Effect of Temperature on Development Rate and Survival of \u3ci\u3eNomophila Nearctica\u3c/i\u3e (Lepidoptera: Pyralidae)

Development of Nomophila nearctica was studied under six constant tempera- tures in controlled temperature cabinets. Developmental threshold temperatures for egg, larval, and prepupal-pupal stages were 8.9, 1l.5, and 9.2°C. The overall mean developmental threshold temperature for all stages was 9.9°C. Degree-day summa- tions, based on the above threshold temperatures, averaged 50, 304, and 181 DD for the egg, larval, and prepupal-pupal stages, respectively. Total heat units of 535 DD are required for development from oviposition to adult emergence. Head capsule measurements indicated six larval instars

Vestibular-induced vomiting after vestibulocerebellar lesions

Vestibular stimulation, by sinusoidal electrical polarization of the labyrinths of decerebrate cats which can produce vomiting and related activity which resembles motion sickness was examined. The symptoms include panting, salivation, swallowing, and retching as well as vomiting. These symptoms can be produced in cats with lesions of the posterior cerebellar vermis. It is suggested that a transcerebellar pathway from the vestibular apparatus through the nodulus and uvula to the vomiting center is not essential for vestibular induced vomiting and the occurrence of many symptoms of motion

Vomiting Center reanalyzed: An electrical stimulation study

Electrical stimulation of the brainstem of 15 decerebrate cats produced stimulus-bound vomiting in only 4 animals. Vomiting was reproducible in only one cat. Effective stimulating sites were located in the solitary tract and reticular formation. Restricted localization of a vomiting center, stimulation of which evoked readily reproducible results, could not be obtained

CURRENT ISSUES AFFECTING TRADE AND TRADE POLICY: AN ANNOTATED LITERATURE REVIEW

This review provides a base of literature describing current issues and research on the impacts of lobalization and the industrialization of agriculture and recent approaches to analyze and model agricultural trade and trade policies. Three key factors of the survey are differentiated goods, global economic integration and international supply chain linkages. The review covers 182 publications, which are presented alphabetically by author with a brief annotation describing how it relates to the above criteria. The articles are also indexed by keyword. A brief summary highlights the documented literature and includes a series of issues for future discussion and research.International Relations/Trade,

Magnetocaloric effect in Gd/W thin film heterostructures

In an effort to understand the impact of nanostructuring on the magnetocaloric effect, we have grown and studied gadolinium in MgO/W(50 $\textrm{\AA}$)/[Gd(400 $\textrm{\AA}$)/W(50 $\textrm{\AA}$)]$_8$ heterostructures. The entropy change associated with the second order magnetic phase transition was determined from the isothermal magnetization for numerous temperatures and the appropriate Maxwell relation. The entropy change peaks at a temperature of 284 K with a value of approximately 3.4 J/kg-K for a 0-30 kOe field change; the full width at half max of the entropy change peak is about 70 K, which is significantly wider than that of bulk Gd under similar conditions. The relative cooling power of this nanoscale system is about 240 J/kg, somewhat lower than that of bulk Gd (410 J/kg). An iterative Kovel-Fisher method was used to determine the critical exponents governing the phase transition to be $\beta=0.51$, and $\gamma=1.75$. Along with a suppressed Curie temperature relative to the bulk, the fact that the convergent value of $\gamma$ is that predicted by the 2-D Ising model may suggest that finite size effects play an important role in this system. Together, these observations suggest that nanostructuring may be a promising route to tailoring the magnetocaloric response of materials

Simulation of electron transport in quantum well devices

Double barrier resonant tunneling diodes (DBRTD) have received much attention as possible terahertz devices. Despite impressive experimental results, the specifics of the device physics (i.e., how the electrons propagate through the structure) are only qualitatively understood. Therefore, better transport models are warranted if this technology is to mature. In this paper, the Lattice Wigner function is used to explain the important transport issues associated with DBRTD device behavior

The Angular Momentum Operator in the Dirac Equation

The Dirac equation in spherically symmetric fields is separated in two different tetrad frames. One is the standard cartesian (fixed) frame and the second one is the diagonal (rotating) frame. After separating variables in the Dirac equation in spherical coordinates, and solving the corresponding eingenvalues equations associated with the angular operators, we obtain that the spinor solution in the rotating frame can be expressed in terms of Jacobi polynomials, and it is related to the standard spherical harmonics, which are the basis solution of the angular momentum in the Cartesian tetrad, by a similarity transformation.Comment: 13 pages,CPT-94/P.3027,late