Low-Amplitude-Noise Laser for AURIGA Detector Optical Readout

We implemented a laser system to be used in an optical transduction chain for the gravitational-wave bar detector AURIGA (Antenna Ultracriogenica Risonante per l'Indagine Gravitazionale Astronomica; Ultracryogenic Resonant Antenna for Astronomical Gravitational Investigation). This system is based on a Nd:YAG laser and includes quantum-limited power stabilization in the acoustic range, deep phase modulation and near-quantum-limited rf detection for locking onto optical cavities, and coupling to a single-mode polarization-maintaining optical fiber without deterioration of performance. Such a system has wide applications in optical metrology.     

A new cacospongionolide inhibitor of human secretory phospholipase A2 from the Tyrrhenian sponge Fasciospongia cavernosa and absolute configuration of cacospongionolides

A new inhibitor of human secretory phospholipase A2 (PLA2), cacospongionolide E (4a), has been isolated from the Tyrrhenian sponge Fasciospongia cavernosa. The structure was proposed on the basis of spectroscopic data and by chemical transformations. The absolute configuration of cacospongionolides 2a-4a was established using the modified Mosher's method. Cacospongionolide E was the most potent inhibitor toward human synovial PLA2, showing higher potency than the reference compound manoalide and exerting no signs of toxicity on human neutrophils. It showed high activity in the Artemia salina bioassay and moderate toxicity in the fish (Gambusia affinis) lethality assay.     

Deformation and fracture of cork in tension

Various properties related to the deformation and fracture of cork in tension were experimentally determined, including the Young's modulus, the stress and strain at fracture and the fracture toughnessK _Ic. The transverse isotropy of cork implies that there are three independent systems of mode I crack propagation andK _Ic was measured for each. The mechanisms of deformation and fracture were identified by SEM microscope observation ofin situ deformation and of the fracture surfaces and crack paths. Two fundamental mechanisms of fracture occur: crack propagation along the lateral cell walls in non-radial tension, withK _Ic = 94±16 kPam^1/2 and crack propagation by breaking the cell walls in radial tension withK _Ic=125±14 kPam^1/2. In radial tension, local fractures that do not propagate due to crack stopping were observed which lead to serrations in the tensile curves for that direction. The strain to fracture in this direction is considerably larger than in the perpendicular (non-radial) directions.     

Mapping of several abnormal hemoglobins by horizontal polyacrylamide gel isoelectric focusing

The relative mobilities of serveral human hemoglobin variants were studied by use of an isoelectric focusing method in a thin-layer horizontal polyacrylamide gel. The technic is described in detail and a preliminary mapping of these variants is presented. It appears that thin-layer gel isoelectric focusing is a method that is rapid, highly reproducible and easily applicable in laboratories concerned with the study of hemoglobinopathies.     

Hemoglobin Dakar = Hb Grady: demonstration by a new approach to the analysis of the tryptic core region of the alpha chain and oxygen equilibrium properties

Preliminary studies have suggested that in Hb Dakar, histidine alpha112 was substituted by a glutamine. A re-investigation on this hemoglobin is presented in this report. A structural study has been performed using a new approach to analyse the tryptic core region of the human hemoglobin alpha chain. After tryptic digestion of the aminoethylated alpha chain, a secondary digestion of the tryptic core was carried out with chymotrypsin and with another protease, thermolysin. Analyses of the chymotryptic and thermolytic peptides indicated that the structure of Hb Dakar was identical to that of Hb Grady previously described by Huisman et al. who showed the insertion of three amino acid residues in position alpha115 or alpha118. The insertion, which was localized near two residues involved in the alpha1beta1 contact, did not produce a dissociation into dimers. Functional studies demonstrated a a slightly increased oxygen affinity, a lowered cooperativity and a normal Bohr effect. The low amount of the abnormal hemoglobin (8%) may in part be explained by a slight instability of the molecule.     

Effects of afternoon naps on physiological variables performance and self-reported activation

Fluctuations in physiological variables resulting from naps and the relationship of these to previously studies changes in performance and subjective activation associated with napping were examined. The subjects were eighteen healthy male university students who habitually slept 1/2-2 hr in the afternoon. Measurements were obtained of our physiological variables, from a continuous 10-min auditory reaction time task and two factors of an Activation. Deactivation Adjective Checklist 20 min before and after a control condition and two electroencephalographically recorded afternoons of sleep. The experimental conditions comprised a 2-hr period of wakefulness, a 1/2 hr nap from 4.35-5.05 p.m., and a 2-hr nap from 3.05-5.05 p.m. Following each sleep treatment, when compared with the control condition, there were statistically significant shifts of improved reaction time performance, and elevated activation as reflected by the two self-report scales, inceased EEG frequency, heart rate, and electrodermal responses. The shifts of increased behavioral efficiency, subjective and physiological activation were approximately equivalent in extent between 2-hr and 1/2-hr naps. These findings indicate that besides the previously reported facilitation by naps of performance and mood, physiological activation is increased following accustomed episodes of afternoon sleep.     

Limitation of the achievable signal-to-noise ratio in optical coherence tomography due to mismatch of the balanced receiver

Owing to the limited spectral response of the fiber directional coupler used in a balanced optical coherence tomography configuration, the spectra are different in the two outputs. This affects unfavorably operation of the balanced photodetector unit. Excess photon noise makes a larger contribution than a directional coupler with a flat spectral response. A theoretical model is developed that shows that an optimum set of parameters may be defined to maximize the achievable signal-to-noise ratio. The model leads to a redefinition of the effective noise bandwidth, which takes into account the nonflat response of the directional coupler used. The model also predicts a limitation on the signal-to-noise ratio even when the stray reflectances in the interferometer are brought to zero.     

Influence of jam processing upon the contents of phenolics,organic acids and free amino acids in quince fruit (<Emphasis Type="Italic">Cydonia oblonga</Emphasis> Miller)

Phenolic compounds, organic acids and free amino acids of quince were evaluated, before and after jam processing, to test the effect of thermal processing in these compounds. In addition, the composition of jams prepared with peeled and unpeeled quinces was compared. Phenolics, organic acids and free amino acids were analysed by HPLC/DAD, HPLC/UV and GC/FID, respectively.     

Changes in sympathetic nerve activity of the mammalian ovary during a normal estrous cycle and in polycystic ovary syndrome: Studies on norepinephrine release

Although it has been known for many years that the ovary is innervated by catecholaminergic nerve fibers and much experimental evidence has strengthened the notion that catecholamines are physiologically involved in the control of ovarian function, scarce evidence has been presented as to the role of sympathetic activity in ovarian pathologies that affect reproductive function. The purpose of this article is to provide a succinct overview of the findings in this area and discuss them relative to the pathology of polycystic ovary syndrome, the most common ovarian pathology in women during their reproductive years.