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Biomedical subjects

R Fazio

Publications and source records attributed to R Fazio.

At least 19 recordsLinked to original sources

Quantum algorithms for Josephson networks.

We analyze possible implementations of quantum algorithms in a system of (macroscopic) Josephson charge qubits. System layout and parameters to realize the Deutsch algorithm with up to three qubits are provided. Special attention is paid to the necessity of entangled states in the various implementations. Further, we demonstrate explicitly that the gates to implement the Bernstein-Vazirani algorithm can be realized by using a system of uncoupled qubits.

Journal Article↗

Shot noise for resonant Cooper pair tunneling.

We study intrinsic noise of current in a superconducting single-electron transistor, taking into account both coherence effects and Coulomb interaction near a Cooper pair resonance. Because of this interplay, the statistics of tunneling events deviates from the Poisson distribution and, more important, it shows even-odd asymmetry in the transmitted charge. The zero-frequency noise is suppressed significantly when the quasiparticle tunneling rates are comparable to the coherent oscillation frequency of Cooper pairs.

Journal Article↗

Detection of geometric phases in superconducting nanocircuits

When a quantum-mechanical system undergoes an adiabatic cyclic evolution, it acquires a geometrical phase factor' in addition to the dynamical one; this effect has been demonstrated in a variety of microscopic systems. Advances in nanotechnology should enable the laws of quantum dynamics to be tested at the macroscopic level, by providing controllable artificial two-level systems (for example, in quantum dots and superconducting devices). Here we propose an experimental method to detect geometric phases in a superconducting device. The setup is a Josephson junction nanocircuit consisting of a superconducting electron box. We discuss how interferometry based on geometrical phases may be realized, and show how the effect may be applied to the design of gates for quantum computation.

Journal Article↗

Re-entrant spin susceptibility of a superconducting grain

We study the spin susceptibility chi of a small, isolated superconducting grain. Because of the interplay between parity effects and pairing correlations, the dependence of chi on temperature T is qualitatively different from the standard BCS result valid in the bulk limit. If the number of electrons on the grain is odd, chi shows a re-entrant behavior as a function of temperature. This behavior persists even in the case of ultrasmall grains where the mean level spacing is much larger than the BCS gap. If the number of electrons is even, chi(T) is exponentially small at low temperatures.

Journal Article↗

Docetaxel neuropathy: a distal axonopathy.

Docetaxel has been implicated as a causative agent in peripheral neuropathy, but pathological changes in peripheral nerve have not been described. During docetaxel treatment a 54-year-old man developed a sensorimotor polyneuropathy when the overall docetaxel dosage was 540 mg/m(2). Neurophysiological investigation revealed a sensorimotor axonal neuropathy. Fascicular sural nerve biopsy showed an axonal neuropathy with a preferentially loss of large myelinated fibers. There was evidence of considerable fiber regeneration. Sensory and motor symptoms progressively improved after docetaxel withdrawal.

Antineoplastic Agents, Phytogenic↗

Effects of gender of subjects and experimenter on susceptibility to motion sickness.

BACKGROUND: It has been reported that females are more susceptible to motion sickness than males, but these reports have failed to take into account the possible effects of the gender of the experimenter and the subjective nature of reports of symptoms of motion sickness. To deal with the first possible confound, we used male and female experimenters. To deal with the second issue, we recorded gastric myoelectric activity so as to be able to quantify gastric tachyarrhythmia, an objective measure that has been shown previously to correlate highly with severity of symptoms. METHOD: There were 34 male and 34 female participants were assigned to either a male or female experimenter. Symptoms of motion sickness were induced by placing participants in an optokinetic drum for an 8-min baseline period followed by a 16-min rotation period. Electrogastrograms (EGGs) were continuously recorded, and reports of symptoms were obtained from the participants every 3 min during rotation. RESULTS: Comparison of male and female subjects' symptom scores revealed that females had higher symptom scores than males; however, no significant main effects for gender of the subject or experimenter were found. However, on a post-session questionnaire, females reported experiencing significantly more GI symptoms than males. Gender comparisons of the change in gastric tachyarrhythmia power from baseline to rotation yielded no significant differences. CONCLUSIONS: Females report more overall symptoms of motion sickness and significantly more GI symptoms than males, but do not show greater increases in gastric tachyarrhythmia during exposure to a rotating drum.

Adolescent↗

Slow deep breathing prevents the development of tachygastria and symptoms of motion sickness.

BACKGROUND: The purpose of this study was to see if slow deep breathing, a non-pharmacological procedure known to increase parasympathetic nervous system (PNS) activity, would prevent the development of gastric dysrhythmias and symptoms of motion sickness when subjects were exposed to a rotating optokinetic drum. METHODS: Participating in this study were 46 healthy males and females aged 17-26 who were pre-tested in the rotating drum and found to be susceptible to motion sickness. They were randomly placed into one of the following three conditions: Slow Deep Breathing (n = 18), Counting Breaths (subjects were asked to count their breaths and asked for the count every 3 min, n = 16), and Control (subjects breathed normally, n = 12). Electrogastrograms were recorded from all subjects during a 6-min baseline and a 16-min rotation period. Subjects were asked about their symptoms every 3 min. RESULTS: A significant difference in percent tachygastria from baseline to rotation was found between the three conditions. Percent tachygastria increased during rotation for the Counting Breaths group and the Control group, but remained the same as baseline for the Slow Deep Breathing group. The Slow Deep Breathing group (5.3) reported significantly fewer symptoms than the Counting Breaths group (9.0), but not the Control group (7.8). CONCLUSION: In conclusion, slow deep breathing in a situation previously demonstrated to provoke tachygastria prevented the development of gastric dysrhythmias and decreased symptoms of motion sickness.

Adolescent↗

Subconjunctival versus intrascleral mitomycin-C in trabeculectomy.

BACKGROUND AND OBJECTIVE: A randomized prospective comparison of sub-Tenon's administration of mitomycin-C (MMC) with intrascleral administration of MMC in trabeculectomy was performed to determine whether intrascleral application is superior to the standard sub-Tenon's application. PATIENTS AND METHODS: Twenty-four eyes of 23 patients were randomized to treatment with MMC (0.27 mg/ml for 5 minutes). The route of administration was subconjunctival in group A and intrascleral in group B. Preoperative and postoperative visual acuity (VA), intraocular pressure (IOP), number of medications, and complications were compared between the two groups. RESULTS: There was no statistically significant difference between the two groups preoperatively regarding VA, IOP, and number of medications. Postoperatively, IOP and number of medications required had decreased significantly in both groups. A significantly larger number of postoperative procedures were required in group B to control IOP (group A = 3, group B = 14, P = .002). CONCLUSION: Both methods of MMC application significantly decreased the IOP and the number of medicines required to control IOP after trabeculectomy. The intrascleral use of MMC resulted in the need for more surgery postoperatively (P = .002).

Aged↗

Clinical and neurophysiological assessment of immunoglobulin therapy in five patients with multifocal motor neuropathy.

High dose intravenous immunoglobulin (IVIg) is an effective treatment for demyelinating neuropathies. IVIg was given to five patients with multifocal motor neuropathy, a motor neuropathy showing a clinical syndrome of asymmetrical weakness and amyotrophy, electrophysiological evidence of motor conduction block and, in many cases, high titres of serum anti-GM1 antibodies. Muscle strength was evaluated by a conventional score before and after each IVIg course. In all patients there was relevant improvement on muscle strength after each immunoglobulin course, but in most cases the clinical benefits partially declined after three to eight weeks. At the eight month follow up, however, the pretreatment examination showed a significant improvement compared with the initial evaluation. The effects of each IVIg course were still present after a number of courses. Electrophysiological study revealed a decrease in conduction block in one or more nerves in all patients. However, conduction block was unchanged or increased in other sites. IVIg treatment did not affect anti-GM1 antibody titres.

Adult↗

Intravenous immunoglobulin treatment in patients with chronic inflammatory demyelinating neuropathy not responsive to other treatments.

Nine patients with chronic inflammatory demyelinating poliradiculoneuropathy (CIDP) were treated with intravenous immunoglobulin. All patients had been previously treated with prednisone and/or plasma exchange without effect. Objective improvement in clinical condition occurred in six patients. One patient became refractory after two treatment courses, two patients had no response. The results indicate that intravenous immunoglobulin has beneficial effects in a high percentage of patients with CIDP who are unresponsive to other treatments.

Adult↗