Environmental Impact on the Southeast Limb of the Cygnus Loop

We analyze observations from the Chandra X-ray Observatory of the southeast knot of the Cygnus Loop supernova remnant. In this region, the blast wave propagates through an inhomogeneous environment. Extrinsic differences and subsequent multiple projections along the line of sight rather than intrinsic shock variations, such as fluid instabilities, account for the apparent complexity of the images. Interactions between the supernova blast wave and density enhancements of a large interstellar cloud can produce the morphological and spectral characteristics. Most of the X-ray flux arises in such interactions, not in the diffuse interior of the supernova remnant. Additional observations at optical and radio wavelengths support this account of the existing interstellar medium and its role in shaping the Cygnus Loop, and they demonstrate that the southeast knot is not a small cloud that the blast wave has engulfed. These data are consistent with rapid equilibration of electron and ion temperatures behind the shock front, and the current blast wave velocity v_{bw} approx 330 km/s. Most of this area does not show strong evidence for non-equilibrium ionization conditions, which may be a consequence of the high densities of the bright emission regions.Comment: To appear in ApJ, April 1, 200

Somatic symptom disorder in dermatology

Somatic symptom disorder (SSD) is defined by the prominence of somatic symptoms associated with abnormal thoughts, feelings, and behaviors related to the symptoms, resulting in significant distress and impairment. Individuals with these disorders are more commonly encountered in primary care and other medical settings, including dermatology practice, than in psychiatric and other mental health settings. What defines the thoughts, feelings, and behaviors as abnormal is that they are excessive, that is, out of proportion to other patients with similar somatic symptoms, and that they result in significant distress and impairment. SSD may occur with or without the presence of a diagnosable dermatologic disorder. When a dermatologic disorder is present, SSD should be considered when the patient is worrying too much about his or her skin, spending too much time and energy on it, and especially if the patient complains of many nondermatologic symptoms in addition. The differential diagnosis includes other psychiatric disorders, including depression, anxiety disorders, delusions of parasitosis, and body dysmorphic disorder

Island biogeography in Southeastern Wisconsin: a progress report.

Ecosystems develop as a result of interactions between the biotic and abiotic components in the environment. Natural systems are diverse and stable when interactions between the community and the supersystem are in balance. Change or perturbation in the supersystem will effect a commensurate change in the natural subsystems. Urbanization results in the remaining natural systems becoming isolated within the urban system-a supersystem quite unlike that which gave rise to the natural system. As a result, the natural subsystem must change in the way in which it interacts with its new supersystem to reach equilibrium. A mechanism for such change in natural systems is succession. Successional patterns as a result of urban influences may be quite different than those expected under natural conditions. In order to evaluate these successional patterns, it is necessary to first assess the forest biotic communities when they are embedded and isolated from each other in a non-forest matrix. Crowell (1975) and others, point out that any discontinuous habitat becomes an island. In this context, isolated forested woodlots, embedded in the agro-urban matrix, are islands. This study attempts to explain how these forest islands function as a regional forest ecosystem. It will also examine the effects of urbanization on these wildland island communities

Cold air drainage: a field experiment

The following descriptions of a 24-hour cycle of the flows of radiant energy in November 1974 were written as follow-up assignments to a class exercise measuring these energy flows at the Field Station (Meteorology 511 - Dynamic Meteorology I: Radiation). All the flows of short-wave (or solar) radiation (wave length less than 3 micrometers) and long-wave radiation (wave lengths 3 to 50 micrometers) were measured, and their interrelations calculated

Vegetation forest island edges: A preliminary report

As the original native forest has been dissected by roads and replaced by farms or towns, the amount of forest edge relative to the area of forest interior has greatly increased. Today forest edge communities are widespread in many man-modified landscapes. However, the role the edge community plays in the regional landscape, and the extent of and variation in the edge community are relatively undefined. The purpose of this study is to determine the nature of forest edge communities. The specific objectives of the study are to: (1) quantitatively survey and assess the forest edge community; (2) determine how forest edge vegetation differs from that of the forest interior; (3) determine if the directional aspect affects the edge vegetation and (4) present guidelines and suggestions for the management of forest habitat islands, particularly as they relate to the edge community

Soil monolith construction: a practical teaching experience for field and lab

Soil formation, structures and differences are difficult to visualize or understand without being able to experience them. Most of us are familiar with the soil profiles (soil sequum) on display in many Soil Conservation Service or County Extension Service offices. Whether an ecologist, engineer, or home gardener, we have all examined the intricate structures, features and horizon development. The objective of this paper is to describe a technique to construct such soil monoliths for classroom use with minimal expense

Shocking Clouds in the Cygnus Loop

With Hubble Space Telescope Wide-Field Planetary Camera 2 observations of the Cygnus Loop supernova remnant, we examine the interaction of an interstellar cloud with the blast wave on physical scales of 10^15 cm. The shock front is distorted, revealing both edge-on and face-on views of filaments and diffuse emission, similar to those observed on larger scales at lower resolution. We identify individual shocks in the cloud of density n~15 cm^-3 having velocity v_s~170 km/s. We also find the morphologically unusual diffuse Balmer-dominated emission of faster shocks in a lower-density region. The obstacle diffracts these shocks, so they propagate at oblique angles with respect to the primary blast wave. The intricate network of diffuse and filamentary H alpha emission arises during the early stage of interaction between the cloud and blast wave, demonstrating that complex shock propagation and emission morphology occur before the onset of instabilities that destroy clouds completely.Comment: 7 pages including 5 figures; 1 color figure; to appear in the ApJ, Oct. 10, 2001; full-resolution figures available at http://www.pha.jhu.edu/~levenson/preprints/cyglhst.p

Landscape patterns and forest island interactions

On March 18, the Field Station welcomed faculty and graduate students involved in the Landscape Pattern Analysis project. This study has both theoretical and practical objectives. The theoretical problems are concerned with island biogeography as outlined by Robert MacArthur and E. O. Wilson were discussed in the Spring 1975 Field Station Bulletin. These questions relate principally to how island size and distance from neighboring islands affect species composition and extinction, i.e., affect the diversity of island communities. These theoretical questions are being approached in a series of studies undertaken jointly by scientists at the Oak Ridge National Laboratory, Rutgers University, The University of Wisconsin-Milwaukee and the University of Wisconsin-Madison

Delayed Onset and Prolonged ECT-Related Delirium

Electroconvulsive therapy (ECT) is effective in the treatment of depression. Delayed post-ECT delirium is rare but can occur in a small subset of patients with risk factors and in most cases resolves with the use of psychotropic medications. We report a unique presentation of a patient who developed a delayed post-ECT delirium with fecal incontinence that commenced 24 hours after the administration of ECT. The condition resolved spontaneously after 48 hours without the use of psychotropic medications