Feasibility of ultrasound hyperthermia in the treatment of malignant brain tumors

In order to test the biological feasibility of using ultrasound-generated hyperthermia for the treatment of brain tumors, damage threshold studied and thermal dosimetry studies as a function of temperature were performed in 44 acute experiments in cats. Bilateral craniotomies were performed to expose the dural surface. Ultrasonic radiation was applied for 50 minutes at different intensities to generate temperatures up to 48 degrees C. Thermal fields were mapped using an electrode array of three triple-junction thermocouple probes. Each probe left a track easily identified histologically. Serial sections of each brain were cut and stained, allowing for precise correlation of histology and thermocouple location and temperature. At temperatures of less than 42 degrees C for 50 minutes, no evidence of damage could be detected in either gray or white matter. At 43 degrees C partial loss of neurons was seen in the brain adjacent to the probe, but at the same temperature in white matter, only edema was seen. At temperatures of 44-45 degrees C there was definite loss of both neurons in the gray matter and myelin tracts in the white matter. The lesions created by using ultrasound-generated hyperthermia were sharply marginated. This sharp demarcation histologically correlated well with the abrupt fall off in temperature as a function of distance from the lesion edge. The results of this study are important in two respects. First, it demonstrates that ultrasound can effectively heat the brain in an extremely controlled and precise manner. Second, the brain can withstand temperatures to 42 degrees C without showing histological evidence of damage, which is the temperature range at which neoplastic cells begin to show cytotoxic effects.     

A tapered undulator experiment at the ELBE far infrared hybrid-resonator oscillator free electron laser

A tapered undulator experiment was carried out at the ELBE far-infrared free electron laser (FEL). The oscillator FEL makes use of a hybrid optical resonator. The main motivation was to see whether the presence of a dispersive medium in the form of a waveguide in the resonator has any effect on the outcome. The FEL saturated power and the wavelength shifts have been measured as a function of both positive as well as negative undulator field amplitude tapering. In contrast to the typical high-gain FELs where positive tapering proves beneficial for the output power we observed an improvement of performance at negative taper. During the same experiments we studied the characteristics of the detuning curves. The width of the curves indicates a maximum small signal gain for zero taper while the output peak power increases with negative taper. The saturated power output, the detuning curve characteristics, and the wavelength shifts agrees with the theoretical predictions. Details of the experiment are presented.     

Effective Key Management Protocol for Extremely Self-Motivated Environment

ABSTRACT

Ad hoc networks provide solutions to a variety of deployed applications by creating networks on-the-fly. Key management is a significant issue for adequate security. To ensure secure group communication, keys need to be changed whenever the group changes. The highly dynamic nature of ad hoc networks makes this task challenging. The major problems for key management techniques to group applications are inefficiency and out-of-synchronization. The proposed cluster-based batch re-keying has a significant effect to unravel these problems.     

Toward a psychoanalytic understanding of multiple personality disorder

The author suggests a developmental psychoanalytic frame from which to understand the clinical phenomenology of multiple personality disorder (MPD). Annihilation anxiety and fears of nonbeing are understood as central; they are seen as resulting from actual early traumatic impingements at key developmental periods. Alter "personalities" are conceptualized as functional delusional processes that serve to maintain self-cohesion. The alters are brought about through the subject's lack of capacity for illusion. Some therapeutic implications regarding a psychoanalytic stance are discussed.     

Immature teratoma of the ovary with a neural component ("solid" teratoma). A clinicopathologic study of 20 cases

Twenty cases of immature teratoma of the ovary with a neural component are analyzed. A plea is made for use of the nomenclature adopted from the new World Health Organization classification of ovarian tumors, the past confusion over terminology and histogenesis of this rare tumor is discussed. All the primary tumors in the present series contained at least some immature tissues (predominantly of neural origin) and were thus graded from 1 to 3 according to the criteria of Thurlbeck and Scully. No grade 0 tumors ("benign solid teratomas") were identified. We believe that thorough sectioning almost always insures the identification of immature elements. The prognosis was closely related to the histologic grade, but correlated poorly withthe clinical stage, the latter being influenced by the common finding (25 per cent of the cases in this series) of peritoneal implants composed exclusively of mature glial tissue, which is associated with a benign clinical evolution. This phenomenon of maturation or differentiation appears to be the rule rather than the exception in this tumor, since implants are usually of better or equal differentiation when compared with their primary tumors and older patients tend to have lower grade tumors than younger patients. Since the majority of patients with this tumor are young, primary surgical therapy should be conservative, unilateral salpingooophorectomy often being sufficient. Spontaneous or operative rupture of the tumor capsule carries an increased risk of subsequent dissemination. We have noted impressive clinical responses in patients with disseminated tumors of a high histologic grade after treatment with triple chemotherapy (vincristine, actinomycin D, and cyclophosphamide) but do not recommend adjuvant therapy in patients with only grade 0 implants.     

Hydrophobic nano-carrier for lysozyme adsorption

In this work, poly(HEMA–APH) nanoparticles were synthesized by surfactant-free emulsion polymerization technique. Magnetic behaviour was introduced by simple addition of Fe₃O₄ into the polymerization medium. Characterization of the nanoparticle was carried out by FTIR, ESR, SEM, AFM and EDX analyses. These synthesized magnetic nanoparticles were used for adsorption of lysozyme. For this purpose, adsorption conditions were optimized and maximum lysozyme binding capacity was found to be 278.8 mg g^?1 polymer in pH 7.0 phosphate buffer at 25^°C. Desorption and reusability properties of the nanoparticles were investigated and lysozyme adsorption efficiency did not change significantly at the end of the 10 successive reuses.     

Cognitions in generalized anxiety disorder and panic disorder patients

Forty-three patients with generalized anxiety disorder (GAD) and 44 patients with panic disorder (PD) were given a standardized interview about thoughts and images during times of anxiety. The two groups differed significantly regarding the ideational content of anxiety. GAD patients experienced more thoughts focusing on themes of mental catastrophes and other catastrophes when suffering from anxiety or anxiety attacks, while PD patients mostly described the theme of physical catastrophes. Only 34% (n = 30) of the total sample reported experiencing images when feeling anxious/having panic. For PD patients (70%) onset of anxiety or panic attacks was precipitated by somatic symptoms (a physical feeling). GAD patients reported that onset of anxiety was precipitated by all three alternatives given: a physical feeling (42%), anxious thoughts (37%), or "it all came at once" (21%). The implications of these results are discussed.     

Performance metrics for windows used in real-time DFT-basedmultiple-tone frequency excision

The capability of direct-sequence spread-spectrum receivers to reject narrowband interference can be significantly improved by eliminating narrowband energy in the received signal through a real-time discrete Fourier transform (RT-DFT) process. However, the loss in received signal strength due to this frequency excision process can be significant. In this paper, we present a theoretical framework for evaluating the performance of alternative combinations of time weighting functions (windows), fractions of overlap in overlap-and-add architectures, and frequency-domain mapping algorithms. The sensitivity loss due to time weighting is presented for variable overlaps and several different windows. A set of window metrics is defined that provides a means of calculating distortion losses for an arbitrary number of interfering tones with uniformly distributed center frequencies. Theoretical results are confirmed by simulation. These results can be used to compare sensitivities of alternative RT-DFT frequency excision direct-sequence spread-spectrum systems and to calculate the standoff range of a finite number of in-band tone emitters