Long distance propagation of a polarized neutron beam in zero magnetic field

A beam of fully polarized cold neutrons was transported through a zero magnetic field region of 70 m length without loss of polarization. The purpose of this exercise was twofold: firstly, to demonstrate that the new zero-field neutron spin-echo method will work also for very long neutron flight paths; secondly, to prove in the most direct way that the neutron free-flight region of the ILL neutron-antineutron oscillation experiment was indeed sufficiently field-free (“quasifree condition”) by using the neutrons themselves as a magnetometer. To this purpose the residual magnetic field integrals in the long “zero-field” region were measured with a conventional neutron spin-echo method. The overall spin precession angle of the neutrons during their flight through the long zero-field region was found to be less than 2°.     

Failure analysis of a hot extrusion die used for Al-Li alloy processing

Al-Li alloys being developed as lighter, substitutes for conventional high strength Al alloys are to be processed by routine methods. During extrusion of a 8090 Al-Li alloy, the extrusion die container failed causing some alarm. This failed die container was analysed to examine if the failure was caused by interaction of Li diffusing out of Al-Li alloy with the carbides of die steel. The evidence, although not conclusive, is sufficient to exercise caution during such processing.     

Effects of a Nd—Fe—B magnetic filler on the crystallization of poly(phenylene sulfide)

The crystallization of poly(phenylene sulfide) (PPS) in a polymer–magnetic Nd—Fe—B powder suspension was studied. Isothermal crystallization behavior was analyzed by way of differential scanning calorimetry, and the kinetics were described via the Avrami equation. The Avrami parameters and the crystallization times were strongly affected by both the particle size and the presence of a coupling agent coated on the filler particles. The small Nd—Fe—B particles exhibited long induction and half‐times, whereas the large particles tended to have short crystallization times. Particles ranging from 38 to 150 μ appeared to have similar crystallization times and to have no significant change in the value of Avrami index with melt crystallization temperature. As a result of these analyses, the dynamic mechanical properties were determined to correlate the fundamental polymer crystallization characteristics and the physical properties of the PPS binder. The enhancement of the wetting of the filler to the binder was promoted through the coupling agent, as confirmed by dynamic mechanical testing performed on the samples. The storage modulus typically decreased because of the presence of the uncoated small particles. Conversely, the loss modulus was enhanced because of the presence of the coated small particles in the PPS binder. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1091–1102, 2002     

Multidimensional augmented current equation including velocityovershoot

The augmented drift-diffusion current equation, which includes velocity overshoot effects through the space derivatives of the electric field, cannot be directly extended beyond one dimension. A new formalism is developed which considers the carrier heating and the distribution relaxation effects to obtain a multidimensional augmented drift diffusion current equation. The equivalent mobility containing the velocity overshoot correction is derived from the perturbation analysis on the carrier temperature using the energy balance equation. The issues related to the numerical implementation of this generalized model and the validity of the assumptions are also discussed     

Diagnostic and prognostic relevance of malignancy-associated changes in cervical smears

OBJECTIVE: For approximately 15 years, malignancy-associated changes (MACs) have been consistently found by means of high-resolution cytometry in different tissues, especially in visually normal appearing cervical cells. Their biologic nature is not yet fully understood. The aim of this investigation was to assess the expression of MACs in cervical smears and to evaluate their prognostic relevance. STUDY DESIGN: This study was performed on normal intermediate cells obtained from 53 cytologically positive and 78 cytologically negative cervical smears. From a second sample, 31 cases showing negative cytology were selected for a prospective longitudinal study. Densitometric and texture features were generated, and MACs were described on the basis of multivariate discriminant analysis. RESULTS: Discrimination between positive and negative cases was possible, with a correct classification rate of approximately 80%. After a mean period of 29.5 months, we noted no statistically significant increase in the incidence of cervical intraepithelial neoplasia in the group of healthy but MAC-positive women as compared to those who were MAC negative. CONCLUSION: MACs were constantly expressed in the epithelium of the cervix. Although their prognostic relevance remains unclear, MACs play an important role in the effort to automate cervical cytology.     

Mikrotechnik für Raumfahrtanwendungen

This contribution describes the preparation, based upon a chemically amplified novolak resist (CAR), electron beam lithography, and ECR plasma etching, of structures with a high aspect ratio (10∶1) and lateral dimensions in the sub-micrometer range (150nm–300nm) which may serve as collector surfaces for sub-μm dust particles in a space experiment.     

Radiation characteristics of an infinite dielectric-coated axiallyslotted cylindrical antenna partly embedded in a ground plane

The radiation characteristics of an axial slot on a dielectric-coated conducting circular cylinder embedded in a semi-circle in an infinite ground plane (GP) are examined. The boundary-value method is employed to obtain the solution with the aid of the partial orthogonality of the trigonometric functions. The resulting dual infinite series involved in the solution is then truncated to generate numerical results. The geometry considered here is important because it can be implemented on the body of any mobile communication system. Moreover the GP adds a new parameter to the slotted dielectric-coated conducting circular cylindrical antenna and can be used in beam shaping and to enhance the antenna performance     

Surveillance after colorectal cancer surgery

Early diagnosis of local and distant recurrences of colorectal cancer remains difficult and there is no agreement on the effectiveness of follow-up in these patients. The aim of this study is to assess the value of our method of follow-up. We consider 239 patients with colorectal cancer and at least 2 years follow-up following radical resection. A local recurrence appeared in 26 patients (10.9%), a distant metastasis in 41 (17.1%), while in seven (2.9%) local and distant recurrences appeared simultaneously. Local recurrence was detected because of an increase in carcinoembryonic antigen (CEA) level in 15 patients (57.7%), during a scheduled endoscopy in four (15.4%) and because of symptoms in seven (26.9%). In seven patients (26.9%) a radical resection was possible. Distant metastases were detected by CEA levels in 20 patients (48.8%), by ultrasonography (U.S.) in 12 (29.3%) and by chest X-ray in five (12.2%). In 13 of 26 patients with liver metastases a resection was performed. This study shows that few patients benefit from follow-up and only CEA levels and liver U.S. performed intensively between 15 and 36 months after surgery are useful in early detection of recurrences. A modification of the follow-up to the single patient, according to the stage, location and grading of cancer, could improve the results, so lowering the costs of this expensive practice.     

Beugung am Kegel elliptischen Querschnitts und die Sommerfeldsche Lösung des Halbebenenproblems

Übersicht In dieser Arbeit wird die Beugung am Kegel elliptischen Querschnitts behandelt. Wir leiten zwei Greensche Funktionen ab, die der Dirichlet- bzw. der Neumann-Bedingung auf dem Kegel genügen und die Ausstrahlungsbedingung erfüllen. Das Randwertproblem wird zurückgeführt auf die Lösung eines zweiparametrigen Eigenwertproblems mit zwei gekoppelten Laméschen Differentialgleichungen. Wir analysieren insbesondere die Beugung einer ebenen Welle an der sektorförmigen Fläche. Im Grenzfall eines Sektoröffnungswinkels von 180° gehen die Reihenentwicklungen unter Zuhilfenahme eines speziellen Gegenbauerschen Additionstheorems und einer erzeugenden Funktion für Besselfunktionen mit ganzzahligem und halbzahligem Index über in die Sommerfeldsche Lösung des Halbebenenproblems.

---

Diffraction by an elliptic cone and Sommerfeld's half-plane solution

Contents In this article we examine the diffraction by an elliptic cone. We derive two Green's functions satisfying the Dirichlet-resp. Neumann-condition on the boundary of the cone. The boundary value problem is reduced to a two-parametric eigenvalue problem with two coupled Lamé equations. We analyse the diffraction of a plane wave by a plane angular sector. In the limiting case of a sector angle of 180° the series expansions pass — using a special form of Gegenbauer's addition theorem and the generating function for Bessel functions with integral and half-integral indices — into Sommerfeld's half-plane solution.