A UHF 4th-order band-pass filter based on contour-mode PZT-on-silicon resonators

A UHF 4th-order band-pass filter (BPF) based on the subtraction of two 2nd-order contour-mode resonators with slightly different resonance frequencies is presented. The resonators consists of a 1 μm pulsed-laser deposited (PLD) lead zirconate titanate (PZT) thin-film on top of a 3 μm silicon (PZT-on-Si). The resonators are actuated in-phase and their outputs are subtracted. Utilizing this technique, the outputs of the resonators are added up constructively while the feed-through signals are eliminated. The BPF presented a bandwidth of approximately 28.6 MHz and more than 30 dB stopband rejection at around 700 MHz

Metastability and the Casimir Effect in Micromechanical Systems

Electrostatic and Casimir interactions limit the range of positional stability of electrostatically-actuated or capacitively-coupled mechanical devices. We investigate this range experimentally for a generic system consisting of a doubly-clamped Au suspended beam, capacitively-coupled to an adjacent stationary electrode. The mechanical properties of the beam, both in the linear and nonlinear regimes, are monitored as the attractive forces are increased to the point of instability. There "pull-in" occurs, resulting in permanent adhesion between the electrodes. We investigate, experimentally and theoretically, the position-dependent lifetimes of the free state (existing prior to pull-in). We find that the data cannot be accounted for by simple theory; the discrepancy may be reflective of internal structural instabilities within the metal electrodes.Comment: RevTex, 4 pages, 4 figure

Subclinical immune reactions to viral infections may correlate with child and adolescent diagnosis of attention-deficit/hyperactivity disorder: A preliminary study from Turkey

Background: Attention-Deficit/Hyperactivity Disorder (ADHD) is one of the most common neuro-developmental disorders of childhood and  adolescence. Studies focusing on the relationship of infectious agents and ADHD are scarce. It is also known that cerebellar injury may lead to  hyperactive behavior. This study aimed to evaluate the relationship  between viral agents of cerebellitis and the diagnosis of ADHD.Methods: The study group was formed of 60 consecutive ADHD patients and 30 healthy children. IgG levels for VZV; HSV-1, CMV, Measles, Mumps, Rubella and EBV were evaluated.Results: Males were significantly higher among patients with ADHD (65% vs. 40%, p=0.025). Patients with ADHD displayed significantly higher positivity for measles IgG (80% vs. 60%, p=0.044). When patients with ADHD were classified according to their pubertal status, adolescents with ADHD displayed higher positivity for mumps (100% vs. 74.4%, p=0.043). Most of the patients were diagnosed with ADHD-Combined or  Hyperactive/Impulsive Subtypes (56.6%) while 43.3% were diagnosed with ADHD-predominantly inattentive type. When patients with subtypes of ADHD were compared in terms of seropositivity, it was found that patients with ADHD-Combined/ Hyperactive-Impulsive subtypes had significantly elevated reactions for Rubella (100% vs. 88.5%, p=0.044).Conclusion: Although limited to a single center and may be prone to sampling biases, our results may support the notion that immune reactions may be related with ADHD among children and adolescents. Further,  prospective studies from multiple centers are needed to support our  findings and establish causality.Key words: ADHD, infection, immunology, measles, rubella, mumps, Ig

Fibre Degradation Rate of Perennial Ryegrass Varieties Measured Using Three Techniques: \u3cem\u3eIn Situ\u3c/em\u3e Nylon Bag, \u3cem\u3ein Vivo\u3c/em\u3e Rumen Evacuation and \u3cem\u3ein Vitro\u3c/em\u3e Gas Production

In Western Europe, perennial ryegrass is the most widely used grass species for grazing cattle, because of its high productivity, palatability and nutritive value. However, the low dry matter intake (DMI) of perennial ryegrass pasture has been identified as a major factor limiting milk production of high producing dairy cows. Altering the chemical, physical and mechanical characteristics that contribute to its low DMI through grass breeding and the choice of variety may be a way forward in trying to maximise its DMI. This study aimed to examine whether perennial ryegrass varieties differ in their NDF degradation rates (kdNDF)

Large uterus: what is the limit for a laparoscopic approach?

Hysterectomy is the most common surgical gynecologic procedure, which is frequently related to the treatment of leiomyoma. The laparoscopic hysterectomy is associated with a shorter hospital stay, fewer infection rates, and a faster return to daily activities. Most gynecologists do not recommend a hysterectomy via the vagina or a laparoscopic-assisted vaginal hysterectomy (LAVH) in the case of a uterus weighing more than 300 g. This case report presents the case of an LAVH undertaken in a 43-year-old patient with a uterus weighing 2,800 g. There are no definite guidelines concerning the procedure for a large uterus, and the literature is vague regarding the best surgical procedure for these cases. The size of the uterus does not seem to be an absolute contraindication for endoscopic surgery. This procedure relies entirely on the surgeon’s abilit

Nonequilibrium Electron Interactions in Metal Films

Ultrafast relaxation dynamics of an athermal electron distribution is investigated in silver films using a femtosecond pump-probe technique with 18 fs pulses in off-resonant conditions. The results yield evidence for an increase with time of the electron-gas energy loss rate to the lattice and of the free electron damping during the early stages of the electron-gas thermalization. These effects are attributed to transient alterations of the electron average scattering processes due to the athermal nature of the electron gas, in agreement with numerical simulations

Three-dimensional fractal geometry for gas permeation in microchannels

The novel concept of a microfluidic chip with an integrated three-dimensional fractal geometry with nanopores, acting as a gas transport membrane, is presented. The method of engineering the 3D fractal structure is based on a combination of anisotropic etching of silicon and corner lithography. The permeation of oxygen and carbon dioxide through the fractal membrane is measured and validated theoretically. The results show high permeation flux due to low resistance to mass transfer because of the hierarchical branched structure of the fractals, and the high number of the apertures. This approach offers an advantage of high surface to volume ratio and pores in the range of nanometers. The obtained results show that the gas permeation through the nanonozzles in the form of fractal geometry is remarkably enhanced in comparison to the commonly-used polydimethylsiloxane (PDMS) dense membrane. The developed chip is envisioned as an interesting alternative for gas-liquid contactors that require harsh conditions, such as microreactors or microdevices, for energy applications