Search

Although dramatic amphibian population declines have been reported worldwide, our understanding of the extent of the declines in Latin America, where amphibian diversity is high, is limited to a few well-documented studies. To better understand the geographic extent of declines, their possible causes, and the measures needed to improve Latin American scientists' ability to research the phenomenon and make effective management recommendations, we convened three regional workshops with 88 Latin American herpetologists and conservationists. Population declines are widespread in Latin America. At least 13 countries have experienced declines, and in 40 cases species are now thought to be extinct or extirpated in a country where they once occurred. Declines or extinctions have affected 30 genera and nine families of amphibians. Most declines have occurred in remote highlands, above 500 m in elevation in Central America and above 1000 m in the Andes. Most documented declines occurred in the 1980s. Of the possible causes studied to date, climate change appears to be important at one site and chytrid fungal disease has been identified at sites in three countries. Although many monitoring studies are currently underway in a variety of habitats, most studies are recent and of short duration. In a signed resolution, workshop participants called for greater collaboration and communication among scientists working in Latin America to understand the geographic extent of population declines and the distribution of possible causal factors. In situ conservation is important to protect habitats, but captive-rearing programs for species subject to imminent extinction are also needed. Better understanding of the taxonomy and natural history of amphibians and more funding for research and monitoring are critical to developing a scientific basis for management action to arrest and reverse population declines.

This essay briefly describes a few of the problems associated with using personhood language to defend the right to life of the pre-implantation embryo. Arguing that an immaterial soul explains the personal identity of an embryo is problematic for many people because there is no apparent spiritual activity in the unborn. While some scholars argue that the embryo has the potential to act as an adult person and thus should be protected from harm, others contend that potentiality alone is insufficient reason to ascribe special moral worth to the embryo in utero. For Thomas Aquinas, the soul is not only the life-principle that organizes the human body, but it is also that by which the human being thinks and wills. By making suitable corrections to Aristotle's hylomorphic depiction of the soul–body relation, I suggest that a rational soul must be present from the moment of conception and that it is at the service of the (embryonic) person. What is of critical importance here is to accept that a human being is present from the moment of conception, something the vast majority of embryologists maintain, notwithstanding the inveiglement of those who state that the pre-implantation blastocyst is simply a disorganized clump of cells.

The purpose of this paper is to provide a review of hybrid hydrofoil vehicle technology and feasibility designs, both military and commercial, that have been explored during the last several decades. A hybrid hydrofoil consists of a conventional monohull form with the addition of a long, slender, single strut and lower body added to its keel. The lower body buoyant lift is augmented by the dynamic lift from a fully-submerged foil system. Foil dynamic lift comes into play at speeds of about 12 to 15 knots and above, at which time the upper hull is lifted from the water surface leaving only the small waterplane of the single strut at the interface. The foil automatic control system maintains predetermined flying height and provides a stable platform in waves. The foil surfaces are sufficiently powerful to counter roll, pitch and heave motions that would be imparted to a conventional monohull in waves. Propulsion of a hybrid hydrofoil is provided by one or more prime movers in the upper hull, either driving through a mechanical Z-drive, or an electric transmission system, to one or more propellers on the stern of the lower hull. An alternate arrangement is to place the entire propulsion system in the lower hull, thereby eliminating a Z-drive requirement. The hybrid hydrofoil designs to be described will include USCG patrol craft, U.S. Navy long-range missile patrol craft, multi-mission deploy able vehicle, multi-mission support vehicle, and small combatant, along with several commercial versions of the hybrid hydrofoil concept.

Previous studies of shareholder rights plans (poison pills) have emphasized short-term valuation effects in the context of specific takeover attempts. This paper analyzes rights largely adopted in ‘neutral’ environments. Using a paired-case control approach, differences between rights and non-rights firms are examined. Positive long-term valuation effects are associated with restructurings, while negative performance is associated with ownership/control influences. The evidence supports a multiple signalling model in which investors use subsequent information to revise probabilities concerning control preferences of management and directors.

Early-stage lesions of Kaposi's sarcoma (KS) are composed of single-layered, highly flattened cells lining collagen bundles, whereas late-stage lesions contain densely packed, spindle-shaped cells. We examined the progression of KS lesions in oral mucosa and lymph nodes from patients with AIDS, using antibodies specific for blood vascular endothelial cells (Factor VIII-related antigen) and their basement membrane (Type IV collagen and laminin). In addition, the plant lectin Ulex europaeus, which selectively stains blood vessels, was also used. In early-stage KS lesions, fibronectin, laminin and Type IV collagen were co-distributed at the interface between KS cells and collagen bundles; Factor VIII-related antigen and Ulex europaeus lectin staining was present in vascular channels and in the KS cells. However, in late-stage lesions, few if any KS cells stained with antibody to Factor VIII-associated antigen, although endothelial cells lining blood vessels were positive. Strong staining for laminin and Type IV collagen was present in a pericellular pattern throughout the nodular late-stage lesions. Since lymphatic capillary endothelium does not produce basement-membrane-specific macromolecules, these results support the conclusion that KS cells are related to blood vascular endothelium but eventually lose certain endothelium-specific markers as the cells are transformed into the spindle-shaped cell type.

In this paper several hybrid surface ship concepts are described and their estimated speed-power and range performance compared under calm and rough water conditions. The concepts analysed are the Small Waterplane Area Single Hull (SWASH) Ship, Hydrofoil Small Waterplane Area Ship (HYSWAS), Large Hydrofoil Hybrid Ship (LAHHS), Hydrofoil Air Cushion Ship (HYACS) and Small Waterplane Area Air Cushion Ship (SWAACS). All concepts investigated are of 2,000-ton (2,032-tonne) displacement having various combinations of buoyancy, foil lift or powered static-lift from an air cushion. Analysis showed that HYSWAS and LAHHS with about 70% buoyant lift and 30% dynamic lift are expected to have generally favourable characteristics in both calm and rough water over a broad speed spectrum leading to relatively good speed and range performance. These concepts therefore, appear to be promising configurations for future consideration. However, for special purpose missions, where for instance only a segment of speed spectrum is dominant or rough water operations are not anticipated, other hybrid forms may show potential and might be pursued further. Order from BSRA as No. 49,257.

One hundred patients irradiated for cancers of the oral cavity, oropharynx, and nasopharynx were evaluated for the occurrence of osteonecrosis and associated predisposing factors. Selection was based on availability of complete dental records, a minimum of six months follow-up, and treatment fields, which included maxilla and/or mandible. Bone doses were calculated by using radiotherapy treatment records, port films, and isodose distributions. Osteonecrosis developed in 19 of 78 dentulous patients and in 3 of 22 edentulous patients. The time of development of osteonecrosis varied; in 15 cases osteonecrosis occurred more than one year after treatment. The most important risk factor for the development of osteonecrosis was the radiation dose to bone, particularly in the less vascular mandible. Osteonecrosis 7500 rads to the bone. None of the patients who received less than 6500 rads developed osteonecrosis. The risk was significantly greater when teeth were removed after therapy compared with those individuals with extractions before radiation or no extractions at all.

We determined the distribution of 2 components of the extracellular matrix, fibronectin and laminin, in normal, premalignant, and malignant oral mucosa. Both indirect immunofluorescence and avidin-biotin complex immunoperoxidase techniques were used with antisera to each glycoprotein. Fibronectin was consistently present in the basement membrane and connective tissue of normal, leukoplakic and malignant oral mucosa regardless of anatomic site. A continuous laminin-reactive basement membrane structure separated tumor parenchyma from the associated stroma except in areas of invasion in which no laminin staining was evident.

a This fine book represents the latest, and in many ways the most complete, report on the early experiences with U.S. airline deregulation.' Like its predecessors, the analysis covers essentially the first two years or so of deregulation experience: most of the data series end either on or before June 1981, and thus before the traumas associated with the PATCO strike of August 1981 and the major economic recession of 1982.2 The authors were all actively involved in implementing U.S. airline deregulation. Bailey was a member of the Civil Aeronautics Board, Graham was a CAB staff economist, and Kaplan was the CAB's director of economic analysis during the period just before and after formal enactment and signing of the Airline Deregulation Act in October 1978. As a consequence, the book is especially strong on reports and descriptions of the maneuvers and logic underlying the decisions of the CAB during the transition to deregulation. In particular, the authors provide strong insights on how pre-Airline Deregulation Act decisions anticipated and were designed to help facilitate the process of deregulation. In other respects, however, the book's contribution is not so distinct or original. Specifically, most of the basic findings are, not surprisingly, consistent with those in earlier reports on the initial postderegulation experience. In essence, the book, besides providing some new insights based upon the "inside experience" of the authors, somewhat extends the data base upon which the earlier findings were founded, and in a few instances, particularly in the analysis of airline competitive behavior, brings some new analytical tools or tests to bear on the problem. For example, with regard to what is probably the most important economic aspect of deregulation, airline pricing policy, Bailey, Graham, and Kaplan find that: (1) airline fares since deregulation have become more and more cost related; (2) the airlines have made greater use of offpeak price concessions to improve capacity utilization; and (3) more differentiated fares, reflecting not only cost differences but demand elasticity and other market differences as well, have generally emerged. They also find that this differentiation has perhaps worked less to the advantage of small-town travellers than to those living in and around major hub cities-although their evidence on this is weaker than that found in some other