18,994 research outputs found

    The Current Birth Rate

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    A Low Cost and Labor Efficient Method for Rearing Black Cutworms (Lepidoptera: Noctuidae)

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    The black cutworm, Agrotis ipsilon (Hufnagel), has been and continues to be the subject of many biological and control studies in the north-central states. Interest in this insect can often be traced to its status as a major, but sporadic pest of field com in the region

    To Repair or Replace: That Is The Restorative Question

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    Objective/Aims: During dental visits, patients spend the majority of their time with their dental hygienist. At these recall appointments the patient’s face-to-face time with the dentist may be short. At this part of the appointment the dentist may diagnose the need for restorative treatment for the patient. Part of the hygienist’s responsibility is to explain treatment options for teeth with restorative needs. The purpose of this review of literature is to provide both options for restoration of dentition to a functional/aesthetic state. Methods: Studies pertaining to the topic were searched using PubMed database. Keywords used in the search were amalgam, composite, restoration, replace, repair, and contraindications. Results: Of the references received multiple outcomes has been recorded. Research shows that when it comes to composite restorations generally doctors will replace them in order to get an accurate color shade to match the patient’s teeth. In regards to posterior teeth there are multiple risk factors for repairing amalgam such as endodontic involvement and denture care. Conclusion: Due to the positive results of both repairing and replacing restorations, it ultimately comes down to a patient to patient basis. Practitioners must also take into consideration risk factors that the patient may present with, cost association/coverage, and patient preference. It is responsibility of the dental hygienist to inform patients of these variables regarding their restorative treatments so they may make an informed decision.https://scholarscompass.vcu.edu/denh_student/1010/thumbnail.jp

    Mineralogical, optical, geochemical, and particle size properties of four sediment samples for optical physics research

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    X-ray diffraction and spectroscopy were used to investigate the mineralogical and chemical properties of the Calvert, Ball Old Mine, Ball Martin, and Jordan Sediments. The particle size distribution and index of refraction of each sample were determined. The samples are composed primarily of quartz, kaolinite, and illite. The clay minerals are most abundant in the finer particle size fractions. The chemical properties of the four samples are similar. The Calvert sample is most notably different in that it contains a relatively high amount of iron. The dominant particle size fraction in each sample is silt, with lesser amounts of clay and sand. The indices of refraction of the sediments are the same with the exception of the Calvert sample which has a slightly higher value

    Comment on "What does the Letelier-Gal'tsov metric describe?"

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    We show that the Letelier-Gal'tsov (LG) metric describing multiple crossed strings in relative motion does solve the Einstein equations, in spite of the discontinuity uncovered recently by Krasnikov [gr-qc/0502090] provided the strings are straight and moving with constant velocities.Comment: 3 page

    The Letelier-Gal'tsov spacetime revisited

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    Contrary to a recent claim by Anderson ["The Mathematical Theory of Cosmic Strings", I.O.P. Publishing, Bristol 2003], we show that the Letelier-Gal'tsov metric does represent a system of crossed straight infinite cosmic strings moving with arbitrary constant velocities.Comment: 3 page

    Simulations of Pattern Formation in Vibrated Granular Media

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    We present simulations of peak pattern formation in vibrated two-dimensional (2D) granulates and measure the dispersion relation of the pattern for various frequencies, accelerations, cell sizes, and layer heights. We report the first quantitative data from numerical simulations showing an interesting dependence of the pattern wavelength on the acceleration and the system size. Our results are related to recent experimental findings and theoretical predictions for gravity waves.Comment: 6 pages PS-file including figures, (version accepted at Europhys. Lett. 26.10.96

    Simulations of dense granular flow: Dynamic Arches and Spin Organization

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    We present a numerical model for a two dimensional (2D) granular assembly, falling in a rectangular container when the bottom is removed. We observe the occurrence of cracks splitting the initial pile into pieces, like in experiments. We study in detail various mechanisms connected to the `discontinuous decompaction' of this granular material. In particular, we focus on the history of one single long range crack, from its origin at one side wall, until it breaks the assembly into two pieces. This event is correlated to an increase in the number of collisions, i.e. strong pressure, and to a momentum wave originated by one particle. Eventually, strong friction reduces the falling velocity such that the crack may open below the slow, high pressure `dynamic arch'. Furthermore, we report the presence of large, organized structures of the particles' angular velocities in the dense parts of the granulate when the number of collisions is large.Comment: Submitted to J. Phys.

    Rotating non-asymptotically flat black rings in charged dilaton gravity

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    We derive new rotating, non-asymptotically flat black ring solutions in five-dimensional Einstein-Maxwell-dilaton gravity with dilaton coupling constant α=8/3\alpha=\sqrt{8/3} which arises from a six-dimensional Kaluza-Klein theory. As a limiting case we also find new rotating, non-asymptotically flat five-dimensional black holes. The solutions are analyzed and the mass, angular momentum and charge are computed. A Smarr-like relation is found. It is shown that the first law of black hole thermodynamics is satisfied.Comment: 21 pages, LaTeX; v2 a reference added, typos correcte
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