Forward scatter target strength extraction in a marine environment (L)

A 48 m rail with a moving receiver was used to measure forward scattering from a spherical shell lying on the bottom in the Gulf of Mexico. The target was mid-way between the source and rail, on a line from the source bisecting the rail. The major obstacle to the measurement of forward scattering is the much stronger source signal which overlaps the scattered signal in space and time. Here, forward scattered target strength is obtained by processing the received signals using a wavenumber filter to remove the incident wave. The result compares favorably to that obtained from numerical predictions.

Structural-acoustic modeling for three-dimensional freefield and littoral environments with verification and validation

This paper describes a high-order, finite-element-based, three-dimensional time-harmonic model for large-scale exterior structural-acoustics problems. It is applicable to both freefield and littoral environments. For the freefield case, the infinite exterior is treated as a homogeneous linear acoustic medium. For littoral applications, the water or air and the sediment domains are each treated as linear homogeneous, semi-infinite half-spaces with piecewise-constant properties. Both domains admit complex-valued wave speeds to enable the inclusion of damping. The finite element formulation uses a variational statement which naturally incorporates the transmission-condition at the water or air-sediment interface. The truncation of the infinite exterior is realized using an infinite-element for the freefield case, and the perfectly-matched-layer approximation for littoral applications. Computation of the farfield quantities is done based on an integral representation which, for the littoral cases, uses efficient approximations for the appropriate Green's function. Numerical computations are presented for a series of progressively more complex problems, and are used to verify the model against analytic and other numerical solutions and validate it based on the experimental data for scattering from elastic scatterers as measured in freefield and sediment pool laboratory facilities.

Role of immunofluorescence microscopy in dermatology

This paper gives a survey about most of the dermatological and infectious cutaneous diseases in which immunofluorescence (IF) microscopy is an important, often decisive tool to reach diagnosis. In tabular form, bullous autoimmune disorders such as pemphigus and pemphigoid diseases, connective tissue diseases, vasculitides, mechanobullous disorders and cutaneous infectious agents and the respective IF findings are listed. Different IF methods and especially important aspects such as taking a biopsy at the right spot or how to send samples are described. Clinical pictures of a broad spectrum of cutaneous diseases are set in combination with the IF microscopic results and the value of special but still routine investigations such as the salt split skin test (SSST) or the antigen mapping (AM) method is demonstrated especially in a set of identical or atypical clinical pictures. Immunofluorescence microscopy has not lost it´s value and should be performed in each dermatological centre in the sense of "Do not miss a diagnosis by not performing IF!"

Exploiting forward scattering for detecting submerged proud/half-buried unexploded ordnance

Laboratory underwater bistatic scattering measurements are reported for free, proud, and half-buried unexploded ordnances for 0 degrees and 90 degrees source angles. Forward echoes are larger than backscattered returns, and half burial significantly decreases the latter but not the former. Results agree with analytic predictions borrowed from radar. The forward echo and source signal are separated by measurements made with and without the target, a method not possible in a target search. For this, a method is described that uses knowledge of the source location and the hyperbolic character in time-cross range of the signals received at points along a line.

Bistatic scattering from submerged unexploded ordnance lying on a sediment

The broadband bistatic target strengths (TSs) of two submerged unexploded ordnance (UXO) targets have been measured in the NRL sediment pool facility. The targets-a 5 in. rocket and a 155 mm projectile-were among the targets whose monostatic TSs were measured and reported previously by the authors. Bistatic TS measurements were made for 0 degrees (target front) and 90 degrees (target side) incident source directions, and include both backscattered and forward scattered echo angles over a complete 360 degrees with the targets placed proud of the sediment surface. For the two source angles used, each target exhibits two strong highlights: a backscattered specular-like echo and a forward scattered response. The TS levels of the former are shown to agree reasonably well with predictions, based on scattering from rigid disks and cylinders, while the levels of the latter with predictions from radar cross section models, based on simple geometric optics appropriately modified. The bistatic TS levels observed for the proud case provide comparable or higher levels of broadband TS relative to free-field monostatic measurements. It is concluded that access to bistatic echo information in operations aimed at detecting submerged UXO targets could provide an important capability.

[Acute alcohol intoxication in adolescents: preliminary results of a pilot project in Munich]

OBJECTIVE

To present preliminary results of a pilot project on the prevention of alcohol-associated problems in adolescents with acute alcohol intoxication.

METHOD

Questionnaires were filled in by 110 of 128 adolescents (85.9% response rate) who had been admitted to a hospital in Munich, Germany, between December 2007 and July 2008, because of alcohol intoxication. Data were obtained on sociodemographic characteristics, alcohol intoxication and drinking patterns, and were analysed using descriptive methods.

RESULTS

Half of these adolescents mainly suffered from moderate to severe degrees of alcohol intoxication. Drinking patterns leading to alcohol intoxication were characterized by relatively low drinking frequency interspersed by episodes of excessive alcohol intake (binge drinking). Thirteen (14.8%) of the adolescents reported previous hospital admissions for alcohol intoxication, nine (17.3%) did not know about the life-threatening danger of alcohol intoxication and twelve (22.2%) reported taking illegal drugs within the last 12 months.

CONCLUSION

Adolescents who had been admitted to hospital because of alcohol intoxication had a drinking pattern which put them at a higher risk for alcohol intoxication and acute alcohol-related problems than adolescents in the general population. Re-admission to hospital within 12 months because of alcohol intoxication, revealing a lack of knowledge about the life-threatening danger of alcohol intoxications and of consuming illegal drugs, may indicate an increased risk for alcohol-related problems. This points to the need for preventive action in adolescents showing these indicators, a need that was met within this pilot project by brief intervention.

Broadband acoustic scattering measurements of underwater unexploded ordnance (UXO)

In order to evaluate the potential for detection and identification of underwater unexploded ordnance (UXO) by exploiting their structural acoustic response, we carried out broadband monostatic scattering measurements over a full 360 degrees on UXO's (two mortar rounds, an artillery shell, and a rocket warhead) and false targets (a cinder block and a large rock). The measurement band, 1-140 kHz, includes a low frequency structural acoustics region in which the wavelengths are comparable to or larger than the target characteristic dimensions. In general, there are aspects that provide relatively high target strength levels ( approximately -10 to -15 dB), and from our experience the targets should be detectable in this structural acoustics band in most acoustic environments. The rigid body scattering was also calculated for one UXO in order to highlight the measured scattering features involving elastic responses. The broadband scattering data should be able to support feature-based separation of UXO versus false targets and identification of various classes of UXO as well.

Cesium uptake from aqueous solutions by bentonite: a comparison of multicomponent sorption with ion-exchange models

The removal of cesium from concentrated aqueous solutions into Ca/Mg-bentonite for a wide range of bentonite-to-water (m/V) ratios was studied experimentally and theoretically. Using the batch technique, the equilibrium of Cs uptake was measured. The nonlinear character of cesium sorption substantially influenced by the m/V ratio was observed. The experimental data were evaluated using the multicomponent Langmuir isotherm and an ion-exchange model based on the ion-exchange reaction between Cs+ and M2+ (Ca2+/Mg2+) initially sorbed on bentonite. Constants k1,Cs = 0.521 mmol.g-1, k2,Cs = 968 L.mol-1, and k2,M = 592 L.mol-1 were obtained for Cs uptake described by multicomponent Langmuir isotherm. For the ion-exchange model, the thermodynamic equilibrium constant K = 75.5 mL.g-1 with a standard deviation of sK = 17.4 mL.g-1 was determined. Using the t test, the calculated data of multicomponent Langmuir and ion-exchange isotherms were fit to experimental data, and the best agreement was obtained for the ion-exchange model. The results show that Cs uptake by bentonite could be substantially decreased in systems with a high bentonite-to-water (m/V) ratio as a consequence of the presence of desorbed divalent cations in the liquid phase.

[Psychosocial stress preceding drug-related deaths]

This article analyses drug-related deaths in the German Federal States of Bavaria (Munich, Nuremberg and Augsburg counties) during 1999 and Baden-Wurttemberg (Stuttgart and Mannheim counties) during 1999 and in the first half of 2000. The persons who had been in contact with drug care services were studied for psychosocial stress preceding drug-related deaths. Epidemiological data from different sources (police, relatives, counselling centres, detoxification clinics, therapy and substitution treatment) were collated to estimate factors of psychosocial stress preceding drug deaths. The results in both Laender indicate high prevalence rates of a history of at least one non-fatal overdose (approx. 50%) or a suicide attempt (approx. 35%). More than 40% of the deceased had been suffering from at least one additional mental disorder, in most cases from depression. At least one critical life event (in most cases, a relapse) or a period of abstinence (i.e., due to imprisonment, therapy or detoxification) during the past three months before death was reported for more than half of the addicts. The results were discussed in the light of data on opiate users and the general population. Improved specialist training of therapeutic and medical workers as well as of any other co-operating professionals is considered a necessary prerequisite for an early detection of risk factors.