Deletion of Gαq/11 or Gαs proteins in gonadotropes differentially affects gonadotropin production and secretion in mice

GnRH regulates gonadal function via its stimulatory effects on gonadotropin production by pituitary gonadotrope cells. GnRH is released from the hypothalamus in pulses and GnRH pulse frequency differentially regulates FSH and LH synthesis and secretion. The GnRH receptor (GnRHR) is a G protein-coupled receptor that canonically activates Gαq/11-dependent signaling upon ligand binding. However, the receptor can also couple to Gαs and in vitro data suggest that toggling between different G proteins may contribute to GnRH pulse frequency decoding. For example, as we show here, knockdown of Gαs impairs GnRH-stimulated FSH synthesis at low, but not high pulse frequency in a model gonadotrope-derived cell line. We next used a Cre-lox conditional knockout approach to interrogate the relative roles of Gαq/11 and Gαs proteins in gonadotrope function in mice. Gonadotrope-specific Gαq/11 knockouts exhibit hypogonadotropic hypogonadism and infertility, akin to the phenotypes seen in GnRH- or GnRHR-deficient mice. In contrast, under standard conditions, gonadotrope-specific Gαs knockouts produce gonadotropins at normal levels and are fertile. However, the LH surge amplitude is blunted in Gαs knockout females and post-gonadectomy increases in FSH and LH are reduced in both males and females. These data suggest that GnRH may signal principally via Gαq/11 to stimulate gonadotropin production, but that Gαs plays important roles in gonadotrope function in vivo when GnRH secretion is enhanced.

Femtosecond lasers for eye surgery applications: historical overview and modern low pulse energy concepts

This review provides an overview of the historical development and modern applications of femtosecond (fs) lasers in ophthalmology, with a focus on the optical concepts involved. fs-Laser technology is unique because it allows very precise cutting inside the eye through optically transparent tissue, without a need for any mechanical openings. fs-Lasers were historically first used for refractive cornea surgery, later also for therapeutic cornea procedures and lens surgery. Further new areas of ophthalmic application are under development. The latest laser system concept is low pulse energy and high pulse frequency: by using larger numerical aperture focusing optics, the pulse energy required for optical breakdown decreases, and athermal tissue cutting with minimal side effects is enabled.

Investigation on Bidirectional Pulse Electrochemical Micromachining of Micro Dimples

Through-mask electrochemical micromachining (TMEMM) is a promising method to prepare micro dimples on the surface of metallic parts. However, the workpiece is machined one by one in traditional TMEMM. This paper introduced bidirectional pulse to TMEMM to improve the machining efficiency. Two masked workpieces were placed face to face, and connected to the ends of the bidirectional pulse power supply. Along with the change of the pulse direction, the polarities of the two workpieces were interchanged periodically, and micro dimples could be prepared on both workpieces at one time. The simulation and experiment results indicated that with bidirectional pulse mode, micro dimples with same the profile can be prepared on two workpieces at one time, and the dimension of micro dimple was smaller than that with unidirectional pulse mode. In bidirectional pulse current, the pulse frequency and pulse duty cycle played an important role on the preparation of micro dimple. With high pulse frequency and low pulse duty cycle, it is useful to reduce the undercut of micro dimple and improve the machining localization. With the pulse duty cycle of 20% and pulse frequency of 10 kHz, micro dimples with etch factor (EF) of 3 were well prepared on both workpieces surface.

Pulsed Nd:YAG laser machining of nitinol: An experimental investigation

Nickel–Titanium (Ni-Ti) shape memory alloy, commonly called nitinol alloys, finds its primary application in the production of biomedical implants, mainly because of itsrare properties such asshape memory, superelasticity and superior biocompatibility. Laser cutting is anon-traditional machining process for the production ofparts with close tolerances andcomplex geometry. Electrical discharge machining (EDM) of nitinol is associated with more heat-affected zone (HAZ) and recast layer thickness. This article aims to study nitinol’s machining characteristics by alaser source with good beam quality to have a less HAZ, recast layer and striations. Experiments were designed and carried out using central composite designs (CCD) by a pulsed Nd:YAG laser. Analysis based on the different parameters chosen was conducted to determine the parameters; effects, including laser power, frequency and cutting speed concerning the surface roughness. From the results, it is observed that the presence of HAZ is measured up to1. 48 mm from the machined surface. The topography analysis reveals that the striation is identified at high speeds, with less pulse overlapping by columnar micro channels, which can be reduced at high pulse frequency.

A New Filter Concept for High Pulse-Frequency 3-Phase AFE Motor Drives

The size of back-to-back converters with active front end is significantly determined by the size of the passive filter components. This paper presents a new complete EMC filter concept for this type of converter system that is effective on the input and the output. This involves filtering the main common mode interferences from the grid and motor sides with a single CM choke. Since only the difference of the generated common mode voltage-time areas of both converters is absorbed by this component, the size of the required filter can be greatly reduced compared to conventional filter concepts. The concept is validated on a grid feeding inverter that can be connected to the public distribution network with an output power of 63 kW. The size reduction is demonstrated by means of a design example on a system with the same power and electrical requirements. It is elaborated why, applying the new filter concept, the impedance of the DC link potentials to ground and other electrical potentials should be as high as possible and therefore associated parasitic capacitances should be minimized. From this requirement, rules for the design of the power modules of PFC and motor converters for the application of this filter concept are derived.

Effect of Pulsed Ultrasound on Plasma Morphology and Its Changing Mechanism

Arc plasma shape under pulsed and continuous ultrasound field were studied in this research using self-developed welding device which combines arc and ultrasound field coaxially. The results show that, compared with the arc of conventional tungsten inert gas welding, the shape of arc under pulsed ultrasound field relate to the pulse frequency. From 1 Hz to 20 Hz, the arc plasma expands and contracts periodically in one pulse. When more than 20 Hz, the arc plasma contracts as the pulse frequency increases. During high pulse frequency, the arc shape become steady and similar to those in continuous ultrasound field. When in 500 Hz, the contraction ratio of arc projected area under pulsed ultrasound field reaches 38 %, comparing with 30 % of the same power continuous ultrasound field, i.e., in high frequency, low power pulsed ultrasound can obtain arc control effect similar to high power continuous ultrasound, raising ultrasound energy efficiency. The mechanism of ultrasonic influence on arc is analyzed based on sound pressure and acoustic streaming.

Femtosecond-Laser Assisted Surgery of the Eye: Overview and Impact of the Low-Energy Concept

This article provides an overview of both established and innovative applications of femtosecond (fs)-laser-assisted surgical techniques in ophthalmology. Fs-laser technology is unique because it allows cutting tissue at very high precision inside the eye. Fs lasers are mainly used for surgery of the human cornea and lens. New areas of application in ophthalmology are on the horizon. The latest improvement is the high pulse frequency, low-energy concept; by enlarging the numerical aperture of the focusing optics, the pulse energy threshold for optical breakdown decreases, and cutting with practically no side effects is enabled.

Scan Pattern Characterization of Velodyne VLP-16 Lidar Sensor for UAS Laser Scanning

Many lightweight lidar sensors employed for UAS lidar mapping feature a fan-style laser emitter-detector configuration which results in a non-uniform pattern of laser pulse returns. As the role of UAS lidar mapping grows in both research and industry, it is imperative to understand the behavior of the fan-style lidar sensor to ensure proper mission planning. This study introduces sensor modeling software for scanning simulation and analytical equations developed in-house to characterize the non-uniform return density (i.e., scan pattern) of the fan-style sensor, with special focus given to a popular fan-style sensor, the Velodyne VLP-16 laser scanner. The results indicate that, despite the high pulse frequency of modern scanners, areas of poor laser pulse coverage are often present along the scanning path under typical mission parameters. These areas of poor coverage appear in a variety of shapes and sizes which do not necessarily correspond to the forward speed of the scanner or the height of the scanner above the ground, highlighting the importance of scan simulation for proper mission planning when using a fan-style sensor.

Spatio-temporal Control of ERK Pulse Frequency Coordinates Fate Decisions during Mammary Acinar Morphogenesis

The signaling events controlling proliferation, survival, and apoptosis during mammary epithelial acinar morphogenesis remain poorly characterized. By imaging single-cell ERK activity dynamics in MCF10A acini, we find that these fates depend on the frequency of ERK pulses. High pulse frequency is observed during initial acinus growth, correlating with rapid cell motility. Subsequent decrease in motility correlates with lower ERK pulse frequency and quiescence. Later, during lumen formation, coordinated ERK waves emerge across multiple cells of an acinus, correlating with high and low ERK pulse frequency in outer surviving and inner dying cells respectively. A PIK3CA H1047R mutation, commonly observed in breast cancer, increases ERK pulse frequency and inner cell survival, causing loss of lumen formation. Optogenetic entrainment of ERK pulses causally connects high ERK pulse frequency with inner cell survival. Thus, fate decisions during acinar morphogenesis are fine-tuned by different spatio-temporal coordination modalities of ERK pulse frequency.