18,557 research outputs found

    Experiment at Nebraska The First Two Years of a Cluster College

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    In November 1968 the Board of Regents of the University of Nebraska was asked to react to a document coming from a faculty-student committee charged with examining the feasibility of establishing an innovating college on the Lincoln campus. It attempted to spell out the need for such innovation, and it offered a plan for fulfilling the need that it delineated. This is that document: 1 Within the past generation a new kind of student, a new kind of faculty, and a new kind of university have developed. To meet the challenges which these changes present and to provide for an educational and national future whose nature is unforseeable, many persons have concluded that there is a need for experiments in university curriculum and organization. The purpose of such endeavors should be a graduate who is sharply aware of himself, his society, and his world, able and desirous of continuing his liberal and professional education beyond the classroom. The New Students Students who come to the University are different from those who came twenty years ago.! A larger number of high school graduates choose to enroll than before and, of those who come, a larger number graduate. Though the numbers are greater, their quality is not inferior often. Television and other instruments of mass communication have provided them with astonishing funds of miscellaneous information, some of it inaccurate, much of it irrelevant, and part of it useful. In addition, many have traveled widely. The new students come to us with new formal preparation. High school science programs have been set up by distinguished scientists, the new math has become widespread-and public school English has undergone elaborate revision. In the future, advanced placement programs promise to change drastically the relation of entering students to the University. Perhaps more important, the temper of the undergraduates seems to be changing. The students have learned to react quickly to situations far from home ground, and echoes of Vietnam and Berkeley can be heard in Lincoln. In some universities the students have not hesitated to bite the hand that presumes to feed them, and generally students are becoming increasingly critical of their courses, professors, and colleges. They complain that universities have made them numbers on IBM cards, anonymous to teachers and advisers, and a gray mass to their administrators. They resent a lack of individual attention. For the past two years-at least responsible students through their official channels (e.g. ASUN [Associated Students of University of Nebraska]) have undertaken to scrutinize university programs. It is significant that the disgruntled students are not the weakest. The most critical are often the brightest, the most committed socially, and the most responsible morally. The best seem to be the most critical

    Spatio-Temporal Low Count Processes with Application to Violent Crime Events

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    There is significant interest in being able to predict where crimes will happen, for example to aid in the efficient tasking of police and other protective measures. We aim to model both the temporal and spatial dependencies often exhibited by violent crimes in order to make such predictions. The temporal variation of crimes typically follows patterns familiar in time series analysis, but the spatial patterns are irregular and do not vary smoothly across the area. Instead we find that spatially disjoint regions exhibit correlated crime patterns. It is this indeterminate inter-region correlation structure along with the low-count, discrete nature of counts of serious crimes that motivates our proposed forecasting tool. In particular, we propose to model the crime counts in each region using an integer-valued first order autoregressive process. We take a Bayesian nonparametric approach to flexibly discover a clustering of these region-specific time series. We then describe how to account for covariates within this framework. Both approaches adjust for seasonality. We demonstrate our approach through an analysis of weekly reported violent crimes in Washington, D.C. between 2001-2008. Our forecasts outperform standard methods while additionally providing useful tools such as prediction intervals

    Ridge Production in High-Multiplicity Hadronic Ultra-Peripheral Proton-Proton Collisions

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    An unexpected result at the RHIC and the LHC is the observation that high-multiplicity hadronic events in heavy-ion and proton-proton collisions are distributed as two "ridges", approximately flat in rapidity and opposite in azimuthal angle. We propose that the origin of these events is due to the inelastic collisions of aligned gluonic flux tubes that underly the color confinement of the quarks in each proton. We predict that high-multiplicity hadronic ridges will also be produced in the high energy photon-photon collisions accessible at the LHC in ultra-peripheral proton-proton collisions or at a high energy electron-positron collider. We also note the orientation of the flux tubes between the quark and antiquark of each high energy photon will be correlated with the plane of the scattered proton or lepton. Thus hadron production and ridge formation can be controlled in a novel way at the LHC by observing the azimuthal correlations of the scattering planes of the ultra-peripheral protons with the orientation of the produced ridges. Photon-photon collisions can thus illuminate the fundamental physics underlying the ridge effect and the physics of color confinement in QCD.Comment: Presented by SJB at Photon 2017: The International Conference on the Structure and the Interactions of the Photon and the International Workshop on Photon-Photon Collisions. CERN, May 22-26, 2017. References adde

    Characterization of the Active Site and Insight into the Binding Mode of the Anti-angiogenesis Agent Fumagillin to the Manganese(II)-Loaded Methionyl Aminopeptidase from \u3cem\u3eEscherichia coli\u3c/em\u3e

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    EPR spectra were recorded for methionine aminopeptidase from Escherichia coli (EcMetAP-I) samples (~2.5 mM) to which one and two equivalents of Mn(II) were added (the latter is referred to as [MnMn(EcMetAP-I)]). The spectra for each sample were indistinguishable except that the spectrum of [MnMn(EcMetAP-I)] was twice as intense. The EPR spectrum of [MnMn(EcMetAP-I)] exhibited the characteristic six-line g≈2 EPR signal of mononuclear Mn(II) with A av(55Mn)=9.3 mT (93 G) and exhibited Curie-law temperature dependence. This signal is typical of Mn(II) in a ligand sphere comprising oxygen and/or nitrogen atoms. Other features in the spectrum were observed only as the temperature was raised from that of liquid helium. The temperature dependences of these features are consistent with their assignment to excited state transitions in the S=1, 2 ... 5 non-Kramer’s doublets, due to two antiferromagnetically coupled Mn(II) ions with an S=0 ground state. This assignment is supported by the observation of a characteristic 4.5 mT hyperfine pattern, and by the presence of signals in the parallel mode consistent with a non-Kramers’ spin ladder. Upon the addition of the anti-angiogenesis agent fumagillin to [MnMn(EcMetAP-I)], very small changes were observed in the EPR spectrum. MALDI-TOF mass spectrometry indicated that fumagillin was, however, covalently coordinated to EcMetAP-I. Therefore, the inhibitory action of this anti-angiogenesis agent on EcMetAP-I appears to involve covalent binding to a polypeptide component at or near the active site rather than direct binding to the metal ions

    Evidence for pronounced quark loop effects in QCD

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    We have measured the hadron spectrum in lattice QCD, using staggered fermions, for 0 (the quenched approximation), 2 and 4 light degenerate dynamical quarks. In addition to earlier results involving extrapolations in valence quark masses for fixed dynamical mass, we also report results where we extrapolate in the dynamical mass for 4 flavors. We see a marked difference in the hadron spectrum for 2 and 4 flavors; the hadron spectrum is nearly parity doubled for 4 flavors, indicating smaller effects of chiral symmetry breaking. This pronounced effect in the hadron spectrum cannot be removed by a simple change in scale as the number of light quark flavors is changed. Further simulations at larger volume are needed to rule out finite volume effects.Comment: 5 pages, 4 figures. Presented at Lattice QCD on Parallel Computers, Tsukuba, Japan, march 199

    Herbicide impacts on exotic grasses and a population of the critically endangered herb "Calystegia affinis" (Convolvulaceae) on Lord Howe Island

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    Introduced perennial grasses are capable of altering the habitat of native species, causing reductions in population size and vigour, and potentially affecting life-history processes such as survival, pollination and seedling recruitment. We examined the utility of herbicide treatment on two exotic grasses, Pennisetum clandestinum (Kikuyu) and Stenotaphrum secundatum (Buffalo grass) to restore the habitat of Calystegia affinis, a critically endangered species endemic to Lord Howe and Norfolk Islands. Using two herbicides, Asset (designed to affect only grasses) and Glyphosate (a general herbicide), we compared effectiveness in reducing grass cover on a population of Calystegia affinis. We protected Calystegia plants from the herbicides by ensuring their leaves were covered by plastic bags during herbicide application. Both herbicides were similarly effective in reducing grass cover after four weeks and had no noticeable adverse affect on Calystegia (suggesting the plastic bag protection was effective). After 26 weeks, Glyphosate was more effective in maintaining a reduced grass cover. Plots treated with either herbicide had a greater relative increase in abundance of Calystegia stems compared to untreated controls. The Glyphosate treatment resulted in the greatest relative increase in stem abundance, but this was not significantly greater than in the Asset treatment. We consider that spraying with Glyphosate treatment, with follow-up monitoring and spot-spraying, will assist the recovery of the Calystegia affinis population. Ultimately, the maintenance of a weed-free zone at the forest edge will provide suitable habitat for additional recruitment of this and other native species

    Detection of an Extrasolar Planet Atmosphere

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    We report high precision spectrophotometric observations of four planetary transits of HD 209458, in the region of the sodium resonance doublet at 589.3 nm. We find that the photometric dimming during transit in a bandpass centered on the sodium feature is deeper by (2.32 +/- 0.57) x 10^{-4} relative to simultaneous observations of the transit in adjacent bands. We interpret this additional dimming as absorption from sodium in the planetary atmosphere, as recently predicted from several theoretical modeling efforts. Our model for a cloudless planetary atmosphere with a solar abundance of sodium in atomic form predicts more sodium absorption than we observe. There are several possibilities that may account for this reduced amplitude, including reaction of atomic sodium into molecular gases and/or condensates, photoionization of sodium by the stellar flux, a low primordial abundance of sodium, or the presence of clouds high in the atmosphere.Comment: 26 pages, 8 figures, accepted by ApJ 2001 November 1
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