270 research outputs found

    Control and ultrasonic actuation of a gas-liquid interface in a microfluidic chip

    Full text link
    This article describes the design and manufacturing of a microfluidic chip, allowing for the actuation of a gas-liquid interface and of the neighboring fluid. A first way to control the interface motion is to apply a pressure difference across it. In this case, the efficiency of three different micro-geometries at anchoring the interface is compared. Also, the critical pressures needed to move the interface are measured and compared to theoretical result. A second way to control the interface motion is by ultrasonic excitation. When the excitation is weak, the interface exhibits traveling waves, which follow a dispersion equation. At stronger ultrasonic levels, standing waves appear on the interface, with frequencies that are half integer multiple of the excitation frequency. An associated microstreaming flow field observed in the vicinity of the interface is characterized. The meniscus and associated streaming flow have the potential to transport particles and mix reagents

    Maximum Likelihood Estimator for Hidden Markov Models in continuous time

    Full text link
    The paper studies large sample asymptotic properties of the Maximum Likelihood Estimator (MLE) for the parameter of a continuous time Markov chain, observed in white noise. Using the method of weak convergence of likelihoods due to I.Ibragimov and R.Khasminskii, consistency, asymptotic normality and convergence of moments are established for MLE under certain strong ergodicity conditions of the chain.Comment: Warning: due to a flaw in the publishing process, some of the references in the published version of the article are confuse

    Double Duct to Mucosa Pancreaticojejunostomy for Bifid Pancreatic Duct following Pylorus Preserving Pancreaticoduodenectomy: A Case Report

    Get PDF
    Bifid pancreatic duct represents a relatively rare anatomical variation of the pancreatic ductal system, in which the main pancreatic duct is bifurcated along its length. This paper describes the challenging surgical management of a 68-year-old male patient, with presumptive diagnosis of periampullary malignancy who underwent a successful double duct to mucosa pancreaticojejunostomy for bifid pancreatic duct. Following pylorus preserving pancreaticoduodenectomy, careful intraoperative inspection of the cut surface of the residual dorsal pancreas identified the main in addition to the secondary pancreatic duct orifice. Bifid duct anatomy was confirmed via intraoperative probing and direct visualization of the ductal orifices. A decision was made for the performance of an end-to-site double duct to mucosa pancreaticojejunostomy. Postoperative outcome was favorable without any complications. Although bifid pancreatic duct is relatively rare, pancreatic surgeons should be aware of this anatomical variation and be familiar with the surgical techniques for its successful management. Lack of knowledge and surgical expertise for dealing with this anatomical variant may lead to serious, life threatening postoperative complications following pancreatic resections

    Nanolaminate Deformable Mirrors

    Get PDF
    LLNL is developing nanolaminate-based deformable mirrors for terrestrial and space-based optical systems. We are combining two complementary technologies: high-spatial-density electrostatic actuators and thin, flexible, lightweight nanolaminate foils. Electrostatic actuation of MEMS-like structures provides densely-spaced, repeatable deflections on the order of 10 {micro}m. Nanolaminate foils provide a mirror surface that is simultaneously flexible enough to deform under electrostatic forces and tough enough to survive handling and bonding. We are working on two similar deformable mirrors that will demonstrate the feasibility of nanolaminate-based deformable mirrors over a wide range of size scales. The high-density device has a pitch of 1.255 mm between 1,024 square pixels. The large-scale device has a pitch of 9 mm between 76 hexagonal pixels [1], [2]

    Deformable Nanolaminate Optics

    Get PDF
    We are developing a new class of deformable optic based on electrostatic actuation of nanolaminate foils. These foils are engineered at the atomic level to provide optimal opto-mechanical properties, including surface quality, strength and stiffness, for a wide range of deformable optics. We are combining these foils, developed at Lawrence Livermore National Laboratory (LLNL), with commercial metal processing techniques to produce prototype deformable optics with aperture sizes up to 10 cm and actuator spacing from 1 mm to 1 cm and with a range of surface deformation designed to be as much as 10 microns. The existing capability for producing nanolaminate foils at LLNL, coupled with the commercial metal processing techniques being used, enable the potential production of these deformable optics with aperture sizes of over 1 m, and much larger deformable optics could potentially be produced by tiling multiple deformable segments. In addition, based on the fabrication processes being used, deformable nanolaminate optics could potentially be produced with areal densities of less than 1 kg per square m for applications in which lightweight deformable optics are desirable, and deformable nanolaminate optics could potentially be fabricated with intrinsically curved surfaces, including aspheric shapes. We will describe the basic principles of these devices, and we will present details of the design, fabrication and characterization of the prototype deformable nanolaminate optics that have been developed to date. We will also discuss the possibilities for future work on scaling these devices to larger sizes and developing both devices with lower areal densities and devices with curved surfaces

    Comparative analysis of two complete Corynebacterium ulcerans genomes and detection of candidate virulence factors

    Get PDF
    Trost E, Al-Dilaimi A, Papavasiliou P, et al. Comparative analysis of two complete Corynebacterium ulcerans genomes and detection of candidate virulence factors. BMC Genomics. 2011;12(1): 383.ABSTRACT: Corynebacterium ulcerans has been detected as a commensal in domestic and wild animals that may serve as reservoirs for zoonotic infections. During the last decade, the frequency and severity of human infections associated with C. ulcerans appear to be increasing in various countries. As the knowledge of genes contributing to the virulence of this bacterium was very limited, the complete genome sequences of two C. ulcerans strains detected in the metropolitan area of Rio de Janeiro were determined and characterized by comparative genomics: C. ulcerans 809 was initially isolated from an elderly woman with fatal pulmonary infection and C. ulcerans BR-AD22 was recovered from a nasal sample of an asymptomatic dog. The circular chromosome of C. ulcerans 809 has a total size of 2,502,095 bp and encodes 2,182 predicted proteins, whereas the genome of C. ulcerans BR-AD22 is 104,279 bp larger and comprises 2,338 protein-coding regions. The minor difference in size of the two genomes is mainly caused by additional prophage-like elements in the C. ulcerans BR-AD22 chromosome. Both genomes show a highly similar order of orthologous coding regions; and both strains share a common set of 2,076 genes, demonstrating their very close relationship. A screening for prominent virulence factors revealed the presence of phospholipase D (Pld), neuraminidase H (NanH), endoglycosidase E (EndoE), and subunits of adhesive pili of the SpaDEF type that are encoded in both C. ulcerans genomes. The rbp gene coding for a putative ribosome-binding protein with striking structural similarity to Shiga-like toxins was additionally detected in the genome of the human isolate C. ulcerans 809. The molecular data deduced from the complete genome sequences provides considerable knowledge of virulence factors in C. ulcerans that is increasingly recognized as an emerging pathogen. This bacterium is apparently equipped with a broad and varying set of virulence factors, including a novel type of a ribosome-binding protein. Whether the respective protein contributes to the severity of human infections (and a fatal outcome) remains to be elucidated by genetic experiments with defined bacterial mutants and host model systems

    E-mode Planar L g = 35 nm In 0.7 Ga 0.3 As MOSFETs with InP/Al 2 O 3 /HfO 2 (EOT = 0.8 nm) Composite Insulator

    Get PDF
    Abstract We have successfully demonstrated a three-step recess process to fabricate high performance E-mode planar InGaAs MOSFETs. Our devices feature a composite gate insulator with InP/Al 2 O 3 /HfO 2 . An L g =35 nm InGaAs MOSFET with EOT = ~ 0.8 nm exhibits V T = 0.17 V, R ON = 285 Ohm-μm, DIBL = 135 mV/V and S = 115 mV/dec, as well as a negligible dispersion and hysteresis behavior. Most importantly, our device displays the highest value of g m_max > 2 mS/μm at V DS = 0.5 V in any III-V MOSFETs. Introduction The outstanding carrier transport properties of III-V compound semiconductors have fueled interest on these materials for use in the channel material of a future scaled CMOS technology In this paper, we propose a three-step recess process that allows us to fabricate high performance enhancement-mode (E-mode) planar InGaAs MOSFETs with InP/Al 2 O 3 /HfO 2 composite insulator. Our long-and short-channel MOSFETs with EOT = ~ 0.8 nm exhibits excellent carrier transport properties and logic characteristics

    Severe axial vertebral rotation treated with a modified Boston brace: a case report

    Get PDF
    We report the case of a 13-year-old Caucasian girl suffering from severe axial rotation of the T5 to L4 vertebrae. The patient (initially examined during a school screening study) was at first considered to be suspicious of suffering from scoliosis due to a highly positive Adam's forward bending test. However, her radiographic evaluation revealed the existence of axial rotation in 12 of her vertebrae, without inclination in the sagittal and coronal planes. After an observation period of 12 months and due to the fact that both her physical appearance and the measured vertebral rotation deteriorated, the patient was given a modified thoracolumbar Boston brace that had an immediate positive derotational effect on all but two vertebrae. Twenty four months later, the progress of the vertebral rotation(s) seems to have been halted and most affected vertebrae appear to be stabilized in their new, 'post-brace', reduced position, with better results shown when the Boston brace is worn. The patient remains under constant medical observation. The application of a modified Boston brace seems to have served well (so far) a useful purpose for reducing and stabilizing this case of severe axial vertebral rotation, providing less deformity and (possibly) offering a better final cosmetic result
    corecore