RF properties of a X-band hybrid photoinjector

An INFN-LNF/UCLA/SAPIENZA collaboration is developing a hybrid photoinjector in X-band. A hybrid photoinjector is a novel high brightness electron source that couples a standing wave cell cavity (acting as an RF gun) directly to a multi-cell travelling-wave structure. This configuration offers a number of advantages over the split standing wave/travelling-wave system. Most notably the reflected RF transient is almost completely suppressed, thus eliminating the need for a circulator and the bunch lengthening effect that occurs in the drift section of the split system. These properties allow scaling of the device to higher field and frequencies, which should dramatically improve beam brightness. The RF coupling between the standing and the traveling wave sections is accomplished in the fourth cell encountered by the beam, with the SW section electrically coupled to it on-axis. This mode of coupling is particularly advantageous, as it is accompanied by a 90° phase shift in the accelerating field, resulting in strong velocity bunching effects on the beam that reverse the usual bunch lengthening induced after the gun exit in standard 1.6 cell photoinjectors. In this scenario, from the beam dynamics point of view, it is seen that device may produce ten's of femtosecond beams at ∼3.5 MeV and the emittance compensation dynamics remains manageable even in the presence of strong compression. We present here a survey of the device characteristics. In particular we show the results of the electromagnetic simulations, a beam dynamics analysis related to the temperature tuning of the SW and TW section, and a RF characterization using bead pull and scattering coefficient measurements of a device prototype.     

Fluorescence-based zinc ion sensor for zinc ion release from pancreatic cells

In this paper, we describe the synthesis and characterization of analytical properties of fluorescence-based zinc ion-sensing glass slides and their application in monitoring zinc ion release from beta pancreatic cells in cell cultures. To fabricate the sensors, the zinc ion indicator ZnAF-2 {6-[N-[N',N'-bis(2-pyridinylmethyl)-2-aminoethyl]amino-3',6'-dihydroxyspiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one} was modified to include a sufficiently long linking aliphatic chain with a terminal carboxyl functional group. The recently synthesized ZnAF-2 zinc ion indicator provided high zinc ion selectivity in physiological solutions containing millimolar levels of calcium and other possible interfering cations. The carboxyl-modified ZnAF-2 was conjugated to the activated surface of glass slides, which then served as zinc ion sensors. It was possible to grow pancreatic cells directly on the zinc-sensing glass slide or on a membrane placed on these glass slides. The sensors were used to monitor zinc ion release events from glucose-stimulated pancreatic cells. The study showed that the zinc ion sensors responded effectively to the release of zinc ions from pancreatic cells at the nanomolar level with high selectivity and rapid subsecond response time.     

InP DHBT-based distributed amplifier for 100 Gbit/s modulator driver operation

A distributed amplifier for use as a modulator driver in next generation optical data communication systems has been manufactured using InP double-hetero bipolar transistor (DHBT) technology with an emitter size of 0.7 times 1 mum². The amplifier achieved a gain of 21 dB and a 3 dB bandwidth of 120 GHz, resulting in a gain-bandwidth product of 1.35 THz. Clearly open 100 Gbit/s 231/1 non-return-to-zero pseudorandom bit sequence (NRZ PRBS) eye diagrams with an output voltage swing of 2.3 V have been measured.     

Role of the stress-activated protein kinases in endothelin-induced cardiomyocyte hypertrophy

3-beta-Hydroxysteroid dehydrogenase (3-beta-HSD) activity coded for by the A44L gene of vaccinia virus (VV) was demonstrated in CV-1 cultures infected by all five VV strains tested, viz. WR, Praha virus, DRYVAX Wyeth-derived virus (DD), LIVP and MVA. Deletion of the A44L gene in two Praha virus-derived clones (the moderately virulent P13 and the highly attenuated P20), the WR and DD viruses resulted in absence of 3-beta-HSD activity from infected cultures. The virulence for mice of P13 was not affected, and that of WR was only slightly decreased, by the A44L gene deletion. Recombinant VVs expressing either varicella-zoster virus glycoprotein E (VZV-gE) or hepatitis B virus preS2-S protein (HBV-preS2-S) and their respective A44L deleted mutants were used in immunogenicity tests in mice. In terms of antibody response to VV and the recombinant proteins, the deletion resulted in a lowering the immunogenicity in the moderately virulent clone P13 virus and its progenies. In the highly attenuated P20 and DD viruses and their progenies no effects were apparent.     

Wavelength tuning of high-speed InGaAs-GaAs-AlGaAs pseudomorphicMQW lasers via impurity-free interdiffusion

The impurity-free interdiffusion technique has been utilized to modify the operating wavelength of high-speed In_0.3Ga_0.65As-GaAs multiple quantum well lasers. Modulation bandwidths of up to 26 GHz (I_bias=50 mA) and modulation current efficiency factors of 5 GHz/mA^1/2 are demonstrated for 3×100 μm² ridge waveguide lasers following wavelength shifts of 32 nm (34 meV). These results demonstrate the feasibility of fabricating monolithic multiple wavelength laser arrays in which each element is capable of low-bias-current direct modulation at bandwidths exceeding 20 GHz     

Environmental complexity, cerebral change, and behavior.

The overall program relating brain processes to behavior in animals concerns both hereditary and environmental factors that have been demonstrated to affect learning ability. Rats subjected to an enriched environment (involving environmental complexity and training) "consistently develop greater weight of cerebral cortex than do their impoverished littermates… [and] the cortical/subcortical weight ratio is consistently greater for the enriched than for the restricted rats… ." The average diameter of capillaries in the cortex is greater in enriched than in impoverished animals. The total activity of acetylcholinesterase is found to increase slightly but consistently in the enriched animals. (23 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reflections on APA divisional structure.

Discusses the divisional structure of the American Psychological Association (APA) and argues that endless numbers of divisions could be created. A revised structure would consist of basic divisions that would be relatively permanent and ad hoc divisions that would be created for a short period and would reflect current, possibly transitory, interests. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cerebral changes in rats exposed individually to an enriched environment.

Gave 275 male Berkeley S1 rats injections of saline or 2mg/kg of methamphetamine. Ss either remained in the home cage or were placed individually into an enriched environment for 2 hr/day during the light or dark hours. Ss placed singly in large enriched-environment cages over a 30-day period were different from home-cage control littermates in weights of brain sections and in brain-enzyme activities. These differences were small, however, unless S's interaction with the stimulus objects was facilitated. Such priming was accomplished by placement in the dark under the influence of methamphetamine. It is concluded that social stimulation, which previously has always been included in the enriched condition, is unnecessary. (25 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prospective sexual behavior.

Discusses W. B. Miller's (see record 1984-17604-001) use of the term "proceptive" in his analysis of reproductive freedom. It is argued that the continuum from contraceptive to proceptive forms only one part of the complex spectrum of human sexual behavior and that, because much of modern human sexuality deliberately avoids conception and reproduction, it is essential to consider the continuum from "conceptive" to "extraceptive" as well. It is suggested that most people will probably exercise some degree of proceptive sex choice as to their offspring when that choice does not require surgical procedures like amniocentesis and when the effectuation does not demand abortion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Idiodynamics vis-à-vis psychology.

Questions the adequacy of the distinction between the nomothetic and idiographic approaches to personality introduced by G. W. Allport (1937) and proposes 3 types of explanatory but complementary norms instead: nomothetic, demographic, and idiodynamic. Idiographic (trait-oriented) and idiodynamic (event-oriented) approaches are differentiated. It is shown that over the past century, psychology, operationally considered, has been a coordinate composite of the other major sciences. Idiodynamics, focusing on the experiential events of a particular personality (idioverse), is at the center of this coordinate gamut. It is proposed that the norms in conjunction with the coordinates be reassembled to conceptualize the parameters of the idioverse. It is suggested that the organic, cultural, and idiodynamic milieus blend through a matrix that produces experiential uniqueness. Three empirical methods for exploring this idioverse are described, including the reciprocity of experimenter–experimentee interaction, self-generated measures for evaluating cognate responses of the same idioverse, and the hermeneutic analysis of 3 levels of communication. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)