Stochastic emergence of inflaton fluctuations in a SdS primordial universe with large-scale repulsive gravity from a 5D vacuum

We develop a stochastic approach to study scalar field fluctuations of the inflaton field in an early inflationary universe with a black-hole (BH), which is described by an effective 4D SdS metric. Considering a 5D Ricci-flat SdS static metric, we implement a planar coordinate transformation, in order to obtain a 5D cosmological metric, from which the effective 4D SdS metric can be induced on a 4D hypersurface. We found that at the end of inflation, the squared fluctuations of the inflaton field are not exactly scale independent and becomes sensitive with the mass of the BH.Comment: version accepted in European Physical Journal Plu

Null Geodesics in Five Dimensional Manifolds

We analyze a class of 5D non-compact warped-product spaces characterized by metrics that depend on the extra coordinate via a conformal factor. Our model is closely related to the so-called canonical coordinate gauge of Mashhoon et al. We confirm that if the 5D manifold in our model is Ricci-flat, then there is an induced cosmological constant in the 4D sub-manifold. We derive the general form of the 5D Killing vectors and relate them to the 4D Killing vectors of the embedded spacetime. We then study the 5D null geodesic paths and show that the 4D part of the motion can be timelike -- that is, massless particles in 5D can be massive in 4D. We find that if the null trajectories are affinely parameterized in 5D, then the particle is subject to an anomalous acceleration or fifth force. However, this force may be removed by reparameterization, which brings the correct definition of the proper time into question. Physical properties of the geodesics -- such as rest mass variations induced by a variable cosmological ``constant'', constants of the motion and 5D time-dilation effects -- are discussed and are shown to be open to experimental or observational investigation.Comment: 19 pages, REVTeX, in press in Gen. Rel. Gra

Bumpers College of Agricultural, Food and Life Sciences Professional Development Opportunities and their Impact on Perceptions of Career Preparedness

A student’s undergraduate education is an imperative part of developing career skills that will prepare them to transition from academia to the professional world. Experience outside of the classroom and course material taught in a formal class experience are both important. Their experiences and classes, in college, allow them to develop skills and increase their chances of being successful in the workplace (Suvedi et al., 2016). Chickering’s Seven Vectors of Student Development were used to help explain the process of student development. A quantitative survey was sent to DBCALFS faculty, staff, and administrators, and a different quantitative survey was sent to DBCAFLS students. A total of 188 usable surveys were returned for students. The study found that faculty, staff, and administrators said that campus affiliated organizational clubs (RSOs), internships, and on campus jobs were offered at the college level in DBCAFLS, and campus affiliated organizational clubs (RSOs), school sponsored study abroad, on campus jobs, and career fairs/networking events were offered at the department level in DBCAFLS. Faculty, staff, and administrators also said that internships, on campus jobs, off campus jobs, and capstone courses where students connect with professionals, career fairs/networking events, and company visits (business site tours/presentations by employees) had contribution to student employability skills. The study also looked at student perceptions involving importance of employability skills to their future careers, as well as their self-perceived level of competence of performing those skills. Student respondents ranked solving problems, identifying problems, meeting deadlines, listening attentively, working well with fellow employees, and adapting to situations as having the most importance to their future careers. Student respondents ranked their competence at performing certain employability skills as high including, working well with fellow employees, meeting deadlines, ability to work independently, empathizing with others, understanding the needs of others, and listening attentively. Students rated professional development opportunities in terms of their contribution to their employability skills. The highest-ranking professional development opportunities included campus affiliated organizations (RSOs), off campus jobs, academic courses that incorporate professional development curriculum, church/religious organizations, and social fraternities/sororities

Radiating sources in higher-dimensional gravity

We study a time-dependent 5D metric which contains a static 4D sub-metric whose 3D part is spherically symmetric. An expansion in the metric coefficient allow us to obtain close-to Schwarzschild approximation to a class of spherically-symmetric solutions. Using Campbell's embedding theorem and the induced-matter formalism we obtain two 4D solutions. One describes a source with the stiff equation of state believed to be applicable to dense astrophysical objects, and the other describes a spherical source with a radial heat flow.Comment: Latex, 20 pages, no figures. to appear in J. Math. Phy

MHD Memes

The celebration of Allan Kaufman's 80th birthday was an occasion to reflect on a career that has stimulated the mutual exchange of ideas (or memes in the terminology of Richard Dawkins) between many researchers. This paper will revisit a meme Allan encountered in his early career in magnetohydrodynamics, the continuation of a magnetohydrodynamic mode through a singularity, and will also mention other problems where Allan's work has had a powerful cross-fertilizing effect in plasma physics and other areas of physics and mathematics.Comment: Submitted for publication in IOP Journal of Physics: Conference Series for publication in "Plasma Theory, Wave Kinetics, and Nonlinear Dynamics", Proceedings of KaufmanFest, 5-7 October 2007, University of California, Berkeley, US

Causal Anomalies in Kaluza-Klein Gravity Theories

Causal anomalies in two Kaluza-Klein gravity theories are examined, particularly as to whether these theories permit solutions in which the causality principle is violated. It is found that similarly to general relativity the field equations of the space-time-mass Kaluza-Klein (STM-KK) gravity theory do not exclude violation of causality of G\"odel type, whereas the induced matter Kaluza-Klein (IM-KK) gravity rules out noncausal G\"odel-type models. The induced matter version of general relativity is shown to be an efficient therapy for causal anomalies that occurs in a wide class of noncausal geometries. Perfect fluid and dust G\"odel-type solutions of the STM-KK field equations are studied. It is shown that every G\"odel-type perfect fluid solution is isometric to the unique dust solution of the STM-KK field equations. The question as to whether 5-D G\"odel-type non-causal geometries induce any physically acceptable 4-D energy-momentum tensor is also addressed.Comment: 16 page. LaTex file. To appear in Int. J. Mod. Phys. A (1998

Stabilization of test particles in Induced Matter Kaluza-Klein theory

The stability conditions for the motion of classical test particles in an $n$-dimensional Induced Matter Kaluza-Klein theory is studied. We show that stabilization requires a variance of the strong energy condition for the induced matter to hold and that it is related to the hierarchy problem. Stabilization of test particles in a FRW universe is also discussed.Comment: 15 pages, 1 figure, to appear in Class. Quantum Gra

Fishery independent standing stock surveys of oyster populations in the Virginia sub estuaries of the Chesapeake Bay and a comparison with continuing estimates obtained from fishery dependent data

Extensive description of the Virginia oyster resource and history of its utilization has been given by Haven, Hargis and Kendall (1981), and more recently reviewed by Hargis and Haven (1988). These contributions, among many others, describe a state of continuing decline. To facilitate resource management a fishery independent survey was proposed to and subsequently supported by the Chesapeake Bay Stock Assessment Committee in 1993. This report covers activity on that program for the period October of 1993 through September of 1994. Spatial variability in distribution of oysters within an oyster reef system, and distribution of reefs in the intertidal and/or subtidal regions complicate fishery independent estimation of standing stock. By contrast, fishery dependent estimates of oyster standing stock can be made, where adequate data on effort and temporal changes in landings exist, through application of Leslie-DeLury regression analysis (Barber and Mann, 1991). Intensive, fishery independent estimates are rare but pivotal to examination of spawning capabilities of broodstock supporting commercial fisheries and related requirements for establishment of fishery catch quotas. The James River, Virginia has served as the focal point for the Virginia oyster industry for over a century, being the source of the majority of seed oysters that were transplanted for grow-out to locations within the Virginia portion of the Chesapeake Bay and much further afield in the Middle Atlantic states (Haven et al, 1981). The Rappahannock River in Virginia was, for many years, a source of large and valued oysters for both the shucking and half shell trade. It is surprising that comparatively little effort has been previously expended to estimate standing stock in both the James and Rappahannock Rivers given the acknowledged need for such data in fishery management. Continuing losses of productive oyster reef over the past three decades to Haplosporidium nelsoni, commonly known as MSX, and Perkinsus marinus, commonly known as Dermo , in the higher salinity regions of both rivers, combined with increased fishing pressure on all remaining stocks, have emphasized the need for working estimates of standing stock. This need has been further exaggerated in the James River by a change in emphasis in the past decade from the harvesting of seed oysters to larger market oysters, and the reduction in size limit of the latter from three to two-and-one-half inches maximum dimension (although this action was reversed with an increase in minimum market size to three inches for the 1994-1995 season). The fishery is now facing the dilemma of exploiting the limited remaining broodstock from the James River in order to retain a viable fishery for market oysters, while simultaneously threatening the long term future of the river as a seed producing location

Fishery independent standing stock surveys of oyster populations in Virginia 1997

Extensive description of the Virginia oyster resource and history of its utilization has been given by Haven, Hargis and Kendall (1981), and more recently reviewed by Hargis and Haven (1988). These contributions, among many others, describe a state of continuing decline. The James River, Virginia has served as the focal point for the Virginia oyster industry for over a century, being the source of the majority of seed oysters that were transplanted for grow-out to locations within the Virginia portion of the Chesapeake Bay and much further afield in the Middle Atlantic states (Haven et al, 1981). The Rappahannock River in Virginia was, for many years, a source of large and valued oysters for both the shucking and half shell trade. Other subestuaries and embayments in the Virginia portion of the Chesapeake Bay have served variously as both seed oyster (e.g. the Great Wicomico and Piankatank Rivers) and market oyster (Mobjack Bay, Tangier Sound and Pocomoke Sound) sources for the once substantial historical fishety. Until the initiation of the current project with suppmt of the Chesapeake Bay Stock Assessment Committee of NOAA (hereafter CBSAC) there was little effort to estimate standing stocks of oysters in the Virginia subestuaries, especially the James and Rappahannock Rivers. Continuing losses of productive oyster reef over the past 35 years to Haplosporidium nelsoni, commonly known as MSX, and Perkinsus marinus, commonly known as Dermo , in the higher salinity regions of the Bay and the subestuaries, combined with increased fishing pressure on all remaining stocks, have emphasized the need for working estimates of standing stock. This need has been further exaggerated in the James River by a change in emphasis in the past decade from the harvesting of seed oysters to larger market oysters, and the reduction in size limit of the latter from three to two-and-one-half inches maximum dimension for the 1988 through 1994 public oyster fishing seasons. The fishery continues to exploit the limited remaining broodstock from the James River in order to retain a viable fishery for market oysters, while simultaneously threatening the long term future of the river as the only functional seed producing location in the Virginia portion of the Chesapeake Bay. (more ..

The Big Bang as a Phase Transition

We study a five-dimensional cosmological model, which suggests that the universe bagan as a discontinuity in a (Higgs-type) scalar field, or alternatively as a conventional four-dimensional phase transition.Comment: 10 pages, 2 figures; typo corrected in equation (18); 1 reference added; version to appear in International Journal of Modern Physics