The failure of conventional quantum theory to recognize time as an observable and to admit time operators is addressed. Instead of focusing on the existence of a time operator for a given Hamiltonian, we emphasize the role of the Hamiltonian as the generator of translations in time to construct time states. Taken together, these states constitute what we call a timeline. Such timelines are adequate for the representation of any physical state, and appear to exist even for the semi-bounded and (...) discrete Hamiltonian systems ruled out by Pauli’s theorem. However, the step from a timeline to a valid time operator requires additional assumptions that are not always met. Still, this approach illuminates the issues surrounding the construction of time operators, and establishes timelines as legitimate alternatives to the familiar coordinate and momentum bases of standard quantum theory. (shrink)

In this study, we present data on graduate students' actual experiences in dealing with impaired peers and faculty predictions of how students would deal with such situations. A total of 29 faculty and 73 graduate students responded to a survey of 40 randomly selected clinical psychology training programs. Student respondents were almost universally (95%) aware of peers whom they regarded as impaired in their professional functioning, and half (49%) the sample reported being aware of a peer's ethical impropriety. Faculty overestimated (...) the number of students who said they "did nothing" when confronted with the resulting ethical dilemma and underestimated the degree of conflict and turmoil (i.e., anger, frustration, dismay) that students reported experiencing. Faculty also estimated that students would be more concerned with peer loyalty issues, whereas students indicated that they were strongly motivated by ethical considerations. Ethics curricula ought more thoroughly to address affective concerns through experiential learning vehicles such as faculty modeling, simulation exercises, and small-group discussion. (shrink)

Silencing of tumor suppressor genes (TSGs), by DNA methylation, is well known in adult cancers. However, based on the “stem cell” theory of tumorigenesis, the early epigenetic events arising in malignant precursors remain unknown. A recent report1 demonstrates that, while pluripotent embryonic stem cells lack DNA methylation and possess a “bivalent” pattern of activating and repressive histone marks in numerous TSGs, analogous multipotent malignant cells derived from germ cell tumors (embryonic carcinoma cells) gain additional silencing modifications to those same genes. (...) These results suggest a possible mechanism by which aberrant differentiation, mediated by histone and DNA methylation, instigates tumor progression. BioEssays 29:842–845, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

Graphical AbstractScience and technology consortia provide a viable solution for the recent unsustainable academic growth in biomedical research.

Extinction deeply colors the way we think about conservation and the role of humans in nature. It is easy to overlook how recently, in fact, it has entered our consciousness. Only in the last two centuries has science sought to critically study life's origins, development, and diversification. Only in the last several generations have we identified and calibrated life's five major extinction events and speculated on their causes and effects. And only in recent decades have we come to appreciate the (...) still‐unfolding fate of life's diversity under the increasing influence of humanity. The story of extinction has continually changed as this monumental process of interdisciplinary synthesis and imagination has unfolded. Geology, paleontology, taxonomy, biogeography, and evolutionary biology have allowed us to comprehend the deep temporal and broad spatial dynamics of the extinction story. Archaeology, cultural anthropology, and environmental and economic history have illuminated the role of humans in altering the trajectory of species, landscapes, and ecosystems over the millennia. Ecology, genetics, population biology, and conservation biology have revealed the more recent patterns in life's vulnerability and resilience. As a phenomenon, extinction is as old as life itself. As a story shaping our consciousness, values, and intentions, it is still new. And it is uncomfortable. (shrink)

Increasing societal concerns regarding the potential deleterious effects of future climate change have galvanized efforts to manage the problem both through reduction of greenhouse gases and through development of plans to reduce the impacts of climate change that cannot be avoided. These critical activities require making decisions under conditions of considerable uncertainty regarding future conditions in physical and human systems. As the focus on providing information about future climate for taking actions to cope with climate change, the science of uncertainty (...) of climate change will develop more and more with the needs of decision makers in mind. (shrink)

Die Autoren sind katholische Priester und stellen das christliche Menschenbild und die Ethik der Gesundheitssorge in den Mittelpunkt. Herausgearbeitet wird die ihrer Ansicht nach besondere ethische Verantwortung der Pflegekräfte in ihren Beziehungen zu Patienten, Angehörigen und Ärzten bei Fragen der Lebens- und Sterbehilfe.