Structural Transition in a Fluid of Spheroids: A Low-Density Vestige of Jamming.

A thermodynamically equilibrated fluid of hard spheroids is a simple model of liquid matter. In this model, the coupling between the rotational degrees of freedom of the constituent particles and their translations may be switched off by a continuous deformation of a spheroid of aspect ratio t into a sphere (t=1). We demonstrate, by experiments, theory, and computer simulations, that dramatic nonanalytic changes in structure and thermodynamics of the fluids take place, as the coupling between rotations and translations is made to vanish. This nonanalyticity, reminiscent of a second-order liquid-liquid phase transition, is not a trivial consequence of the shape of an individual particle. Rather, free volume considerations relate the observed transition to a similar nonanalyticity at t=1 in structural properties of jammed granular ellipsoids. This observation suggests a deep connection to exist between the physics of jamming and the thermodynamics of simple fluids.

Structure and interactions in fluids of prolate colloidal ellipsoids: comparison between experiment, theory, and simulation.

The microscopic structure of fluids of simple spheres is well known. However, the constituents of most real-life fluids are non-spherical, leading to a coupling between the rotational and translational degrees of freedom. The structure of simple dense fluids of spheroids - ellipsoids of revolution - was only recently determined by direct experimental techniques [A. P. Cohen, E. Janai, E. Mogilko, A. B. Schofield, and E. Sloutskin, Phys. Rev. Lett. 107, 238301 (2011)]. Using confocal microscopy, it was demonstrated that the structure of these simple fluids cannot be described by hard particle models based on the widely used Percus-Yevick approximation. In this paper, we describe a new protocol for determining the shape of the experimental spheroids, which allows us to expand our previous microscopy measurements of these fluids. To avoid the approximations in the theoretical approach, we have also used molecular dynamics simulations to reproduce the experimental radial distribution functions g(r) and estimate the contribution of charge effects to the interactions. Accounting for these charge effects within the Percus-Yevick framework leads to similar agreement with the experiment.

Fluid suspensions of colloidal ellipsoids: direct structural measurements.

A fluid of spheroids, ellipsoids of revolution, is among the simplest models of the disordered matter, where positional and rotational degrees of freedom of the constituent particles are coupled. However, while highly anisometric rods, and hard spheres, were intensively studied in the last decades, the structure of a fluid of spheroids is still unknown. We reconstruct the structure of a simple fluid of spheroids, employing direct confocal imaging of colloids, in three dimensions. The ratio t between the polar axis and the equatorial diameter for both our prolate and oblate spheroids is not far from unity, which gives rise to a delicate interplay between rotations and translations. Strikingly, the measured positional interparticle correlations are significantly stronger than theoretically predicted, indicating that further theoretical attention is required, to fully understand the coupling between translations and rotations in these fundamental fluids.

Analgesic efficacy of modified pectoral block plus serratus plane block in breast augmentation surgery: A randomised, controlled, triple-blind clinical trial. / Eficacia analgésica del bloqueo pectoral modificado más bloqueo del plano del serrato en mamoplastia subpectoral: ensayo clínico, controlado, aleatorizado, triple ciego.

INTRODUCTION: Prosthetic breast surgery is a very common plastic surgery procedure, but its postoperative analgesic management is a challenge for the surgical team. The purpose of the present study is to validate the analgesic efficacy of pectoral block and serratus plane block in retropectoral mammoplasty. PATIENTS AND METHODS: A randomised, controlled, triple-blind, clinical trial was designed, and included 30 patients undergoing retropectoral augmentation mammoplasty. All of them had a modified PECII block and a serratus plane block with a total volume of 40ml per breast. In 15 of them bupivacaine 0.25% (GPEC) was injected and in the other 15 patients saline was used (GC). Standardised management of anaesthesia and postoperative analgesia was performed. Intra-operative haemodynamic parameters required for postoperative analgesia, and a numeric verbal scale on arrival in the recovery unit were measured and at 3, 6, and 24h. The quality perceived by patients and surgeons was also measured. RESULTS: Post-operative pain was significantly better in GPEC (5.3±2.3 vs. 2.9±2.7; P=.018). No significant differences were observed at 3, 6, and 24h. The surgeons rated the anaesthetic-analgesic quality as very good in 80% of the cases in GPEC versus 33% in CG (P=.01). CONCLUSIONS: The use of these blocks is a good perioperative analgesic strategy in the multimodal management of retropectoral augmentation mammoplasty.

The PECS II block as a major analgesic component for clavicle operations: A description of 7 case reports. / Bloqueo PEC II como componente mayor analgésico para operaciones de clavícula: descripción de 7 casos y revisión de la literatura.

Clavicle fractures correspond to 35% of traumatic fractures of the shoulder girdle. Regional anaesthesia has shown better analgesic results than systemic treatment for perioperative management. Innervation of the clavicle is complex, at present its knowledge raises controversy. The lateral pectoral nerve through the innervating musculature predominantly participates in the lateral and anterior part of the clavicle. The following report of 7 cases describes the effective postoperative analgesia of modified PEC II block in patients with middle third clavicle fracture or acromioclavicular dislocation who underwent a modified PEC II block for postoperative pain management, in the context of a multimodal analgesia. The potential advantage of this management over other analgesic procedures should be evaluated in specific clinical trials.

Histologic classification of the combined nevus. Analysis of the variable expression of melanocytic nevi.

The designation combined nevus gives recognition to mixed cytologic patterns. In the common variant, plump, pigmented spindle cells form fascicles among nests of ordinary nevus cells. In other variants, one or several cellular components that share cytologic features with either a blue nevus or a Spitz nevus are represented. Ninety-five cases, 49% of which were of the common type, were studied. Grossly, most of the lesions were darkly pigmented papules or nodules. The clinical diagnosis in three-fourths of the cases was nevus, blue nevus, or melanoma. Fifteen percent had concomitant histologic features of melanocytic dysplasia, and most of these lesions were of the common type. For the common variant, the cytologic features, pattern of apparent infiltration, and variable representation of the features of a premalignant melanocytic dysplasia often mislead a pathologist in interpreting and predicting biologic potential. In combined nevi, the phenotypic diversity and genetic lability of melanocytic nevus cells is manifested.

Predictors of episiotomy use at first spontaneous vaginal delivery.

OBJECTIVE: To identify factors associated with the use of episiotomy at spontaneous vaginal delivery. METHODS: We studied 1576 consecutive term, singleton, spontaneous vaginal deliveries in nulliparas at Brigham & Women's Hospital between December 1, 1994 and July 31, 1995. The association of demographic variables and obstetric factors with the rate of episiotomy use were examined. Adjusted odds ratios (OR) and confidence intervals (CI) were estimated from multiple logistic regression analysis. RESULTS: The overall rate of episiotomy was 40.6% (640 of 1576). Midwives performed episiotomies at a lower rate (21.4%) than faculty (33.3%) and private providers (55.6%) (P =. 001). After controlling for confounding factors with logistic regression, private practice provider was the strongest predictor of episiotomy use (OR, 4.1; 95% CI, 3.1, 5.4) followed by faculty provider (OR, 1.7; 95% CI, 1.1, 2.5), prolonged second stage of labor (OR, 1.8; 95% CI, 1.2, 2.7), fetal macrosomia (OR, 1.6; 95% CI, 1.1, 2.5), and epidural analgesia (OR 1.4, 95% CI, 1.1, 1.8). CONCLUSION: The strongest factor associated with episiotomy at delivery was the category of obstetric provider. Obstetric and demographic factors evaluated did not readily explain this association.

Interpregnancy interval and disparity in term small for gestational age births between black and white women.

OBJECTIVE: To examine the influence of interpregnancy interval on the elevated risk of term small for gestational age (SGA) births to black women. METHODS: This study is a secondary analysis of data from the Delivery Interview Program, a hospital-based cohort study of 12,718 women conducted at the Boston Hospital for Women from 1977 to 1980. The current analysis was limited to black and white parous women who gave birth to term infants during the study and whose last previous pregnancies had also resulted in term, live births. There were 578 black and 3400 white women who met these criteria. The rates of term SGA births for black and white women were calculated according to six interpregnancy intervals (6 or less, 6-12, 12-24, 24-36, 36-60, or longer than 60 months). Multiple logistic regression was used to control for confounding. RESULTS: The overall rate of term SGA births was 6.4% for black women compared with 3.9% for white women (relative risk [RR] 1.7, 95% confidence interval [CI] 1.2, 2.4). Black women were also more likely than white women to have interpregnancy intervals of 6 months or less (9.2% black, 4.8% white; RR 1.9, 95% CI 1.4, 2.6). At every interpregnancy interval, black women had a higher rate of term SGA births than white women. After controlling for interpregnancy interval in a logistic regression analysis, the increased risk of SGA delivery among black women remained unchanged (odds ratio 1.7, 95% CI 1.1, 2.5). CONCLUSION: Although black women were more likely than white women to have SGA births and short interpregnancy intervals, differences in interpregnancy intervals between the races did not explain the disparity in term SGA births.

Epidural analgesia and third- or fourth-degree lacerations in nulliparas.

OBJECTIVE: To determine if epidural analgesia is associated with differences in rates of severe perineal trauma during vaginal deliveries. METHODS: We studied 1942 consecutive, low-risk, term, vaginal deliveries in nulliparas, including spontaneous and induced labors, at a single institution from December 1994 to August 1995. The rate of third- and fourth-degree lacerations was compared for women who had and did not have epidural analgesia for labor-pain relief. Statistical significance was determined using chi2. Logistic regression analyses were used to evaluate associations while controlling for possible confounding variables. RESULTS: Overall rates of third- and fourth-degree lacerations were 10.8% (n = 210) and 3.4% (n = 63), respectively. Epidural analgesia was given to 1376 (70.9%) women. Among women who had epidurals, 16.1% (221 of 1376) had severe perineal lacerations compared with 9.7% (n = 55) of the 566 women who did not have epidurals (P < .001; odds ratio [OR] 1.8, 95% confidence interval [CI] 1.3, 2.4). When controlling for birth weight, use of oxytocin, and maternal age in logistic regression analysis, epidural remained a significant predictor of severe perineal injury (OR 1.4, 95% CI 1.0, 2.0). Epidural use is consistently associated with increased operative vaginal deliveries and consequent episiotomies, so we constructed a logistic regression model to evaluate whether the higher rates of those procedures were responsible for the effect of epidurals on severe perineal traumas. With operative vaginal delivery and episiotomy in the model, epidural was no longer an independent predictor of perineal injury (OR 0.9, 95% CI 0.6, 1.3). CONCLUSION: Epidural analgesia is associated with an increase in the rate of severe perineal trauma because of the more frequent use of operative vaginal delivery and episiotomy.

Treatment of osteoarthritis of the elbow: a comparison of open and arthroscopic debridement.

PURPOSE: To assess the effectiveness of open and minimally invasive techniques in the debridement of osteoarthritis of the elbow, we compared the Outerbridge-Kashiwagi (O-K) procedure with an arthroscopic modification in which arthroscopic debridement and fenestration of the olecranon fossa was performed. TYPE OF STUDY: The study took the form of a nonrandomized control trial in which subjects were allocated to a treatment depending on the hospital of presentation. MATERIALS AND METHODS: Assessment using the Mayo Clinic elbow function chart enabled comparison of the outcome in 18 cases treated by the O-K procedure and 26 patients treated by arthroscopic debridement and fenestration of the olecranon fossa. Mean follow-up was 35.3 months (minimum 12 months). Of the patients treated by the O-K procedure, 14 were men and 4 were women with a mean age of 55 years. In 83% of patients, the diagnosis was primary osteoarthritis, with the remainder post-traumatic arthritis. The patients treated by arthroscopic debridement and fenestration of the olecranon fossa included 24 men and 2 women with a mean age of 46 years, and a diagnosis of primary osteoarthritis in 91% and post-traumatic arthritis in the remainder. No patients were excluded from the study or refused to be included. RESULTS: Both procedures were shown to be effective, with no major complications. Patients treated by arthroscopic debridement and fenestration of the olecranon fossa achieved better relief of pain (P <.10), whereas those patients undergoing the O-K procedure achieved significantly greater improvement in range of flexion (P <.05). No difference between the procedures in terms of patient-perceived overall effectiveness of the surgery was found. CONCLUSIONS: In conclusion, in the treatment of osteoarthritis of the elbow, arthroscopic debridement and fenestration of the olecranon fossa may be a more suitable procedure when painful symptoms predominate. In contrast, the O-K procedure is a significantly better procedure for improving the range of flexion where this is a particular problem.

An uncommon injury of the thumb.

Ulnar collateral ligament rupture of the thumb is a relatively common injury that is often missed in the emergency department. This in combination with an interphalangeal joint dislocation of the ipsilateral thumb is rare and we report such a case. The importance of looking specifically for an associated ulnar collateral ligament laxity in any injury to the thumb is highlighted. The force producing a combination of ulnar collateral ligament rupture with ipsilateral simultaneous injury to the thumb is often severe enough to cause complete rupture of the ligament, necessitating open repair.

Advances in the diagnosis and management of chronic pulmonary aspiration in children.

Chronic pulmonary aspiration (CPA) in children is an important cause of recurrent pneumonia, progressive lung injury, respiratory disability and death. It is sporadic, intermittent and variable, and often occurs in children with complicated underlying medical conditions and syndromes that produce symptoms indistinguishable from CPA. For most types of aspiration there is no gold-standard diagnostic test. The diagnosis of CPA is currently made clinically with some supporting diagnostic evaluations, but often not until significant lung injury has been sustained. Despite multiple diagnostic techniques, the diagnosis or exclusion of CPA in children is challenging. This is of particular concern given the outcome of unrecognised progressive lung injury and the invasiveness of definitive therapies. Although new techniques have been introduced since the 1990s and significant advances in the understanding of dysphagia and gastro-oesophageal reflux have been made, characterisation of the aspirating child remains elusive.

Diagnostic and treatment implications of nasal obstruction in snoring and obstructive sleep apnea.

LEARNING OBJECTIVES: The purpose of this review is to highlight fundamental aspects of obstructive sleep apnea (OSA), and to present an overview of the medical literature that pertains to the clinical interplay between various allergy-related disorders, nasal patency, and OSA. This should enable the reader to play a more proactive role in the diagnosis, management, and prevention of OSA. DATA SOURCES: Relevant reviews, texts, and articles. The MEDLINE database was used to find related literature. CONCLUSIONS: In predisposed individuals, OSA, sleep fragmentation, and the sequelae of disturbed sleep often result from nasal obstruction. Since breathing through the nose appears to be the preferred route during sleep, nasal obstruction frequently leads to nocturnal mouth breathing, snoring, and ultimately to OSA. Allergists can thus play a vital role in assessing sleep problems in their patients with allergic rhinitis and other upper respiratory disorders, in treating these problems more aggressively, and in some instances, in preventing them.

Focused rigidity casting: a prospective randomised study.

Focused rigidity casting was compared with standard casting in a randomised prospective study. Two hundred consecutive patients attending a fracture clinic were assigned to have either a standard cast consisting of synthetic or plaster of paris, or a focused rigidity cast of synthetic material. Patients were assessed using a specially developed scoring system termed the Bradford Plaster Index. In patients with fractures of the base of fifth metatarsal, focused rigidity casting proved superior to traditional techniques for ability score (p=0.0001), satisfaction score (p=0.0023), overall impairment of function (p=0.019), limitation of movement following cast removal (p=0.024) and in limitation of muscle strength following cast removal (p=0.001). In fractures of the distal radius, focused rigidity casting was superior for ability score (p=0.0002) and satisfaction score (p=0.00009). Patients with scaphoid fractures were better for satisfaction score (p=0.0483). Compared with the standard technique, focused rigidity casting has been shown to be superior to traditional methods with regard to satisfaction and functional scores without any detriment to clinical results.

Arthroplasty of the shoulder in rheumatoid arthritis with rotator cuff dysfunction.

We carried out a retrospective analysis of 17 total shoulder replacements using the reversed Delta III prosthesis in patients with rheumatoid arthritis of the glenohumeral joint complicated by rotator cuff dysfunction. Outcome was assessed using the Constant-Murley scoring system. In addition, general health status was assessed with the Short Form Health Survey and radiographical analysis of the prostheses undertaken. Mean age at the time of surgery was 64 years. Thirteen shoulders were followed up for more than 5 years (mean 87 months). Median Constant-Murley score was 59.0; median scores for general health were 33.40 and 49.36 for the physical and mental components respectively. Radiographical analysis revealed evidence of lucencies about the humeral component in all cases and about the glenoid component in five cases. Despite the good clinical results, the high incidence of radiographical lucencies is of concern.

Impingement fracture of the anteromedial tibial margin: a radiographic sign of combined posterolateral complex and posterior cruciate ligament disruption.

Marginal fractures of the tibial plateau are associated with a high incidence of soft tissue injuries to the stabilising structures of the knee joint. Injuries to the anterior cruciate ligament are associated with the Segond fracture and impingement fractures of the posteromedial tibial plateau. Recognition of these fractures aids diagnosis of these injuries. Marginal fractures of the tibial plateau associated with posterior cruciate ligament injuries are less common, though recently a "reverse" Segond fracture has been recognised. We describe a fracture of the anteromedial tibial plateau associated with complete disruption of the posterior cruciate ligament and posterolateral complex.

Review: systemic effects of femoral nailing: from Küntscher to the immune reactivity era.

Intramedullary nailing is the preferred treatment for stabilizing femoral diaphyseal fractures. Despite the superior biomechanical advantages over other implants, its use especially in some selected groups of patients, has been questioned because of possible harmful systemic effects of intramedullary reaming. The lung seems to be the primary target for fat embolization and for mediated effects by inflammatory reactions. The latter are initiated in the immediate aftermath after injury, and femoral nailing can amplify these responses. The role of reaming in the context of early femoral fracture fixation in the patient experiencing trauma is debatable. This review article focuses on the evidence that has emerged during the past century regarding the systemic effects of femoral nailing.

No increase in rates of early-onset neonatal sepsis by non-group B Streptococcus or ampicillin-resistant organisms.

OBJECTIVE: We assessed the impact of a risk-based approach to group B Streptococcus (GBS) prophylaxis on the rates of early-onset neonatal sepsis (EONS). STUDY DESIGN: A retrospective cohort study of neonates born at a tertiary-care hospital from 1990 to 1996 was performed. Cases of EONS were identified among neonates born in a period without GBS prophylaxis (1990-1992) and compared with those born in a period with GBS prophylaxis (1993-1996). The antibiotic susceptibility data on each organism isolated in the blood culture were obtained. RESULTS: In the period without prophylaxis, 99 cases of EONS were identified among 25,934 neonates for a rate of 3.8 per 1000 births. In the period with prophylaxis, 90 cases of EONS occurred among 34,262 neonates for a rate of 2.6 per 1000. The rate of GBS-EONS significantly decreased between the 2 periods (from 1.9 to 1.1, P =.01). There was a trend toward a decrease in the rate of EONS caused by non-GBS gram-positive organisms (from 1.2 to 0.7, P =.06). There was no significant increase in the rate of EONS caused by gram-negative or ampicillin-resistant organisms. CONCLUSIONS: A risk-based approach to GBS prophylaxis reduced the incidence of GBS-EONS at a tertiary-care hospital. This decrease was not accompanied by an increase in the incidence of EONS by non-GBS or ampicillin-resistant organisms.

Low birthweight at term and the timing of fetal exposure to maternal smoking.

OBJECTIVES: This study was undertaken to evaluate the risk of small-for-gestational-age birth for women who stop smoking or begin to smoke during pregnancy. METHODS: Women with term singleton pregnancies from a hospital-based cohort of 11,177 were classified as (1) nonsmokers; (2) smoked throughout pregnancy; (3) smoked during first trimester only; (4) smoked during first and second trimesters only; and (5) smoked during second and third trimesters or during third trimester only. Risk of small-for-gestational-age birth according to smoking category was estimated and adjusted for confounding factors by logistic regression. RESULTS: Women who stopped smoking by the third trimester were not at increased risk of small-for-gestational-age birth compared with nonsmokers. Women who began smoking during the second or third trimester had an elevated risk of small-for-gestational-age birth (odds ratio [OR] = 1.83; 95% confidence interval [CI] = 1.25, 2.67) similar to that for women who smoked throughout pregnancy (OR = 2.20; 95% CI = 1.90, 2.54). Risk of small-for-gestational-age birth increased with the number of cigarettes smoked during the third trimester. CONCLUSIONS: It is during the third trimester that smoking retards fetal growth, presenting a compelling opportunity for smoking cessation interventions. Programs must emphasize the importance of not resuming smoking late in pregnancy.