Outcomes of the collapse of a large bubble in water at high ambient pressures.

Presented here are observations of the outcomes of the collapses of large single bubbles in H_{2}O and D_{2}O at high ambient pressures. Experiments were carried out in a high-pressure spherical resonator at ambient pressures of up to 30 MPa and acoustic pressures up to 35 MPa. Monitoring of the collapse events and their outcomes was accomplished using multiframe high-speed photography. Among the observations to be presented are the temporal and spatial evolution of light emissions produced by the collapse events, which were observed to last on the order of 30 ns and have time independent radii on the order of 30µm; the production of Rayleigh-Taylor jets which were observed to travel distances of up to 70µm at speeds in excess of 4500 m/s; the entrainment of the light emitting regions in the jets' remnants; the production of spheroidal objects around the collapse points of the bubbles, far from any surface of the resonator; and the traversal and emergence of the Rayleigh-Taylor jets through the spherical objects. These spheroidal objects appear to behave as amorphous solids and form at locations where hydrodynamics predicts pressures in excess of the known transition pressures of water into the high-pressure crystalline ices, Ice-VI and Ice-VII.

Estudio de prevalencia sobre el síndrome de Burnout o Desgaste Profesional en los Cirujanos Ortopédicos de Andalucía / Prevalence study on burnout syndrome or Professional Burnout in Andalusia Orthopaedic Surgeons

Objetivo: Determinar la incidencia de desgaste profesional en los cirujanos ortopédicos de Andalucía en el año 2014. Determinar la posible asociación con una serie de factores sociodemográficos y laborales así como conocer las razones a las que los profesionales lo atribuyen y las medidas que propondrían para paliarlo. Material y método: Se diseña un estudio transversal descriptivo entre los 450 cirujanos ortopédicos de Andalucía, socios de la SATO y que tenían facilitada una dirección de email en dicha sociedad. Se envía a través de un enlace de Google Drive, anónimo que constaba de 3 partes: el cuestionario Maslach Burn Out Inventory para medir el grado de burnout, una serie de variables sociodemográficas y laborales y una última parte que constaba de preguntas abiertas sobre lo más negativo de su servicio, lo más positivo y lo que cambiarían para mejorar. Como criterio de inclusión se daba el tener el título de Especialista en Cirugía Ortopédica y Traumatología, estar en activo ejerciendo en la Comunidad Autónoma Andaluza y estar en activo. Resultados: Contestaron la encuesta 106 especialistas (23,5%), hombres el 83% y mujeres el 17%, el mayor grupo se encontraba entre los 30 y los 55 años (55%). El 86% se encontraban casados o con pareja estable y solo el 27% no tenía ningún hijo. El 68% tenían un contrato laboral estable bien con estatutarios del SAS o como laboral indefinido de las Agencias Públicas. El 38% realizaba entre 5-10 guardias al mes ya sea de presencia o de 1º localizado. El 29% presentaba un alto nivel de Burnout y en sus tres dimensiones el 41,5% presentaban un alta nivel de cansancio emocional, el 48,9% un alto nivel de despersonalización y el 37,2% presentaban un bajo nivel de realización personal. El trabajar cerca del lugar de residencia (p=0,018), el tener guardias de presencia física (p=0,007) y el trabajar en una Agencia Pública (p=0,03) se relaciona con un mayor nivel de desgaste profesional. Como factores subjetivos por parte de los encuestados de este desgaste resaltaban la presión asistencial (19,2%), la mala relación sueldo/responsabilidad (17,3%) y el poco reconocimiento del trabajo desempeñado tanto por la administración como por los usuarios (12,5%). El 77% volverían continuarían trabajando de Traumatólogos pero cambiarían el Hospital donde trabajan y solo el 4% estaría dispuesto a cambiar de especialidad con tal de continuar en el mismo centro de trabajo. Conclusiones: El nivel de desgaste profesional de los Traumatólogos de Andalucía en 2014 es moderado y similar al estudio realizado entre los Traumatólogos españoles en 2005 a pesar de estar atravesando por un momento socioeconómico más delicado que en esa fecha. Existe un mayor nivel de desgaste profesional entre los profesionales que viven cerca de su lugar de trabajo, en los que trabajan en las Agencias Públicas y en los que hacen guardias de presencia. Sin embargo no existe relación entre el desgaste profesional y la edad, sexo, tipo de contrato ni número de guardias. El 77% de los profesionales cambiaría de Hospital pero no de especialidad médica

Objective: To determine the incidence of burnout in orthopedic surgeons of Andalusia in 2014. To determine the possible association between burnout and a number of sociodemographic and occupational factors and to know the reasons argued and the measures proposed to alleviate it. Material and methods: A transversal descriptive study was designed. A test was electronically sent to all orthopaedic surgeons working in Andalusia that were members of the Andalusian orthopaedic society (SATO). The test consisted of Maslach burn inventory, some demographic data and some proposals for better well being during work. Inclusion criteria were to be a licensed orthopaedic surgeon, to work in Andalusia and to be active (not retired). Results: Answers were received from 106 specialists (23.5%), 83% men and 17% women, the largest group was between 30 and 55 years (55%). 86% were married or in a stable relationship and only 27% had no son. 68% had a stable employment contract statutory well with SAS or permanent employment with Public Agencies. 38% performed 5-10 on call full-day working activities per month. 29% had a high level of burnout and in its three dimensions 41.5% had a high level of emotional exhaustion, 48.9% a high level of depersonalization and 37.2% had a low level of personal fulfillment . The work near the place of residence (p = 0.018), to have on-call full-day working physically present (p = 0.007) and work on a Public Agency (p = 0.03) were associated with a higher level of burnout. As subjective factors for this burnout, respondents emphasized the workload (19.2%), poor relationship salary / liability (17.3%) and little recognition of the work performed by both the employer and by users (12.5%). 77% would continue working but would change the Hospital where they work and only 4% were willing to change their specialty with such proceeding in the same workplace. Conclusions: The level of burnout of orthopaedic surgeons of Andalusia in 2014 is moderate and similar to a previous study among Spanish Orthopedists performed in 2005, despite being having a poorer socioeconomic scenario. There is a higher level of burnout among professionals who live near their workplace, work in Public Agencies and have on-call full-day working activities. However there is no relationship between burnout and age, sex, type of contract and number of days on-call per month. 77% of professionals would change Hospital but not medical specialty

The effect of static pressure on the strength of inertial cavitation events.

Recent investigations of cavitation in fluids pressurized up to 30 MPa found that the intensity of light emissions increased by 1000-fold over that measured for single bubble sonoluminescence. A series of measurements is reported here to extend this original work by resolving the static pressure dependence of the shock wave and light emissions from the first and the most energetic collapses, along with the total shock wave energy and light emissions for the event. Each of these parameters was found to increase with the static pressure of the fluid. Furthermore, the energy of these shock wave and light emissions was found to increase in proportion to the stored acoustic energy in the system. These findings were corroborated using the Gilmore equation to numerically compute the work done by the liquid during the bubble collapse. The overall findings suggest that the increased collapse strength at high static pressure is due to the increased tension required to generate inertial cavitation, and not an increased pressure gradient between the interior of the vaporous bubble and the surrounding liquid.

Temporally and spatially resolved imaging of laser-nucleated bubble cloud sonoluminescence.

Imaging techniques have been used to capture the temporal and spatial evolution of light emissions from collapsing bubble clouds at high static pressures. Emission events lasting up to 70 ns with peak diameters nearing 1 mm have been observed. Observations of the cloud evolution before and after emission events have been made. Photomultiplier tube monitoring has been employed in conjunction with imaging to study the temporal characteristics of light emission.

The effect of static pressure on the inertial cavitation threshold.

The amplitude of the acoustic pressure required to nucleate a gas or vapor bubble in a fluid, and to have that bubble undergo an inertial collapse, is termed the inertial cavitation threshold. The magnitude of the inertial cavitation threshold is typically limited by mechanisms other than homogeneous nucleation such that the theoretical maximum is never achieved. However, the onset of inertial cavitation can be suppressed by increasing the static pressure of the fluid. The inertial cavitation threshold was measured in ultrapure water at static pressures up to 30 MPa (300 bars) by exciting a radially symmetric standing wave field in a spherical resonator driven at a resonant frequency of 25.5 kHz. The threshold was found to increase linearly with the static pressure; an exponentially decaying temperature dependence was also found. The nature and properties of the nucleating mechanisms were investigated by comparing the measured thresholds to an independent analysis of the particulate content and available models for nucleation.

Optical nucleation of bubble clouds in a high pressure spherical resonator.

An experimental setup for nucleating clouds of bubbles in a high-pressure spherical resonator is described. Using nanosecond laser pulses and multiple phase gratings, bubble clouds are optically nucleated in an acoustic field. Dynamics of the clouds are captured using a high-speed CCD camera. The images reveal cloud nucleation, growth, and collapse and the resulting emission of radially expanding shockwaves. These shockwaves are reflected at the interior surface of the resonator and then reconverge to the center of the resonator. As the shocks reconverge upon the center of the resonator, they renucleate and grow the bubble cloud. This process is repeated over many acoustic cycles and with each successive shock reconvergence, the bubble cloud becomes more organized and centralized so that subsequent collapses give rise to stronger, better defined shockwaves. After many acoustic cycles individual bubbles cannot be distinguished and the cloud is then referred to as a cluster. Sustainability of the process is ultimately limited by the detuning of the acoustic field inside the resonator. The nucleation parameter space is studied in terms of laser firing phase, laser energy, and acoustic power used.

Suppression of an acoustic mode by an elastic mode of a liquid-filled spherical shell resonator.

The purpose of this paper is to report on the suppression of an approximately radial (radially symmetric) acoustic mode by an elastic mode of a water-filled, spherical shell resonator. The resonator, which has a 1-in. wall thickness and a 9.5-in. outer diameter, was externally driven by a small transducer bolted to the external wall. Experiments showed that for the range of drive frequencies (19.7-20.6 kHz) and sound speeds in water (1520-1570 m/s) considered in this paper, a nonradial (radially nonsymmetric) mode was also excited, in addition to the radial mode. Furthermore, as the sound speed in the liquid was changed, the resonance frequency of the nonradial mode crossed with that of the radial one and the amplitude of the latter was greatly reduced near the crossing point. The crossing of the eigenfrequency curves of these two modes was also predicted theoretically. Further calculations demonstrated that while the radial mode is an acoustic one associated with the interior fluid, the nonradial mode is an elastic one associated with the shell. Thus, the suppression of the radial acoustic mode is apparently caused by the overlapping with the nonradial elastic mode near the crossing point.

Validez de la estimación visual como método diagnóstico de la hemorragia postparto severa en un Hospital Universitario. Bogotá 2007 / Validity of visual estimation of blood loss as diagnostic tool in severe post partum hemorrhage in an university hospital. Bogotá. 2007

Antecedentes. La dificultad para diagnosticar una hemorragia anormal postparto radica en la necesidad de esperar la presencia de signos clínicos de hipovolemia para confirmarla. Objetivo. Evaluar la exactitud diagnóstica de la estimación visual para el diagnóstico de hemorragia postparto severa inmediata (HPPI) luego de parto vaginal. Material y métodos. Se realizó un estudio de exactitud diagnóstica, aprobado por los comités de ética e investigaciones de las instituciones participantes, en una cohorte de embarazadas atendidas por parto vaginal en un hospital universitario. El gold estándar de referencia fue definido como un complejo de signos clínicos y de laboratorio: necesidad de maniobras terapéuticas para el control de la hemorragia, caída de más de 10% del hematocrito o necesidad de transfusión. Resultados. La incidencia de HPPI fue de 10,7% en 168 pacientes incluidas. La mediana de volumen estimado de sangrado fue de 375 mL mientras que la mediana del volumen real observado fue de 475 mL. Para el diagnóstico y manejo clínico de HPPI, el volumen estimado mayor de 500 mL tuvo una sensibilidad y especificidad de 77,8 y 73,3% respectivamente. Cuando el sangrado estimado superó los 800 mL, la sensibilidad y especificidad fueron 44,4 y 94% siendo este punto el que mejor clasificó las pacientes con necesidad de tratamiento para la hemorragia postparto severa inmediata. Conclusiones. La estimación visual del sangrado intraparto como prueba diagnóstica aislada es poco sensible y específica para diagnosticar hemorragia postparto severa inmediata por la tendencia a subestimar la magnitud real del sangrado.

Transient cavitation in high-quality-factor resonators at high static pressures.

It is well known that cavitation collapse can generate intense concentrations of mechanical energy, sufficient to erode even the hardest metals and to generate light emissions visible to the naked eye [sonoluminescence (SL)]. Considerable attention has been devoted to the phenomenon of "single bubble sonoluminescence" (SBSL) in which a single stable cavitation bubble radiates light flashes each and every acoustic cycle. Most of these studies involve acoustic resonators in which the ambient pressure is near 0.1 MPa (1 bar), and with acoustic driving pressures on the order of 0.1 MPa. This study describes a high-quality factor, spherical resonator capable of achieving acoustic cavitation at ambient pressures in excess of 30 MPa (300 bars). This system generates bursts of violent inertial cavitation events lasting only a few milliseconds (hundreds of acoustic cycles), in contrast with the repetitive cavitation events (lasting several minutes) observed in SBSL; accordingly, these events are described as "inertial transient cavitation." Cavitation observed in this high pressure resonator is characterized by flashes of light with intensities up to 1000 times brighter than SBSL flashes, as well as spherical shock waves with amplitudes exceeding 30 MPa at the resonator wall. Both SL and shock amplitudes increase with static pressure.

Experimental observations of bubble response and light intensity near the threshold for single bubble sonoluminescence in an air-water system.

Single bubble sonoluminescence in an air-water system has been shown to occur along a unique surface in the acoustic pressure-ambient radius-gas concentration parameter space where the bubble is stable both in shape and in (average) size. In this paper, we show how the bubble deviates from the expected path (traced by the shape-instability threshold as a function of pressure) in order to reach the observed stability. We also present measurements of the expansion ratio (R(max)/R(0)) for bubbles near the threshold for light emission. The results suggest that maximal bubble radial response is an insufficient criterion for the onset of light emission, and we present data for the dependence of the emitted light on several parameters.

Expression of 11beta-hydroxysteroid dehydrogenase type 2 in an ACTH-producing small cell lung cancer.

Non-pituitary tumors that produce adrenocorticotropic hormone (ACTH) exhibit resistance to the normal feedback effects of glucocorticoids on proopiomelanocortin (POMC) gene expression. This glucocorticoid resistance is typically complete, although some tumors show only relative glucocorticoid resistance in the clinical setting. The molecular mechanisms responsible for these clinical pathophysiologic observations are unknown, but might include glucocorticoid receptor defects or aberrant expression of enzymes or transporters that exclude glucocorticoids from access to their intracellular receptors. We examined whether ACTH-producing non-pituitary tumor cells might express 11beta-hydroxysteroid dehydrogenase (11beta-HSD), the principal 'gatekeeper' enzyme known to metabolize glucocorticoids. 11Beta-HSD mRNA and enzyme activity were assessed in DMS-79 cells, a line derived from an ACTH-producing small cell lung cancer. RT-PCR studies showed expression of mRNA encoding 11beta-HSD2 but not 11beta-HSD1 in DMS-79 cells. Control human fibroblasts expressed predominantly 11beta-HSD1 but also had detectable 11beta-HSD2 mRNA, while HepG2 hepatoma cells also expressed only 11beta-HSD2 mRNA. Whole cell assays in DMS-79 cells revealed 11beta-HSD activity with a Km for cortisol of 26.1 +/- 9.0 nM and Vmax of 57.0 +/- 5.9 pmol/h/mg protein. HepG2 cells expressed a similar high affinity enzyme activity, while control fibroblasts expressed 11beta-HSD activity with a Km for cortisol of 652 nM. Conversion of cortisol to cortisone in DMS-79 cells was inhibited to 7% of baseline by addition of 10 microM glycyrrhetinic acid. Dexamethasone (20 nM) was converted to a single product in DMS-79 cells at a rate of 17.2 pmol/h/mg protein; this activity was also inhibited by glycyrrhetinic acid. We conclude that DMS-79 cells express 11beta-HSD2. While DMS-79 cells harbor additional defects in glucocorticoid signaling, these data suggest that expression of 11beta-HSD2 might contribute to the development of the glucocorticoid-resistant phenotype of some ACTH-producing tumors.

Time-dependent changes of serum gastrin and gastrin receptors in the rat oxyntic mucosa after proximal gastric vagotomy.

Proximal gastric vagotomy (PGV) is a first-choice approach for the surgical treatment of duodenal peptic ulcer. However, a high percentage of recidivism takes place after this surgical strategy. To study the possible involvement of gastrin in ulcer recidivism, serum gastrin levels and gastrin receptors in gastric mucosa were determined at several times after PGV in rats. Gastrin concentration was determined using a commercial radioimmunoassay kit and gastrin receptors were analyzed in oxyntic mucosa membrane preparations using 125I-labeled 15-Leu-gastrin-17 as label. Our results show a significant, time-dependent increase in serum gastrin concentration, reaching highest values at 12 weeks after PGV. Similarly, a significant increase in the number of gastrin receptors (Bmax) and in the dissociation constant (Kd) occurred from 1 to 12 weeks post-PGV. Since gastrin exerts a positive feedback effect on its receptors, the PGV-dependent increase in serum gastrin concentration explains the up-regulation of the gastrin receptors in the rat oxyntic mucosa. Furthermore, an increase in the number of gastrin receptors after vagotomy may be at least partially responsible for the recidivism in duodenal peptic ulcers after this surgical approach.

Plasma corticotropin and cortisol responses to ovine corticotropin-releasing hormone (CRH), arginine vasopressin (AVP), CRH plus AVP, and CRH plus metyrapone in patients with Cushing's disease.

The CRH test may sometimes be useful in the differential diagnosis of Cushing's syndrome, because most patients with pituitary ACTH-dependent Cushing's syndrome (Cushing's disease) respond to CRH, but those with other causes of Cushing's syndrome usually do not. However, about 10% of Cushing's disease patients fail to respond to CRH. We wondered if we could eliminate these false negative results either by exploiting the potential additive or synergistic effects of another ACTH secretagogue or by reducing glucocorticoid inhibition of CRH's ACTH-releasing effect. We compared the effect on plasma ACTH and cortisol in 51 patients with Cushing's disease of administering ovine CRH (1 microgram/kg BW, i.v.) alone, arginine vasopressin (AVP; 10 U, i.m.) alone, the combination of CRH and AVP, and CRH after pretreatment with metyrapone (1 g, orally, every 4 h for three doses; CRH + MET). The rates of nonresponse (ACTH increment, < 35%; cortisol increment, < 20%) to AVP and CRH alone were 26% and 8%, respectively; all patients responded to CRH + AVP. The lack of response was not due to improper administration or rapid metabolism of the agonist, because plasma CRH and AVP concentrations were similar in responders and nonresponders. A synergistic ACTH response to CRH + AVP occurred in 65% of the patients. MET pretreatment increased basal plasma ACTH levels in most patients and induced the greatest mean peak ACTH response to CRH, but 8% of the patients did not respond to CRH + MET with an ACTH increment of 35% or more. Because all of the Cushing's disease patients tested in this study responded to the combination of CRH + AVP, whereas 8% failed to respond to CRH alone, we conclude that CRH + AVP administration may provide a more reliable test for the differential diagnosis of ACTH-dependent Cushing's syndrome than administration of CRH alone. Whether this improved sensitivity is accompanied by unaltered specificity for Cushing's disease must be tested in patients with chronic ectopic ACTH syndrome.

Glucocorticoid receptor structure and function in an adrenocorticotropin-secreting small cell lung cancer.

ACTH secretion by tumors of nonpituitary origin is characteristically resistant to negative feedback regulation by glucocorticoids. One possible mechanism for the phenomenon could be a structural defect in the intracellular glucocorticoid receptor (GR). We studied the GR in DMS-79 cells derived from a human ACTH-secreting small cell lung cancer. Compared with control cells, DMS-79 cells were found to have greatly diminished GR ligand-binding activity and immunoreactive 94-kilodalton (kDa) GR content. Northern blot analysis revealed expression of GR transcripts that appeared to be slightly larger than those in control cells. A DMS-79 cell GR cDNA was cloned by reverse transcription/polymerase chain reaction amplification of mRNA using primers specific for full-length normal GR. The derived sequence of this full-length GR differed from the reported sequence by a single altered codon (G to A; Asn to Ser at codon 363) outside the steroid-binding domain. This N363S DMS-79 GR functioned normally to activate a target gene [mouse mammary tumor virus-chloramphenicol acetyl transferase (MMTV-CAT)] in transient transfection experiments in COS cells. Evidence for expression of a second type of GR mRNA was obtained by screening a DMS-79 cell cDNA library. This GR cDNA contained normal GR sequence up to nucleotide 2155, corresponding exactly to the end of exon 7 in the normal GR gene. The sequence appended to the GR sequences was not matched by any known sequence in DNA databases and included an in-frame termination codon after only 6 bases. The predicted truncated GR protein product (GR delta) has a mol wt of 73,740 and lacks most of the ligand-binding domain. Transient transfection of the GR delta form into COS cells did not reveal any dominant negative effect on the function of a cotransfected normal GR.(ABSTRACT TRUNCATED AT 250 WORDS)

Mie scattering from a sonoluminescing air bubble in water.

A single bubble of air in water can emit pulses of blue-white light that have durations of less than 50 ps while it is oscillating in an acoustic standing wave. The emission is called sonoluminescence. A knowledge of the bubble diameter throughout the cycle, and in particular near the time of sonoluminescence emission, can provide important information about the phenomenon. A new Mie scattering technique is developed to determine the size of the bubble through its expansion and collapse during the acoustic cycle. The technique does not rely on an independent means of calibration or on accurate measurements of the scattered intensity.

Presence of the N-methyl-D-aspartate-associated glycine receptor agonist, D-serine, in human temporal cortex: comparison of normal, Parkinson, and Alzheimer tissues.

The amino acid D-serine (D-Ser), previously recognized as a pharmacological tool for potentiating neuronal activity mediated by the N-methyl-D-aspartate (NMDA) receptor complex, in vitro and in vivo, has been observed in several brain regions of the rat and mouse, most prominently in cortex. In addition to reconfirming the presence and distribution of D-Ser in rat brain, we have observed, for the first time, endogenous, free D-Ser in temporal cortex of normal human brains at a level of 2.18 +/- 0.12 nmol/mg of protein, representing 15 +/- 2% of the free L-Ser pool. The D- and L-Ser specific content and the D/L-Ser ratio obtained from temporal cortex of Parkinson and Alzheimer brains did not differ significantly from those of controls. However, at the levels observed here, and considering its specificity and affinity for the NMDA-associated glycine receptor, endogenous D-Ser is a plausible NMDA receptor glycine site agonist.