Depolarizing GABAergic conductances regulate the balance of excitation to inhibition in the developing retinotectal circuit in vivo

Neurotransmission during development regulates synaptic maturation in neural circuits, but the contribution of different neurotransmitter systems is unclear. We investigated the role of GABAA receptor-mediated Cl- conductances in the development of synaptic responses in the Xenopus visual system. Intracellular Cl- concentration ([Cl-]i) was found to be high in immature tectal neurons and then falls over a period of several weeks. GABAergic synapses are present at early stages of tectal development and, when activated by optic nerve stimulation or visual stimuli, induce sustained depolarizing Cl- conductances that facilitate retinotectal transmission by NMDA receptors. To test whether depolarizing GABAergic inputs cooperate with NMDA receptors during activity-dependent maturation of glutamatergic synapses, we prematurely reduced [Cl-]i in tectal neurons in vivo by expressing the Cl- transporter KCC2. This blocked the normal developmental increase in AMPA receptor-mediated retinotectal transmission and increased GABAergic synaptic input to tectal neurons. Therefore, depolarizing GABAergic transmission plays a pivotal role in the maturation of excitatory transmission and controls the balance of excitation and inhibition in the developing retinotectal circuit

Zero Field precession and hysteretic threshold currents in spin torque oscillators with tilted polarizer

Using non-linear system theory and numerical simulations we map out the static and dynamic phase diagram in zero applied field of a spin torque oscillator with a tilted polarizer (TP-STO).We find that for sufficiently large currents, even very small tilt angles (beta>1 degree) will lead to steady free layer precession in zero field. Within a rather large range of tilt angles, 1 degree< beta <19 degree, we find coexisting static states and hysteretic switching between these using only current. In a more narrow window (1 degree<beta<5 degree) one of the static states turns into a limit cycle (precession). The coexistence of static and dynamic states in zero magnetic field is unique to the tilted polarizer and leads to large hysteresis in the upper and lower threshold currents for TP-STO operation.Comment: 5 pages, 4 figure

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Jenny Lambert latest Furman student to receive Truman Awar

A planar respiration sensor based on a capaciflector structure

Respiratory diseases, such as asthma and chronic obstructive pulmonary disease (COPD), affect more than 300 million people worldwide. Devices such as the pneumotachograph are currently used within a clinical environment for measuring the inhalation, expiration, and respiration cycle but are physically large and not suitable for home use by patients. A small, lightweight respiration sensor for use in the home environment allows patients to monitor respiratory rate in a simple manner. The capaciflector was originally developed by NASA as a capacitive proximity sensor for collision detection in robots. We have found that the device can also be used to detect breathing patterns in humans by attaching it to the chest. In this article, we discuss the simulation, construction, and testing of a capaciflector for use as a respiration sensor and describe how it can be interfaced to a microcontroller in order to allow us wireless data transmission over a Wi-Fi signal

Disorder strength and field-driven ground state domain formation in artificial spin ice: experiment, simulation and theory

Quenched disorder affects how non-equilibrium systems respond to driving. In the context of artificial spin ice, an athermal system comprised of geometrically frustrated classical Ising spins with a two-fold degenerate ground state, we give experimental and numerical evidence of how such disorder washes out edge effects, and provide an estimate of disorder strength in the experimental system. We prove analytically that a sequence of applied fields with fixed amplitude is unable to drive the system to its ground state from a saturated state. These results should be relevant for other systems where disorder does not change the nature of the ground state.Comment: The manuscript has been reworked. To be published in Phys. Rev. Let

An outbreak of abortions, stillbirths and malformations in a Spanish sheep flock associated with a bovine viral diarrhoea virus 2-contaminated orf vaccine

Bovine viral diarrhoea virus (BVDV) is a pestivirus that affects both cattle and sheep, causing an array of clinical signs, which include abortions and malformations in the offspring. Manufacturing of modified live virus (MLV) vaccines often includes the use of bovine-derived products, which implies a risk of contamination with viable BVDV. Recently, the circulation of a specific strain of BVDV 2b among Spanish sheep flocks, associated with outbreaks of abortions and malformations, and whose origin was not determined, has been observed. On February 2018, a MLV orf vaccine was applied to a 1, 600 highly prolific sheep flock in the Northeast of Spain that included 550 pregnant ewes. In May 2018, during the lambing season, an unusual high rate (72.7%) of abortions, stillbirths, congenital malformations and neurological signs in the offspring was observed. It was estimated that about 1, 000 lambs were lost. Three 1- to 3-day-old affected lambs and a sealed vial of the applied vaccine were studied. Lambs showed variable degrees of central nervous system malformations and presence of pestiviral antigen in the brain. Molecular studies demonstrated the presence of exactly the same BVDV 2b in the tissues of the three lambs and in the orf vaccine, thus pointing to a pestivirus contamination in the applied vaccine as the cause of the outbreak. Interestingly, sequencing at the 5'-untranslated region-(UTR) of the contaminating virus showed a complete match with the virus described in the previously reported outbreaks in Spain, thus indicating that the same contaminated vaccine could have also played a role in those cases. This communication provides a clear example of the effects of the application of this contaminated product in a sheep flock. The information presented here can be of interest in putative future cases of suspected circulation of this or other BVDV strains in ruminants

Competence acquisition for single-incision laparoscopic cholecystectomy

BACKGROUND AND OBJECTIVES: Within the past few years, there has been a push for an even more minimally invasive approach to biliary disease with the adoption of single-incision laparoscopic cholecystectomy. We sought to compare 4 individual surgeon experiences to define whether there exists a learning curve for performing single-incision laparoscopic cholecystectomy. METHODS: We performed a retrospective review 290 single-incision laparoscopic cholecystectomies performed by a group of general surgeons, with varying levels of experience and training, at 3 institutions between May 2008 and September 2010. The procedure times were recorded for each single-incision laparoscopic cholecystectomy, ordered chronologically for each surgeon, and subsequently plotted on a graph. The patients were also combined into cohorts of 5 and 10 cases to further evaluate for signs of improvement in operative efficiency. RESULTS: Of the 4 surgeons involved in the study, only 1 (surgeon 4, laparoscopic fellowship trained with \u3c5 \u3eyears\u27 experience) confirmed the presence of a learning curve, reaching proficiency within the first 15 cases performed. The other surgeons had more variable procedure times, which did not show a distinct trend. When we evaluated the cases by cohorts of 5 cases, surgeon 4 had a significant difference between the first and last cohort. Increased body mass index resulted in a slightly longer operative time (P \u3c .0063). The conversion rate to multiport laparoscopic surgery was 3.1%. CONCLUSIONS: Our results indicate that among experienced general surgeons, there does not seem to be a significant learning curve when transitioning from conventional laparoscopic cholecystectomy to single-incision laparoscopic cholecystectomy. The least experienced surgeon in the group, surgeon 4, appeared to reach proficiency after 15 cases. Greater than 5 years of experience in laparoscopic surgery appears to provide surgeons with a sufficient skill set to obviate the need for a single-incision laparoscopic cholecystectomy learning curve

Revised theory of transient mass fluctuations

Abstract Several publications during the last 10 years by Woodward and colleagues have indicated a theory, based on general relativity, that has: (1) predicted transient mass fluctuations; (2) cited a specific embodiments where a net average force would be present; (3) suggested a few ways that this theory might be tested in the laboratory; and (4) have reported such test results incorporating these embodiments. In this paper we show that: (1) the average force predicted by Woodward occurred only because of a neglected term in a product derivative, and that when the neglected term is correctly returned, the average force vanishes; (2) this vanishment of the average force occurs for arbitrary forcing functions, not just the sinusoidal one considered by Woodward; (3) the transient mass fluctuation, predicted by Woodward, was developed in a theory which neglected local gravitational and electrodynamic forces which are several dozen orders of magnitude greater; (4) a less incomplete theory considering local gravitational forces produces a vastly smaller transient mass fluctuation