The collision efficiency in a shear flow

Fluid flows with cohesive particles are present in oil industry (e.g. natural gas/oil with hydrates, wax or asphaltenes), medicine (e.g. blood cells), nano- and ferro-fluidic applications (e.g. fluids with nanoparticles subject to the van der Waals and electrostatic interactions) and even in astrophysics (e.g. grains in planetary rings). Such flows may lead to formation of agglomerates that, for example in pipelines, may result in unwanted phenomena such as formation of deposits. The main process parameter governing this is the “collision efficiency”, which is the ratio of the number of collisions resulting in agglomeration to the total number of collisions. This is commonly considered to depend on the relativemagnitudes of attractive and repulsive interactions during a collision. The effect of the particles' mechanical properties on the agglomeration efficiency has, however, not yet been studied. In this paper the agglomeration efficiency is studied as a function of inter-particle friction, stiffness, density and volume fraction by numerical simulation. By running direct numerical simulations (DNS) with Lagrangian particle tracking of a shear flow laden with solid particles, the parameters influencing the agglomeration efficiency are demonstrated and their effects quantified. Finally, an expression that relates the collision efficiency to the salient dimensionless physical parameters is proposed.     

Adiabatic coupling in tapered air-silica microstructured opticalfiber

We study adiabatic mode propagation in tapered air-silica microstructured optical fibers and demonstrate efficient coupling into a robust high-delta microstructured fiber. In the waist region of the taper, the core mode is tightly confined by the air holes and exhibits properties similar to a high-delta waveguide such as enhanced peak intensity and widely flattened anomalous dispersion. We exploit these properties to generate tunable self-frequency shifting Raman solitons over the communications window from 1.3 μm to 1.65 μm, with over 60% conversion efficiency These fiber devices are practical for several reasons: they can be fusion spliced to standard single-mode fibers with relatively low loss, they are mechanically strong, due to the supporting cladding, and because the mode is isolated from the surrounding air interface, they can potentially be recoated allowing for packaging     

Acoustic reflex threshold and loudness discomfort level: relationships in children with profound hearing losses

Acoustic reflex thresholds (ART) and loudness discomfort levels (LDL) were obtained from 51 ears of 34 deaf children using broad band noise and pure tones. Both thresholds and levels were recorded using the psychophysical method of tracking. Results indicate that the relationship between ART and LDL is at variance with similar data for normal hearing individuals. Specifically, in over 39% of these deaf children LDL was obtained at a lower intensity than ART. Implications for hearing aid fitting with deaf children are discussed.     

When the patient wants facial cosmetic surgery

Cosmetic facial surgery can improve appearance but it cannot make everyone beautiful (or handsome) or solve all problems. The patient must be well motivated and must comprehend the limitations of the procedures. Procedures useful in providing a more youthful appearance include blepharoplasty, browlift and face-lift. Sometimes all three are indicated. Chemical face peeling is used for correction of fine skin lines.     

Neural control of ventilation in the lamprey

Tidal breathing of adult lampreys is produced by a single phase of excitation that compresses the branchial basket for exhalation. Inhalation is due to passive recoil. Motoneurons are located primarily in the ipsilateral motor nucleus of the vagus and exhibit periodic bursts of excitatory synaptic potentials from unidentified generator cells in the medulla. Respiratory discharges continue in the isolated brain and can be recorded from the vagal roots. The frequency of bursts increases with temperature in a manner roughly similar to that of intact animals. However, the discharges of the isolated brain are not very sensitive to altered pH or oxygen content in the bathing fluid. Mechanoreceptors in the gill can initiate "cough" responses and may modulate normal breathing.     

Knotting of a flow-directed catheter about a cardiac structure

A new ganglion identified as the bursal ganglion is described from male Moniliformis moniliformis. This ganglion is located adjacent to the pseudocoel and longitudinal muscle fibers and medial to the dorsal lacunar canal about 1 mm from the posterior end of males with non-everted bursa. The ganglion consists of four large club-shaped cells with single nuclei and bipolar neurons. The ganglion cells are paired with one neuron from each cell innervating the opposite side of the worm.     

Videoendoscopic diagnosis of esophageal motility disorders

PURPOSE: Looking for a valid, reliable, and feasible method to collect data on the performances of practicing family physicians, the authors compare the measurement characteristics of a multiple-station examination (MSE) using standardized patients with those of a video assessment of regular consultations in daily practice (practice video assessment, PVA). METHOD: In a cross-sectional study, consultations of 90 family physicians were videotaped both in an MSE and in their daily practices. Peer-observers used a validated instrument (MAAS-Global) to assess the physicians' communication with patients and their medical performances. The physicians were randomly divided into two groups, comparable for demographic characteristics, and half underwent the assessments in reverse order to test for time-order effects. Content validity, criterion validity, reliability, and feasibility of the two methods were compared. RESULTS: Content validity of the PVA was superior to that of the MSE, since the domain of general family practice care was better covered. Observed participants judged the videotaped practice consultations to be "natural," whereas hardly any family physician, after reviewing the videotaped consultations of the MSE, recognized his or her usual working style. Specific criteria made it possible to standardize real practice. Concerning criterion validity, only the medical-performance components of the two methods correlated. No correlation was found for the communication components. Real-practice performance proved to be less influenced by observation than was performance during the MSE. The reliabilities of the two methods, expected to be better in the controlled MSE, were comparable. The administration of the PVA was more flexible, less costly, and better accepted by the family physicians than was that of the MSE. CONCLUSION: Assessment for quality improvement of family physicians' practices by video observation in daily practice is superior to video assessment in a simulated setting using standardized patients.     

The evaluation of women with schizophrenia

BACKGROUND AND PURPOSE: A diagnosis of cancer is a contraindication for the use of therapeutic ultrasound (US). Continuous US applied to murine tumors has resulted in larger and heavier tumors compared with controls. We compared tumor growth using low-power continuous US and energy-matched pulsed US. SUBJECTS: Female C57BL/6 mice (N = 174) were used. METHODS: Animals received subcutaneous injections of methylcholanthrene tumor cells. The mice were randomly divided into three groups: 60 mice that received low-power continuous US for 5 minutes at 0.75 W/cm2 (LC US group), 63 mice that received pulsed US for 12.5 minutes at 1.5 W/cm2 (pulsed US group), and 51 mice that served as a control group. The LC and pulsed US groups received equal US energy. Both experimental groups received 10 treatments of 3-MHz US, which was applied directly over the tumor. The control group received identical handling but no US. After treatment, the tumors were excised, weighed, and measured. A one-way analysis of variance, followed by Newman-Keuls post hoc testing, was used to analyze the data. RESULTS: Mean tumor weights (in grams) and volumes (in cubic millimeters) were 0.563 g and 564 mm3 for the LC US group, 0.560 g and 525 mm3 for the pulsed US group, and 0.516 g and 406 mm3 for the control group. CONCLUSION AND DISCUSSION: Reducing total US energy will result in less growth of murine tumors. When infusing equal energy, continuous and pulsed US will produce similar effects on tumor growth.     

Parathyroid hormone (1-34) increased total body bone mass in aged female rats

Daily subcutaneous administration of bovine parathyroid hormone (PTH)(1-34) stimulates bone formation and increases bone mass in rat tibiae, femora and lumbar spine. However, the effects of PTH on the whole body bone mineral content and density determined by dual energy x-ray absortiometry (DEXA) have not been previously reported in rats. Eighteen-month-old intact female rats were subcutaneously injected daily with 0, 40, 80 or 160 micrograms/kg/day of bovine PTH (1-34) for either 15 or 60 days. Whole body DEXA was performed at 1 day before autopsy, and bone area, bone mineral content (BMC) and bone mineral density (BMD) of the total body were determined. Total femoral, tibial and lumbar spine BMD was also determined ex vivo. Cancellous bone histomorphometry was performed on sections of double-labeled proximal tibial metaphyses. Whole body bone mineral content and density were significantly increased by 60 days, but not by 15 days, of PTH treatment at all dose groups compared with vehicle controls. Lumbar vertebral and total femoral BMD was significantly increased at all doses of PTH by 15 days of administration and further increased by 60 days. All doses of PTH increased trabecular bone area in proximal tibial metaphyses by 15 days and further increased by 60 days. All doses of PTH increased trabecular bone area in proximal tibial metaphyses by 15 days and further increased by 60 days. In proximal tibial cancellous bone, dose-dependent increases in percent labeled perimeter, mineral apposition rate and bone formation rate-bone volume referent were found between 40 and 160 micrograms/kg of PTH treatment by 15 days, and no further increases were found by 60 days. Our results showed that in aged female rats, bovine PTH(1-34) increased bone formation and total body bone mass.