Rotating polygon instability of a swirling free surface flow

We explain the rotating polygon instability on a swirling fluid surface [G. H. Vatistas, J. Fluid Mech. 217, 241 (1990) and Jansson et al., Phys. Rev. Lett. 96, 174502 (2006)] in terms of resonant interactions between gravity waves on the outer part of the surface and centrifugal waves on the inner part. Our model is based on potential flow theory, linearized around a potential vortex flow with a free surface for which we show that unstable resonant states appear. Limiting our attention to the lowest order mode of each type of wave and their interaction, we obtain an analytically soluble model, which, together with estimates of the circulation based on angular momentum balance, reproduces the main features of the experimental phase diagram. The generality of our arguments implies that the instability should not be limited to flows with a rotating bottom (implying singular behavior near the corners), and indeed we show that we can obtain the polygons transiently by violently stirring liquid nitrogen in a hot container.

[Transurethral resection (TUR) in saline plasma vaporization of the prostate versus standard TUR of the prostate: an economic evaluation]

OBJECTIVE

To evaluate and compare the hospital costs of the transurethral resection in saline plasma vaporization of the prostate (TURis-PVP) and the standard TUR of the prostate (TURP).

BACKGROUND

their efficiency and short terms outcomes are similar.

PATIENTS AND METHODS

In an observational retrospective and monocentric study, 86 consecutive patients with benign prostatic enlargement (BPE) secondary to benign prostatic hyperplasia (BPH) were enrolled in two non randomized groups. TURP was performed in 44 cases and TURis-PVP in 42 cases. Patients with prostate cancer, urethral stenosis or bladder neck stenosis were not included. Hospital costs with a 3-month follow-up were measured using the database and hospital cost accounting system of the Medical Information Department.

RESULTS

Patients from both series had similar preoperative characteristics concerning the age, ASA score, urologic history, and antithrombosis treatments. Catheterization period, complications and rehospitalisation rates were similar. With TURis-PVP, prostatic volume was larger (60±24mL vs. 42±16mL; P<0.05), hospital stay was shorter (4.0±2.8days vs. 4.4±2.1days; P<0.05), single-used materials costs were higher (332±64€ vs. 40±18€; P<0.05). The costs of the first hospitalization were 3721±843€ with TURis-PVP and were 3712±880€ with TURP (P=0.14). Global costs with a 3-month follow-up were 3867±1104€ with TURis-PVP and were 4074±1624€ with TURP (P=0.53).

CONCLUSION

In this study, the costs for the hospital are lightly higher in TURis-PVP, due to single use systems, but there is no significant difference for global costs between TURP and TURis-PVP with a 3-month follow-up difference for the health care system.

Over-expression of a cytosolic isoform of the HbCuZnSOD gene in Hevea brasiliensis changes its response to a water deficit

Hevea brasiliensis is the main commercial source of natural rubber. Reactive oxygen species (ROS) scavenging systems are involved in various biotic and abiotic stresses. Genetic engineering was undertaken to study the strengthening of plant defences by antioxidants. To that end, Hevea transgenic plant lines over-expressing a Hevea brasiliensis cytosolic HbCuZnSOD gene were successfully established and regenerated. Over-expression of the HbCuZnSOD gene was not clearly related to an increase in SOD activity in plant leaves. The impact of HbCuZnSOD gene over-expression in somatic embryogenesis and in plant development are presented and discussed. The water deficit tolerance of two HbCuZnSOD over-expressing lines was evaluated. The physiological parameters of transgenic plantlets subjected to a water deficit suggested that plants from line TS4T8An displayed lower stomatal conductance and a higher proline content. Over-expression of the HbCuZnSOD gene and activation of all ROS-scavenging enzymes also suggested that protection against ROS was more efficient in the TS4T8An transgenic line.

[Surgical treatment of pulmonary arterial hypertension]

INTRODUCTION

Pulmonary arterial hypertension (PAH) is a severe disease that has undergone a dramatic improvement in therapeutic management over the past 20 years. Among the new therapeutic options, surgery has the potential to dramatically improve or, in some cases, cure PAH.

BACKGROUND

Surgical treatment of PAH includes pulmonary endarterectomy which can cure PAH when the cause is obstruction of the pulmonary arteries by fibrous tissue resulting from pulmonary embolism, by tumours as angiosarcomas, and echinococcus cysts. Transplantation is required in end-stage PAH after failure of medical treatment. Atrial septostomy and Potts procedure are palliative surgical procedures that can delay transplantation.

VIEWPOINT

Extracorporeal cardiopulmonary support is the latest surgical improvement, not only as a bridge to transplantation in end-stage PAH but also during recovery after transplantation or pulmonary endarterectomy.

CONCLUSIONS

Surgery is part of the therapeutic management of PAH. Dialogue between physicians and surgeons is a prerequisite for any reasoned therapeutic decision.

Workplace bullying and psychotropic drug use: the mediating role of physical and mental health status

OBJECTIVES

The association between workplace bullying and psychotropic drug use is not well established. This study was aimed at exploring the association between workplace bullying, and its characteristics, and psychotropic drug use and studying the mediating role of physical and mental health.

METHODS

The study population consisted of a random sample of 3132 men and 4562 women of the working population in the south-east of France. Workplace bullying, evaluated using the validated instrument elaborated by Leymann, and psychotropic drug use, as well as covariates, were measured using a self-administered questionnaire. Covariates included age, marital status, presence of children, education, occupation, working hours, night work, physico-chemical exposures at work, self-reported health, and depressive symptoms. Statistical analysis was performed using logistic regression analysis and was carried out separately for men and women.

RESULTS

Workplace bullying was strongly associated with psychotropic drug use. Past exposure to bullying increased the risk for this use. The more frequent and the longer the exposure to bullying, the stronger the association with psychotropic drug use. Observing bullying on someone else at the workplace was associated with psychotropic drug use. Adjustment for covariates did not modify the results. Additional adjustment for self-reported health and depressive symptoms reduced the magnitude of the associations, especially for men.

CONCLUSIONS

The association between bullying and psychotropic drug use was found to be significant and strong and was partially mediated by physical and mental health.

Phenology, growth and physiological adjustments of oil palm (Elaeis guineensis) to sink limitation induced by fruit pruning

BACKGROUND AND AIMS

Despite its simple architecture and small phenotypic plasticity, oil palm has complex phenology and source-sink interactions. Phytomers appear in regular succession but their development takes years, involving long lag periods between environmental influences and their effects on sinks. Plant adjustments to resulting source-sink imbalances are poorly understood. This study investigated oil palm adjustments to imbalances caused by severe fruit pruning.

METHODS

An experiment with two treatments (control and complete fruit pruning) during 22 months in 2006-2008) and six replications per treatment was conducted in Indonesia. Phenology, growth of above-ground vegetative and reproductive organs, leaf morphology, inflorescence sex differentiation, dynamics of non-structural carbohydrate reserves and light-saturated net photosynthesis (A(max)) were monitored.

KEY RESULTS

Artificial sink limitation by complete fruit pruning accelerated development rate, resulting in higher phytomer, leaf and inflorescence numbers. Leaf size and morphology remained unchanged. Complete fruit pruning also suppressed the abortion of male inflorescences, estimated to be triggered at about 16 months before bunch maturity. The number of female inflorescences increased after an estimated lag of 24-26 months, corresponding to time from sex differentiation to bunch maturity. The most important adjustment process was increased assimilate storage in the stem, attaining nearly 50 % of dry weight in the stem top, mainly as starch, whereas glucose, which in controls was the most abundant non-structural carbohydrate stored in oil palm, decreased.

CONCLUSIONS

The development rate of oil palm is in part controlled by source-sink relationships. Although increased rate of development and proportion of female inflorescences constituted observed adjustments to sink limitation, the low plasticity of plant architecture (constant leaf size, absence of branching) limited compensatory growth. Non-structural carbohydrate storage was thus the main adjustment process.

Workplace bullying and sleep disturbances: findings from a large scale cross-sectional survey in the French working population

STUDY OBJECTIVES

The purpose of this study was to explore the associations between workplace bullying, the characteristics of workplace bullying, and sleep disturbances in a large sample of employees of the French working population.

DESIGN

Workplace bullying, evaluated using the validated instrument developed by Leymann, and sleep disturbances, as well as covariates, were measured using a self-administered questionnaire. Covariates included age, marital status, presence of children, education, occupation, working hours, night work, physical and chemical exposures at work, self-reported health, and depressive symptoms. Statistical analysis was performed using logistic regression analysis and was carried out separately for men and women.

SETTING

General working population.

PARTICIPANTS

The study population consisted of a random sample of 3132 men and 4562 women of the working population in the southeast of France.

RESULTS

Workplace bullying was strongly associated with sleep disturbances. Past exposure to bullying also increased the risk for this outcome. The more frequent the exposure to bullying, the higher the risk of experiencing sleep disturbances. Observing someone else being bullied in the workplace was also associated with the outcome. Adjustment for covariates did not modify the results. Additional adjustment for self-reported health and depressive symptoms diminished the magnitude of the associations that remained significant.

CONCLUSIONS

The prevalence of workplace bullying (around 10%) was found to be high in this study as well was the impact of this major job-related stressor on sleep disturbances. Although no conclusion about causality could be drawn from this cross-sectional study, the findings suggest that the contribution of workplace bullying to the burden of sleep disturbances may be substantial.

Role of transitory carbon reserves during adjustment to climate variability and source-sink imbalances in oil palm (Elaeis guineensis)

Oil palm (Elaeis guineensis Jacq.) is a perennial, tropical, monocotyledonous plant characterized by simple architecture and low phenotypic plasticity, but marked by long development cycles of individual phytomers (a pair of one leaf and one inflorescence at its axil). Environmental effects on vegetative or reproductive sinks occur with various time lags depending on the process affected, causing source-sink imbalances. This study investigated how the two instantaneous sources of carbon assimilates, CO(2) assimilation and mobilization of transitory non-structural carbohydrate (NSC) reserves, may buffer such imbalances. An experiment was conducted in Indonesia during a 22-month period (from July 2006 to May 2008) at two contrasting locations (Kandista and Batu Mulia) using two treatments (control and complete fruit pruning treatment) in Kandista. Measurements included leaf gas exchange, dynamics of NSC reserves and dynamics of structural aboveground vegetative growth (SVG) and reproductive growth. Drought was estimated from a simulated fraction of transpirable soil water. The main sources of variation in source-sink relationships were (i) short-term reductions in light-saturated leaf CO(2) assimilation rate (A(max)) during seasonal drought periods, particularly in Batu Mulia; (ii) rapid responses of SVG rate to drought; and (iii) marked lag periods between 16 and 29 months of environmental effects on the development of reproductive sinks. The resulting source-sink imbalances were buffered by fluctuations in NSC reserves in the stem, which mainly consisted of glucose and starch. Starch was the main buffer for sink variations, whereas glucose dynamics remained unexplained. Even under strong sink limitation, no negative feedback on A(max) was observed. In conclusion, the different lag periods for environmental effects on assimilate sources and sinks in oil palm are mainly buffered by NSC accumulation in the stem, which can attain 50% (dw:dw) in stem tops. The resulting dynamics of growth and production are complex because several dozen phytomers of different phenological ages develop at any given time and interact with a common pool of reserves.

Comparative use of perioperative chemotherapy (CT) in non-small cell lung cancer (NSCLC) between 2004 and 2007

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Background: Adjuvant (ADJ) platinum-based CT has become a new standard of care for patients (pts) with resected stage II and III NSCLC, and is discussed in selected stage IB pts. Impact of positive randomized trials which showed significant survival improvement (first published in 2004) on the use of ADJ CT has been poorly studied to date. Methods: A retrospective study of consecutive pts with NSCLC who underwent curative surgery during the first half of year 2004 and 2007 in the surgical center Marie Lannelongue (France) was conducted. Logistic regression models were employed to identify cofactors associated with the use of ADJ CT (excluding stage IV). Odds ratio (OR) > 1 corresponds to a more frequent use than in reference group. Results: A total of 240 pts (116 in 2004, 124 in 2007) underwent curative surgery for NSCLC (11% IA; 30% IB; 27% II; 27% III; 5% IV). Among all pts, 12 % received neoADJ CT (less in 2007, 8% vs 16% p=.04), 35% ADJ (4% both). Reasons for not receiving ADJ CT included stage I (34%), death (11%), comorbidities (10%), poor performance status (10%), advanced age (8%), post-operative complications (7%), patient refusal (3%). More ADJ CT was prescribed in 2007 (41% vs 30% in 2004, p=.009). Overall, 45% of pts with stage II-III received ADJ CT in 2004 versus 69% did so in 2007. In multivariate analysis (194 pts), ADJ CT was associated with the year of inclusion (OR=2.67 p=.009), stage (stage II, OR=6.77, stage III, OR=16.85; p<.0001), serious medical history (OR=.41 p=.01) and salvage surgery (OR=.26 p=.03). Cisplatin was the preferred platinum compound in 76% of neoADJ regimens (mostly cisplatin-docetaxel), and 70% of ADJ CT (mostly cisplatin-vinorelbine). Conclusions: The presentation and publication of “positive” ADJ CT trials had significantly increased prescription of ADJ CT in pts with stage II-III NSCLC. Nevertheless 31% of the stage II-III did not received CT mostly because of comorbidities, highlighting the need of a personalized CT.

No significant financial relationships to disclose.

Combining convective/capillary deposition and AFM oxidation lithography for close-packed directed assembly of colloids

We combine convective/capillary deposition and oxidation lithography by atomic force microscopy to direct the close-packed assembly of colloids on SiOx patterns fabricated on silicon substrates previously functionalized with a hydrophobic monolayer of octadecyltrimethoxysilane. The efficiency of this original generic method, which is well adapted to integrate colloids into silicon devices, is demonstrated for 100 nm colloidal latex nanoparticles and Escherichia coli bacteria in aqueous suspensions. A three-step mechanism involving convective flow and capillary forces appears to be responsible for these close-packed assemblies of colloids onto SiOx patterns.

Orchestration of transpiration, growth and carbohydrate dynamics in rice during a dry-down cycle

The regulation of carbohydrate metabolism and source-sink relationships among organs play a key role in plant adaptation to drought. This study aimed at characterising the dynamics of transpiration, development, growth and carbon metabolism, as well as the expression of invertase genes, in response to drought during a dry-down cycle. Three 1-month experiments were conducted in controlled environment using the rice genotype IR64 (Oryza sativa L., indica). Plant leaf relative transpiration and expansion rates decreased linearly when fraction of transpirable soil water (FTSW) dropped below 0.66 and 0.58, respectively. Hexose and starch concentration responses to FTSW in a given organ were generally linear and opposite: in source leaves, hexose concentration increased and starch decreased, and vice versa in sink leaves and roots. Sucrose remained constant in source leaves and increased slightly in sink leaves. Starch reserves built up during stress in sink organs were rapidly mobilised upon rewatering, indicating its involvement in a mechanism to ensure recovery. Expression of cell-wall and vacuolar invertase genes under stress increased in sink leaves, interpreted as a mechanism to maintain sink activity (cell wall) and osmotic adjustment (vacuolar). It is concluded that carbohydrate metabolism in sink organs under drought is highly regulated, and important for stress adaptation.

Surgical Management of Mediastinal Goiters: When Is a Sternotomy Required?

OBJECTIVE

Mediastinal goiters are frequently diagnosed, particularly in the elderly population. However, factors associated with an increased risk of median sternotomy have not been analyzed systematically.

METHODS

Between 1980 and 2004, a total of 185 patients underwent surgery for mediastinal goiters in our institution. There were 126 women and 59 men with a median age of 68 years (range 24 to 94 years). The goiters were left-sided in 77 patients, right-sided in 69 patients, and bilateral in 39 patients.

RESULTS

Clinical presentation was mainly dyspnea (37 %), palpation of a cervical mass (35 %), superior vena cava syndrome (5 %), dysphagia (4 %) and dysphonia (4 %). Goiters measured between 5 and 23 cm (median 10 cm) and were prevascular (38 %), retrovascular and paratracheal (33 %), and retrotracheal (27 %). Aberrant intrathoracic goiters were observed in 4 patients (2 %). The large majority of goiters could be removed transcervically, regardless of the location and extension of the goiters. A sternotomy was required in 13 patients (6 %), mainly because of recurrent goiter ( P = 0.1), ectopic goiter ( P < 0.001), or invasive carcinoma ( P < 0.001). Superior vena cava syndrome, emergent airway compression, dysphagia, retrotracheal goiter, or crossover goiters were not found to be associated with an increased risk of sternotomy. One patient (0.5 %) died postoperatively from massive intraoperative carcinomatous pulmonary emboli. Histology demonstrated a thyroid carcinoma in 18 patients (10 %).

CONCLUSIONS

Surgery for mediastinal goiters should always be considered, even in elderly patients because of the high risk of tracheal compression and the low morbidity of the surgery. Most mediastinal goiters are benign and can be removed through a cervical approach. Sternotomy should only be performed in cases of previous cervical thyroidectomy, invasive carcinoma, or ectopic goiter.