeV gamma‐ray emission from a number of objects. This paper reports observations of six galactic and three extragalactic objects using the Cherenkov image technique. With the introduction of a high‐resolution camera (1/4° pixel) in 1988, the Crab Nebula was detected at a significance level of 20 σ in 30 hours of on‐source observation. Upper limits at a fraction of the Crab flux are set for most of the other objects, based on the absence of any significant dc excess or periodic effect when an a priori Monte Carlo determined imaging selection criterion (the ‘‘azwidth cut’’) is employed. There are weak indications that one source, Hercules X‐1, may be an episodic emitter. The Whipple detection system will be improved shortly with the addition of a second reflector 11 m in diameter (GRANITE) for stereoscopic viewing of showers. The combination of the two‐reflector system should have a signal‐to‐noise advantage of 103 over a simple nonimaging Cherenkov receiver.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87437/2/47_1.pd

Harmonic Vibrational Excitations in Disordered Solids and the "Boson Peak"

We consider a system of coupled classical harmonic oscillators with spatially fluctuating nearest-neighbor force constants on a simple cubic lattice. The model is solved both by numerically diagonalizing the Hamiltonian and by applying the single-bond coherent potential approximation. The results for the density of states $g(\omega)$ are in excellent agreement with each other. As the degree of disorder is increased the system becomes unstable due to the presence of negative force constants. If the system is near the borderline of stability a low-frequency peak appears in the reduced density of states $g(\omega)/\omega^2$ as a precursor of the instability. We argue that this peak is the analogon of the "boson peak", observed in structural glasses. By means of the level distance statistics we show that the peak is not associated with localized states

The effects of feeding and transport length on the welfare of white rhinoceroses (Ceratotherium simum simum) during long-distance translocations : a preliminary study

Translocation is a valuable conservation tool, but poses significant risks for the transported rhinoceroses. Interventions reducing these risks are required to ensure positive welfare during transportation. The aim of this study was to evaluate the effect of journey duration and feeding during the transport of white rhinoceroses (Ceratotherium simum simum). A total of 32 animals were transported by road during two events, five days apart. Fifteen rhinoceroses in the first transport event (37.0 ± 2.4 hr duration) were not fed, while 17 rhinoceroses in the second event (32.2 ± 1.5 hr duration) were offered lucerne. Blood samples were collected at capture and after transport for the evaluation of changes in serum clinical chemistry analytes. The Wilcoxon rank-sum test was used to compare differences between the groups. In all rhinoceroses, transport resulted in changes in serum electrolyte, metabolite and enzyme concentrations, indicating a loss in total body water, nutritional shifts, stress and fatigue. Fed rhinoceroses, transported over a shorter time, displayed greater changes in osmolality (p < 0.006), serum sodium and chloride concentrations (p = 0.005 and = 0.001, respectively) indicating a greater degree of total body water loss than non-fed rhinoceroses. Feeding and a shorter transport duration reduced, but did not prevent, nutritional challenges. A greater increase in the muscle enzymes CK and AST (p = 0.027 and = 0.001, respectively), indicated greater fatigue in non-fed rhinoceroses transported over a longer time. Further work to distinguish the effects of feeding and journey duration is required to better understand the role feeding may play in mitigating welfare challenges during rhinoceros translocation.The International Rhino Foundation rhino research grant, a donation from the South African Veterinary Association Wildlife Group Research Fund, as well as departmental funding.http://www.jsava.co.zaam2023Centre for Veterinary Wildlife Studie