Role of different negative pressure values in the process of infected wounds treated by vacuum-assisted closure: an experimental study.

Science.gov (United States)

Zhou, Min; Yu, Aixi; Wu, Gang; Xia, Chengyan; Hu, Xiang; Qi, Baiwen

2013-10-01

Vacuum-assisted closure (VAC) device is widely used to treat infected wounds in clinical work. Although the effect of VAC with different negative pressure values is well established, whether different negative pressures could result in varying modulation of wound relative cytokines was not clear. We hypothesise that instead of the highest negative pressure value the suitable value for VAC is the one which is the most effective on regulating wound relative cytokines. Infected wounds created on pigs' back were used to investigate the effects of varying negative pressure values of VAC devices. Wounds were treated with VAC of different negative pressure values or moist gauze, which was set as control. The VAC foam, semiocclusive dresses and moist gauze were changed on days 3, 5, 7 and 9 after wounds were created. When changing dressings, tissues from wounds were harvested for bacteria count and histology examination including Masson's trichrome stain and immunohistochemistry for microvessels. Western blot was carried out to test the expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF). Results showed that on days 3 and 5 the number of bacteria in wounds treated by VAC with 75, 150, 225 and 300 mmHg was significantly decreased compared with that in wounds treated by gauze and 0 mmHg pressure value. However, there was no difference in wounds treated with negative pressure values of 75 , 150, 225 and 300 mmHg at any time spot. Immunohistochemistry showed that more microvessels were generated in wounds treated by VAC using 75 and 150 mmHg negative pressure comparing with that using 225 and 300 mmHg on days 3 and 5. However this difference vanished on days 7 and 9. Morphological evaluation by Masson's trichrome staining showed increased collagen deposition in VAC of 75 and 150 mmHg compared with that in VAC of 225 and 300 mmHg. Western blot showed that the expression of VEGF and bFGF significantly increased when the wounds

Perceived social pressure not to experience negative emotion is linked to selective attention for negative information.

Science.gov (United States)

Bastian, Brock; Pe, Madeline Lee; Kuppens, Peter

2017-02-01

Social norms and values may be important predictors of how people engage with and regulate their negative emotional experiences. Previous research has shown that social expectancies (the perceived social pressure not to feel negative emotion (NE)) exacerbate feelings of sadness. In the current research, we examined whether social expectancies may be linked to how people process emotional information. Using a modified classical flanker task involving emotional rather than non-emotional stimuli, we found that, for those who experienced low levels of NE, social expectancies were linked to the selective avoidance of negative emotional information. Those who experienced high levels of NE did not show a selective avoidance of negative emotional information. The findings suggest that, for people who experience many NEs, social expectancies may lead to discrepancies between how they think they ought to feel and the kind of emotional information they pay attention to.

Variations of Negative Pressure Wound Therapy

African Journals Online (AJOL)

a living reaction which serves to eradicate necrotic tissue and suppress bacterial propagation. In order to gain maximum advantages from NPWT, not only the negative pressure environment, but also the selection of the most suitable dressing material will be necessary. Regarding the treatment of diabetic foot ulcers, there.

Negative pressure characteristics of an evaporating meniscus at nanoscale

Directory of Open Access Journals (Sweden)

Maroo Shalabh

2011-01-01

Full Text Available Abstract This study aims at understanding the characteristics of negative liquid pressures at the nanoscale using molecular dynamics simulation. A nano-meniscus is formed by placing liquid argon on a platinum wall between two nano-channels filled with the same liquid. Evaporation is simulated in the meniscus by increasing the temperature of the platinum wall for two different cases. Non-evaporating films are obtained at the center of the meniscus. The liquid film in the non-evaporating and adjacent regions is found to be under high absolute negative pressures. Cavitation cannot occur in these regions as the capillary height is smaller than the critical cavitation radius. Factors which determine the critical film thickness for rupture are discussed. Thus, high negative liquid pressures can be stable at the nanoscale, and utilized to create passive pumping devices as well as significantly enhance heat transfer rates.

Relaxation effects in ionic mobility and cluster formation: negative ions in SF6 at high pressures

International Nuclear Information System (INIS)

Juarez, A M; De Urquijo, J; Hinojosa, G; Hernandez-Avila, J L; Basurto, E

2010-01-01

The relaxation effects of the ionic mobility and the formation of negative-ion clusters in SF 6 are studied in this work. For this purpose, we have measured the mobility of negative ions in SF 6 over the pressure range 100-800 Torr at a fixed value of density-normalized electric field, E/N, of 20 Td (1 Townsend = 10 -17 V cm 2 ). The data obtained show a clear dependence of the negative-ion drift velocity on drift distance. It is observed that the drift velocity (mobility) reaches a steady-state value only for drift distances above 2 cm, over the studied pressure range. In addition to this, we have observed that the ionic mobility depends strongly on the gas pressure. An explanation of this dependence of the ionic mobility on gas pressure is given in terms of a negative-ion clustering formation process. It was found that the assumption of a linear dependence of the cluster ion mass on pressure provides a satisfactory explanation for the observed mobilities.

Negative-pressure wound therapy with instillation: international consensus guidelines.

Science.gov (United States)

Kim, Paul J; Attinger, Christopher E; Steinberg, John S; Evans, Karen K; Lehner, Burkhard; Willy, Christian; Lavery, Larry; Wolvos, Tom; Orgill, Dennis; Ennis, William; Lantis, John; Gabriel, Allen; Schultz, Gregory

2013-12-01

Negative-pressure wound therapy with instillation is increasingly utilized as an adjunct therapy for a wide variety of wounds. Despite its growing popularity, there is a paucity of evidence and lack of guidance to provide effective use of this therapy. A panel of experts was convened to provide guidance regarding the appropriate use of negative-pressure wound therapy with instillation. A face-to-face meeting was held where the available evidence was discussed and individual clinical experience with this therapy was shared. Follow-up communication among the panelists continued until consensus was achieved. The final consensus recommendations were derived through more than 80 percent agreement among the panelists. Nine consensus statements were generated that address the appropriate use of negative-pressure wound therapy with instillation. The question of clinical effectiveness of this therapy was not directly addressed by the consensus panel. This document serves as preliminary guidelines until more robust evidence emerges that will support or modify these consensus recommendations.

Negative-pressure and low-pressure hydrocephalus: the role of cerebrospinal fluid leaks resulting from surgical approaches to the cranial base.

Science.gov (United States)

Filippidis, Aristotelis S; Kalani, M Yashar S; Nakaji, Peter; Rekate, Harold L

2011-11-01

Negative-pressure and low-pressure hydrocephalus are rare clinical entities that are frequently misdiagnosed. They are characterized by recurrent episodes of shunt failure because the intracranial pressure is lower than the opening pressure of the valve. In this report the authors discuss iatrogenic CSF leaks as a cause of low- or negative-pressure hydrocephalus after approaches to the cranial base. The authors retrospectively reviewed cases of low-pressure or negative-pressure hydrocephalus presenting after cranial approaches complicated with a CSF leak at their institution. Three patients were identified. Symptoms of high intracranial pressure and ventriculomegaly were present, although the measured pressures were low or negative. A blocked communication between the ventricles and the subarachnoid space was documented in 2 of the cases and presumed in the third. Shunt revisions failed repeatedly. In all cases, temporary clinical and radiographic improvement resulted from external ventricular drainage at subatmospheric pressures. The CSF leaks were sealed and CSF communication was reestablished operatively. In 1 case, neck wrapping was used with temporary success. Negative-pressure or low-pressure hydrocephalus associated with CSF leaks, especially after cranial base approaches, is difficult to treat. The solution often requires the utilization of subatmospheric external ventricular drains to establish a lower ventricular drainage pressure than the drainage pressure created in the subarachnoid space, where the pressure is artificially lowered by the CSF leak. Treatment involves correction of the CSF leak, neck wrapping to increase brain turgor and allow the pressure in the ventricles to rise to the level of the opening pressure of the valve, and reestablishing the CSF route.

Abdominal compartment syndrome and open abdomen management with negative pressure devices.

Science.gov (United States)

Surace, Alessandra; Ferrarese, Alessia; Marola, Silvia; Cumbo, Jacopo; Valentina, Gentile; Borello, Alessandro; Solej, Mario; Martino, Valter; Nano, Mario

2015-01-01

Abdominal compartment syndrome (ACS) is defined as an increase of intra-abdominal pressure (IAH) to values higher than 20 mmHg, associated with reduced perfusion and organ dysfunction. There is a classification of open abdomen which stratifies patients according to the natural history of improvement or clinical deterioration. The aim of treatment is to maintain the open abdomen at the lowest level and to prevent progression to a more complex level. Surgical treatment essentially consists in abdominal decompression by leaving the abdomen open. Analysis of the literature shows that negative pressure increases the rate of primary fascial closure; entero-cutaneous fistulas are seen in a minority of cases, without seeming consequence of the application of the dressing. Open abdomen management consists of three treatment stages: acute (24-48 hours), intermediate (from 48 hours to 10 days) and late or reconstruction (from 10 days to the final closure). It's important to recognize patients at risk of IAH and the first signs of ACS and intervene early with abdominal decompression if this will establish itself. Management of the open abdomen is now facilitated by negative pressure devices, which positively affect the morbidity and mortality of patients with ACS.

Incisional Negative Pressure Wound Therapy

DEFF Research Database (Denmark)

Hyldig, Nana

the rate of surgical wound infection and wound exudate post-caesarean and that wound infection had a negative impact on quality of life one month after surgery. Alongside the clinical trial, a trial-based cost-effectiveness analysis demonstrated that the treatment is cost-effective in a high......Women with a pre-gestational body mass index (BMI) above 30 kg/m2 giving birth by caesarean section are at high risk of surgical wound infection compared with women with a BMI below 30 kg/m2. Incisional Negative Pressure Wound Therapy (iNPWT) is one strategy to reduce the rate of surgical wound...... a randomised controlled trial in two tertiary and three teaching hospitals in three regions of Denmark, the Happy Belly Study, investigating the effectiveness of iNPWT in a population of obese women after caesarean section. The Happy Belly Study has demonstrated that prophylactic iNPWT significantly reduced...

Negative-Pressure Hydrocephalus: A Case Report on Successful Treatment Under Intracranial Pressure Monitoring with Bilateral Ventriculoperitoneal Shunts.

Science.gov (United States)

Pandey, Sajan; Jin, Yi; Gao, Liang; Zhou, Cheng Cheng; Cui, Da Ming

2017-03-01

Negative-pressure hydrocephalus (NegPH), a very rare condition of unknown etiology and optimal treatment, usually presents postneurosurgery with clinical and imaging features of hydrocephalus, but with negative cerebrospinal fluid pressure. We describe a NegPH case of -3 mm Hg intracranial pressure that was successfully treated to achieve 5 mm Hg under continuous intracranial pressure monitoring with horizontal positioning, head down and legs elevated to 10°-15°, neck wrapping for controlled venous drainage, chest and abdomen bandages, infusion of 5% dextrose fluid to lower plasma osmolarity (Na + , 130-135 mmol/L), daily cerebrospinal fluid drainage >200 mL, and arterial blood gas partial pressure of carbon dioxide >40 mm Hg. Copyright © 2016 Elsevier Inc. All rights reserved.

Contrastive Analysis and Research on Negative Pressure Beam Tube System and Positive Pressure Beam Tube System for Mine Use

Science.gov (United States)

Wang, Xinyi; Shen, Jialong; Liu, Xinbo

2018-01-01

Against the technical defects of universally applicable beam tube monitoring system at present, such as air suction in the beam tube, line clogging, long sampling time, etc., the paper analyzes the current situation of the spontaneous combustion fire disaster forecast of mine in our country and these defects one by one. On this basis, the paper proposes a research thought that improving the positive pressure beam tube so as to substitute the negative pressure beam tube. Then, the paper introduces the beam tube monitoring system based on positive pressure technology through theoretical analysis and experiment. In the comparison with negative pressure beam tube, the paper concludes the advantage of the new system and draws the conclusion that the positive pressure beam tube is superior to the negative pressure beam tube system both in test result and test time. At last, the paper proposes prospect of the beam tube monitoring system based on positive pressure technology.

Negative pressure driven phase transformation in Sr doped SmCoO₃.

Science.gov (United States)

Arshad Farhan, M; Javed Akhtar, M

2010-02-24

Atomistic computer simulation techniques based on energy minimization procedures are utilized for the structural investigation of perovskite-type SmCoO(3). A reliable potential model is derived which reproduces both cubic as well as orthorhombic phases of SmCoO(3). We observe a negative chemical pressure induced structural phase transformation from distorted perovskite (orthorhombic) to perfect perovskite (cubic) due to the substitution of Sr(2 + ) at the Sm(3 + ) sites. However, external hydrostatic pressure shows isotropic compression and no pressure-induced structural transformation is observed up to 100 GPa. To maintain the electroneutrality of the system, charge compensation is through oxygen vacancies which results in the brownmillerite-type structure. A defect model is proposed, which is consistent with experimental results. The solution energies for divalent and trivalent cations are also calculated. These results show that the cations having ionic radii less than 0.75 Å will occupy the Co sites and those with ionic radii larger than 0.75 Å will substitute at the Sm sites.

Proposed application of lower body negative pressure to cardiology

Science.gov (United States)

Schmidt, E. V.; Debusk, R. F.; Popp, R. L.

1975-01-01

Potential medical applications are presented of lower body negative pressure to the evaluation and treatment of cardiac patients. The essential features of an LBNP unit and the basic cardiovascular physiology of lower body negative pressure (LBNP) testing are described. Some of the results of previous spaceflight experiences and bedrest studies are summarized. The deconditioning effects of weightlessness experienced by orbiting astronauts are compared with the effects of bedrest restrictions prescribed for convalescing cardiac patients. The potential of LBNP for evaluating both pharmacological and physical activity regimens was examined, particularly in relation to post-myocardial infarction and coronary artery bypass patients. Applications of LBNP to the cardiac catheterization laboratory and the out-patient follow-up of cardiac patients are proposed.

Foliar δ13C Showed No Altitudinal Trend in an Arid Region and Atmospheric Pressure Exerted a Negative Effect on Plant δ13C

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Zixun Chen

2017-07-01

Full Text Available Previous studies have suggested foliar δ13C generally increases with altitude. However, some observations reported no changes or even decreased trends in foliar δ13C. We noted that all the studies in which δ13C increased with elevation were conducted in the human regions, whereas those investigations in which δ13C did not vary or decreased were conducted in areas with water stress. Thus, we proposed that the pattern of increasing δ13C with elevation is not a general one, and that δ13C may remain unchanged or decrease in plants grown in arid environments. To test the hypothesis, we sampled plants along altitude gradients on the shady and sunny slopes of Mount Tianshan characterized by arid and semiarid climates. The measurements of foliar δ13C showed no altitudinal trends for the plants grown on either of the slopes. Therefore, this study supported our hypothesis. In addition, the present study addressed the effect of atmospheric pressure on plant δ13C by accounting for the effects of temperature and precipitation on δ13C. This study found that the residual foliar δ13C increased with increasing altitude, suggesting that atmospheric pressure played a negative role in foliar δ13C.

Novel cavitation fluid jet polishing process based on negative pressure effects.

Science.gov (United States)

Chen, Fengjun; Wang, Hui; Tang, Yu; Yin, Shaohui; Huang, Shuai; Zhang, Guanghua

2018-04-01

Traditional abrasive fluid jet polishing (FJP) is limited by its high-pressure equipment, unstable material removal rate, and applicability to ultra-smooth surfaces because of the evident air turbulence, fluid expansion, and a large polishing spot in high-pressure FJP. This paper presents a novel cavitation fluid jet polishing (CFJP) method and process based on FJP technology. It can implement high-efficiency polishing on small-scale surfaces in a low-pressure environment. CFJP uses the purposely designed polishing equipment with a sealed chamber, which can generate a cavitation effect in negative pressure environment. Moreover, the collapse of cavitation bubbles can spray out a high-energy microjet and shock wave to enhance the material removal. Its feasibility is verified through researching the flow behavior and the cavitation results of the negative pressure cavitation machining of pure water in reversing suction flow. The mechanism is analyzed through a computational fluid dynamics simulation. Thus, its cavitation and surface removal mechanisms in the vertical CFJP and inclined CFJP are studied. A series of polishing experiments on different materials and polishing parameters are conducted to validate its polishing performance compared with FJP. The maximum removal depth increases, and surface roughness gradually decreases with increasing negative outlet pressures. The surface becomes smooth with the increase of polishing time. The experimental results confirm that the CFJP process can realize a high material removal rate and smooth surface with low energy consumption in the low-pressure environment, together with compatible surface roughness to FJP. Copyright © 2017 Elsevier B.V. All rights reserved.

Stress and Negative Relationship Quality among Older Couples: Implications for Blood Pressure.

Science.gov (United States)

Birditt, Kira S; Newton, Nicky J; Cranford, James A; Ryan, Lindsay H

2016-09-01

The cardiovascular system may represent a significant pathway by which marriage and stress influence health, but research has focused on married individuals cross-sectionally. This study examined associations among chronic stress, negative spousal relationship quality, and systolic blood pressure over time among middle-aged and older husbands and wives. Participants were from the nationally representative longitudinal Health and Retirement Study. A total of 1,356 (N = 2,712) married and cohabitating couples completed psychosocial and biomeasure assessments in waves 2006 and 2010. Analyses examined whether Wave 1 (2006) relationship quality and stress were associated with changes in blood pressure over time. The effects of stress and negative relationship quality were dyadic and varied by gender. Husbands had increased blood pressure when wives reported greater stress, and this link was exacerbated by negative spousal relationship quality. Negative relationship quality predicted increased blood pressure when both members of the couple reported negative quality relations. Findings support the dyadic biopsychosocial model of marriage and health indicating: (a) stress and relationship quality directly effect the cardiovascular system, (b) relationship quality moderates the effect of stress, and (c) the dyad rather than only the individual should be considered when examining marriage and health. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Negative Pressures and the First Water Siphon Taller than 10.33 Meters.

Directory of Open Access Journals (Sweden)

Francisco Vera

Full Text Available A siphon is a device that is used to drain a container, with water rising inside a hose in the form of an inverted U and then going down towards a discharge point placed below the initial water level. The siphon is the first of a number of inventions of the ancients documented about 2.000 years ago by Hero of Alexandria in his treatise Pneumatics, and although the explanation given by Hero was essentially correct, there is nowadays a controversy about the underlying mechanism that explains the working of this device. Discussions concerning the physics of a siphon usually refer to concepts like absolute negative pressures, the strength of liquid's cohesion and the possibility of a siphon working in vacuum or in the presence of bubbles. Torricelli understood the working principle of the barometer and the impossibility of pumping water out of wells deeper than 10.33 m. Following Torricelli's ideas it would also not be possible to build a siphon that drives pure water to ascend higher than 10.33 m. In this work, we report the first siphon that drives water (with surfactant to ascend higher than the Torricellian limit. Motivated by the rising of sap in trees, we built a 15.4 m siphon that shows that absolute negative pressures are not prohibited, that cohesion plays an important role in transmitting forces through a fluid, and that surfactants can help to the transport of water in a metastable regime of negative pressures.

Management of High-Voltage Burns of the Hand and Wrist with Negative Pressure Dressing

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Nazım Gümüş

2017-12-01

Full Text Available Objective: Negative pressure dressing stimulates wound healing by promoting cellular proliferation and regeneration. It also removes interstitial edema and increases local blood flow, resulting in rapid growth of the granulation tissue. We used the dressing method in deep hand and wrist burns caused by high-voltage electrical current, which leads to progressive tissue necrosis, elevated compartment pressure, and deep tissue edema, to reveal if subatmospheric pressure could limit the zone of injury or ongoing tissue necrosis after electrical burn. Material and Methods: Six hands of five patients, who came in contact with high-voltage electrical wire carrying more than 1000 volts, are presented in this study. Hands and wrists were seriously injured and contracted. After the initial treatment involving fluid resuscitation, fasciotomy, carpal tunnel release, and debridement, a negative pressure dressing was applied to the wounds of hand, wrist, and forearm with 125 mm Hg continuous pressure, and maintained for 20 days. Results: When negative pressure dressing was stopped on the 20th day, significant granulation tissue developed over the hand and forearm wounds. However, wrist wounds needed more debridement and repeated dressings because of the presence of necrosis. Edema of the hands subsided significantly during the use of negative pressure dressing. Time to closure for hand and forearm wounds decreased considerably. Moreover, in one wrist, spontaneous closure was achieved at about one month. All hands except one treated with negative pressure dressing could be saved from amputation; however, significant tissue loss developed, needing complex reconstruction procedures. One hand was amputated because of the permanent loss of blood perfusion. Conclusion: The management of high-voltage burns of hand and wrist with subatmospheric pressure appears to be capable of reducing hand edema and accelerating closure of the wounds. It seems that negative

[How children show positive and negative relationships on their drawings].

Science.gov (United States)

Gramel, Sabine

2005-01-01

This study analyses, whether pictures of children showing a positive relationship are significantly different from those showing a negative one with respect to several criteria. The study involved a random selection of 45 children aged 4;6 to 11;6 years. The children painted a picture with themselves and a person they liked and a picture of themselves with someone they disliked. For the most part, the children drew pictures of themselves with peers both with respect to positive as well as negative images. In an interview afterwards, the children specified the criteria in their drawings by which the quality of the particular relationship can be identified. Positive and negative relationship paintings differ in the character of activity described. The sun as an element in children's paintings is painted not more frequent on positive compared to negative pictures. The colour black is used more often in the drawings signifying negative relationships. While girls used more colour in negative relationship drawings, boys used more colour in the positive ones. There was no significant difference in the use of favourite colours and decorative elements between the two groups. Only in negative relationship drawings people were looking away from each other. Smiling individuals were more common in the positive relationship pictures and in pictures painted by the 6 to 8 year olds. A greater distance between the individuals emerged on negative relationship drawings of the girls.

Rapid Onset Acute Epiglottitis Leading to Negative Pressure Pulmonary Edema

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V Saraswat

2007-01-01

Full Text Available Pulmonary edema is a potentially life-threatening complication of acute airway obstruction. It develops rapidly, without warning, in young healthy individuals. Two forms of post-obstructive pulmonary edema (POPE (also known as negative pressure pulmonary edema, NPPE have been identified. POPE I follows sudden, severe upper airway obstruction. POPE II occurs following surgical relief of chronic upper airway obstruction. Treatment for both is supportive. Full and rapid recovery can be expected with appropriate management. A case report of a middle aged man with acute onset epiglottitis who developed negative pressure pulmonary edema after intubation is presented. The report includes a brief discussion on etiology, clinical features and management dilemma of acute upper airway obstruction.

Negative Pressure Pulmonary Edema after Reversing Rocuronium-Induced Neuromuscular Blockade by Sugammadex

Directory of Open Access Journals (Sweden)

Manzo Suzuki

2014-01-01

Full Text Available Negative pressure pulmonary edema (NPPE is a rare complication that accompanies general anesthesia, especially after extubation. We experienced a case of negative pressure pulmonary edema after tracheal extubation following reversal of rocuronium-induced neuromuscular blockade by sugammadex. In this case, the contribution of residual muscular block on the upper airway muscle as well as large inspiratory forces created by the respiratory muscle which has a low response to muscle relaxants, is suspected as the cause.

Negative Pressure Pulmonary Edema Following use of Laryngeal Mask Airway (LMA

Directory of Open Access Journals (Sweden)

Yesim Bayraktar

2013-06-01

Full Text Available Negative pressure pulmonary edema (NPPE following upper airway obstruction is a non-cardiogenic pulmonary edema. The first cause in the etiology of NPPE is developed laryngospasm after intubation or extubation, while the other causes are epiglotitis, croup, hiccups, foreign body aspiration, pharyngeal hematoma and oropharyngeal tumors.The Late diagnosis and treatment causes high morbidity and mortality. The protection of the airway and maintainance of arterial oxygenation will be life saving.In this article we aimed to report  a case of negative pressure pulmonary edema, resolved succesfully after treatment, following use of laryngeal mask airway (LMA.

Facets of negative affectivity and blood pressure in middle-aged men

Directory of Open Access Journals (Sweden)

Cornel V. Igna

2013-04-01

Full Text Available Research results suggesting that facets of negative affectivity, i.e. anxiety, anger-hostility, and depression, relate to incident cardiovascular diseases have been steadily increasing. Evidence for depression has been especially extensive. Elevated blood pressure, a major risk factor of cardiovascular diseases, is one probable mediator in this context. The purpose of this study was to clarify the relationship of specific key elements of depressive disposition, i.e. depressive symptoms, hopelessness and vital exhaustion, with health behavior and blood pressure. Study sample was comprised of 710 middle-aged men. Participants completed self-report questionnaires assessing health behavior, depressive symptoms, vital exhaustion and hopelessness. Statistical analyses involved descriptive analyses, correlations and path analysis. Depressive symptoms and vital exhaustion associated with several unfavorable lifestyles such as smoking, alcohol consumption, and inactivity (standardized solution coefficients: 0.10, 0.14, 0.17, accordingly. However, no significant direct associations with blood pressure could be found for depressive symptoms or vital exhaustion. Hopelessness associated only with unhealthy diet (standardized solution coefficient -0.10 Moreover, for hopelessness, results showed a direct but inverse association with systolic blood pressure (standardized solution coefficient -0.08. Results suggest that the previously reported relations of depression and vital exhaustion with blood pressure could be mediated by unfavorable lifestyles. The relation of hopelessness with adverse health behaviors seems to be less significant. Also, the role of hopelessness as a risk factor of elevated blood pressure is not supported by the results of this study.

Treatment Experience of Continuous Negative Pressure Drainage in the Acute Anterior Mediastinal Infection of Oropharyngeal Origined

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Anping CHEN

2018-04-01

Full Text Available Background and objective Mediastinal infection is a serious infection of mediastinal connective tissue, with more complications and higher mortality. Application of broad-spectrum antibiotics and nutritional support, early sufficient drainage is the key to successful treatment. In the mode of drainage, this paper discusses the application of continuous negative pressure drainage technique to treat acute anterior mediastinal infection of severe mouth pharynx source, and the good results are summarized and shared. Methods In January to December in 2017, a total of 17 cases treated acute mediastinal infection is derived from the throat, has formed a mediastinal abscess, surgery adopts retrosternal counterpart negative pressure drainage way, namely the sternum nest and free sternum xiphoid process under the incision on the first mediastinal clearance, make breakthrough and placed drainage device, suture closed wound, continuous negative pressure drainage, negative pressure using 3 cm-5 cm water column. Results Among the 17 patients, 14 patients were relieved by continuous negative pressure drainage, and then the drainage tube was removed. In 2 cases, the infection broke into the right thoracic cavity, and the closed drainage caused the negative pressure to disappear, and the negative pressure drainage was replaced by the conventional drainage, and the drainage tube was removed after the drainage tube was clear. One patient had formed a mediastinal abscess incision drainage time later, complicated with septic shock and sepsis, resulting in the death of multiple organ failure. Conclusion The traditional treatment of severe acute mediastinal infection is sternal incision and drainage. Continuous negative pressure drainage adequate drainage of mediastinal can relieve patients' pain, effusion, and avoid the dressing out repeatedly. It is an effective method. However, there are limitations in this method, which need to be further optimized.

Negative pressure wound therapy for the treatment of infected wounds with exposed knee joint after patellar fracture.

Science.gov (United States)

Lee, Sang Yang; Niikura, Takahiro; Miwa, Masahiko; Sakai, Yoshitada; Oe, Keisuke; Fukazawa, Takahiro; Kawakami, Yohei; Kurosaka, Masahiro

2011-06-14

Treatment of soft tissue defects with exposed bones and joints, resulting from trauma, infection, and surgical complications, represents a major challenge. The introduction of negative pressure wound therapy has changed many wound management practices. Negative pressure wound therapy has recently been used in the orthopedic field for management of traumatic or open wounds with exposed bone, nerve, tendon, and orthopedic implants. This article describes a case of a patient with a large soft tissue defect and exposed knee joint, in which negative pressure wound therapy markedly improved wound healing. A 50-year-old man presented with an ulceration of his left knee with exposed joint, caused by severe wound infections after open reduction and internal fixation of a patellar fracture. After 20 days of negative pressure wound therapy, a granulated wound bed covered the exposed bones and joint.To our knowledge, this is the first report of negative pressure wound therapy used in a patient with a large soft tissue defect with exposed knee joint. Despite the chronic wound secondary to infection, healing was achieved through the use of the negative pressure wound therapy, thus promoting granulation tissue formation and closing the joint. We suggest negative pressure wound therapy as an alternative option for patients with lower limb wounds containing exposed bones and joints when free flap transfer is contraindicated. Our result added to the growing evidence that negative pressure wound therapy is a useful adjunctive treatment for open wounds around the knee joint. Copyright 2011, SLACK Incorporated.

Incisional Negative Pressure Wound Therapy in High Risk Patients Undergoing Panniculectomy: A Prospective Randomized Controlled Trial

Science.gov (United States)

2018-01-16

Complications Wounds; Negative Pressure Wound Therapy; Wound Healing Delayed; Incisional; Panniculectomy; Incisional Negative Pressure Wound Therapy; Incisional Vac; Wound Vac; Obese; Renal Failure; Kidney Transplant; Complications; Wound Healing Complication

Negative interstitial pressure in the peritendinous region during exercise

DEFF Research Database (Denmark)

Langberg, Henning; Skovgaard, D; Bülow, J

1999-01-01

of these observations, microdialysis was performed in the peritendinous region with a colloid osmotic active substance (Dextran 70, 0.1 g/ml) added to the perfusate with the aim of counteracting the negative tissue pressure. Dialysate volume was found to be fully restored (100 +/- 4%) during exercise. It is concluded...

Negative magnetoresistance of pitch-based carbon fibers Temperature and pressure dependence

Science.gov (United States)

Hambourger, P. D.

1986-01-01

The negative transverse magnetoresistance of high-modulus pitch-based carbon fibers has been measured over the temperature range 1.3-4.2 K at ambient pressure and at 4.2 K under hydrostatic pressure up to 16 kbar. At low fields (less than 0.5 torr) the magnitude of the magnetoresistance increases markedly as the temperature is lowered from 4.2 K to 1.3 K, in disagreement with Bright's theoretical model, and decreases with pressure at the rate -0.6 percent/kbar.

Negative pressure darwinism: survival of the fittest paradigm.

Science.gov (United States)

Miller, Michael; Bybordi, Farhad

2009-07-01

The use of negative pressure for wound healing has been based on a set of parameters and devices that until recently were combined into a single paradigm. Despite historical and more recent evidence providing viable alternative considerations, it is only recently that this paradigm and its tenets have come into question. As the understanding of the limits of the current paradigm and specific instances of its benefits and drawbacks are identified, shifts in the paradigm must take place if the therapy is to evolve, develop, and continue to be efficacious. The pertinence of the concept of survival of the fittest is used to explore the need for a paradigm shift in negative pressure wound therapy.

Negative pressure dressing combined with a traditional approach for ...

African Journals Online (AJOL)

2011-07-21

Jul 21, 2011 ... Deep burns of the calvarium due to high-voltage electrical current present serious therapeutic challenges in the healing. In this study, as an alternative approach to the treatment of burned skull, negative pressure dressing is used to facilitate separation of the necrotic bones from healthy margins of the ...

An anesthetic management of negative pressure pulmonary edema

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Dipti Raj

2016-01-01

Full Text Available Negative pressure pulmonary edema (NPPE is one of the common complications of upper airway obstruction seen by anesthesiologist during either in induction or emergence sometimes both. Patients who have experienced NPPE are generally healthy without comorbidities. NPPE is a result of marked decrease in intrathoracic pressure caused by ventilator efforts against a closed glottis resulting in disruption of normal intravascular Starling mechanism, leading to transudation of intravascular protein, and fluids into the pulmonary interstitium. The onset of NPPE is usually rapid and without prompt recognition and intervention, the outcome can be fatal. This case report is of a 40-year-old female adult, who underwent right-sided percutaneous nephrolithotomy for stone in the right kidney otherwise uncomplicated surgical procedure.

Management of Pharyngocutaneous Fistula With Negative-Pressure Wound Therapy.

Science.gov (United States)

Teixeira, Sérgio; Costa, Joana; Bartosch, Isabel; Correia, Bernardo; Silva, Álvaro

2017-06-01

Pharyngocutaneous fistula is a common complication of laryngopharyngeal surgery and is associated with increased morbidity and mortality. Beyond the classical management, negative-pressure wound therapy (NPWT) can be an alternative and effective treatment. Two patients with pT3N0M0 squamous cell carcinoma of pyriform sinus were subjected to total laryngectomy and pharyngoesophageal reconstruction of a circular (patient 1) and an anterior wall defect (patient 2) with radial forearm free flap and pectoralis major muscle flap, respectively. Both developed a pharyngocutaneous fistula and NPWT was used.A significant decrease of the fistula aperture and exudate was observed after 22 and 21 days of NPWT in patients 1 and 2, respectively. After that standard wound care was instituted and closure of the fistulae was accomplished in 5 and 7 days, respectively. Negative-pressure wound therapy can be an effective treatment for pharyngocutaneous fistula closure, either in the setting of fistulae that persist besides multiple surgical revisions using muscle flaps or as a first-line therapy when fistulae develops.

Controlling a negative loaded hydraulic cylinder using pressure feedback

DEFF Research Database (Denmark)

Hansen, M.R.; Andersen, T.O.

2010-01-01

This paper is concerned with the inherent oscillatory nature of pressure compensated velocity control of a hydraulic cylinder subjected to a negative load and suspended by means of an over-center valve. Initially, a linearized stability analysis of such a hydraulic circuit is carried out clearly ...... in a nonlinear time domain simulation model validating the linear stability analysis....

Cervical spine disease may result in a negative lumbar spinal drainage trial in normal pressure hydrocephalus: case report.

Science.gov (United States)

Komotar, Ricardo J; Zacharia, Brad E; Mocco, J; Kaiser, Michael G; Frucht, Stephen J; McKhann, Guy M

2008-10-01

In this case report, we present a patient with normal pressure hydrocephalus in whom a lumbar drainage trial yielded a false-negative result secondary to cervical spondylosis. An 80-year-old woman presented with classic symptoms of normal pressure hydrocephalus as well as evidence of cervical myelopathy. Magnetic resonance imaging of the brain and spine showed enlarged ventricles and single-level cervical canal narrowing. An initial lumbar drainage trial was performed, which revealed negative results. The patient then underwent cervical decompression and fusion. Despite this procedure, the patient's symptoms continued to worsen. A repeat lumbar drainage trial was performed with positive results. Subsequently, a ventriculoperitoneal shunt was placed, resulting in significant improvement of her symptoms. This case report illustrates how altered cerebrospinal fluid flow dynamics may impact the accuracy of the lumbar spinal drainage trial in patients with normal pressure hydrocephalus.

Perceiving social pressure not to feel negative predicts depressive symptoms in daily life.

Science.gov (United States)

Dejonckheere, Egon; Bastian, Brock; Fried, Eiko I; Murphy, Sean C; Kuppens, Peter

2017-09-01

Western societies often overemphasize the pursuit of happiness, and regard negative feelings such as sadness or anxiety as maladaptive and unwanted. Despite this emphasis on happiness, the amount of people suffering from depressive complaints is remarkably high. To explain this apparent paradox, we examined whether experiencing social pressure not to feel sad or anxious could in fact contribute to depressive symptoms. A sample of individuals (n = 112) with elevated depression scores (Patient Health Questionnaire [PHQ-9] ≥ 10) took part in an online daily diary study in which they rated their depressive symptoms and perceived social pressure not to feel depressed or anxious for 30 consecutive days. Using multilevel VAR models, we investigated the temporal relation between this perceived social pressure and depressive symptoms to determine directionality. Primary analyses consistently indicated that experiencing social pressure predicts increases in both overall severity scores and most individual symptoms of depression, but not vice versa. A set of secondary analyses, in which we adopted a network perspective on depression, confirmed these findings. Using this approach, centrality analysis revealed that perceived social pressure not to feel negative plays an instigating role in depression, reflected by the high out- and low instrength centrality of this pressure in the various depression networks. Together, these findings indicate how perceived societal norms may contribute to depression, hinting at a possible malignant consequence of society's denouncement of negative emotions. Clinical implications are discussed. © 2017 Wiley Periodicals, Inc.

Using portable negative pressure wound therapy devices in the home care setting

Directory of Open Access Journals (Sweden)

Burke JR

2014-12-01

Full Text Available Joshua R Burke, Rachael Morley, Mustafa Khanbhai Academic Surgery Unit, Education and Research Centre, University Hospital of South Manchester, Manchester, UK Abstract: Negative pressure wound therapy (NPWT is the continuous or intermittent application of subatmospheric pressure to the surface of a wound that improves the wound environment, accelerates healing, and reduces wound closure time. Since its first documented use, this technology has lent itself to a number of adaptations, most notably, the development of portable devices facilitating treatment in the home care setting. With advancing surgical standards, wound healing is an important rate-limiting factor in early patient discharge and often a major cost of inpatient treatment. The efficacy of NPWT in the home care setting has been investigated through rate of wound closure, time in care, and patient experience. Rate of wound closure is the most appropriate primary end point. Much can be gleaned from patient experience, but the future success of portable NPWT will be measured on time in care and therefore cost effectiveness. However, there is a lack of level 1a evidence demonstrating increased efficacy of portable over inpatient NPWT. The development of portable NPWT is an encouraging innovation in wound care technology, and extending the benefits to the home care setting is both possible and potentially more beneficial. Keywords: portable, negative pressure wound therapy, vacuum-assisted closure, topical negative pressure therapy

Use of dynamic CT in acute respiratory distress syndrome (ARDS) with comparison of positive and negative pressure ventilation

Energy Technology Data Exchange (ETDEWEB)

Helm, Emma; Babyn, Paul [Hospital for Sick Children, Department of Diagnostic Imaging, Toronto (Canada); Talakoub, Omid; Alirezaie, Javad [Ryerson University, Department of Electrical and Computer Engineering, Toronto, ON (Canada); Grasso, Francesco; Engelberts, Doreen; Kavanagh, Brian P. [Hospital for Sick Children and the University of Toronto, Departments of Anesthesia and Critical Care Medicine and the Program in Pulmonary and Experimental Medicine, Toronto (Canada)

2009-01-15

Negative pressure ventilation via an external device ('iron lung') has the potential to provide better oxygenation with reduced barotrauma in patients with ARDS. This study was designed to see if oxygenation differences between positive and negative ventilation could be explained by CT. Six anaesthetized rabbits had ARDS induced by repeated saline lavage. Rabbits were ventilated with positive pressure ventilation (PPV) and negative pressure ventilation (NPV) in turn. Dynamic CT images were acquired over the respiratory cycle. A computer-aided method was used to segment the lung and calculate the range of CT densities within each slice. Volumes of ventilated lung and atelectatic lung were measured over the respiratory cycle. NPV was associated with an increased percentage of ventilated lung and decreased percentage of atelectatic lung. The most significant differences in ventilation and atelectasis were seen at mid-inspiration and mid-expiration (ventilated lung NPV=61%, ventilated lung PPV=47%, p<0.001; atelectatic lung NPV=10%, atelectatic lung PPV 19%, p<0.001). Aeration differences were not significant at end-inspiration. Dynamic CT can show differences in lung aeration between positive and negative ventilation in ARDS. These differences would not be appreciated if only static breath-hold CT was used. (orig.)

Head holder using negative pressure bag packed with plastic beads in xenon CT CBF study

International Nuclear Information System (INIS)

Araki, Yuzo; Sakai, Noboru

2003-01-01

Employing analysis of cerebral blood flow (CBF) confidence maps, we investigated the usefulness of a head holder using a negative pressure bag packed with plastic beads in a xenon CT CBF study. A total of 272 consecutive patients for the CBF study were enrolled and classified into 3 groups: 88 patients with a negative pressure bag (M group), 87 patients with an air pillow (A group), and 97 patients with a sponge pillow (S group). The degree of effect of head movements on the CBF measurement in each patient was expressed as a confidence value (mean of the confidence values at one CT slice). The mean of confidence value in the M group (0.461) was statistically lower than that in the A group (0.866) and that in the S group (1.043). These findings showed that the head holder described here was useful for obtaining CBF maps of high quality in a xenon CT CBF study. (author)

The use of negative pressure wave treatment in athlete recovery ...

African Journals Online (AJOL)

Background: Athletes need to recover fully to maximise performance in competitive sport. Athletes who replenish more quickly and more efficiently are able to train harder and more intensely. Elite athletes subjectively report positive results using lower body negative pressure (LBNP) treatment as an alternate method for ...

Patients' experiences of negative pressure wound therapy for the treatment of wounds: a review.

Science.gov (United States)

Upton, D; Stephens, D; Andrews, A

2013-01-01

To review the research on patients' experiences of undergoing negative pressure wound therapy (NPWT). A literature search was carried out using the following databases: Academic Search Complete, CINAHL, PsychINFO, MEDLINE, PubMed and PsyARTICLES. The search covered the period from 2001 to 2012, using the key words: ['negative pressure wound therapy' OR 'vacuum-assisted closure' OR 'topical negative therapy'] AND ['patients' experiences' OR 'psychological' OR 'stress' OR 'anxiety' OR 'wellbeing' OR 'pain' OR 'quality of life' OR 'physical']. Twenty-five relevant articles were included. NPWT is generally considered to be successful in reducing wound depth and facilitating healing. However, studies have highlighted a number of issues that need to be considered. For example, the type of dressing used during treatment can have a significant effect on patients' experience of pain. Furthermore, the NPWT system can cause patients to feel anxious due to both the patient and the health professional being unfamiliar with this form of treatment. It can also restrict patients' daily care and wider social life, which may result in a negative self-image and low self-esteem. Despite this, some studies have reported positive improvements to patients' quality of life. Additionally, since NPWT can lead to faster healing, any detrimental impact upon patients' wellbeing may be short-term and less prolonged than that of other treatments. Compared with other treatments, there is evidence to show that NPWT can lead to faster wound healing, and a reduced frequency of dressing changes and other treatments. However, there are a number of challenges with the use of NPWT, which need to be explored further so that improvements can be made. Specifically, certain aspects of NPWT may impact negatively on patients' wellbeing, albeit short-term. Therefore, research needs to explore patients' experience of NPWT throughout the treatment process and to consider how this can be improved to minimise any

Measurement of negative ion mobilities in O2 and O3 mixtures at atmospheric pressure

International Nuclear Information System (INIS)

Itoh, H.; Norimoto, K.; Hayashi, T.

1998-01-01

Mobility measurements of negative molecular oxygen ions in pure oxygen and in an oxygen-ozone mixture are reported. A cascaded gap consisting of an ion drift gap and an ion detection gap was used in the experiment. The ion detection gap was formed by a positive point and a grounded plane electrode was operated at atmospheric pressure. The zero field mobility of negative molecular oxygen ions was determined to be 2.07+-0.02 cm 2 /V.s. A somewhat higher value of oxygen mobility was found at higher electric field/pressure ratios; this is presumed to be due to negative ozone ions. When changing the electric field/pressure ratio the mobility of negative oxygen ions in oxygen-ozone mixtures becomes smaller than that in pure oxygen; this is probably due to the cumulative effect of other particles produced by silent discharges. (J.U.)

Use of negative-pressure dressings and split-thickness skin grafts following penile shaft reduction and reduction scrotoplasty in the management of penoscrotal elephantiasis.

Science.gov (United States)

Stokes, Tracey H; Follmar, Keith E; Silverstein, Ari D; Weizer, Alon Z; Donatucci, Craig F; Anderson, Everett E; Erdmann, Detlev

2006-06-01

From 1988 to 2005, 8 men who presented with penoscrotal elephantiasis underwent penile shaft degloving and reduction scrotoplasty, followed by transplantation of a split-thickness skin graft (STSG) to the penile shaft. The etiology of elephantiasis in these patients included self-injection of viscous fluid and postsurgical obstructive lymphedema. In the 6 most recent cases, negative-pressure dressings were applied over the STSG to promote graft take, and STSG take rate was 100%. The results of our series corroborate those of a previous report, which showed circumferential negative-pressure dressings to be safe and efficacious in bolstering STSGs to the penile shaft. Furthermore, these results suggest that the use of negative-pressure dressings may improve graft take in this patient population.

The paradox of negative pressure wound therapy--in vitro studies.

Science.gov (United States)

Kairinos, Nicolas; Solomons, Michael; Hudson, Donald A

2010-01-01

Negative-pressure wound therapy (NPWT) has revolutionised wound care. Yet, it is still not understood how hypobaric tissue pressure accelerates wound healing. There is very little reported on the relevant physics of any substance subjected to suction in this manner. The common assumption is that applying suction to a substance is likely to result in a reduction of pressure in that substance. Although more than 250 research articles have been published on NPWT, there are little data verifying whether suction increases or decreases the pressure of the substance it is applied to. Clarifying this basic question of physics is the first step in understanding the mechanism of action of these dressings. In this study, pressure changes were recorded in soft plasticene and processed meat, using an intracranial tissue pressure microsensor. Circumferential, non-circumferential and cavity NPWT dressings were applied, and pressure changes within the underlying substance were recorded at different suction pressures. Pressures were also measured at 1cm, 2 cm and 3 cm from the NPWT placed in a cavity. In all three types of NPWT dressings, the underlying substance pressure was increased (hyperbaric) as suction pressure increased. Although there was a substantial pressure increase at 1cm, the rise in pressure at the 2-cm and 3-cm intervals was minimal. Substance pressure beneath all types of NPWT dressing is hyperbaric in inanimate substances. Higher suction pressures generate greater substance pressures; however, the increased pressure rapidly dissipates as the distance from the dressing is increased. The findings of this study on inanimate objects suggest that we may need to review our current perception of the physics underlying NPWT dressings. Further research of this type on living tissues is warranted. Copyright (c) 2009 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Early activation of the coagulation system during lower body negative pressure

DEFF Research Database (Denmark)

Zaar, M; Johansson, P I; Nielsen, L B

2009-01-01

We considered that a moderate reduction of the central blood volume (CBV) may activate the coagulation system. Lower body negative pressure (LBNP) is a non-invasive means of reducing CBV and, thereby, simulates haemorrhage. We tested the hypothesis that coagulation markers would increase following...... moderate hypovolemia by exposing 10 healthy male volunteers to 10 min of 30 mmHg LBNP. Thoracic electrical impedance increased during LBNP (by 2.6 +/- 0.7 Omega, mean +/- SD; P pressure decreased (84 +/- 5 to 80...

Origin of superconductivity in KFe2As2 under positive and negative pressures and relation to other Fe-based families

Science.gov (United States)

Valenti, Roser

KFe2As2 shows an intricate behavior as a function of pressure. At ambient pressure the system is superconductor with a low critical temperature Tc=3.4 K and follows a V-shaped pressure dependence of Tc for moderate pressures with a local minimum at a pressure of 1.5 GPa. Under high pressures Pc=15 GPa, KFe2As2 exhibits a structural phase transition from a tetragonal to a collapsed tetragonal phase accompanied by a boost of the superconducting critical temperature up to 12 K. On the other hand, negative pressures realized through substitution of K by Cs or Rb decrease Tc down to 2.25K. In this talk we will discuss recent progress on the understanding of the microscopic origin of this pressure-dependent behavior by considering a combination of ab initio density functional theory with dynamical mean field theory and spin fluctuation theory calculations. We will argue that a Lifshitz transition associated with the structural collapse changes the pairing symmetry from d-wave (tetragonal) to s+/- (collapsed tetragonal) at high pressures while at ambient and negative pressures correlation effects appear to be detrimental for superconductivity. Further, we shall establish cross-links to the chalcogenide family, in particular FeSe under pressure. The Deutsche Forschungsgemeinschaft (DFG) is gratefully acknowledged for financial support.

Timer switch to convert suction apparatus for negative pressure wound therapy application

Directory of Open Access Journals (Sweden)

Surath Amarnath

2014-01-01

Full Text Available Background: Negative pressure wound therapy (NPWT is an established modality in the treatment of chronic wounds, open fractures, and post-operative wound problems. This method has not been widely used due to the high cost of equipment and consumables. This study demonstrates an indigenously developed apparatus which gives comparable results at a fraction of the cost. Readily available materials are used for the air-tight dressing. Materials and Methods: Equipment consists of suction apparatus with adjustable pressure valve set to a pressure 125-150 mmHg. An electronic timer switch with a sequential working time of 5 min and a standby time of 3 min provides the required intermittent negative pressure. Readily available materials such as polyvinyl alcohol sponge, suction drains and steridrapes were used to provide an air tight wound cover. Results: A total of 90 cases underwent 262 NPWT applications from 2009 to 2014. This series, comprised of 30 open fractures, 21 post-operative and 39 chronic wounds. The wound healing rate in our study was comparable to other published studies using NPWT. Conclusion: The addition of electronic timer switch will convert a suction apparatus into NPWT machine, and the results are equally effective compared to more expensive counter parts. The use of indigenous dressing materials reduces the cost significantly.

Negative pressure therapy for the treatment of complex wounds

Directory of Open Access Journals (Sweden)

RENAN VICTOR KÜMPEL SCHMIDT LIMA

Full Text Available ABSTRACT The objective of this study is to evaluate the effectiveness of negative pressure therapy (NPT in the treatment of complex wounds, with emphasis on its mechanisms of action and main therapeutic indications. We searched the Pubmed / Medline database for articles published from 1997 to 2016, and selected the most relevant ones. The mechanisms of action of NPT involveboth physical effects, such as increased perfusion, control of edema and exudate, reduction of wound dimensions and bacterial clearance, and biological ones, such as the stimulation of granulation tissue formation, microdeformations and reduction of Inflammatory response. The main indications of NPT are complex wounds, such as pressure ulcers, traumatic wounds, operative wound dehiscences, burns, necrotizing wounds, venous ulcers, diabetic wounds, skin grafts, open abdomen, prevention of complications in closed incisions and in the association with instillation of solutions in infected wounds.

Pulse Waveform and Transcranial Doppler Analysis during Lower Body Negative Pressure

Science.gov (United States)

1993-04-01

26, 23]. The application of negative pressure to the body for scientific or medical purposes was first used in 1841 by Junod , who used it to create a...localized hyperemia [26]. Junod also suggested that it could be used prior to invasive surgical procedures, since the syncope it was able to produce

Dynamic isolation technologies in negative pressure isolation wards

CERN Document Server

Xu, Zhonglin

2017-01-01

This book presents novel design principles and technologies for dynamic isolation based on experimental studies. These approaches have now become the local standard in Beijing and are currently being promoted for use nationwide. Further, the book provides details of measures and guidelines for the design process. Departing from the traditional understanding that isolation wards should be designed with high negative pressure, airtight doors and fresh air, it establishes the basis for designing biological clean rooms, including isolation wards, using a simple and convenient scientific approach. This book is intended for designers, engineers, researchers, hospital management staff and graduate students in heating ventilation air conditioning (HVAC), air cleaning technologies and related areas.

Rapid Onset Acute Epiglottitis Leading to Negative Pressure Pulmonary Edema

OpenAIRE

V Saraswat; P V Madhu; Suresh S Kumar

2007-01-01

Pulmonary edema is a potentially life-threatening complication of acute airway obstruction. It develops rapidly, without warning, in young healthy individuals. Two forms of post-obstructive pulmonary edema (POPE) (also known as negative pressure pulmonary edema, NPPE) have been identified. POPE I follows sudden, severe upper airway obstruction. POPE II occurs following surgical relief of chronic upper airway obstruction. Treatment for both is supportive. Full and rapid recovery can be expecte...

Negative pressure wound therapy and external fixation device: a simple way to seal the dressing.

Science.gov (United States)

Bulla, Antonio; Farace, Francesco; Uzel, André-Pierre; Casoli, Vincent

2014-07-01

Negative pressure therapy is widely applied to treat lower limb trauma. However, sealing a negative pressure dressing in the presence of an external fixation device may be difficult and time consuming. Therefore, screws, pins, wires, etc, may preclude the vacuum, preventing the plastic drape to perfectly adhere to the foam. To maintain the vacuum, we tried to prevent air leaking around the screws putting bone wax at the junction between the pins and the plastic drape. This solution, in our hands, avoids air leakage and helps maintain vacuum in a fast and inexpensive way.

Study on the hydrogen negative ion in low pressure discharges

International Nuclear Information System (INIS)

Bruneteau, A.M.

1983-07-01

A new use of negative hydrogen ions is the production of intense fast neutral atom beams useful in plasma heating in thermonuclear heating. That is one of the reasons that started this study. The density of negative hydrogen ions in diffusion, and multipole-type low pressure (10 -3 - 10-2 Torr) discharges is deduced from the various formation and destruction processes of the species present in these discharges. The H - ions are essentially produced by dissociative attachment to vibrationally excited molecules and destroyed by processes the relative importance of which is discussed as a function of the discharge parameters. The experimental study of the density of the H - ions, measured by photodetachment, as a function of these parameters, coroborates the theoretical model [fr

Negative pressure wound therapy and nurse education.

Science.gov (United States)

Cray, Amy

2017-08-10

there can be serious consequences for patients if negative pressure wound therapy (NPWT) is performed incorrectly and patient safety must be paramount. The existing literature was found to mainly concentrate on the use of the technology from the patient perspective. This article examines the opinions of nurses who apply the therapy. five staff nurses from different areas with differing experience levels were interviewed in a semi-structured manner. The transcribed interviews were coded, sorted into themes and analysed. the themes were: enhancing knowledge and understanding, managing problematic pumps, formalised and interactive training, and efficacy and healing. There was a lack of standardised training provided for the nurses interviewed. Overall the nurses were aware of the basic evidence behind the treatment but would have liked additional support in this area as well as some practical, less pressured training. This complements the existing literature. nurses are expected to learn difficult and highly specialised skills quickly within a busy ward environment, often with no prior training or preparation. As things can go wrong, with the potential for patient harm, it is vital that nurses get these skills right first time, but it is difficult to do this in a practical, fast and cost-effective way. There is scope for future research in the area and perhaps the development of an online training tool to assist nurses in understanding and undertaking a new procedure.

Hemolysis During Open-Heart Surgery With Vacuum-Assisted Venous Drainage at Different Negative Pressures in Pediatric Patients Weighing Less Than 10 kilograms.

Science.gov (United States)

Kwak, Jae Gun; Lee, Jinkwon; Park, Minkyoung; Seo, Yu-Jin; Lee, Chang-Ha

2017-03-01

This study examined the degree of hemolysis during vacuum-assisted venous drainage at different negative pressures to identify an adequate negative pressure that provides effective venous drainage without significant hemolysis in open-heart surgery in children weighing less than 10 kg. Patients weighing less than 10 kg who underwent surgery for ventricular septal defect or atrial septal defect from 2011 to 2014 were enrolled. We used one of four negative pressures (20, 30, 40, or 60 mm Hg) for each patient. We measured haptoglobin, plasma hemoglobin, aspartate aminotransferase, and lactate dehydrogenase levels in the patients' blood three times perioperatively and determined the potential correlation between the change in each parameter with the level of negative pressure. Forty-six patients were enrolled in this study (mean age: 7.1 ± 7.0 months, mean body weight: 6.1 ± 1.8 kg). There were no significant differences according to the degree of negative pressure with respect to patient age, body weight, cardiopulmonary bypass (CPB) time, aorta cross-clamping time, blood flow during CPB, or lowest body temperature. All parameters that we measured reflected progression of hemolysis during CPB; however, the degree of change in the parameters did not correlate with negative pressure. In pediatric patients weighing less than 10 kg, the change in the degree of hemolysis did not differ with the amount of negative pressure. We may apply negative pressures up to 60 mm Hg without increasing the risk of hemolysis, with almost same the level of hemolysis using negative pressures of 20, 30, and 40 mm Hg for effective venous drainage and an ideal operative field during open-heart surgery.

The evidence-based principles of negative pressure wound therapy in trauma & orthopedics.

Science.gov (United States)

A, Novak; Khan, Wasim S; J, Palmer

2014-01-01

Negative pressure wound therapy is a popular treatment for the management of both acute and chronic wounds. Its use in trauma and orthopedics is diverse and includes the acute traumatic setting as well as chronic troublesome wounds associated with pressure sores and diabetic foot surgery. Efforts have been made to provide an evidence base to guide its use however this has been limited by a lack of good quality evidence. The following review article explores the available evidence and describes future developments for its use in trauma and orthopaedic practice.

Solvation pressure as real pressure: I. Ethanol and starch under negative pressure

CERN Document Server

Uden, N W A V; Faux, D A; Tanczos, A C; Howlin, B; Dunstan, D J

2003-01-01

The reality of the solvation pressure generated by the cohesive energy density of liquids is demonstrated by three methods. Firstly, the Raman spectrum of ethanol as a function of cohesive energy density (solvation pressure) in ethanol-water and ethanol-chloroform mixtures is compared with the Raman spectrum of pure ethanol under external hydrostatic pressure and the solvation pressure and hydrostatic pressure are found to be equivalent for some transitions. Secondly, the bond lengths of ethanol are calculated by molecular dynamics modelling for liquid ethanol under pressure and for ethanol vapour. The difference in bond lengths between vapour and liquid are found to be equivalent to the solvation pressure for the C-H sub 3 , C-H sub 2 and O-H bond lengths, with discrepancies for the C-C and C-O bond lengths. Thirdly, the pressure-induced gelation of potato starch is measured in pure water and in mixtures of water and ethanol. The phase transition pressure varies in accordance with the change in solvation pre...

Temporal evolution of atmosphere pressure plasma jets driven by microsecond pulses with positive and negative polarities

Science.gov (United States)

Shao, Tao; Yang, Wenjin; Zhang, Cheng; Fang, Zhi; Zhou, Yixiao; Schamiloglu, Edl

2014-09-01

Current-voltage characteristics, discharge images, and optical spectra of atmospheric pressure plasma jets (APPJs) are studied using a microsecond pulse length generator producing repetitive output pulses with different polarities. The experimental results show that the APPJs excited by the pulses with positive polarity have longer plume, faster propagation speed, higher power, and more excited species, such as \\text{N}2 , O, He, \\text{N}2+ , than that with the negatively excited APPJs. The images taken using an intensified charge-coupled device show that the APPJs excited by pulses with positive polarity are characterized by a bullet-like structure, while the APPJs excited by pulses with negative polarity are continuous. The propagation speed of the APPJs driven by a microsecond pulse length generator is about tens of km/s, which is similar to the APPJs driven by a kHz frequency sinusoidal voltage source. The analysis shows that the space charge accumulation effect plays an important role during the discharge. The transient enhanced electric field induced by the accumulated ions between the needle-like electrode and the nozzle in the APPJs excited by pulses with negative polarity enhances electron field emission from the cathode, which is illustrated by the bright line on the time-integrated images. This makes the shape of the APPJ excited using pulses with negative polarity different from the bullet-like shape of the APPJs excited by pulses with positive polarity.

Negative pressure wound therapy in pediatric surgery: How and when to use.

Science.gov (United States)

de Jesus, Lisieux Eyer; Martins, Alana Bandeira; Oliveira, Pablo Baptista; Gomes, Fernanda; Leve, Thais; Dekermacher, Samuel

2018-04-01

Negative pressure wound therapy (NPWT) has been widely adopted to treat laparostomy, abdominal compartment syndrome (ACS) and complicated wounds associated with tissue loss. The method presents specific aspects, advantages and indications in Pediatrics. Our aim is to review the evidence available about NPWT in children. Active search for papers about NPWT in Pediatric patients. Papers referring to orthopedic problems, wound complications after Cardiac Surgery or burns were excluded. The method shows good results to treat ACS, complicated wounds and abdominal wall malformations in neonates, including prematures. Periwound skin protection, monitoring of fluid losses and fine tuning of negative pressure levels according to age are necessary. Less pain, quicker recovery, less frequent dressing changes, possible recovery of exposed surgical hardware, granulation and shrinkage of the wound are advantages of the method over other kinds of dressing. NPWT is contraindicated over blood vessels and exposed nerves. Debridement is needed before usage over necrotic areas. Enteric fistulae are not contraindications. Complications are rare, mainly foam retention and dermatitis/skin maceration. The possibility of fistulae being caused by NPWT remains debatable. NPWT is widely used in Pediatrics, including neonates and premature, but the evidence available about the method is scarce and low quality. Complications are uncommon and mostly manageable. A possible causal relationship between NPWY and enteric fistula remains unclear. Adult devices and parameters have been adapted to children's use. Extra care is needed to protect the delicate tissues of Pediatric patients. Comparative research to define differential costs, indications and advantages of the method, specific indications and limits of NWTP in Pediatrics is needed. Review. IV. Copyright © 2017 Elsevier Inc. All rights reserved.

Early use of negative pressure therapy in combination with silver dressings in a difficult breast abscess.

Science.gov (United States)

Richards, Alastair J; Hagelstein, Sue M; Patel, Girish K; Ivins, Nicola M; Sweetland, Helen M; Harding, Keith G

2011-12-01

Combining silver-based dressings with negative pressure therapy after radical excision of chronically infected breast disease is a novel application of two technologies. One patient with complex, chronic, infected breast disease underwent radical excision of the affected area and was treated early with a combination of silver-based dressings and topical negative pressure therapy. The wound was then assessed sequentially using clinical measurements of wound area and depth, pain severity scores and level of exudation. It is possible to combine accepted techniques with modern dressing technologies that result in a positive outcome. In this case, the combination of a silver-based dressing with negative pressure therapy following radical excision proved safe and was well tolerated by the patient. Full epithelisation of the wound was achieved and there was no recurrence of the infection for the duration of the treatment. © 2011 The Authors. © 2011 Blackwell Publishing Ltd and Medicalhelplines.com Inc.

Negative pressure pulmonary edema after nasal fracture reduction in an obese female patient: a case report

Directory of Open Access Journals (Sweden)

Choi EK

2015-08-01

Full Text Available Eunkyung Choi,1 Junggu Yi,1 Younghoon Jeon,2 1Department of Anesthesiology and Pain Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea; 2Department of Anesthesiology and Pain Medicine, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea Abstract: Postoperative negative pressure pulmonary edema (NPPE is a rare, but well-known life-threatening complication of acute upper airway obstruction (UAO which develops after general anesthesia. The pronounced inspiratory efforts following UAO lead to excessive negative inspiratory pressure, which may cause acute pulmonary edema. Early recognition and prompt treatment of NPPE is necessary to prevent patient morbidity and mortality. In addition, the physician should carefully manage the patient who has risk factors of UAO to prevent this situation. We experienced a case of NPPE following laryngospasm after tracheal extubation in an obese patient who underwent open reduction of orbital wall and nasal bone surgery. Keywords: airway obstruction, negative pressure pulmonary edema, laryngospasm, nasal surgery, obese

Differential effects of lower body negative pressure and upright tilt on splanchnic blood volume

Science.gov (United States)

Taneja, Indu; Moran, Christopher; Medow, Marvin S.; Glover, June L.; Montgomery, Leslie D.; Stewart, Julian M.

2015-01-01

Upright posture and lower body negative pressure (LBNP) both induce reductions in central blood volume. However, regional circulatory responses to postural changes and LBNP may differ. Therefore, we studied regional blood flow and blood volume changes in 10 healthy subjects undergoing graded lower-body negative pressure (−10 to −50 mmHg) and 8 subjects undergoing incremental head-up tilt (HUT; 20°, 40°, and 70°) on separate days. We continuously measured blood pressure (BP), heart rate, and regional blood volumes and blood flows in the thoracic, splanchnic, pelvic, and leg segments by impedance plethysmography and calculated regional arterial resistances. Neither LBNP nor HUT altered systolic BP, whereas pulse pressure decreased significantly. Blood flow decreased in all segments, whereas peripheral resistances uniformly and significantly increased with both HUT and LBNP. Thoracic volume decreased while pelvic and leg volumes increased with HUT and LBNP. However, splanchnic volume changes were directionally opposite with stepwise decreases in splanchnic volume with LBNP and stepwise increases in splanchnic volume during HUT. Splanchnic emptying in LBNP models regional vascular changes during hemorrhage. Splanchnic filling may limit the ability of the splanchnic bed to respond to thoracic hypovolemia during upright posture. PMID:17085534

Effect of Negative Pressure on Proliferation, Virulence Factor Secretion, Biofilm Formation, and Virulence-Regulated Gene Expression of Pseudomonas aeruginosa In Vitro

Directory of Open Access Journals (Sweden)

Guo-Qi Wang

2016-01-01

Full Text Available Objective. To investigate the effect of negative pressure conditions induced by NPWT on P. aeruginosa. Methods. P. aeruginosa was cultured in a Luria–Bertani medium at negative pressure of −125 mmHg for 24 h in the experimental group and at atmospheric pressure in the control group. The diameters of the colonies of P. aeruginosa were measured after 24 h. ELISA kit, orcinol method, and elastin-Congo red assay were used to quantify the virulence factors. Biofilm formation was observed by staining with Alexa Fluor® 647 conjugate of concanavalin A (Con A. Virulence-regulated genes were determined by quantitative RT-PCR. Results. As compared with the control group, growth of P. aeruginosa was inhibited by negative pressure. The colony size under negative pressure was significantly smaller in the experimental group than that in the controls (p<0.01. Besides, reductions in the total amount of virulence factors were observed in the negative pressure group, including exotoxin A, rhamnolipid, and elastase. RT-PCR results revealed a significant inhibition in the expression level of virulence-regulated genes. Conclusion. Negative pressure could significantly inhibit the growth of P. aeruginosa. It led to a decrease in the virulence factor secretion, biofilm formation, and a reduction in the expression level of virulence-regulated genes.

A comparative study of the efficacy of topical negative pressure moist dressings and conventional moist dressings in chronic wounds

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Tauro Leo

2007-01-01

Full Text Available Aim: To assess the efficacy of topical negative pressure moist wound dressing as compared to conventional moist wound dressings in improving the healing process in chronic wounds and to prove that negative pressure dressings can be used as a much better treatment option in the management of chronic wounds. Materials and Methods: This is a prospective comparative study of data from 112 patients with chronic wounds, of which 56 patients underwent topical negative pressure dressings (17 diabetic, 10 pressure sores, nine ischemic, two varicose, 10 post-infective raw areas and eight traumatic - six had bone exposed, two orthopaedic prosthesis exposed. The remaining 56 patients underwent conventional moist dressings (20 diabetic, two ischemic, 15 pressure sores, three varicose, eight post-infective raw areas and eight traumatic - five had bone exposed, three orthopaedic prosthesis exposed. The results were compared after 10 days. The variables compared were, rate of granulation tissue formation as a percentage of ulcer area covered, skin graft take up as the percentage of ulcer surface area and duration of hospital stay. The variables were compared using Unpaired Student′s t test. A " P" value < 0.05 was considered significant. Results: Out of 56 patients who underwent topical negative pressure dressings, six (10.71% were failures, due to failure in maintaining topical negative pressure due to defective sealing technique; these were included into the study group. After 10 days, the mean rate of granulation tissue formation was 71.43% of ulcer surface area. All these 56 cases underwent split-thickness skin grafting. The mean graft take-up was 79.29%. The mean hospital stay was 32.64 days. In the remaining 56 patients, the mean rate of granulation tissue formation was 52.85% of ulcer surface area. The mean graft take-up was only 60.45% of the total ulcer surface area. The mean hospital stay was 60.45 days. Conclusion: To conclude, topical negative

Improved wound management by regulated negative pressure-assisted wound therapy and regulated, oxygen- enriched negative pressure-assisted wound therapy through basic science research and clinical assessment

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Moris Topaz

2012-01-01

Full Text Available Regulated negative pressure-assisted wound therapy (RNPT should be regarded as a state-of-the-art technology in wound treatment and the most important physical, nonpharmaceutical, platform technology developed and applied for wound healing in the last two decades. RNPT systems maintain the treated wound′s environment as a semi-closed, semi-isolated system applying external physical stimulations to the wound, leading to biological and biochemical effects, with the potential to substantially influence wound-host interactions, and when properly applied may enhance wound healing. RNPT is a simple, safe, and affordable tool that can be utilized in a wide range of acute and chronic conditions, with reduced need for complicated surgical procedures, and antibiotic treatment. This technology has been shown to be effective and safe, saving limbs and lives on a global scale. Regulated, oxygen-enriched negative pressure-assisted wound therapy (RO-NPT is an innovative technology, whereby supplemental oxygen is concurrently administered with RNPT for their synergistic effect on treatment and prophylaxis of anaerobic wound infection and promotion of wound healing. Understanding the basic science, modes of operation and the associated risks of these technologies through their fundamental clinical mechanisms is the main objective of this review.

Homogeneous nucleation in liquid nitrogen at negative pressures

Energy Technology Data Exchange (ETDEWEB)

Baidakov, V. G., E-mail: baidakov@itp.uran.ru; Vinogradov, V. E.; Pavlov, P. A. [Russian Academy of Sciences, Institute of Thermal Physics, Ural Branch (Russian Federation)

2016-10-15

The kinetics of spontaneous cavitation in liquid nitrogen at positive and negative pressures has been studied in a tension wave formed by a compression pulse reflected from the liquid–vapor interface on a thin platinum wire heated by a current pulse. The limiting tensile stresses (Δp = p{sub s}–p, where p{sub s} is the saturation pressure), the corresponding bubble nucleation frequencies J (10{sup 20}–10{sup 22} s{sup –1} m{sup –3}), and temperature induced nucleation frequency growth rate G{sub T} = dlnJ/dT have been experimentally determined. At T = 90 K, the limiting tensile stress was Δp = 8.3 MPa, which was 4.9 MPa lower than the value corresponding to the boundary of thermodynamic stability of the liquid phase (spinodal). The measurement results were compared to classical (homogeneous) nucleation theory (CNT) with and without neglect of the dependence of the surface tension of critical bubbles on their dimensions. In the latter case, the properties of new phase nuclei were described in terms of the Van der Waals theory of capillarity. The experimental data agree well with the CNT theory when it takes into account the “size effect.”.

The Influence of the Bed with a Semiopen Hood on Bacteria Removal in a Negative-Pressure Isolation Room

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Jeng-Min Huang

2014-06-01

Full Text Available This study numerically investigates the influence of a sickbed with a semiopened hood on bacteria removal in a negative-pressure isolation room. The parameters include air change rate, lying style, the length and height of hood, flow rate allotments, and the positions of outlets. The results show that the hood has excellent effect on the removal of contaminated air, which is much better than the case without hood. The flow field of patient's face up cough is very different from face side cough, and the contaminated air cannot be removed properly through one air outlet. There are three outlets on the hood, set straight above the patient's face and at both sides. The allotment of the exhaust flow rate of the upper outlet to that of side outlets is suggested to be 4: 6. When the total air change rate is above 6 ACH, the hood length has slight influence on pollutant removal. The increase of hood height has a negative impact when the patient coughs lying on back. When the side exhaust flow rate is high, the hood height has a slight impact for face side cough. The recommended air change rate for the negative-pressure ward with sickbed hood is above 5 ACH.

Characterization and management trends of negative and positive impacts of tourism in show caves

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Heros Augusto Santos Lobo

2015-08-01

Full Text Available Caves are one of the most fragile environments on Earth ’s surface, in function of physical, atmospheric and biological specificities. The natural characteristics associated with cultural aspects of local people are the reasons to tourist potential of caves. However, the tourist use of caves can generate negative impacts on the environment. This consequence happens when inappropriate procedures of planning and management of tourism are used. Negative impacts are described in this review, as also indications of management techniques to avoid, decrease or eliminate the negative consequences of tourism in caves. Positive impacts are also presented, in order to achieve a sustainable tourism in show caves. The conclusion argues that the negative impacts should not be considered as impediments to tourism in caves. It is important to know these impacts and use it as a key to get previous answers which allow to raise the sustainability of show caves.

A systematic review of topical negative pressure therapy for acute and chronic wounds

NARCIS (Netherlands)

Ubbink, D. T.; Westerbos, S. J.; Nelson, E. A.; Vermeulen, H.

2008-01-01

Topical negative pressure (TNP) therapy is becoming increasingly popular for all kinds of wounds. Its clinical and cost effectiveness is unclear. A search of randomized controlled trials (RCTs) on TNP in adult patients with all kinds of wounds in all settings was undertaken in Medline, Embase,

The partitioning of nanoparticles to endothelium or interstitium during ultrasound-microbubble-targeted delivery depends on peak-negative pressure

Energy Technology Data Exchange (ETDEWEB)

Hsiang, Y.-H.; Song, J.; Price, R. J., E-mail: rprice@virginia.edu [University of Virginia, Department of Biomedical Engineering (United States)

2015-08-15

Patients diagnosed with advanced peripheral arterial disease often face poor prognoses and have limited treatment options. For some patient populations, the therapeutic growth of collateral arteries (i.e. arteriogenesis) that bypass regions affected by vascular disease may become a viable treatment option. Our group and others are developing therapeutic approaches centered on the ability of ultrasound-activated microbubbles to permeabilize skeletal muscle capillaries and facilitate the targeted delivery of pro-arteriogenic growth factor-bearing nanoparticles. The development of such approaches would benefit significantly from a better understanding of how nanoparticle diameter and ultrasound peak-negative pressure affect both total nanoparticle delivery and the partitioning of nanoparticles to endothelial or interstitial compartments. Toward this goal, using Balb/C mice that had undergone unilateral femoral artery ligation, we intra-arterially co-injected nanoparticles (50 and 100 nm) with microbubbles, applied 1 MHz ultrasound to the gracilis adductor muscle at peak-negative pressures of 0.7, 0.55, 0.4, and 0.2 MPa, and analyzed nanoparticle delivery and distribution. As expected, total nanoparticle (50 and 100 nm) delivery increased with increasing peak-negative pressure, with 50 nm nanoparticles exhibiting greater tissue coverage than 100 nm nanoparticles. Of particular interest, increasing peak-negative pressure resulted in increased delivery to the interstitium for both nanoparticle sizes, but had little influence on nanoparticle delivery to the endothelium. Thus, we conclude that alterations to peak-negative pressure may be used to adjust the fraction of nanoparticles delivered to the interstitial compartment. This information will be useful when designing ultrasound protocols for delivering pro-arteriogenic nanoparticles to skeletal muscle.

The partitioning of nanoparticles to endothelium or interstitium during ultrasound-microbubble-targeted delivery depends on peak-negative pressure

International Nuclear Information System (INIS)

Hsiang, Y.-H.; Song, J.; Price, R. J.

2015-01-01

Patients diagnosed with advanced peripheral arterial disease often face poor prognoses and have limited treatment options. For some patient populations, the therapeutic growth of collateral arteries (i.e. arteriogenesis) that bypass regions affected by vascular disease may become a viable treatment option. Our group and others are developing therapeutic approaches centered on the ability of ultrasound-activated microbubbles to permeabilize skeletal muscle capillaries and facilitate the targeted delivery of pro-arteriogenic growth factor-bearing nanoparticles. The development of such approaches would benefit significantly from a better understanding of how nanoparticle diameter and ultrasound peak-negative pressure affect both total nanoparticle delivery and the partitioning of nanoparticles to endothelial or interstitial compartments. Toward this goal, using Balb/C mice that had undergone unilateral femoral artery ligation, we intra-arterially co-injected nanoparticles (50 and 100 nm) with microbubbles, applied 1 MHz ultrasound to the gracilis adductor muscle at peak-negative pressures of 0.7, 0.55, 0.4, and 0.2 MPa, and analyzed nanoparticle delivery and distribution. As expected, total nanoparticle (50 and 100 nm) delivery increased with increasing peak-negative pressure, with 50 nm nanoparticles exhibiting greater tissue coverage than 100 nm nanoparticles. Of particular interest, increasing peak-negative pressure resulted in increased delivery to the interstitium for both nanoparticle sizes, but had little influence on nanoparticle delivery to the endothelium. Thus, we conclude that alterations to peak-negative pressure may be used to adjust the fraction of nanoparticles delivered to the interstitial compartment. This information will be useful when designing ultrasound protocols for delivering pro-arteriogenic nanoparticles to skeletal muscle

Evaluation of negative pressure vacuum-assisted system in acute and chronic wounds closure: our experience.

Science.gov (United States)

Chiummariello, S; Guarro, G; Pica, A; Alfano, C

2012-10-01

Negative-pressure therapy or vacuum-assisted closure (VAC) has been used in clinical applications since the 1940's and has increased in popularity over the past decade. This dressing technique consists of an open cell foam dressing put into the wound cavity, a vacuum pump produces a negative pressure and an adhesive drape. A controlled sub atmospheric pressure from 75 to 150 mmHg is applied. The vacuum-assisted closure has been applied by many clinicians to chronic wounds in humans; however it cannot be used as a replacement for surgical debridement. The initial treatment for every contaminated wound should be the necrosectomy. The VAC therapy has a complementary function and the range of its indications includes pressure sores, stasis ulcers, chronic wounds such as diabetic foot ulcers, post traumatic and post operative wounds, infected wounds such as necrotizing fasciitis or sternal wounds, soft-tissue injuries, bone exposed injuries, abdominal open wounds and for securing a skin graft. We describe our experience with the VAC dressing used to manage acute and chronic wounds in a series of 135 patients, with excellent results together with satisfaction of the patients.

Hemodynamic differences between continual positive and two types of negative pressure ventilation.

Science.gov (United States)

Lockhat, D; Langleben, D; Zidulka, A

1992-09-01

In seven anesthetized dogs, ventilated with matching lung volumes, tidal volumes, and respiratory rates, we compared the effects on cardiac output (CO), arterial venous oxygen saturation difference (SaO2 - SVO2), and femoral and inferior vena cava pressure (1) intermittent positive pressure ventilation with positive end-expiratory pressure (CPPV); (2) iron-lung ventilation with negative end-expiratory pressure (ILV-NEEP); (3) grid and wrap ventilation with NEEP applied to the thorax and upper abdomen (G&W-NEEP). The values of CO and SaO2 - SVO2 with ILV-NEEP were similar to those with CPPV. However, with G&W-NEEP as compared with ILV-NEEP, mean CO was greater (2.9 versus 2.6 L/min, p = 0.02) and mean (SaO2 - SVO2) was lower (26.6% versus 28.3%, p = NS). Mean PFEM-IVC was higher with G&W-NEEP than with the other types of ventilation. We conclude that (1) ILV-NEEP is hemodynamically equivalent to CPPV and (2) G&W-NEEP has less adverse hemodynamic consequences. has less adverse hemodynamic consequences.

The effects of superimposed tilt and lower body negative pressure on anterior and posterior cerebral circulations

OpenAIRE

Tymko, Michael M.; Rickards, Caroline A.; Skow, Rachel J.; Ingram?Cotton, Nathan C.; Howatt, Michael K.; Day, Trevor A.

2016-01-01

Abstract Steady?state tilt has no effect on cerebrovascular reactivity to increases in the partial pressure of end?tidal carbon dioxide (PETCO 2). However, the anterior and posterior cerebral circulations may respond differently to a variety of stimuli that alter central blood volume, including lower body negative pressure (LBNP). Little is known about the superimposed effects of head?up tilt (HUT; decreased central blood volume and intracranial pressure) and head?down tilt (HDT; increased ce...

Topical negative pressure therapy Recent experience of the department of plastic surgery at Ibn Sina University Hospital, Rabat, Morocco

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Abdelmoughit Echchaoui

2014-12-01

Full Text Available IntroductionThe topical negative pressure therapy (TNP is a non-invasive method to treat chronic and acute wounds locally, using a continuous or intermittent negative pressure.The objective of this study is to present the first experience of this type of treatment used in clinical cases in our department. By presenting these cases, we highlight indication and efficiency of this new technique applied in relatively complicated situations, at the same time it also allows a significant improvement in treating injuries and chronic wounds.Materials and methodsIn this study, we present the recent experience of the Department of Reconstructive and Plastic Surgery of the University Hospital Center of Avicenne in Rabat. This therapy was used for the first time this year (in 2014, in three young patients who presented with chronic wounds associated with local and general factors that are unfavorable for the healing process.ResultsIn all three of our cases we obtained highly satisfactory clinical results.TNP allows wounds to bud in a shorter time, as well as a fast healing by second intention due to controlled wound healing or split-skin graft without using flaps. This enables to decrease the margin of error, the time and the number of dressing replacements, and to reduce the length of hospital stay.ConclusionThis is an expensive and specific equipment. However, the cost-benefit ratio analysis shows that it is an essential method that should be part of our therapeutic strategies.Keywords: loss of substance, negative pressure, budding, healing.  

Increase in vagal activity during hypotensive lower-body negative pressure in humans

DEFF Research Database (Denmark)

Sander-Jensen, K; Mehlsen, J; Stadeager, C

1988-01-01

Progressive central hypovolemia is characterized by a normotensive, tachycardic stage followed by a reversible, hypotensive stage with slowing of the heart rate (HR). We investigated circulatory changes and arterial hormone concentrations in response to lower-body negative pressure (LBNP) in six...... volunteers before and after atropine administration. LBNP of 55 mmHg initially resulted in an increase in HR from 55 +/- 4 to 90 +/- 5 beats/min and decreases in mean arterial pressure (MAP) from 94 +/- 4 to 81 +/- 5 mmHg, in central venous pressure from 7 +/- 1 to -3 +/- 1 mmHg, and in cardiac output from 6.......1 +/- 0.5 to 3.7 +/- 0.11/min. Concomitantly, epinephrine and norepinephrine levels increased. After 8.2 +/- 2.3 min of LBNP, the MAP had decreased to 41 +/- 7 mmHg and HR had decreased to 57 +/- 3 beats/min. Vasopressin increased from 1.2 +/- 0.3 to 137 +/- 45 pg/ml and renin activity increased from 1...

Interrogative pressure in simulated forensic interviews: the effects of negative feedback.

Science.gov (United States)

McGroarty, Allan; Baxter, James S

2007-08-01

Much experimental research on interrogative pressure has concentrated on the effects of leading questions, and the role of feedback in influencing responses in the absence of leading questions has been neglected by comparison. This study assessed the effect of negative feedback and the presence of a second interviewer on interviewee responding in simulated forensic interviews. Participants viewed a videotape of a crime, answered questions about the clip and were requestioned after receiving feedback. Compared with neutral feedback, negative feedback resulted in more response changes, higher reported state anxiety and higher ratings of interview difficulty. These results are consistent with Gudjonsson and Clark's (1986) model of interrogative suggestibility. The presence and involvement of a second interviewer did not significantly affect interviewee responding, although trait anxiety scores were elevated when a second interviewer was present. The theoretical and applied implications of these findings are considered.

The Influence of the Bed with a Semiopen Hood on Bacteria Removal in a Negative-Pressure Isolation Room

OpenAIRE

Jeng-Min Huang; Hsiang-Tai Cheng

2014-01-01

This study numerically investigates the influence of a sickbed with a semiopened hood on bacteria removal in a negative-pressure isolation room. The parameters include air change rate, lying style, the length and height of hood, flow rate allotments, and the positions of outlets. The results show that the hood has excellent effect on the removal of contaminated air, which is much better than the case without hood. The flow field of patient's face up cough is very different from face side coug...

Negative-pressure in treatment of persistent post-traumatic subcutaneous emphysema with respiratory failure: Case report and literature review

Directory of Open Access Journals (Sweden)

Jakov Mihanović

2018-02-01

Full Text Available Subcutaneous emphysema may aggravate traumatic pneumothorax treatment, especially when mechanical ventilation is required. Expectative management usually suffices, but when respiratory function is impaired surgical treatment might be indicated. Historically relevant methods are blowhole incisions and placement of various drains, often with related wound complications. Since the first report of negative pressure wound therapy for the treatment of severe subcutaneous emphysema in 2009, only few publications on use of commercially available sets were published. We report on patient injured in a motor vehicle accident who had serial rib fractures and bilateral pneumothorax managed initially in another hospital. Due to respiratory deterioration, haemodynamic instability and renal failure patient was transferred to our Intensive Care Unit. Massive and persistent subcutaneous emphysema despite adequate thoracic drainage with respiratory deterioration and potentially injurious mechanical ventilation with high airway pressures was the indication for active surgical treatment. Negative-pressure wound therapy dressing was applied on typical blowhole incisions which resulted in swift emphysema regression and respiratory improvement. Negative pressure wound therapy for decompression of severe subcutaneous emphysema represents simple, effective and relatively unknown technique that deserves wider attention.

Experimental evidence for negative turgor pressure in small leaf cells of Robinia pseudoacacia L versus large cells of Metasequoia glyptostroboides Hu et W.C.Cheng. 1. Evidence from pressure-volume curve analysis of dead tissue.

Science.gov (United States)

Yang, Dongmei; Pan, Shaoan; Ding, Yiting; Tyree, Melvin T

2017-03-01

This paper provides a mini-review of evidence for negative turgor pressure in leaf cells starting with experimental evidence in the late 1950s and ending with biomechanical models published in 2014. In the present study, biomechanical models were used to predict how negative turgor pressure might be manifested in dead tissue, and experiments were conducted to test the predictions. The main findings were as follows: (i) Tissues killed by heating to 60 or 80 °C or by freezing in liquid nitrogen all became equally leaky to cell sap solutes and all seemed to pass freely through the cell walls. (ii) Once cell sap solutes could freely pass the cell walls, the shape of pressure-volume curves was dramatically altered between living and dead cells. (iii) Pressure-volume curves of dead tissue seem to measure negative turgor defined as negative when inside minus outside pressure is negative. (iv) Robinia pseudoacacia leaves with small palisade cells had more negative turgor than Metasequoia glyptostroboides with large cells. (v) The absolute difference in negative turgor between R. pseudoacacia and M. glyptostroboides approached as much as 1.0 MPa in some cases. The differences in the manifestation of negative turgor in living versus dead tissue are discussed. © 2016 John Wiley & Sons Ltd.

Magnetosphere and ionosphere response to a positive-negative pulse pair of solar wind dynamic pressure

Science.gov (United States)

Tian, A.; Degeling, A. W.

2017-12-01

Simulations and observations had shown that single positive/negative solar wind dynamic pressure pulse would excite geomagnetic impulsive events along with ionosphere and/or magnetosphere vortices which are connected by field aligned currents(FACs). In this work, a large scale ( 9min) magnetic hole event in solar wind provided us with the opportunity to study the effects of positive-negative pulse pair (△p/p 1) on the magnetosphere and ionosphere. During the magnetic hole event, two traveling convection vortices (TCVs, anti-sunward) first in anticlockwise then in clockwise rotation were detected by geomagnetic stations located along the 10:30MLT meridian. At the same time, another pair of ionospheric vortices azimuthally seen up to 3 MLT first in clockwise then in counter-clockwise rotation were also appeared in the afternoon sector( 14MLT) and centered at 75 MLAT without obvious tailward propagation feature. The duskside vortices were also confirmed in SuperDARN radar data. We simulated the process of magnetosphere struck by a positive-negative pulse pair and it shows that a pair of reversed flow vortices in the magnetosphere equatorial plane appeared which may provide FACs for the vortices observed in ionosphere. Dawn dusk asymmetry of the vortices as well as the global geomagnetism perturbation characteristics were also discussed.

Who Chokes Under Pressure? The Big Five Personality Traits and Decision-Making under Pressure.

Science.gov (United States)

Byrne, Kaileigh A; Silasi-Mansat, Crina D; Worthy, Darrell A

2015-02-01

The purpose of the present study was to examine whether the Big Five personality factors could predict who thrives or chokes under pressure during decision-making. The effects of the Big Five personality factors on decision-making ability and performance under social (Experiment 1) and combined social and time pressure (Experiment 2) were examined using the Big Five Personality Inventory and a dynamic decision-making task that required participants to learn an optimal strategy. In Experiment 1, a hierarchical multiple regression analysis showed an interaction between neuroticism and pressure condition. Neuroticism negatively predicted performance under social pressure, but did not affect decision-making under low pressure. Additionally, the negative effect of neuroticism under pressure was replicated using a combined social and time pressure manipulation in Experiment 2. These results support distraction theory whereby pressure taxes highly neurotic individuals' cognitive resources, leading to sub-optimal performance. Agreeableness also negatively predicted performance in both experiments.

Children Do Show Negative Priming: Further Evidence for Early Development of an Intact Selective Control Mechanism

Science.gov (United States)

Frings, Christian; Feix, Silke; Rothig, Ulrike; Bruser, Charlotte; Junge, Miriam

2007-01-01

Reactions to stimuli that were shortly before presented as distractors are usually slowed down; this phenomenon is known as negative priming. Negative priming is an accepted index for tapping into selective control mechanisms. Although this effect is well established for adults, it has been claimed that children do not show negative priming.…

Global model analysis of negative ion generation in low-pressure inductively coupled hydrogen plasmas with bi-Maxwellian electron energy distributions

International Nuclear Information System (INIS)

Huh, Sung-Ryul; Kim, Nam-Kyun; Jung, Bong-Ki; Chung, Kyoung-Jae; Hwang, Yong-Seok; Kim, Gon-Ho

2015-01-01

A global model was developed to investigate the densities of negative ions and the other species in a low-pressure inductively coupled hydrogen plasma with a bi-Maxwellian electron energy distribution. Compared to a Maxwellian plasma, bi-Maxwellian plasmas have higher populations of low-energy electrons and highly vibrationally excited hydrogen molecules that are generated efficiently by high-energy electrons. This leads to a higher reaction rate of the dissociative electron attachment responsible for negative ion production. The model indicated that the bi-Maxwellian electron energy distribution at low pressures is favorable for the creation of negative ions. In addition, the electron temperature, electron density, and negative ion density calculated using the model were compared with the experimental data. In the low-pressure regime, the model results of the bi-Maxwellian electron energy distributions agreed well quantitatively with the experimental measurements, unlike those of the assumed Maxwellian electron energy distributions that had discrepancies

Comparison of Outcomes for Normal Saline and an Antiseptic Solution for Negative-Pressure Wound Therapy with Instillation.

Science.gov (United States)

Kim, Paul J; Attinger, Christopher E; Oliver, Noah; Garwood, Caitlin; Evans, Karen K; Steinberg, John S; Lavery, Larry A

2015-11-01

Negative-pressure wound therapy with instillation is an adjunctive treatment that uses periodic instillation of a solution and negative pressure for a wide diversity of wounds. A variety of solutions have been reported, with topical antiseptics as the most frequently chosen option. The objective of this study was to compare the outcomes of normal saline versus an antiseptic solution for negative-pressure wound therapy with instillation for the adjunctive treatment of infected wounds. This was a prospective, randomized, effectiveness study comparing 0.9% normal saline versus 0.1% polyhexanide plus 0.1% betaine for the adjunctive treatment of infected wounds that required hospital admission and operative débridement. One hundred twenty-three patients were eligible, with 100 patients randomized for the intention-to-treat analysis and 83 patients for the per-protocol analysis. The surrogate outcomes measured were number of operative visits, length of hospital stay, time to final surgical procedure, proportion of closed or covered wounds, and proportion of wounds that remained closed or covered at the 30-day follow-up. There were no statistically significant differences in the demographic profiles in the two cohorts except for a larger proportion of male patients (p = 0.004). There was no statistically significant difference in the surrogate outcomes with the exception of the time to final surgical procedure favoring normal saline (p = 0.038). The authors' results suggest that 0.9% normal saline may be as effective as an antiseptic (0.1% polyhexanide plus 0.1% betaine) for negative-pressure wound therapy with instillation for the adjunctive inpatient management of infected wounds. Therapeutic, II.

Increased serum urea to creatinine ratio and its negative correlation with arterial pressure in canine babesiosis.

Science.gov (United States)

Zygner, Wojciech; Gójska-Zygner, Olga

2014-09-01

The increase of the serum urea to creatinine ratio (UCR) was observed in dogs infected with Babesia canis. Previous studies have suggested that decrease of blood pressure can be one of the reasons for this phenomenon. In this work statistically significant increase of the UCR was observed in dogs with babesiosis. Comparison of the UCR between 23 azotaemic dogs and 25 non-azotaemic dogs infected with Babesia canis showed statistically significantly higher mean of the UCR in azotaemic dogs. Correlations between UCR and systolic, diastolic and mean arterial pressure (SAP, DAP and MAP) in 48 dogs infected with B. canis were negative (UCR and SAP: r = -0.3909; UCR and DAP: r = -0.3182; UCR and MAP: r = -0.3682) and statistically significant (p high, and there was no statistically significant correlation between UCR and arterial pressures in azotaemic dogs. Thus, it seems that decrease of blood pressure in dogs with babesiosis explains only partially the cause of increased UCR in infected dogs. The other authors suggested hyperureagenesis and myocardial injury as a potential reason for the increased UCR in canine babesiosis. Thus, further studies are needed to determine causes of increased UCR in dogs with babesiosis, especially on the connection between UCR changes and the concentrations of plasma cardiac troponins and ammonia, and the occurrence of occult blood on fecal examination.

Cardiovascular response to lower body negative pressure stimulation before, during, and after space flight

Science.gov (United States)

Baisch, F.; Beck, L.; Blomqvist, G.; Wolfram, G.; Drescher, J.; Rome, J. L.; Drummer, C.

2000-01-01

BACKGROUND: It is well known that space travel cause post-flight orthostatic hypotension and it was assumed that autonomic cardiovascular control deteriorates in space. Lower body negative pressure (LBNP) was used to assess autonomic function of the cardiovascular system. METHODS: LBNP tests were performed on six crew-members before and on the first days post-flight in a series of three space missions. Additionally, two of the subjects performed LBNP tests in-flight. LBNP mimics fluid distribution of upright posture in a gravity independent way. It causes an artificial sequestration of blood, reduces preload, and filtrates plasma into the lower part of the body. Fluid distribution was assessed by bioelectrical impedance and anthropometric measurements. RESULTS: Heart rate, blood pressure, and total peripheral resistance increased significantly during LBNP experiments in-flight. The decrease in stroke volume, the increased pooling of blood, and the increased filtration of plasma into the lower limbs during LBNP indicated that a plasma volume reduction and a deficit of the interstitial volume of lower limbs rather than a change in cardiovascular control was responsible for the in-flight response. Post-flight LBNP showed no signs of cardiovascular deterioration. The still more pronounced haemodynamic changes during LBNP reflected the expected behaviour of cardiovascular control faced with less intravascular volume. In-flight, the status of an intra-and extravascular fluid deficit increases sympathetic activity, the release of vasoactive substances and consequently blood pressure. Post-flight, blood pressure decreases significantly below pre-flight values after restoration of volume deficits. CONCLUSION: We conclude that the cardiovascular changes in-flight are a consequence of a fluid deficit rather than a consequence of changes in autonomic signal processing.

Human Commercial Models' Eye Colour Shows Negative Frequency-Dependent Selection.

Directory of Open Access Journals (Sweden)

Isabela Rodrigues Nogueira Forti

Full Text Available In this study we investigated the eye colour of human commercial models registered in the UK (400 female and 400 male and Brazil (400 female and 400 male to test the hypothesis that model eye colour frequency was the result of negative frequency-dependent selection. The eye colours of the models were classified as: blue, brown or intermediate. Chi-square analyses of data for countries separated by sex showed that in the United Kingdom brown eyes and intermediate colours were significantly more frequent than expected in comparison to the general United Kingdom population (P<0.001. In Brazil, the most frequent eye colour brown was significantly less frequent than expected in comparison to the general Brazilian population. These results support the hypothesis that model eye colour is the result of negative frequency-dependent selection. This could be the result of people using eye colour as a marker of genetic diversity and finding rarer eye colours more attractive because of the potential advantage more genetically diverse offspring that could result from such a choice. Eye colour may be important because in comparison to many other physical traits (e.g., hair colour it is hard to modify, hide or disguise, and it is highly polymorphic.

Cost study of dermal substitutes and topical negative pressure in the surgical treatment of burns

NARCIS (Netherlands)

Hop, M.J.; Bloemen, M.C.T.; van Baar, M.E.; Nieuwenhuis, M.K.; van Zuijlen, P.P.M.; Polinder, S.; Middelkoop, E.

2014-01-01

AbstractBackground A recently performed randomised controlled trial investigated the clinical effectiveness of dermal substitutes (DS) and split skin grafts (SSG) in combination with topical negative pressure (TNP) in the surgical treatment of burn wounds. In the current study, medical and

Formation and Morphology Evolution of Anodic TiO2 Nanotubes under Negative Pressure

International Nuclear Information System (INIS)

Lu, Hongyan; Fan, Haowen; Jin, Rong; Chong, Bin; Shen, Xiaoping; Yan, Shuo; Zhu, Xufei

2016-01-01

Highlights: • Nernst equation is applied to explain electrochemical reactions during anodization. • Longer nanotubes were obtained under 0.02 MPa, as compared to atmospheric conditions. • The total anodizing current was separated into ionic current and electronic current. • Explanation for the particularity of nanotubes obtained under 0.02 MPa is presented. - Abstract: Anodic TiO 2 nanotubes (ATNTs) have attracted extensive interest in the past decade. ATNTs are generally fabricated by anodization of Ti foils under atmospheric conditions (0.1 MPa). To date, the growth kinetics of ATNTs remains unclear. Herein anodizations of Ti foils under negative pressure are designed to overcome this challenge. Longer nanotubes were fabricated under negative pressure, as compared to atmospheric conditions. Variations of the nanotube length and surface morphology of ATNTs provide evidences for oxygen bubble mould, in which the ionic current contributes to nanotube growth while the electronic current gives rise to the oxygen evolution. Nernst equation was firstly applied to simulate variations of electronic current and ionic current during anodization. The in-depth analysis of the morphology variations could help elucidate the formation mechanism, thus paving the way for the optimization of the synthesis process of ATNTs.

EURAMET.M.P-S9: comparison in the negative gauge pressure range -950 to 0 hPa

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Saxholm, S.; Otal, P.; AltintaS, A.; Bermanec, L. G.; Durgut, Y.; Hanrahan, R.; Kocas, I.; Lefkopoulos, A.; Pražák, D.; Sandu, I.; Åetina, J.; Spohr, I.; Steindl, D.; Tammik, K.; Testa, N.

2016-01-01

A comparison in the negative gauge pressure range was arranged in the period 2011 - 2012. A total of 14 laboratories participated in this comparison: BEV (Austria), CMI (Czech Republic), DANIAmet-FORCE (Denmark), EIM (Greece), HMI/FSB-LPM (Croatia), INM (Romania), IPQ (Portugal), LNE (France), MCCAA (Malta), METROSERT (Estonia), MIKES (Finland), MIRS/IMT/LMT (Slovenia), NSAI (Ireland) and UME (Turkey). The project was divided into two loops: Loop1, piloted by MIKES, and Loop2, piloted by LNE. The results of the two loops are reported separately: Loop1 results are presented in this paper. The transfer standard was Beamex MC5 no. 25516865 with internal pressure module INT1C, resolution 0.01 hPa. The nominal pressure range of the INT1C is -1000 hPa to +1000 hPa. The nominal pressure points for the comparison were 0 hPa, -200 hPa, -400 hPa, -600 hPa, -800 hPa and -950 hPa. The reference values and their uncertainties as well as the difference uncertainty between the laboratory results and the reference values were determined from the measurement data by Monte Carlo simulations. Stability uncertainty of the transfer standard was included in the final difference uncertainty. Degrees of equivalences and mutual equivalences between the laboratories were calculated. Each laboratory reported results for all twelve measurement points, which means that there were 168 reported values in total. Some 163 of the 168 values (97 %) agree with the reference values within the expanded uncertainties, with a coverage factor k = 2. Among the laboratories, four different methods were used to determine negative gauge pressure. It is concluded that special attention must be paid to the measurements and methods when measuring negative gauge pressures. There might be a need for a technical guide or a workshop that provides information about details and practices related to the measurements of negative gauge pressure, as well as differences between the different methods. The comparison is

Using negative pressure therapy for improving skin graft taking on genital area defects following Fournier gangrene.

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Orhan, Erkan; Şenen, Dilek

2017-09-01

Fournier's gangrene is an infective necrotizing fasciitis of the perineal, genital and perianal regions. Treatment includes aggressive surgical debridement that often results in extensive loss of genital skin. Skin grafts may be used for reconstruction but skin grafting of the male genitalia is diffucult because the penis and scrotum are mobile and deformable. A variety of methods are used to secure skin graft to recipient beds. We used negative pressure therapy (NPT) to secure skin grafts and improve skin graft taking. We used negative pressure therapy for graft fixation in 13 male patients who underwent debridements with the indication of Fournier gangrene, and whose defects formed were reconstructed with grafts between January 2009, and January 2014. Information about age of the patients, sessions of negative pressure therapy applied before, and after reconstruction, duration of hospital stay, and graft losses during postoperative period were recorded. Median age of the patients was 56.15 (46-72) years. NPT was applied to patients for an average of 6.64 sessions (4-12) before and 1 sessions after graft reconstruction. Patients were hospitalized for an average of 26.7 (20-39) days. Any graft loss was not seen after NPT. Because of the peculiar anatomy of the genital region, anchoring of grafts is difficult so graft losses are often encountered. Use of NPT for ensuring graft fixation on the genital region prevents skin graft shearing.

[Efficacy observation on application of negative pressure therapy in the treatment of superficial partial-thickness scald wound in children].

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Shen, Chuan-an; Chai, Jia-ke; Tuo, Xiao-ye; Cai, Jian-hua; Li, Dong-jie; Zhang, Lin; Zhu, Hua; Cai, Jin-dong

2013-02-01

To observe the effect of negative pressure therapy in the treatment of superficial partial-thickness scald in children. Three hundred and seven children with superficial partial-thickness scald hospitalized from August 2009 to May 2012 were divided into negative pressure therapy group (NPT, n = 145) and control group (C, n = 162) according to the random number table. Patients in group NPT were treated with negative pressure from within post injury day (PID) 3 to PID 9 (with -16 kPa pressure), while traditional occlusive dressing method was used in group C. Changes in body temperature, wound healing condition, frequency of dressing change were compared between group NPT and group C. Bacterial culture results of wounds were compared before and after treatment in group NPT. Volume of drained transudate per one percent of wound area was recorded in group NPT on PID 1 to PID 3. Data were processed with t test or chi-square test. The incidence of high fever was significantly lower in group NPT (26.9%, 39/145) than in group C (63.6%, 103/162, χ(2) = 41.419, P partial-thickness scald.

Effect of negative pressure therapy on repair of soft tissues of the lower extremities in patients with neuropathic and neuroischaemic forms of diabetic foot syndrome

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Ekaterina Leonidovna Zaytseva

2014-06-01

Full Text Available Aim. To evaluate the efficiency of topical negative pressure wound therapy (NPWT compared with standard therapy for the regeneration of the soft tissues of the lower extremities in patients with diabetic foot syndrome. Materials and Methods. The effects of negative pressure therapy on the clinical (size, tissue oxygenation, histological (light microscopy and immunohistochemical (CD68, MMP-9, TIMP-1 aspects of repair of the soft tissue of the lower extremities in patients with diabetes mellitus were compared with those of standard treatment. Thirty-one patients with diabetic foot ulcers were included in the study from the moment of debridement until the plastic closure of the wound. During the perioperative period, 13 patients received NPWT (-90 to -120 mmHg and 18 patients received standard therapy. Results. A reduction of the wound area (26.6%?17.2% and the depth of the defects (40.5%?25.6% were achieved with negative pressure therapy compared with baseline data. In the control group, the corresponding values were 25.3%?19.4% and 21.8%?21.6%, respectively. The results of transcutaneous oximetry showed a greater increase in the level of local hemodynamics in the study group (p

Papineau debridement, Ilizarov bone transport, and negative-pressure wound closure for septic bone defects of the tibia.

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Karargyris, Orestis; Polyzois, Vasilios D; Karabinas, Panayiotis; Mavrogenis, Andreas F; Pneumaticos, Spyros G

2014-08-01

Ilizarov pioneered bone transport using a circular external fixator. Papineau described a staged technique for the treatment for infected pseudarthrosis of the long bones. This article presents a single-stage Papineau technique and Ilizarov bone transport, and postoperative negative-pressure wound dressing changes for septic bone defects of the tibia. We studied the files of seven patients (mean age, 32 years) with septic bone defects of the tibia treated with a Papineau technique and Ilizarov bone transport in a single stage, followed by postoperative negative-pressure wound dressing changes. All patients had septic pseudarthrosis and skin necrosis of the tibia. The technique included a single-stage extensive surgical debridement of necrotic bone, open bone grafting with cancellous bone autograft and bone transport, and postoperative negative-pressure wound dressing changes for wound closure. The mean time from the initial injury was 6 months (range, 4-8 months). The mean follow-up was 14 months (range, 10-17 months). All patients experienced successful wound healing at a mean of 29 days. Six patients experienced successful bone regeneration and union at the docking side at a mean of 6 months. One patient experienced delayed union at the docking site, which was treated with autologous cancellous bone grafting. Two patients experienced pin track infection, which was successfully treated with antibiotics and pin site dressing changes. All patients were able to return to their work and previous levels of activity, except one patient who had a stiff ankle joint and had to change his job. No patient experienced recurrence of infection, or fracture of the regenerated or transported bone segment until the period of this study. The combined Papineau and Ilizarov bone transport technique with negative-pressure wound closure provides for successful eradication of the infection, reconstruction of the bone defect, and soft-tissue closure. A single-stage surgical treatment is

Negative Gauge Pressure Moisture Management and Secure Adherence Device for Prosthetic Limbs

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2013-03-01

prosthesis feels like it is sliding up and down or falling off when I am active. D. I have been more active than normal as a result of this prosthesis ...temperature. 3. My prosthesis feels like it is sliding up and down or falling off when I am active. 4. I have been more active than normal as a result of...objective of this research was to develop and test a novel prosthesis incorporating a negative gauge pressure moisture management and secure

Development of micropump-actuated negative pressure pinched injection for parallel electrophoresis on array microfluidic chip.

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Li, Bowei; Jiang, Lei; Xie, Hua; Gao, Yan; Qin, Jianhua; Lin, Bingcheng

2009-09-01

A micropump-actuated negative pressure pinched injection method is developed for parallel electrophoresis on a multi-channel LIF detection system. The system has a home-made device that could individually control 16-port solenoid valves and a high-voltage power supply. The laser beam is excitated and distributes to the array separation channels for detection. The hybrid Glass-PDMS microfluidic chip comprises two common reservoirs, four separation channels coupled to their respective pneumatic micropumps and two reference channels. Due to use of pressure as a driving force, the proposed method has no sample bias effect for separation. There is only one high-voltage supply needed for separation without relying on the number of channels, which is significant for high-throughput analysis, and the time for sample loading is shortened to 1 s. In addition, the integrated micropumps can provide the versatile interface for coupling with other function units to satisfy the complicated demands. The performance is verified by separation of DNA marker and Hepatitis B virus DNA samples. And this method is also expected to show the potential throughput for the DNA analysis in the field of disease diagnosis.

Flame Atmospheric Pressure Chemical Ionization Coupled with Negative Electrospray Ionization Mass Spectrometry for Ion Molecule Reactions.

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Cheng, Sy-Chyi; Bhat, Suhail Muzaffar; Shiea, Jentaie

2017-07-01

Flame atmospheric pressure chemical ionization (FAPCI) combined with negative electrospray ionization (ESI) mass spectrometry was developed to detect the ion/molecule reactions (IMRs) products between nitric acid (HNO 3 ) and negatively charged amino acid, angiotensin I (AI) and angiotensin II (AII), and insulin ions. Nitrate and HNO 3 -nitrate ions were detected in the oxyacetylene flame, suggesting that a large quantity of nitric acid (HNO 3 ) was produced in the flame. The HNO 3 and negatively charged analyte ions produced by a negative ESI source were delivered into each arm of a Y-shaped stainless steel tube where they merged and reacted. The products were subsequently characterized with an ion trap mass analyzer attached to the exit of the Y-tube. HNO 3 showed the strongest affinity to histidine and formed (M histidine -H+HNO 3 ) - complex ions, whereas some amino acids did not react with HNO 3 at all. Reactions between HNO 3 and histidine residues in AI and AII resulted in the formation of dominant [M AI -H+(HNO 3 )] - and [M AII -H+(HNO 3 )] - ions. Results from analyses of AAs and insulin indicated that HNO 3 could not only react with basic amino acid residues, but also with disulfide bonds to form [M-3H+(HNO 3 ) n ] 3- complex ions. This approach is useful for obtaining information about the number of basic amino acid residues and disulfide bonds in peptides and proteins. Graphical Abstract ᅟ.

Negative pressure pulmonary oedema following use of ProSeal LMA

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Richa Jain

2013-01-01

Full Text Available Negative pressure pulmonary oedema (NPPO is a life threatening condition, manifested due to upper airway obstruction in a spontaneously breathing patient. Upper airway obstruction caused by classic laryngeal mask airway (cLMA and ProSeal laryngeal mask airway (PLMA has been reported, and NPPO has also been reported following the use of cLMA. Search of literature did not confirm NPPO following the use of PLMA. We encountered a female patient of NPPO scheduled for incision and drainage of an abscess who had signs of airway obstruction following PLMA insertion. Multiple attempts were made to get patent airway without success. PLMA was replaced with endotracheal tube following which pink frothy secretion appeared in breathing circuit. Patient was managed successfully with ICU care.

Cracked rocks with positive and negative Poisson's ratio: real-crack properties extracted from pressure dependence of elastic-wave velocities

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Zaitsev, Vladimir Y.; Radostin, Andrey V.; Dyskin, Arcady V.; Pasternak, Elena

2017-04-01

We report results of analysis of literature data on P- and S-wave velocities of rocks subjected to variable hydrostatic pressure. Out of about 90 examined samples, in more than 40% of the samples the reconstructed Poisson's ratios are negative for lowest confining pressure with gradual transition to the conventional positive values at higher pressure. The portion of rocks exhibiting negative Poisson's ratio appeared to be unexpectedly high. To understand the mechanism of negative Poisson's ratio, pressure dependences of P- and S-wave velocities were analyzed using the effective medium model in which the reduction in the elastic moduli due to cracks is described in terms of compliances with respect to shear and normal loading that are imparted to the rock by the presence of cracks. This is in contrast to widely used descriptions of effective cracked medium based on a specific crack model (e.g., penny-shape crack) in which the ratio between normal and shear compliances of such a crack is strictly predetermined. The analysis of pressure-dependences of the elastic wave velocities makes it possible to reveal the ratio between pure normal and shear compliances (called q-ratio below) for real defects and quantify their integral content in the rock. The examination performed demonstrates that a significant portion (over 50%) of cracks exhibit q-ratio several times higher than that assumed for the conventional penny-shape cracks. This leads to faster reduction of the Poisson's ratio with increasing the crack concentration. Samples with negative Poisson's ratio are characterized by elevated q-ratio and simultaneously crack concentration. Our results clearly indicate that the traditional crack model is not adequate for a significant portion of rocks and that the interaction between the opposite crack faces leading to domination of the normal compliance and reduced shear displacement discontinuity can play an important role in the mechanical behavior of rocks.

A Risk Analysis Methodology to Address Human and Organizational Factors in Offshore Drilling Safety: With an Emphasis on Negative Pressure Test

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Tabibzadeh, Maryam

According to the final Presidential National Commission report on the BP Deepwater Horizon (DWH) blowout, there is need to "integrate more sophisticated risk assessment and risk management practices" in the oil industry. Reviewing the literature of the offshore drilling industry indicates that most of the developed risk analysis methodologies do not fully and more importantly, systematically address the contribution of Human and Organizational Factors (HOFs) in accident causation. This is while results of a comprehensive study, from 1988 to 2005, of more than 600 well-documented major failures in offshore structures show that approximately 80% of those failures were due to HOFs. In addition, lack of safety culture, as an issue related to HOFs, have been identified as a common contributing cause of many accidents in this industry. This dissertation introduces an integrated risk analysis methodology to systematically assess the critical role of human and organizational factors in offshore drilling safety. The proposed methodology in this research focuses on a specific procedure called Negative Pressure Test (NPT), as the primary method to ascertain well integrity during offshore drilling, and analyzes the contributing causes of misinterpreting such a critical test. In addition, the case study of the BP Deepwater Horizon accident and their conducted NPT is discussed. The risk analysis methodology in this dissertation consists of three different approaches and their integration constitutes the big picture of my whole methodology. The first approach is the comparative analysis of a "standard" NPT, which is proposed by the author, with the test conducted by the DWH crew. This analysis contributes to identifying the involved discrepancies between the two test procedures. The second approach is a conceptual risk assessment framework to analyze the causal factors of the identified mismatches in the previous step, as the main contributors of negative pressure test

Matching Biological Mesh and Negative Pressure Wound Therapy in Reconstructing an Open Abdomen Defect

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Fabio Caviggioli

2014-01-01

Full Text Available Reconstruction of open abdominal defects is a clinical problem which general and plastic surgeons have to address in cooperation. We report the case of a 66-year-old man who presented an abdominal dehiscence after multiple laparotomies for a sigmoid-rectal adenocarcinoma that infiltrated into the abdominal wall, subsequently complicated by peritonitis and enteric fistula. A cutaneous dehiscence and an incontinent abdominal wall resulted after the last surgery. The abdominal wall was reconstructed using a biological porcine cross-linked mesh Permacol (Covidien Inc., Norwalk, CT. Negative Pressure Wound Therapy (NPWT, instead, was used on the mesh in order to reduce wound dimensions, promote granulation tissue formation, and obtain secondary closure of cutaneous dehiscence which was finally achieved with a split-thickness skin graft. Biological mesh behaved like a scaffold for the granulation tissue that was stimulated by the negative pressure. The biological mesh was rapidly integrated in the abdominal wall restoring abdominal wall continence, while the small dehiscence, still present in the central area, was subsequently covered with a split-thickness skin graft. The combination of these different procedures led us to solve this complicated case obtaining complete wound closure after less than 2 months.

Physical fitness and cardiovascular response to lower body negative pressure

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Raven, P. B.; Rohm-Young, D.; Blomqvist, C. G.

1984-01-01

Klein et al. (1977) have questioned the concept of endurance training as an appropriate means of preparing for prolonged space flights. Their opinion was mainly based on reports of endurance athletes who had a decreased tolerance to orthostatic or gravitational stress induced by lower body negative pressure (LBNP), upright tilt, or whole body water immersion. The present investigation had the objective to determine if the hemodynamic response to LBNP is different between a high and average fit group of subjects. In addition, the discrete aspect of cardiovascular function which had been altered by chronic training was to be identified. On the basis of the results of experiments conducted with 14 young male volunteers, it is concluded that the reflex response to central hypovolemia is altered by endurance exercise training.

Major bleeding during negative pressure wound/V.A.C.® - therapy for postsurgical deep sternal wound infection - a critical appraisal

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Segers Patrique

2011-09-01

Full Text Available Abstract Negative-pressure wound therapy, commercially known as vacuum-assisted closure (V.A.C.® therapy, has become one of the most popular (and efficacious interim (prior to flap reconstruction or definite methods of managing deep sternal wound infection. Complications such as profuse bleeding, which may occur during negative-pressure therapy but not necessarily due to it, are often attributed to a single factor and reported as such. However, despite the wealth of clinical experience internationally available, information regarding certain simple considerations is still lacking. Garnering information on all the factors that could possibly influence the outcome has become more difficult due to a (fortunate decrease in the incidence of deep sternal wound infection. If more insight is to be gained from fewer clinical cases, then various potentially confounding factors should be fully disclosed before complications can be attributed to the technique itself or improvements to negative-pressure wound therapy for deep sternal wound infection can be accepted as evidence-based and the guidelines for its use adapted. The authors propose the adoption of a simple checklist in such cases.

Using the Solving Problems Together Psychoeducational Group Counseling Model as an Intervention for Negative Peer Pressure

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Hall, Kimberly R.; Rushing, Jeri Lynn; Khurshid, Ayesha

2011-01-01

Problem-focused interventions are considered to be one of the most effective group counseling strategies with adolescents. This article describes a problem-focused group counseling model, Solving Problems Together (SPT), that focuses on working with students who struggle with negative peer pressure. Adapted from the teaching philosophy of…

Evaluation of a Decision-Making Curriculum for Teaching Adolescents with Disabilities to Resist Negative Peer Pressure

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Khemka, Ishita; Hickson, Linda; Mallory, Sarah B.

2016-01-01

This study was designed to assess the impact of a decision-making curriculum (PEER-DM) on the social peer relationship knowledge and self-protective decision-making skills of adolescents with disabilities in hypothetical situations involving negative peer pressure. A randomized design was used to assign students with disabilities from…

Negative-Pressure Cavitation Extraction of Secoisolariciresinol Diglycoside from Flaxseed Cakes

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Hao Tian

2015-06-01

Full Text Available The negative-pressure cavitation extraction (NPCE technique was applied firstly to extract secoisolariciresinol diglucoside (SDG from flaxseed cakes. The significant extraction parameters were screened by fractional factorial design (FFD. The optimal parameters were determined using the central composite design (CCD with the two variables, NaOH amount and the liquid/solid ratio. The conditions of the extraction were optimized by using response surface methodology (RSM. Under the optimal conditions, the extraction yield and the extraction purity of SDG was 16.25 mg/g and 3.86%, respectively. The efficiency of NPCE was compared with that of conventional extraction methods. Our results demonstrated that NPCE was comparable to the well-known ultrasound-assisted extraction in term of extraction yield and purity. This extraction technique has advantages of less time-consuming, low solvent usage and high throughput capability.

Role of Negative Pressure Wound Therapy in Healing of Diabetic ...

African Journals Online (AJOL)

Journal of Surgical Technique and Case Report | Jan-Jun 2011 | Vol-3 | Issue-1. 10. Role of Negative ... case of any difficulty faced in the application of VAC dressings. BLEEDING ISSUE ... show exposed bone, tendon, joint capsule or fascia.

Anomalous thermal expansion, negative linear compressibility, and high-pressure phase transition in ZnAu2(CN) 4 : Neutron inelastic scattering and lattice dynamics studies

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Gupta, Mayanak K.; Singh, Baltej; Mittal, Ranjan; Zbiri, Mohamed; Cairns, Andrew B.; Goodwin, Andrew L.; Schober, Helmut; Chaplot, Samrath L.

2017-12-01

We present temperature-dependent inelastic-neutron-scattering measurements, accompanied by ab initio calculations of the phonon spectra and elastic properties as a function of pressure to quantitatively explain an unusual combination of negative thermal expansion and negative linear compressibility behavior of ZnAu2(CN) 4 . The mechanism of the negative thermal expansion is identified in terms of specific anharmonic phonon modes that involve bending of the -Zn-NC-Au-CN-Zn- linkage. The soft phonon at the L point at the Brillouin zone boundary quantitatively relates to the high-pressure phase transition at about 2 GPa. The ambient pressure structure is also found to be close to an elastic instability that leads to a weakly first-order transition.

Cost-effectiveness of negative pressure wound therapy in patients with many comorbidities and severe wounds of various etiology.

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Driver, Vickie R; Eckert, Kristen A; Carter, Marissa J; French, Michael A

2016-11-01

This study analyzed a cross-section of patients with severe chronic wounds and multiple comorbidities at an outpatient wound clinic, with regard to the cost-effectiveness and cost-benefit of negative pressure wound therapy (intervention) vs. no negative pressure wound therapy (control) at 1 and 2 years. Medicare reimbursement charges for wound care were used to calculate costs. Amputation charges were assessed using diagnosis-related groups. Cost-benefit analysis was based on ulcer-free months and cost-effectiveness on quality-adjusted life-years. Undiscounted costs, benefits, quality-adjusted life-years, undiscounted and discounted incremental net health benefits, and incremental cost-effectiveness ratios were calculated for unmatched and matched cohorts. There were 150 subjects in the intervention group and 154 controls before matching and 103 subjects in each of the matched cohorts. Time to heal for the intervention cohort was significantly shorter compared to the controls (270 vs. 635 days, p = 1.0 × 10 -7 , matched cohorts). The intervention cohort had higher benefits and quality-adjusted life-year gains compared to the control cohort at years 1 and 2; by year 2, the gains were 68-73% higher. In the unmatched cohorts, the incremental net health benefit was $9,933 per ulcer-free month at year 2 for the intervention; the incremental cost-effectiveness ratio was -825,271 per quality-adjusted life-year gained (undiscounted costs and benefits). For the matched cohorts, the incremental net health benefits was only $1,371 per ulcer-free month for the intervention, but the incremental cost-effectiveness ratio was $366,683 per quality-adjusted life-year gained for year 2 (discounted costs and benefits). In a patient population with severe chronic wounds and serious comorbidities, negative pressure wound therapy resulted in faster healing wounds and was more cost-effective with greater cost-benefits than not using negative pressure wound therapy. Regarding overall

Negative pressure therapy (vacuum for wound bed preparation among diabetic patients: case series

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Marcus Castro Ferreira

Full Text Available CONTEXT: Complications from diabetes mellitus affecting the lower limbs occur in 40 to 70% of such patients. Neuropathy is the main cause of ulceration and may be associated with vascular impairment. The wound evolves with necrosis and infection, and if not properly treated, amputation may be the end result. Surgical treatment is preferred in complex wounds without spontaneous healing. After debridement of the necrotic tissue, the wound bed needs to be prepared to receive a transplant of either a graft or a flap. Dressings can be used to prepare the wound bed, but this usually leads to longer duration of hospitalization. Negative pressure using a vacuum system has been proposed for speeding up the treatment. This paper had the objective of analyzing the effects of this therapy on wound bed preparation among diabetic patients. CASE SERIES: Eighty-four diabetic patients with wounds in their lower limbs were studied. A commercially available vacuum system was used for all patients after adequate debridement of necrotic tissues. For 65 patients, skin grafts completed the treatment and for the other 19, skin flaps were used. Wound bed preparation was achieved over an average time of 7.51 days for 65 patients and 10 days for 12 patients, and in only one case was not achieved. CONCLUSIONS: This experience suggests that negative pressure therapy may have an important role in wound bed preparation and as part of the treatment for wounds in the lower limbs of diabetic patients.

An Alternative Treatment Strategy for Complicated Chronic Wounds: Negative Pressure Therapy over Mesh Skin Graft

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Michele Maruccia

2017-01-01

Full Text Available Extensive skin defect represents a real problem and major challenge in plastic and reconstructive surgery. On one hand, skin grafts offer a practical method to deal with skin defects despite their unsuitability for several complicated wounds. On the other hand, negative pressure wound therapy (NPWT, applied before skin grafting, promotes granulation tissue growth. The aim of the study is to evaluate the improvement in wound healing given by the merger of these two different approaches. We treated 23 patients for large wounds of multiple factors. Of these, 15 were treated with the application of V.A.C.® Therapy (KCI Medical S.r.l., Milan, Italy, in combination with skin grafts after a prior unsuccessful treatment of 4 weeks with mesh skin grafts and dressings. Another 8 were treated with only mesh skin graft. Pain reduction and wound area reduction were found statistically significant (p<0.0009, p<0.0001. Infection was resolved in almost all patients. According to our study, the use of the negative pressure wound therapy over mesh skin grafts is significantly effective especially in wounds resistant to conventional therapies, thereby improving the rate of skin graft take.

Comparisons of negative pressure wound therapy and ultrasonic debridement for diabetic foot ulcers: a network meta-analysis.

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Wang, Ruran; Feng, Yanhua; Di, Bo

2015-01-01

a network meta-analysis was performed to compare the strength and weakness of negative pressure wound therapy (NPWT) with ultrasound debridement (UD) as for diabetic foot ulcers (DFU). PubMed, Ovid EMBASE, Web of Science, Cochrane library databases, and Chinese Biomedical Literature Database were searched till February 2015. Clinical compared studies of negative pressure wound therapy and ultrasound debridement were enrolled. The primary efficacy outcomes included healed ulcers, reduction of ulcer areas and time to closure. Secondary amputation including major and minor amputations was used to assess the safety profile. Out of 715 studies, 32 were selected which enrolled 2880 diabetic patients. The pooled analysis revealed that NPWT including vacuum assisted closure (VAC) and vacuum sealing drainage (VSD) were as efficacious as ultrasound debridement improving healed ulcers, odds ratio, 0.86; 95% CI 0.28 to 2.6 and 1.2; 95% CI 0.38 to 4, respectively. However, both were better to standard wound care in wound healing patients. Compared with the standard wound care treated diabetic foot ulcers, NPWT and UD resulted in a significantly superior efficacy in time to wound closure and decrement in area of wound. No significances were observed between NPWT and UD groups in both indicators. Fewer patients tended to receive amputation in NPWT and UD groups compared to standard wound care group. The results of the network meta-analysis indicated that negative pressure wound therapy was similar to ultrasound debridement for diabetic foot ulcers, but better than standard wound care both in efficacy and safety profile.

Comparisons of negative pressure wound therapy and ultrasonic debridement for diabetic foot ulcers: a network meta-analysis

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Wang, Ruran; Feng, Yanhua; Di, Bo

2015-01-01

Objective: a network meta-analysis was performed to compare the strength and weakness of negative pressure wound therapy (NPWT) with ultrasound debridement (UD) as for diabetic foot ulcers (DFU). Methods: PubMed, Ovid EMBASE, Web of Science, Cochrane library databases, and Chinese Biomedical Literature Database were searched till February 2015. Clinical compared studies of negative pressure wound therapy and ultrasound debridement were enrolled. The primary efficacy outcomes included healed ulcers, reduction of ulcer areas and time to closure. Secondary amputation including major and minor amputations was used to assess the safety profile. Results: Out of 715 studies, 32 were selected which enrolled 2880 diabetic patients. The pooled analysis revealed that NPWT including vacuum assisted closure (VAC) and vacuum sealing drainage (VSD) were as efficacious as ultrasound debridement improving healed ulcers, odds ratio, 0.86; 95% CI 0.28 to 2.6 and 1.2; 95% CI 0.38 to 4, respectively. However, both were better to standard wound care in wound healing patients. Compared with the standard wound care treated diabetic foot ulcers, NPWT and UD resulted in a significantly superior efficacy in time to wound closure and decrement in area of wound. No significances were observed between NPWT and UD groups in both indicators. Fewer patients tended to receive amputation in NPWT and UD groups compared to standard wound care group. Conclusions: The results of the network meta-analysis indicated that negative pressure wound therapy was similar to ultrasound debridement for diabetic foot ulcers, but better than standard wound care both in efficacy and safety profile. PMID:26550165

How bacterial cell division might cheat turgor pressure - a unified mechanism of septal division in Gram-positive and Gram-negative bacteria.

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Erickson, Harold P

2017-08-01

An important question for bacterial cell division is how the invaginating septum can overcome the turgor force generated by the high osmolarity of the cytoplasm. I suggest that it may not need to. Several studies in Gram-negative bacteria have shown that the periplasm is isoosmolar with the cytoplasm. Indirect evidence suggests that this is also true for Gram-positive bacteria. In this case the invagination of the septum takes place within the uniformly high osmotic pressure environment, and does not have to fight turgor pressure. A related question is how the V-shaped constriction of Gram-negative bacteria relates to the plate-like septum of Gram-positive bacteria. I collected evidence that Gram-negative bacteria have a latent capability of forming plate-like septa, and present a model in which septal division is the basic mechanism in both Gram-positive and Gram-negative bacteria. © 2017 WILEY Periodicals, Inc.

Genomic analysis of codon usage shows influence of mutation pressure, natural selection, and host features on Marburg virus evolution.

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Nasrullah, Izza; Butt, Azeem M; Tahir, Shifa; Idrees, Muhammad; Tong, Yigang

2015-08-26

The Marburg virus (MARV) has a negative-sense single-stranded RNA genome, belongs to the family Filoviridae, and is responsible for several outbreaks of highly fatal hemorrhagic fever. Codon usage patterns of viruses reflect a series of evolutionary changes that enable viruses to shape their survival rates and fitness toward the external environment and, most importantly, their hosts. To understand the evolution of MARV at the codon level, we report a comprehensive analysis of synonymous codon usage patterns in MARV genomes. Multiple codon analysis approaches and statistical methods were performed to determine overall codon usage patterns, biases in codon usage, and influence of various factors, including mutation pressure, natural selection, and its two hosts, Homo sapiens and Rousettus aegyptiacus. Nucleotide composition and relative synonymous codon usage (RSCU) analysis revealed that MARV shows mutation bias and prefers U- and A-ended codons to code amino acids. Effective number of codons analysis indicated that overall codon usage among MARV genomes is slightly biased. The Parity Rule 2 plot analysis showed that GC and AU nucleotides were not used proportionally which accounts for the presence of natural selection. Codon usage patterns of MARV were also found to be influenced by its hosts. This indicates that MARV have evolved codon usage patterns that are specific to both of its hosts. Moreover, selection pressure from R. aegyptiacus on the MARV RSCU patterns was found to be dominant compared with that from H. sapiens. Overall, mutation pressure was found to be the most important and dominant force that shapes codon usage patterns in MARV. To our knowledge, this is the first detailed codon usage analysis of MARV and extends our understanding of the mechanisms that contribute to codon usage and evolution of MARV.

Negative pressure wound therapy for partial-thickness burns.

Science.gov (United States)

Dumville, Jo C; Munson, Christopher; Christie, Janice

2014-12-15

A burn wound is a complex and evolving injury, with both local and systemic consequences. Burn treatments include a variety of dressings, as well as newer strategies, such as negative pressure wound therapy (NPWT), which, by means of a suction force that drains excess fluids from the burn, tries to promote the wound healing process and minimise progression of the burn wound. To assess the effectiveness of NPWT for people with partial-thickness burns. We searched the Cochrane Wounds Group Specialised Register (searched 04 September 2014); The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 8). All randomised controlled trials (RCTs) and controlled clinical trials (CCTs) that evaluated the safety and effectiveness of NPWT for partial-thickness burns. Two review authors used standardised forms, and extracted the data independently. We assessed each trial for risk of bias, and resolved differences by discussion. One RCT, that was an interim report, satisfied the inclusion criteria. We undertook a narrative synthesis of results, as the absence of data and poor reporting precluded us from carrying out any formal statistical analysis. The trial was at high risk of bias. There was not enough evidence available to permit any conclusions to be drawn regarding the use of NPWT for treatment of partial-thickness burn wounds.

A pilot randomised controlled trial of negative pressure wound therapy to treat grade III/IV pressure ulcers [ISRCTN69032034

Science.gov (United States)

2012-01-01

Background Negative pressure wound therapy (NPWT) is widely promoted as a treatment for full thickness wounds; however, there is a lack of high-quality research evidence regarding its clinical and cost effectiveness. A trial of NPWT for the treatment of grade III/IV pressure ulcers would be worthwhile but premature without assessing whether such a trial is feasible. The aim of this pilot randomised controlled trial was to assess the feasibility of conducting a future full trial of NPWT for the treatment of grade III and IV pressure ulcers and to pilot all aspects of the trial. Methods This was a two-centre (acute and community), pilot randomised controlled trial. Eligible participants were randomised to receive either NPWT or standard care (SC) (spun hydrocolloid, alginate or foam dressings). Outcome measures were time to healing of the reference pressure ulcer, recruitment rates, frequency of treatment visits, resources used and duration of follow-up. Results Three hundred and twelve patients were screened for eligibility into this trial over a 12-month recruitment period and 12/312 participants (3.8%) were randomised: 6 to NPWT and 6 to SC. Only one reference pressure ulcer healed (NPWT group) during follow-up (time to healing 79 days). The mean number of treatment visits per week was 3.1 (NPWT) and 5.7 (SC); 6/6 NPWT and 1/6 SC participants withdrew from their allocated trial treatment. The mean duration of follow-up was 3.8 (NPWT) and 5.0 (SC) months. Conclusions This pilot trial yielded vital information for the planning of a future full study including projected recruitment rate, required duration of follow-up and extent of research nurse support required. Data were also used to inform the cost-effectiveness and value of information analyses, which were conducted alongside the pilot trial. Trial registration Current Controlled Trials ISRCTN69032034. PMID:22839453

A pilot randomised controlled trial of negative pressure wound therapy to treat grade III/IV pressure ulcers [ISRCTN69032034

Directory of Open Access Journals (Sweden)

Ashby Rebecca L

2012-07-01

Full Text Available Abstract Background Negative pressure wound therapy (NPWT is widely promoted as a treatment for full thickness wounds; however, there is a lack of high-quality research evidence regarding its clinical and cost effectiveness. A trial of NPWT for the treatment of grade III/IV pressure ulcers would be worthwhile but premature without assessing whether such a trial is feasible. The aim of this pilot randomised controlled trial was to assess the feasibility of conducting a future full trial of NPWT for the treatment of grade III and IV pressure ulcers and to pilot all aspects of the trial. Methods This was a two-centre (acute and community, pilot randomised controlled trial. Eligible participants were randomised to receive either NPWT or standard care (SC (spun hydrocolloid, alginate or foam dressings. Outcome measures were time to healing of the reference pressure ulcer, recruitment rates, frequency of treatment visits, resources used and duration of follow-up. Results Three hundred and twelve patients were screened for eligibility into this trial over a 12-month recruitment period and 12/312 participants (3.8% were randomised: 6 to NPWT and 6 to SC. Only one reference pressure ulcer healed (NPWT group during follow-up (time to healing 79 days. The mean number of treatment visits per week was 3.1 (NPWT and 5.7 (SC; 6/6 NPWT and 1/6 SC participants withdrew from their allocated trial treatment. The mean duration of follow-up was 3.8 (NPWT and 5.0 (SC months. Conclusions This pilot trial yielded vital information for the planning of a future full study including projected recruitment rate, required duration of follow-up and extent of research nurse support required. Data were also used to inform the cost-effectiveness and value of information analyses, which were conducted alongside the pilot trial. Trial registration Current Controlled Trials ISRCTN69032034.

Validation of lower body negative pressure as an experimental model of hemorrhage

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Shade, Robert E.; Muniz, Gary W.; Bauer, Cassondra; Goei, Kathleen A.; Pidcoke, Heather F.; Chung, Kevin K.; Cap, Andrew P.; Convertino, Victor A.

2013-01-01

Lower body negative pressure (LBNP), a model of hemorrhage (Hem), shifts blood to the legs and elicits central hypovolemia. This study compared responses to LBNP and actual Hem in sedated baboons. Arterial pressure, pulse pressure (PP), central venous pressure (CVP), heart rate, stroke volume (SV), and +dP/dt were measured. Hem steps were 6.25%, 12.5%, 18.75%, and 25% of total estimated blood volume. Shed blood was returned, and 4 wk after Hem, the same animals were subjected to four LBNP levels which elicited equivalent changes in PP and CVP observed during Hem. Blood gases, hematocrit (Hct), hemoglobin (Hb), plasma renin activity (PRA), vasopressin (AVP), epinephrine (EPI), and norepinephrine (NE) were measured at baseline and maximum Hem or LBNP. LBNP levels matched with 6.25%, 12.5%, 18.75%, and 25% hemorrhage were −22 ± 6, −41 ± 7, −54 ± 10, and −71 ± 7 mmHg, respectively (mean ± SD). Hemodynamic responses to Hem and LBNP were similar. SV decreased linearly such that 25% Hem and matching LBNP caused a 50% reduction in SV. Hem caused a decrease in Hct, Hb, and central venous oxygen saturation (ScvO2). In contrast, LBNP increased Hct and Hb, while ScvO2 remained unchanged. Hem caused greater elevations in AVP and NE than LBNP, while PRA, EPI, and other hematologic indexes did not differ between studies. These results indicate that while LBNP does not elicit the same effect on blood cell loss as Hem, LBNP mimics the integrative cardiovascular response to Hem, and validates the use of LBNP as an experimental model of central hypovolemia associated with Hem. PMID:24356525

Robust high pressure stability and negative thermal expansion in sodium-rich antiperovskites Na3OBr and Na4OI2

International Nuclear Information System (INIS)

Wang, Yonggang; Wen, Ting; Park, Changyong; Kenney-Benson, Curtis; Pravica, Michael; Zhao, Yusheng; Yang, Wenge

2016-01-01

The structure stability under high pressure and thermal expansion behavior of Na 3 OBr and Na 4 OI 2 , two prototypes of alkali-metal-rich antiperovskites, were investigated by in situ synchrotron X-ray diffraction techniques under high pressure and low temperature. Both are soft materials with bulk modulus of 58.6 GPa and 52.0 GPa for Na 3 OBr and Na 4 OI 2 , respectively. The cubic Na 3 OBr structure and tetragonal Na 4 OI 2 with intergrowth K 2 NiF 4 structure are stable under high pressure up to 23 GPa. Although being a characteristic layered structure, Na 4 OI 2 exhibits nearly isotropic compressibility. Negative thermal expansion was observed at low temperature range (20–80 K) in both transition-metal-free antiperovskites for the first time. The robust high pressure structure stability was examined and confirmed by first-principles calculations among various possible polymorphisms qualitatively. The results provide in-depth understanding of the negative thermal expansion and robust crystal structure stability of these antiperovskite systems and their potential applications

Lower body negative pressure as a tool for research in aerospace physiology and military medicine

Science.gov (United States)

Convertino, V. A.

2001-01-01

Lower body negative pressure (LBNP) has been extensively used for decades in aerospace physiological research as a tool to investigate cardiovascular mechanisms that are associated with or underlie performance in aerospace and military environments. In comparison with clinical stand and tilt tests, LBNP represents a relatively safe methodology for inducing highly reproducible hemodynamic responses during exposure to footward fluid shifts similar to those experienced under orthostatic challenge. By maintaining an orthostatic challenge in a supine posture, removal of leg support (muscle pump) and head motion (vestibular stimuli) during LBNP provides the capability to isolate cardiovascular mechanisms that regulate blood pressure. LBNP can be used for physiological measurements, clinical diagnoses and investigational research comparisons of subject populations and alterations in physiological status. The applications of LBNP to the study of blood pressure regulation in spaceflight, groundbased simulations of low gravity, and hemorrhage have provided unique insights and understanding for development of countermeasures based on physiological mechanisms underlying the operational problems.

A direct method for determining complete positive and negative capillary pressure curves for reservoir rock using the centrifuge

Energy Technology Data Exchange (ETDEWEB)

Spinler, E.A.; Baldwin, B.A. [Phillips Petroleum Co., Bartlesville, OK (United States)

1997-08-01

A method is being developed for direct experimental determination of capillary pressure curves from saturation distributions produced during centrifuging fluids in a rock plug. A free water level is positioned along the length of the plugs to enable simultaneous determination of both positive and negative capillary pressures. Octadecane as the oil phase is solidified by temperature reduction while centrifuging to prevent fluid redistribution upon removal from the centrifuge. The water saturation is then measured via magnetic resonance imaging. The saturation profile within the plug and the calculation of pressures for each point of the saturation profile allows for a complete capillary pressure curve to be determined from one experiment. Centrifuging under oil with a free water level into a 100 percent water saturated plug results in the development of a primary drainage capillary pressure curve. Centrifuging similarly at an initial water saturation in the plug results in the development of an imbibition capillary pressure curve. Examples of these measurements are presented for Berea sandstone and chalk rocks.

Effect of Leaf Water Potential on Internal Humidity and CO2 Dissolution: Reverse Transpiration and Improved Water Use Efficiency under Negative Pressure.

Science.gov (United States)

Vesala, Timo; Sevanto, Sanna; Grönholm, Tiia; Salmon, Yann; Nikinmaa, Eero; Hari, Pertti; Hölttä, Teemu

2017-01-01

The pull of water from the soil to the leaves causes water in the transpiration stream to be under negative pressure decreasing the water potential below zero. The osmotic concentration also contributes to the decrease in leaf water potential but with much lesser extent. Thus, the surface tension force is approximately balanced by a force induced by negative water potential resulting in concavely curved water-air interfaces in leaves. The lowered water potential causes a reduction in the equilibrium water vapor pressure in internal (sub-stomatal/intercellular) cavities in relation to that over water with the potential of zero, i.e., over the flat surface. The curved surface causes a reduction also in the equilibrium vapor pressure of dissolved CO 2 , thus enhancing its physical solubility to water. Although the water vapor reduction is acknowledged by plant physiologists its consequences for water vapor exchange at low water potential values have received very little attention. Consequences of the enhanced CO 2 solubility to a leaf water-carbon budget have not been considered at all before this study. We use theoretical calculations and modeling to show how the reduction in the vapor pressures affects transpiration and carbon assimilation rates. Our results indicate that the reduction in vapor pressures of water and CO 2 could enhance plant water use efficiency up to about 10% at a leaf water potential of -2 MPa, and much more when water potential decreases further. The low water potential allows for a direct stomatal water vapor uptake from the ambient air even at sub-100% relative humidity values. This alone could explain the observed rates of foliar water uptake by e.g., the coastal redwood in the fog belt region of coastal California provided the stomata are sufficiently open. The omission of the reduction in the water vapor pressure causes a bias in the estimates of the stomatal conductance and leaf internal CO 2 concentration based on leaf gas exchange

Effect of negative pressure therapy on repair of soft tissues of the lower extremities in patients with neuropathic and neuroischaemic forms of diabetic foot syndrome

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Ekaterina Leonidovna Zaytseva

2014-06-01

Full Text Available AimTo evaluate the efficiency of topical negative pressure wound therapy (NPWT compared with standard therapy for the regeneration of the soft tissues of the lower extremities in patients with diabetic foot syndrome.Materials and MethodsThe effects of negative pressure therapy on the clinical (size, tissue oxygenation, histological (light microscopy and immunohistochemical (CD68, MMP-9, TIMP-1 aspects of repair of the soft tissue of the lower extremities in patients with diabetes mellitus were compared with those of standard treatment. Thirty-one patients with diabetic foot ulcers were included in the study from the moment of debridement until the plastic closure of the wound. During the perioperative period, 13 patients received NPWT (-90 to -120 mmHg and 18 patients received standard therapy.ResultsA reduction of the wound area (26.6%±17.2% and the depth of the defects (40.5%±25.6% were achieved with negative pressure therapy compared with baseline data. In the control group, the corresponding values were 25.3%±19.4% and 21.8%±21.6%, respectively. The results of transcutaneous oximetry showed a greater increase in the level of local hemodynamics in the study group (p <0.04. An important criterion for wound preparation for a plastic closure is filling it with granulation tissue by more than 75%. In the study group, 95% of patients had wounds filled with 89.9%±17% of abundant granulation tissue. The histological data of the study group show a significant reduction of oedema by 80% (p <0.05, improved extracellular matrix organization (p <0.05, 90% (p <0.05 dissolution of inflammatory infiltrate and the formation of healthy granulation tissue (p <0.05. Immunohistochemical analysis demonstrated a significant decrease in the number of macrophages in the dermis (CD68 expression (p <0.05. In both groups, the level of MMP-9 was decreased. However, the ratio of MMP-9:TIMP-1 was lower in the study group (p <0.05.ConclusionThe findings suggest that

Histomorphological observation of surgical debridement combined with negative pressure therapy in treatment of diabetic foot

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Jiao-Yun Dong

2017-08-01

Conclusion: Epidermal cells on the fascia side of the flap could be derived from the stem cells. Negative pressure wound therapy would attract not only cells but also other elements such as growth factors, cytokines, some nutrients and extracellular matrix. With the formation of the appropriate microenvironment after debridement, the migrated cells can grow, differentiate and spread, eventually leading to the epithelization on the fascia side of the flap in diabetic foot.

Negative pressure wound therapy in patients with diabetic foot.

Science.gov (United States)

Ulusal, Ali Engin; Sahin, M Sükrü; Ulusal, Betül; Cakmak, Gökhan; Tuncay, Cengiz

2011-01-01

In this study our aim was to compare the results of standard dressing treatment to negative pressure wound therapy (NPWT) performed with a vacuum-assisted closure (VAC) device in patients with diabetic foot ulcers. We assessed the results of 35 patients treated for diabetic foot ulcer between 2006 and 2008. Of these cases, 20 (4 women and 16 men; mean age: 66 years; range: 52-90 years) were treated with standard wet dressings and 16 feet in 15 patients (10 men, 5 women; mean age: 58.9 years; range: 42-83 years) with VAC therapy. The success of treatment was evaluated in terms of hospitalization length and rate of limb salvation. The average hospitalization period with VAC treatment was 32 days compared to 59 days with standard dressing treatment. All patients treated with standard dressings eventually had to undergo amputation. However, the amputation rate was 37% in the VAC treated group and 88% of patients had a functional extremity at the end of treatment. VAC therapy, together with debridement and appropriate antibiotic therapy, enables a higher rate of limb salvage, especially in Wagner Grade 3 and Grade 4 ulcers.

Major bleeding during negative pressure wound/VAC (R) - therapy for postsurgical deep sternal wound infection - a critical appraisal

NARCIS (Netherlands)

van Wingerden, J.J.; Segers, P.; Jekel, L.

2011-01-01

Negative-pressure wound therapy, commercially known as vacuum-assisted closure (V.A.C.(R)) therapy, has become one of the most popular (and efficacious) interim (prior to flap reconstruction) or definite methods of managing deep sternal wound infection. Complications such as profuse bleeding, which

Technical specifications of variable speed motors for negative pressure control in hot cell area

Energy Technology Data Exchange (ETDEWEB)

Kim, Seon Duk; Bang, H. S.; Cho, W. K

2002-01-01

Hot cells are the facilities for handling the high radioactive materials and various R and D activities are performed using hot cells. Therefore the control of air flow in hot cell area is very important technology and it is started with the variable speed motor(VSM) controlling the air handling system in that area. This report describes various technical aspects of VS motors and will be useful for understanding the practical technologies of VS motors and also for optimization of the negative pressure controls in hot cell area.

Diabetic foot wounds: the value of negative pressure wound therapy with instillation.

Science.gov (United States)

Dalla Paola, Luca

2013-12-01

Chronic wounds such as diabetic foot wounds are a tremendous burden to the health care system and often require a multidisciplinary approach to prevent amputations. Advanced technologies such as negative pressure wound therapy (NPWT) and bioengineered tissues have been successfully used in the treatment of these types of complex wounds. However, the introduction of NPWT with instillation (NPWTi) has provided an alternative treatment for treating complex and difficult-to-heal wounds. This article provides an overview of NPWT and the new NPWTi system and describes preliminary experience using NPWTi on patients with complicated infected diabetic foot wounds after surgical debridement and in a multidisciplinary setting. © 2013 The Author. International Wound Journal © 2013 John Wiley & Sons Ltd and Medicalhelplines.com Inc.

The acute effects of lower limb intermittent negative pressure on foot macro- and microcirculation in patients with peripheral arterial disease.

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Øyvind Heiberg Sundby

Full Text Available Intermittent negative pressure (INP applied to the lower leg and foot increases foot perfusion in healthy volunteers. The aim of the present study was to describe the effects of INP to the lower leg and foot on foot macro- and microcirculation in patients with lower extremity peripheral arterial disease (PAD.In this experimental study, we analyzed foot circulation during INP in 20 patients [median (range: 75 (63-84yrs] with PAD. One leg was placed inside an air-tight vacuum chamber connected to an INP-generator. During application of INP (alternating 10s of -40mmHg/7s of atmospheric pressure, we continuously recorded blood flow velocity in a distal foot artery (ultrasound Doppler, skin blood flow on the pulp of the first toes (laser Doppler, heart rate (ECG, and systemic blood pressure (Finometer. After a 5-min baseline sequence (no pressure, a 10-min INP sequence was applied, followed by 5-min post-INP (no pressure. To compare and quantify blood flow fluctuations between sequences, we calculated cumulative up-and-down fluctuations in arterial blood flow velocity per minute.Onset of INP induced an increase in arterial flow velocity and skin blood flow. Peak blood flow velocity was reached 3s after the onset of negative pressure, and increased 46% [(95% CI 36-57, P<0.001] above baseline. Peak skin blood flow was reached 2s after the onset of negative pressure, and increased 89% (95% CI 48-130, P<0.001 above baseline. Cumulative fluctuations per minute were significantly higher during INP-sequences compared to baseline [21 (95% CI 12-30cm/s/min to 41 (95% CI 32-51cm/s/min, P<0.001]. Mean INP blood flow velocity increased significantly ~12% above mean baseline blood flow velocity [(6.7 (95% CI 5.2-8.3cm/s to 7.5 (95% CI 5.9-9.1cm/s, P = 0.03].INP increases foot macro- and microcirculatory flow pulsatility in patients with PAD. Additionally, application of INP resulted in increased mean arterial blood flow velocity.

Oscillatory lower body negative pressure impairs working memory task-related functional hyperemia in healthy volunteers.

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Merchant, Sana; Medow, Marvin S; Visintainer, Paul; Terilli, Courtney; Stewart, Julian M

2017-04-01

Neurovascular coupling (NVC) describes the link between an increase in task-related neural activity and increased cerebral blood flow denoted "functional hyperemia." We previously showed induced cerebral blood flow oscillations suppressed functional hyperemia; conversely functional hyperemia also suppressed cerebral blood flow oscillations. We used lower body negative pressure (OLBNP) oscillations to force oscillations in middle cerebral artery cerebral blood flow velocity (CBFv). Here, we used N-back testing, an intellectual memory challenge as a neural activation task, to test the hypothesis that OLBNP-induced oscillatory cerebral blood flow can reduce functional hyperemia and NVC produced by a working memory task and can interfere with working memory. We used OLBNP (-30 mmHg) at 0.03, 0.05, and 0.10 Hz and measured spectral power of CBFv at all frequencies. Neither OLBNP nor N-back, alone or combined, affected hemodynamic parameters. 2-Back power and OLBNP individually were compared with 2-back power during OLBNP. 2-Back alone produced a narrow band increase in oscillatory arterial pressure (OAP) and oscillatory cerebral blood flow power centered at 0.0083 Hz. Functional hyperemia in response to 2-back was reduced to near baseline and 2-back memory performance was decreased by 0.03-, 0.05-, and 0.10-Hz OLBNP. OLBNP alone produced increased oscillatory power at frequencies of oscillation not suppressed by added 2-back. However, 2-back preceding OLBNP suppressed OLBNP power. OLBNP-driven oscillatory CBFv blunts NVC and memory performance, while memory task reciprocally interfered with forced CBFv oscillations. This shows that induced cerebral blood flow oscillations suppress functional hyperemia and functional hyperemia suppresses cerebral blood flow oscillations. NEW & NOTEWORTHY We show that induced cerebral blood flow oscillations suppress functional hyperemia produced by a working memory task as well as memory task performance. We conclude that oscillatory

Variable day/night bias in 24-h non-invasive finger pressure against intrabrachial artery pressure is removed by waveform filtering and level correction

NARCIS (Netherlands)

Westerhof, Berend E.; Guelen, Ilja; Parati, Gianfranco; Groppelli, Antonella; van Montfrans, Gert A.; Wieling, Wouter; Wesseling, Karel H.; Bos, Willem Jan W.

2002-01-01

Background Twenty-four-hour finger arterial pressure (FAP) recordings show a negative bias against intrabrachial artery pressure (BAP) and the bias is greater during the night thereby overestimating the nocturnal blood pressure dip. We have available a methodology with which to reconstruct BAP from

Negative pressure wound therapy versus standard wound care on quality of life: a systematic review.

Science.gov (United States)

Janssen, A H J; Mommers, E H H; Notter, J; de Vries Reilingh, T S; Wegdam, J A

2016-03-01

Negative pressure wound therapy (NPWT) is a widely accepted treatment modality for open or infected wounds. Premature ending of NPWT occasionally occurs due to negative effects on the quality of life (QoL), however, the actual impact on QoL is unknown. The aim of this review is to analyse the effect of NPWT versus standard wound care (SWC) on QoL when used for the treatment of open or infected wounds. A systematic literature search in a range of databases (PubMed, CINAHL, Medline, Web of Science, Science Direct Freedom Collection, SwetsWise, PSYCArticles and Infrotrac Custom Journals) using the following search terms; 'standard wound care', 'wound dressing', 'dressing', 'treatment', OR 'negative pressure wound therapy [MESH]', OR 'vacuum assisted closure' AND 'quality of life [MESH]', 'patient-satisfaction', OR 'experiences' was performed. Methodological quality was assessed using the methodological index for non-randomised studies (MINORS) checklist. There were 42 studies identified, five matched the inclusion criteria: two randomised clinical trials (RCTs), one clinical comparative study, one exploratory prospective cohort study and one quasi experimental pilot study. Median MINORS-score was 75% (58%-96%). There were seven different questionnaires used to measure QoL or a subsidiary outcome. QoL in the NPWT group was lower in the first week, though no difference in QoL was observed thereafter. This systematic review observed that QoL improved at the end of therapy independent of which therapy was used. NPWT led to a lower QoL during the first week of treatment, possible due to aniexty, after which a similar or better QoL was reported when compared with SWC. It could be suggested that NPWT might be associated with increased anxiety. All authors of this publication have received no financial support or have personal interests conflicting with the objectivity of this manuscript.

Optimization of negative central shear discharges in shaped cross sections

International Nuclear Information System (INIS)

Turnbull, A.D.; Chu, M.S., Taylor, T.S., Casper, T.A., Rice, B.W.; Greene, J.M., Greenfield, C.M., La Haye, R.J., Lao, L.L., Lee, B.J.; Miller, R.L., Ren, C., Strait, E.J., Tritz, K.; Rettig, C.L., Rhodes, T.L.; Sauter, O.

1996-10-01

Magnetohydrodynamic (MHD) stability analyses of Negative Central Shear (NCS) equilibria have revealed a new understanding of the limiting MHD instabilities in NCS experiments. Ideal stability calculations show a synergistic effect between cross section shape and pressure profile optimization; strong shaping and broader pressure independently lead to moderately higher Β limits, but broadening of the pressure profile in a strongly dee-shaped cross- section leads to a dramatic increase in the ideal Β limit. Localized resistive interchange (RI) modes can be unstable in the negative shear region and are most restrictive for peaked pressure profiles. Resistive global modes can also be destabilized significantly below the ideal P limit. Experiments largely confirm the general trends, and diagnostic measurements and numerical stability calculations are found to be in good qualitative agreement. Observed disruptions in NCS discharges with L-mode edge and strongly peaked pressure, appear to be initiated by interactions between the RI, and the global ideal and resistive modes

Effect of aerobic capacity on Lower Body Negative Pressure (LBNP) tolerance in females

Science.gov (United States)

Moore, Alan D., Jr.; Fortney, Suzanne M.; Siconolfi, Steven F.

1993-01-01

This investigation determined whether a relationship exists in females between: (1) aerobic capacity and Lower Body Negative Pressure (LBNP); and (2) aerobic capacity and change in LBNP tolerance induced by bed rest. Nine females, age 27-47 (34.6 plus or minus 6.0 (Mean plus or minus SD)), completed a treadmill-graded exercise test to establish aerobic capacity. A presyncopal-limited LBNP test was performed prior to and after 13 days of bed rest at a 6 deg head-down tilt. LBNP tolerance was quantified as: (1) the absolute level of negative pressure (NP) tolerated for greater than or equal to 60 sec; and (2) Luft's Cumulative Stress Index (CSI). Aerobic capacity was 33.3 plus or minus 5.0 mL/kg/min and ranged from 25.7 to 38.7. Bed rest was associated with a decrease in NP tolerance (-9.04 1.6 kPa(-67.8 plus or minus 12.0 mmHg) versus -7.7 1.1 kPa(-57.8 plus or minus 8.33 mmHg); p = 0.028) and in CSI (99.4 27.4 kPa min(745.7 plus or minus 205.4 mmHg min) versus 77.0 16.9 kPa min (577.3 plus or minus mmHg min); p = 0.008). The correlation between aerobic capacity and absolute NP or CSI pre-bed rest did not differ significantly from zero (r = -0.56, p = 0.11 for NP; and r = -0.52, p = 0.16 for CSI). Also, no significant correlation was observed between aerobic and pre- to post-rest change for absolute NP tolerance (r = -0.35, p = 0.35) or CSI (r = -0.32, p = 0.40). Therefore, a significant relationship does not exist between aerobic capacity and orthostatic function or change in orthostatic function induced by bed rest.

A patient with Graves’ disease showing only psychiatric symptoms and negativity for both TSH receptor autoantibody and thyroid stimulating antibody

Directory of Open Access Journals (Sweden)

Hamasaki Hidetaka

2012-12-01

Full Text Available Abstract Background Both thyroid stimulating hormone (TSH and thyroid stimulating antibody (TSAb negative Graves’s disease (GD is extremely rare. Here we present such a patient. Case presentation The patient was a 76-year-old woman who was diagnosed as having schizophrenia forty years ago. She did not show characteristic symptoms for hyperthyroidism, such as swelling of thyroid, exophthalmos, tachycardia and tremor, however, she showed only psychomotor agitation. Serum free triiodothyronine and free thyroxine levels were elevated and TSH level was suppressed, suggesting the existence of hyperthyroidism. However, both the first generation TSH receptor autoantibody (TRAb1 and the thyroid stimulating autoantibody (TSAb were negative. Slightly increased blood flow and swelling was detected by thyroid echography. Thyroid scintigraphy demonstrated diffuse and remarkably elevated uptake of 123I uptake. Finally, we diagnosed her as having GD. She was treated by using methimazole, and hyperthyroidism and her psychiatric symptoms were promptly ameliorated. Discussion We experienced a patient with GD who did not show characteristic symptoms except for psychiatric symptoms, and also showed negativity for both TRAb1 and TSAb. Thyroid autoantibody-negative GD is extremely rare. Thyroid scintigraphy was useful to diagnose such a patient.

Supine exercise during lower body negative pressure effectively simulates upright exercise in normal gravity

Science.gov (United States)

Murthy, G.; Watenpaugh, D. E.; Ballard, R. E.; Hargens, A. R.

1994-01-01

Exercise within a lower body negative pressure (LBNP) chamber in supine posture was compared with similar exercise against Earth's gravity (without LBNP) in upright posture in nine healthy male volunteers. We measured footward force with a force plate, pressure in soleus and tibialis anterior muscles of the leg with transducer-tipped catheters, calf volume by strain gauge plethysmography, heart rate, and systolic and diastolic blood pressures during two conditions: 1) exercise in supine posture within an LBNP chamber during 100-mmHg LBNP (exercise-LBNP) and 2) exercise in upright posture against Earth's gravity without LBNP (exercise-1 G). Subjects exercised their ankle joints (dorsi- and plantarflexions) for 5 min during exercise-LBNP and for 5 min during exercise-1 G. Mean footward force produced during exercise-LBNP (743 +/- 37 N) was similar to that produced during exercise-1 G (701 +/- 24 N). Peak contraction pressure in the antigravity soleus muscle during exercise-LBNP (115 +/- 10 mmHg) was also similar to that during exercise-1 G (103 +/- 13 mmHg). Calf volume increased significantly by 3.3 +/- 0.5% during exercise-LBNP compared with baseline values. Calf volume did not increase significantly during exercise-1 G. Heart rate was significantly higher during exercise-LBNP (99 +/- 5 beats/min) than during exercise-1 G (81 +/- 3 beats/min). These results indicate that exercise in supine posture within an LBNP chamber can produce similar musculoskeletal stress in the legs and greater systemic cardiovascular stress than exercise in the upright posture against Earth's gravity.

Takotsubo cardiomyopathy precipitated by negative pressure pulmonary oedema following total thyroidectomy

Directory of Open Access Journals (Sweden)

K S Bharathi

2016-01-01

Full Text Available 'Takotsubo cardiomyopathy (TCM' or 'stress cardiomyopathy' is a reversible cardiomyopathy that is precipitated by intense emotional or physical stress. This syndrome is characterised by symptoms mimicking acute coronary syndrome with transient systolic dysfunction associated with regional wall motion abnormalities, which extend beyond a single coronary vascular bed in the absence of obstructive coronary vascular disease. The presentation of TCM and myocardial infarction is similar with sudden onset of chest pain, breathlessness as well as abnormalities in both the electrocardiogram and cardiac enzymes. It is difficult to differentiate between the two until cardiac catheterisation establishes the diagnosis. We report a case of TCM in a post-menopausal female, precipitated by negative pressure pulmonary oedema following total thyroidectomy in whom timely cardiac catheterisation established the diagnosis and influenced the management. Heightened awareness of this unique cardiomyopathy is essential to have a high index of suspicion in at-risk population for the prompt diagnosis of stress-related cardiomyopathy syndromes occurring in the perioperative period.

Negative pressure of the environmental air in the cleaning area of the materials and sterilization center: a systematic review

Directory of Open Access Journals (Sweden)

Caroline Lopes Ciofi-Silva

Full Text Available ABSTRACT Objective: to analyze the scientific evidence on aerosols generated during cleaning activities of health products in the Central Service Department (CSD and the impact of the negative pressure of the ambient air in the cleaning area to control the dispersion of aerosols to adjacent areas. Method: for this literature systematic review the following searches were done: search guidelines, manuals or national and international technical standards given by experts; search in the portal and databases PubMed, Scopus, CINAHL and Web of Science; and a manual search of scientific articles. Results: the five technical documents reviewed recommend that the CSD cleaning area should have a negative differential ambient air pressure, but scientific articles on the impact of this intervention were not found. The four articles included talked about aerosols formed after the use of a ultrasonic cleaner (an increased in the contamination especially during use and pressurized water jet (formation of smaller aerosols 5μm. In a study, the aerosols formed from contaminated the hot tap water with Legionella pneumophila were evaluated. Conclusions: there is evidence of aerosol formation during cleanup activities in CSD. Studies on occupational diseases of respiratory origin of workers who work in CSD should be performed.

Comparison of compensatory reserve during lower-body negative pressure and hemorrhage in nonhuman primates.

Science.gov (United States)

Hinojosa-Laborde, Carmen; Howard, Jeffrey T; Mulligan, Jane; Grudic, Greg Z; Convertino, Victor A

2016-06-01

Compensatory reserve was measured in baboons (n = 13) during hemorrhage (Hem) and lower-body negative pressure (LBNP) using a machine-learning algorithm developed to estimate compensatory reserve by detecting reductions in central blood volume during LBNP. The algorithm calculates compensatory reserve index (CRI) from normovolemia (CRI = 1) to cardiovascular decompensation (CRI = 0). The hypothesis was that Hem and LBNP will elicit similar CRI values and that CRI would have higher specificity than stroke volume (SV) in predicting decompensation. Blood was removed in four steps: 6.25%, 12.5%, 18.75%, and 25% of total blood volume. Four weeks after Hem, the same animals were subjected to four levels of LBNP that was matched on the basis of their central venous pressure. Data (mean ± 95% confidence interval) indicate that CRI decreased (P AUC in Hem (0.94 vs. 0.84) and LBNP (0.94 vs. 0.92). These data support the hypothesis that Hem and LBNP elicited the same CRI response, suggesting that measurement of compensatory reserve is superior to SV as a predictor of cardiovascular decompensation.

A compare between myocardial topical negative pressure levels of -25 mmHg and -50 mmHg in a porcine model

DEFF Research Database (Denmark)

Lindstedt, Sandra; Paulsson, Per; Mokhtari, Arash

2008-01-01

Topical negative pressure (TNP), widely used in wound therapy, is known to stimulate wound edge blood flow, granulation tissue formation, angiogenesis, and revascularization. We have previously shown that application of a TNP of -50 mmHg to the myocardium significantly increases microvascular blo...

Uniaxial Negative Thermal Expansion, Negative Linear Compressibility, and Negative Poisson's Ratio Induced by Specific Topology in Zn[Au(CN)2]2.

Science.gov (United States)

Wang, Lei; Luo, Hubin; Deng, Shenghua; Sun, Ying; Wang, Cong

2017-12-18

The well-known idea of "structure determines properties" can be understood profoundly in the case of hexagonal zinc dicyanometalate. Using density functional theory (DFT) calculations, we show the uniaxial negative thermal expansion (NTE) and negative linear compressibility (NLC) properties of Zn[Au(CN) 2 ] 2 . The temperature dependence of phonon frequencies within the quasi-harmonic approximation (QHA) is investigated. The abnormal phonon hardening (frequency increase on heating) is detected in the ranges of 0-225, 320-345, and 410-430 cm -1 , which can be indicative of the unusual physical properties of Zn[Au(CN) 2 ] 2 . Due to the significance of low-energy phonon frequencies in Zn[Au(CN) 2 ] 2 , in this work, the corresponding vibrational mode of the lowest-frequency optical phonon at the zone center is analyzed. The specific topology of a springlike framework that will produce the effects of a compressed spring on heating and an extended spring under hydrostatic pressure is identified and leads to the coexistence of uniaxial-NTE and NLC behaviors in Zn[Au(CN) 2 ] 2 . The distinguishing phonon group velocity along the a axis and c axis facilitates different responses for both the axes under temperature and hydrostatic pressure field. Through an analysis and visualization of the spatial dependence of elastic tensors, it is found that a negative Poisson's ratio (NPR) is presented in all projection planes due to the specific topology.

Progress of the ''batman'' RF source for negative hydrogen ions

International Nuclear Information System (INIS)

Frank, P.; Heinemann, B.; Kraus, W.; Probst, F.; Speth, E.; Vollmer, O.; Bucalossi, J.; Trainham, R.

1998-01-01

The aim of a collaboration between CEA Cadarache and IPP Garching is to investigate the ability of an rf source to produce negative-ion current densities compatible with ITER NBI requirements (20 mA/cm 2 D-). A standard PlNI-size rf source developed for ASDEX-Upgrade and a three-grid extraction system form the basis of BATMAN (Bavarian Test Machine for Negative Ions). In the case of a pure hydrogen plasma a current density of 5.5 mA/cm 2 at elevated pressure (2.4 Pa) can be reached. Adding small amounts of argon ( 2 . In the low pressure range (0.7 Pa) the negative ion yield is strongly reduced, but with an admixture of argon and a cesium injection the current density is higher approx. by a factor 8 (4 mA/cm 2 ) compared to the pure hydrogen discharge. The negative ion yield shows a saturation with increasing rf power. (author)

Major bleeding during negative pressure wound/V.A.C.®--therapy for postsurgical deep sternal wound infection--a critical appraisal

NARCIS (Netherlands)

van Wingerden, Jan J.; Segers, Patrique; Jekel, Lilian

2011-01-01

Negative-pressure wound therapy, commercially known as vacuum-assisted closure (V.A.C.®) therapy, has become one of the most popular (and efficacious) interim (prior to flap reconstruction) or definite methods of managing deep sternal wound infection. Complications such as profuse bleeding, which

Pressure dependence of glass transition in As2Te3 glass.

Science.gov (United States)

Ramesh, K

2014-07-24

Amorphous solids prepared from their melt state exhibit glass transition phenomenon upon heating. Viscosity, specific heat, and thermal expansion coefficient of the amorphous solids show rapid changes at the glass transition temperature (Tg). Generally, application of high pressure increases the Tg and this increase (a positive dT(g)/dP) has been understood adequately with free volume and entropy models which are purely thermodynamic in origin. In this study, the electrical resistivity of semiconducting As(2)Te(3) glass at high pressures as a function of temperature has been measured in a Bridgman anvil apparatus. Electrical resistivity showed a pronounced change at Tg. The Tg estimated from the slope change in the resistivity-temperature plot shows a decreasing trend (negative dT(g)/dP). The dT(g)/dP was found to be -2.36 °C/kbar for a linear fit and -2.99 °C/kbar for a polynomial fit in the pressure range 1 bar to 9 kbar. Chalcogenide glasses like Se, As(2)Se(3), and As(30)Se(30)Te(40) show a positive dT(g)/dP which is very well understood in terms of the thermodynamic models. The negative dT(g)/dP (which is generally uncommon in liquids) observed for As(2)Te(3) glass is against the predictions of the thermodynamic models. The Adam-Gibbs model of viscosity suggests a direct relationship between the isothermal pressure derivative of viscosity and the relaxational expansion coefficient. When the sign of the thermal expansion coefficient is negative, dT(g)/dP = Δk/Δα will be less than zero, which can result in a negative dT(g)/dP. In general, chalcogenides rich in tellurium show a negative thermal expansion coefficient (NTE) in the supercooled and stable liquid states. Hence, the negative dT(g)/dP observed in this study can be understood on the basis of the Adams-Gibbs model. An electronic model proposed by deNeufville and Rockstad finds a linear relation between Tg and the optical band gap (Eg) for covalent semiconducting glasses when they are grouped

A large-area RF source for negative hydrogen ions

International Nuclear Information System (INIS)

Frank, P.; Feist, J. H.; Kraus, W.; Speth, E.; Heinemann, B.; Probst, F.; Trainham, R.; Jacquot, C.

1998-01-01

In a collaboration with CEA Cadarache, IPP is presently developing an rf source, in which the production of negative ions (H - /D - ) is being investigated. It utilizes PINI-size rf sources with an external antenna and for the first step a small size extraction system with 48 cm 2 net extraction area. First results from BATMAN (Bavarian T lowbar est Machine for N lowbar egative Ions) show (without Cs) a linear dependence of the negative ion yield with rf power, without any sign of saturation. At elevated pressure (1.6 Pa) a current density of 4.5 mA/cm 2 H - (without Cs) has been found so far. At medium pressure (0.6 Pa) the current density is lower by approx. a factor of 5, but preliminary results with Cesium injection show a relative increase by almost the same factor in this pressure range. Langmuir probe measurements indicate an electron temperature T e >2 eV close to the plasma grid with a moderate magnetic filter (700 Gcm). Attempts to improve the performance by using different magnetic configurations and different wall materials are under way

Visual evoked potentials show strong positive association with intracranial pressure in patients with cryptococcal meningitis

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Marcelo Adriano da Cunha Silva Vieira

2015-04-01

Full Text Available Objective : To verify the relationship between intracranial pressure and flash visual evoked potentials (F-VEP in patients with cryptococcal meningitis. Method The sample included adults diagnosed with cryptococcal meningitis admitted at a reference hospital for infectious diseases. The patients were subjected to F-VEP tests shortly before lumbar puncture. The Pearson’s linear correlation coefficient was calculated and the linear regression analysis was performed. Results : Eighteen individuals were subjected to a total of 69 lumbar punctures preceded by F-VEP tests. At the first lumbar puncture performed in each patient, N2 latency exhibited a strong positive correlation with intracranial pressure (r = 0.83; CI = 0.60 - 0.94; p < 0.0001. The direction of this relationship was maintained in subsequent punctures. Conclusion : The intracranial pressure measured by spinal tap manometry showed strong positive association with the N2 latency F-VEP in patients with cryptococcal meningitis.

The efficacy of negative pressure wound therapy in the management of lower extremity trauma: review of clinical evidence.

Science.gov (United States)

Kanakaris, N K; Thanasas, C; Keramaris, N; Kontakis, G; Granick, Mark S; Giannoudis, P V

2007-12-01

A large number of aids have been conceived and introduced into clinical practice (nutritional supplements, local dressings, technical innovations) aimed at facilitating and optimising wound healing in both acute and chronic wound settings. Among these advances, negative pressure wound therapy (NPWT) has been introduced during the last 30 years, and has been analysed in over 400 manuscripts of the English, Russian and German literature. Until very recently, vacuum assisted closure (VAC) (KCI, TX, USA) has been the only readily available commercial device that provides localised negative pressure to the wound and is the predominant agent used to deliver NPWT featured in this review. We conducted a comprehensive review of the existing clinical evidence of the English literature on the applications of NPWT in the acute setting of trauma and burns of the lower extremity. Overall, 16 clinical studies have been evaluated and scrutinised as to the safety and the efficacy of this adjunct therapy in the specific environment of trauma. Effectiveness was comparable to the standard dressing and wound coverage methods. The existing clinical evidence justifies its application in lower limb injuries associated with soft tissue trauma.

Pressure Field Around Underwater Negative Streamers

Czech Academy of Sciences Publication Activity Database

Hoffer, Petr; Koláček, Karel; Lukeš, Petr; Stelmashuk, Vitaliy

2015-01-01

Roč. 43, č. 5 (2015), s. 1787-1792 ISSN 0093-3813 R&D Projects: GA ČR(CZ) GA15-12987S Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100431203 Program:M Institutional support: RVO:61389021 Keywords : Interferometry * plasma generation * pressure measurement * water Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.958, year: 2015

An ABCA1 truncation shows no dominant negative effect in a familial hypoalphalipoproteinemia pedigree with three ABCA1 mutations

Energy Technology Data Exchange (ETDEWEB)

Sorrenson, Brie; Suetani, Rachel J. [Department of Biochemistry, University of Otago, Dunedin (New Zealand); Bickley, Vivienne M.; George, Peter M. [Clinical Biochemistry, Canterbury Health Laboratories, Christchurch (New Zealand); Williams, Michael J.A. [Department of Medicine, University of Otago, Dunedin (New Zealand); Scott, Russell S. [Lipid and Diabetes Research Group, Christchurch Hospital (New Zealand); McCormick, Sally P.A., E-mail: sally.mccormick@otago.ac.nz [Department of Biochemistry, University of Otago, Dunedin (New Zealand)

2011-06-10

Highlights: {yields} Characterisation of an ABCA1 truncation mutant, C978fsX988, in a pedigree with three ABCA1 mutations. {yields} Functional analysis of C978fsX988 in patient fibroblasts and HEK 293 cells shows no cholesterol efflux function. {yields} Allele-specific quantification shows C978fsX988 not expressed at mRNA level in fibroblasts. {yields} Unlike other ABCA1 truncations, C978fsX988 mutant shows no dominant negative effect at mRNA or protein level. -- Abstract: The ATP binding cassette transporter (ABCA1) A1 is a key determinant of circulating high density lipoprotein cholesterol (HDL-C) levels. Mutations in ABCA1 are a major genetic contributor to low HDL-C levels within the general population. Following the finding of three different ABCA1 mutations, p.C978fsX988, p.T1512M and p.N1800H in a subject with hypoalphalipoproteinemia, we aimed to establish whether the p.C978fsX988 truncation exerted a dominant negative effect on the full-length ABCA1 alleles within family members as has been reported for other ABCA1 truncations. Characterisation of the p.C978fsX988 mutant in transfected HEK 293 cells showed it to be expressed as a GFP fusion protein but lacking in cholesterol efflux function. This was in keeping with results from cholesterol efflux assays in the fibroblasts of p.C978fsX988 carriers which also showed impaired efflux. Allele- specific quantification of p.C978fsX988 mRNA and analysis of ABCA1 protein levels in the fibroblasts of p.C978fsX988 heterozygotes showed negligible levels of mRNA and protein expression. There was no evidence of a dominant negative effect on wildtype or p.N1800H protein levels. We conclude that in the case of the p.C978fsX988 truncated mutant a lack of expression precludes it from having a dominant negative effect.

The efficacy of negative pressure wound therapy in treating sacroiliac joint tuberculosis with a chronic sinus tract: a case series.

Science.gov (United States)

Luo, Xiaobo; Tang, Xiangyu; Ma, Yuanzheng; Zhang, Yonggang; Fang, Shuzhi

2015-08-06

Tuberculous sacroiliitis with abscess accounts for approximately 50 % of all sacroiliac joint tuberculosis cases. Tuberculous abscesses spread into the sacroiliac joint capsule, subcutaneous tissue, and the skin, and finally becomes a skin sinus. As there are no previous reports about sacroiliac joint tuberculosis with a chronic sinus, we evaluated its clinical characteristics and management by negative pressure wound therapy. A retrospective analysis of 12 patients with sacroiliac joint tuberculosis with chronic sinuses treated between January 2005 and January 2010 was conducted. Patients were treated with negative pressure wound therapy (NPWT). Treatment was divided into three phases: control phase, standard dressing changes daily for 4 weeks; interphase washout period, dressing changes every 3 days for 1 week; and intervention phase, no dressing changes until minimal sinus tract drainage (sacroiliac joint tuberculosis with a chronic sinus can be difficult. NPWT provides better healing of sacroiliac joint tuberculosis with a chronic sinus than standard dressing changes.

Tolerance of Lower Body Negative Pressure (LBNP) in endurance runners, weightlifters, swimmers and nonathletes

Science.gov (United States)

1980-01-01

Thirteen endurance runners (R), 12 weightlifters (WL), 12 swimmers (SW) and 10 nonathletes (NA) were tested for their tolerance of lower body negative pressure (LBNP) in consecutive 5 minute stages at -20, -30, -40, -50 and -60 torr. Each subject also performed an exercise test on a bicycle ergometer with progressive workloads to exhaustion to determined aerobic capacity. The R had a much higher aerobic capacity than any of the other groups, but a significantly lower LBNP tolerance. While responses in heart rate and pulse pressure were quite similar in all 4 groups, the rate of increase in leg volume relative to LBNP stress (leg compliance, LC) was considerably greater in R than in the other athletes and NA. The greater LC in R could be attributed not only to a more rapid shift of blood to the lower extremities but also to a greater tendency for edema formation, both contributing to a more rapid loss in effective central blood volume for a given LBNP stress. These results substantiate earlier observations which led to the conclusion that endurance running is not advisable as a training regimen for astronauts.

Robust high pressure stability and negative thermal expansion in sodium-rich antiperovskites Na{sub 3}OBr and Na{sub 4}OI{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Wang, Yonggang, E-mail: yyggwang@gmail.com, E-mail: yangwg@hpstar.ac.cn, E-mail: yusheng.zhao@unlv.edu [High Pressure Science and Engineering Center, University of Nevada, Las Vegas, Nevada 89154 (United States); Institute of Nanostructured Functional Materials, Huanghe Science and Technology College, Zhengzhou, Henan 450006 (China); High Pressure Synergetic Consortium (HPSynC), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439 (United States); Wen, Ting [Institute of Nanostructured Functional Materials, Huanghe Science and Technology College, Zhengzhou, Henan 450006 (China); Park, Changyong; Kenney-Benson, Curtis [High Pressure Collaborative Access Team (HPCAT), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439 (United States); Pravica, Michael; Zhao, Yusheng, E-mail: yyggwang@gmail.com, E-mail: yangwg@hpstar.ac.cn, E-mail: yusheng.zhao@unlv.edu [High Pressure Science and Engineering Center, University of Nevada, Las Vegas, Nevada 89154 (United States); Yang, Wenge, E-mail: yyggwang@gmail.com, E-mail: yangwg@hpstar.ac.cn, E-mail: yusheng.zhao@unlv.edu [High Pressure Synergetic Consortium (HPSynC), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439 (United States); Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203 (China)

2016-01-14

The structure stability under high pressure and thermal expansion behavior of Na{sub 3}OBr and Na{sub 4}OI{sub 2}, two prototypes of alkali-metal-rich antiperovskites, were investigated by in situ synchrotron X-ray diffraction techniques under high pressure and low temperature. Both are soft materials with bulk modulus of 58.6 GPa and 52.0 GPa for Na{sub 3}OBr and Na{sub 4}OI{sub 2}, respectively. The cubic Na{sub 3}OBr structure and tetragonal Na{sub 4}OI{sub 2} with intergrowth K{sub 2}NiF{sub 4} structure are stable under high pressure up to 23 GPa. Although being a characteristic layered structure, Na{sub 4}OI{sub 2} exhibits nearly isotropic compressibility. Negative thermal expansion was observed at low temperature range (20–80 K) in both transition-metal-free antiperovskites for the first time. The robust high pressure structure stability was examined and confirmed by first-principles calculations among various possible polymorphisms qualitatively. The results provide in-depth understanding of the negative thermal expansion and robust crystal structure stability of these antiperovskite systems and their potential applications.

Transport properties in GaTe under hydrostatic pressure

International Nuclear Information System (INIS)

Gouskov, L.; Carvalho, M.

1980-01-01

First results of the resistivity rho(perpendicular) and rho(parallel)(perpendicular and parallel to the normal to the cleavage plane) under hydrostatic pressure (1 bar <= P <= 3 kbar) on GaTe grown by the Bridgman method, are given and discussed. The analysis of electrical transport properties of GaTe under pressure, indicates a complex nature of the acceptor level in this material. The activation energy Esub(a) has a negative pressure coefficient which is sample dependent. The comparison of the variations of rho(parallel) and rho(perpendicular) versus pressure shows that the activation energy E of the rho(parallel)/rho(perpendicular) ratio has also a negative pressure coefficient which can be justified in the frame of a one-dimensional disorder model proposed by Maschke and Schmid, in order to explain the transport properties in the direction of the normal to the cleavage plane. (author)

The effect of positive and negative message framing on short term continuous positive airway pressure compliance in patients with obstructive sleep apnea.

Science.gov (United States)

Pengo, Martino F; Czaban, Marcin; Berry, Marc P; Nirmalan, Prajeshan; Brown, Richard; Birdseye, Adam; Woroszyl, Asia; Chapman, Julia; Kent, Brian D; Hart, Nicholas; Rossi, Gian Paolo; Steier, Joerg

2018-01-01

Continuous positive airway pressure (CPAP), the best available treatment for obstructive sleep apnea (OSA), requires long-term compliance to be effective. Behavioral interventions may be used to improve adherence to CPAP. We aimed to investigate whether positive or negative message framing impacts on CPAP compliance in patients with OSA, when compared to standard care. Consenting patients with confirmed OSA were randomly allocated to receive along with their CPAP either positively or negatively framed messages (Pos; Neg), or standard care (Con). Standardized motivational messages were read out to patients during an initial teaching session and through weekly telephone calls. Patients' compliance data were reviewed 2 and 6 weeks following CPAP initiation. We randomized 112 patients to groups that were matched for age, BMI, and OSA severity. The positively framed group (Pos) showed greater CPAP usage after 2 weeks (total use 53.7±31.4 hours) as compared to the negatively framed and the control group (35.6±27.4 and 40.8±33.5 hours, Pframed groups (Pos n=5; Neg n=8; Con n=11; Pframed messages can improve CPAP adherence in patients with OSA in the short-term; however, strategies for implementing its long-term use need to be developed.

Skin graft fixation in severe burns: use of topical negative pressure.

Science.gov (United States)

Kamolz, L P; Lumenta, D B; Parvizi, D; Wiedner, M; Justich, I; Keck, M; Pfurtscheller, K; Schintler, M

2014-09-30

Over the last 50 years, the evolution of burn care has led to a significant decrease in mortality. The biggest impact on survival has been the change in the approach to burn surgery. Early excision and grafting has become a standard of care for the majority of patients with deep burns; the survival of a given patient suffering from major burns is invariably linked to the take rate and survival of skin grafts. The application of topical negative pressure (TNP) therapy devices has demonstrated improved graft take in comparison to conventional dressing methods alone. The aim of this study was to analyze the impact of TNP therapy on skin graft fixation in large burns. In all patients, we applied TNP dressings covering a %TBSA of >25. The following parameters were recorded and documented using BurnCase 3D: age, gender, %TBSA, burn depth, hospital length-of-stay, Baux score, survival, as well as duration and incidence of TNP dressings. After a burn depth adapted wound debridement, coverage was simultaneously performed using split-thickness skin grafts, which were fixed with staples and covered with fatty gauzes and TNP foam. The TNP foam was again fixed with staples to prevent displacement and finally covered with the supplied transparent adhesive film. A continuous subatmospheric pressure between 75-120 mm Hg was applied (VAC®, KCI, Vienna, Austria). The first dressing change was performed on day 4. Thirty-six out of 37 patients, suffering from full thickness burns, were discharged with complete wound closure; only one patient succumbed to their injuries. The overall skin graft take rate was over 95%. In conclusion, we consider that split thickness skin graft fixation by TNP is an efficient method in major burns, notably in areas with irregular wound surfaces or subject to movement (e.g. joint proximity), and is worth considering for the treatment of aged patients.

Water Pressure Distribution on a Twin-Float Seaplane

Science.gov (United States)

Thompson, F L

1930-01-01

This is the second of a series of investigations to determine water pressure distribution on various types of seaplane floats and hulls, and was conducted on a twin-float seaplane. It consisted of measuring water pressures and accelerations on a TS-1 seaplane during numerous landing and taxiing maneuvers at various speeds and angles. The results show that water pressures as great as 10 lbs. per sq. in.may occur at the step in various maneuvers and that pressures of approximately the same magnitude occur at the stern and near the bow in hard pancake landings with the stern way down. At the other parts of the float the pressures are less and are usually zero or slightly negative for some distance abaft the step. A maximum negative pressure of 0.87 lb. Per square inch was measured immediately abaft the step. The maximum positive pressures have a duration of approximately one-twentieth to one-hundredth second at any given location and are distributed over a very limited area at any particular instant.

Evidence for negative effects of elevated intra-abdominal pressure on pulmonary mechanics and oxidative stress.

Science.gov (United States)

Davarcı, I; Karcıoğlu, M; Tuzcu, K; İnanoğlu, K; Yetim, T D; Motor, S; Ulutaş, K T; Yüksel, R

2015-01-01

To compare the effects of pneumoperitoneum on lung mechanics, end-tidal CO2 (ETCO2), arterial blood gases (ABG), and oxidative stress markers in blood and bronchoalveolar lavage fluid (BALF) during laparoscopic cholecystectomy (LC) by using lung-protective ventilation strategy. Forty-six patients undergoing LC and abdominal wall hernia (AWH) surgery were assigned into 2 groups. Measurements and blood samples were obtained before, during pneumoperitoneum, and at the end of surgery. BALF samples were obtained after anesthesia induction and at the end of surgery. Peak inspiratory pressure, ETCO2, and pCO2 values at the 30th minute were significantly increased, while there was a significant decrease in dynamic lung compliance, pH, and pO2 values in LC group. In BALF samples, total oxidant status (TOS), arylesterase, paraoxonase, and malondialdehyde levels were significantly increased; the glutathione peroxidase levels were significantly decreased in LC group. The serum levels of TOS and paraoxonase were significantly higher at the end of surgery in LC group. In addition, arylesterase level in the 30th minute was increased compared to baseline. Serum paraoxonase level at the end of surgery was significantly increased when compared to AWH group. Our study showed negative effects of pneumoperitoneum in both lung and systemic levels despite lung-protective ventilation strategy.

Intermittent negative pressure wound therapy with instillation for the treatment of persistent periprosthetic hip infections: a report of two cases

Directory of Open Access Journals (Sweden)

Söylemez MS

2016-02-01

Full Text Available Mehmet Salih Söylemez,1 Korhan Özkan,2 Bülent Kılıç,3 Samet Erinç41Department of Orthopaedics and Traumatology, Bingöl State Hospital, Bingöl, 2Department of Orthopaedics and Traumatology, Faculty of Medicine, Medeniyet University, Istanbul, 3Department of Orthopaedics and Traumatology, Orthopaedic Surgery Clinic, Istanbul Gelişim University, Tekirdağ, 4Department of Orthopaedics and Traumatology, Istanbul Medeniyet University, Göztepe Training and Research Hospital, Istanbul, TurkeyAbstract: Intermittent negative pressure wound therapy with instillation (NPWTi is starting to be used successfully to treat early periprosthetic infections of endoprostheses. However, few articles have reported the outcome of treatment with intermittent NPWTi for late persistent periprosthetic infections of the hip. In this study, we report two cases who underwent several rounds of radical wound debridement for the treatment of a late persistent periprosthetic infection of the hip. Intermittent NPWTi was used in both cases. Patients were treated successfully and there was no recurrence after 3 and 1 years of follow-up, respectively.Keywords: negative pressure, vacuum-assisted, periprosthetic infection, hip

Positive and negative sudden impulses caused by fast forward and reverse interplanetary shocks

Energy Technology Data Exchange (ETDEWEB)

Andrioli, Vania Fatima; Savian, Jairo Francisco, E-mail: vaniafatima@gmail.com, E-mail: savian@lacesm.ufsm.br [Space Science Laboratory of Santa Maria - LACESM/CT - UFSM, Universidade Federal de Santa Maria - UFSM, Centro Tecnologico, Santa Maria, RS (Brazil); Echer, Ezequiel, E-mail: eecher@dge.inpe.br [National Institute for Space Research - INPE - MCT, Sao Jose dos Campos, SP (Brazil); Schuch, Nelson Jorge, E-mail: njschuch@lacesm.ufsm.br [Southern Regional Space Research Center - CRSPE/INPE - MCT, Universidade Federal de Santa Maria - UFSM, Santa Maria, RS (Brazil)

2007-07-01

Fast forward interplanetary shocks (FFS) are characterized by positive jump in all interplanetary plasma parameters (solar wind speed, temperature and density) and interplanetary magnetic field. However the fast reverse interplanetary shocks (FRS) are characterized by negative jump in all mentioned parameters except solar wind speed. Observations show that FFS cause positive sudden impulses (SI) while FRS cause negative SI in the H-component of the geomagnetic field. In this work we investigate the SI caused by interplanetary shocks. We use the observed plasma parameters, upstream and downstream, to calculate the variation of dynamic pressure. We observe that the SI amplitude is larger for positive SI than for negative ones, as a consequence of the fact that FFS have larger dynamic pressure variations as compared to FRS. (author)

Evaluation of negative-pressure wound therapy for patients with diabetic foot ulcers: systematic review and meta-analysis

Directory of Open Access Journals (Sweden)

Liu S

2017-04-01

Full Text Available Si Liu,1 Chao-zhu He,1 Yan-ting Cai,1 Qiu-ping Xing,1 Ying-zhen Guo,1 Zhi-long Chen,1 Ji-liang Su,1 Li-ping Yang2 1School of Nursing, Nanchang University, 2Department of Endocrinology, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China Objectives: The aim of this study was to perform an updated systematic review and meta-analysis to assess the clinical efficacy, safety, and cost-effectiveness of negative-pressure wound therapy (NPWT in the treatment of diabetic foot ulcers (DFUs.Methods: We searched the Cochrane Library, MEDLINE, EMBASE, Ovid, and Chinese Biological Medicine databases up to June 30, 2016. We also manually searched the articles from reference lists of the retrieved articles, which used the NPWT system in studies of vacuum-assisted closure therapy. Studies were identified and selected, and two independent reviewers extracted data from the studies.Results: A total of eleven randomized controlled trials, which included a total of 1,044 patients, were selected from 691 identified studies. Compared with standard dressing changes, NPWT had a higher rate of complete healing of ulcers (relative risk, 1.48; 95% confidence interval [CI]: 1.24–1.76; P<0.001, shorter healing time (mean difference, −8.07; 95% CI: −13.70–−2.45; P=0.005, greater reduction in ulcer area (mean difference, 12.18; 95% CI: 8.50–15.86; P<0.00001, greater reduction in ulcer depth (mean difference, 40.82; 95% CI: 35.97–45.67; P<0.00001, fewer amputations (relative risk, 0.31; 95% CI: 0.15–0.62; P=0.001, and no effect on the incidence of treatment-related adverse effects (relative risk, 1.12; 95% CI: 0.66–1.89; P=0.68. Meanwhile, many analyses showed that the NPWT was more cost-effective than standard dressing changes.Conclusion: These results indicate that NPWT is efficacious, safe, and cost-effective in treating DFUs. Keywords: diabetic foot ulcers, negative-pressure wound therapy, complete wound closure, amputation, meta

Extraction of low-energy negative oxygen ions for thin film formation

International Nuclear Information System (INIS)

Vasquez, M. Jr.; Sasaki, D.; Kasuya, T.; Wada, M.; Maeno, S.

2011-01-01

Coextraction of low-energy positive and negative ions were performed using a plasma sputter-type ion source system driven by a 13.56 MHz radio frequency (rf) power. Titanium (Ti) atoms were sputtered out from a target and the sputtered neutrals were postionized in oxygen/argon (O 2 /Ar) plasma prior to extraction. The negative O ions were surface-produced and self-extracted. Mass spectral analyses of the extracted ion beams revealed the dependence of the ion current on the incident rf power, induced target bias and O 2 /Ar partial pressure ratio. Ti + current was found to be dependent on Ar + current and reached a saturation value with increasing O 2 partial pressure while the O - current showed a peak current at around 1:9 O 2 /Ar partial pressure ratio. Ti + current was several orders of magnitude higher than that of the O - current.

Revascularization and periapical repair after endodontic treatment using apical negative pressure irrigation versus conventional irrigation plus triantibiotic intracanal dressing in dogs' teeth with apical periodontitis.

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da Silva, Lea Assed Bezerra; Nelson-Filho, Paulo; da Silva, Raquel Assed Bezerra; Flores, Daniel Silva Herzog; Heilborn, Carlos; Johnson, James D; Cohenca, Nestor

2010-05-01

The objective of this study was to evaluate in vivo the revascularization and the apical and periapical repair after endodontic treatment using 2 techniques for root canal disinfection (apical negative pressure irrigation versus apical positive pressure irrigation plus triantibiotic intracanal dressing) in immature dogs' teeth with apical periodontitis. Two test groups of canals with experimentally induced apical periodontitis were evaluated according to the disinfection technique: Group 1, apical negative pressure irrigation (EndoVac system), and Group 2, apical positive pressure irrigation (conventional irrigation) plus triantibiotic intracanal dressing. In Group 3 (positive control), periapical lesions were induced, but no endodontic treatment was done. Group 4 (negative control) was composed of sound teeth. The animals were killed after 90 days and the maxillas and mandibles were subjected to histological processing. The sections were stained with hematoxylin and eosin and Mallory Trichrome and examined under light microscopy. A description of the apical and periapical features was done and scores were attributed to the following histopathological parameters: newly formed mineralized apical tissue, periapical inflammatory infiltrate, apical periodontal ligament thickness, dentin resorption, and bone tissue resorption. Intergroup comparisons were done by the Kruskal-Wallis and Dunn's tests (alpha = 0.05). Although statistically significant difference was found only for the inflammatory infiltrate (P irrigation with the EndoVac system can be considered as a promising disinfection protocol in immature teeth with apical periodontitis, suggesting that the use of intracanal antibiotics might not be necessary. Copyright (c) 2010 Mosby, Inc. All rights reserved.

Negative ion molecule reactions of WF6: evidence for a pressure dependent branching ratio

International Nuclear Information System (INIS)

Viggiano, A.A.; Paulson, J.F.

1984-01-01

Rate coefficients have been measured in a selected ion flow tube (SIFT) for reactions of several negative ions with WF 6 . With the exception of SF - 5 , all the reactant ions studied having an electron detachment energy less than 3.36 eV reacted rapidly by charge exchange. SF - 5 transferred a fluoride ion producing WF - 7 . Ions with detachment energies greater than 3.36 eV associated rapidly with WF - 6 . Br - , with a detachment energy of 3.36 eV, reacted with WF 6 both by ion-neutral association and by charge exchange. The branching ratio for these two channels was found to depend on temperature and pressure. All these data indicate that the electron affinity of WF 6 is nearly equal to that of Br

Negative Life Events and Antenatal Depression among Pregnant Women in Rural China: The Role of Negative Automatic Thoughts.

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Wang, Yang; Wang, Xiaohua; Liu, Fangnan; Jiang, Xiaoning; Xiao, Yun; Dong, Xuehan; Kong, Xianglei; Yang, Xuemei; Tian, Donghua; Qu, Zhiyong

2016-01-01

Few studies have looked at the relationship between psychological and the mental health status of pregnant women in rural China. The current study aims to explore the potential mediating effect of negative automatic thoughts between negative life events and antenatal depression. Data were collected in June 2012 and October 2012. 495 rural pregnant women were interviewed. Depressive symptoms were measured by the Edinburgh postnatal depression scale, stresses of pregnancy were measured by the pregnancy pressure scale, negative automatic thoughts were measured by the automatic thoughts questionnaire, and negative life events were measured by the life events scale for pregnant women. We used logistic regression and path analysis to test the mediating effect. The prevalence of antenatal depression was 13.7%. In the logistic regression, the only socio-demographic and health behavior factor significantly related to antenatal depression was sleep quality. Negative life events were not associated with depression in the fully adjusted model. Path analysis showed that the eventual direct and general effects of negative automatic thoughts were 0.39 and 0.51, which were larger than the effects of negative life events. This study suggested that there was a potentially significant mediating effect of negative automatic thoughts. Pregnant women who had lower scores of negative automatic thoughts were more likely to suffer less from negative life events which might lead to antenatal depression.

Phase Envelope Calculations for Reservoir Fluids in the Presence of Capillary Pressure

DEFF Research Database (Denmark)

Lemus, Diego; Yan, Wei; Michelsen, Michael L.

2015-01-01

the bubble and dew point curves but also other quality lines with vapor fractions between 0 and 1. The algorithm has been used to calculate the phase envelopes of binary, multicomponent and reservoir fluid systems for pore radius from 10 to 50 nm. The presence of capillary pressure changes the saturation...... pressures in the whole phase envelope except at the critical point. The bubble point curve shows a negative change while the dew point curve shows positive and negative changes in the upper dew point branch and the lower dew point branch, respectively. In particular, the cricondentherm is also shifted...

Experimental evidence for negative turgor pressure in small leaf cells of Robinia pseudoacacia L versus large cells of Metasequoia glyptostroboides Hu et W.C. Cheng. 2. Höfler diagrams below the volume of zero turgor and the theoretical implication for pressure-volume curves of living cells.

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Yang, Dongmei; Li, Junhui; Ding, Yiting; Tyree, Melvin T

2017-03-01

The physiological advantages of negative turgor pressure, P t , in leaf cells are water saving and homeostasis of reactants. This paper advances methods for detecting the occurrence of negative P t in leaves. Biomechanical models of pressure-volume (PV) curves predict that negative P t does not change the linearity of PV curve plots of inverse balance pressure, P B , versus relative water loss, but it does predict changes in either the y-intercept or the x-intercept of the plots depending on where cell collapse occurs in the P B domain because of negative P t . PV curve analysis of Robinia leaves revealed a shift in the x-intercept (x-axis is relative water loss) of PV curves, caused by negative P t of palisade cells. The low x-intercept of the PV curve was explained by the non-collapse of palisade cells in Robinia in the P B domain. Non-collapse means that P t smoothly falls from positive to negative values with decreasing cell volume without a dramatic change in slope. The magnitude of negative turgor in non-collapsing living cells was as low as -1.3 MPa and the relative volume of the non-collapsing cell equaled 58% of the total leaf cell volume. This study adds to the growing evidence for negative P t . © 2016 John Wiley & Sons Ltd.

Abdominal Cavity Eventration Treated by Means of the "Open Abdomen" Technique Using the Negative Pressure Therapy System--Case Report and Literature Review.

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Trzeciak, Piotr W; Porzeżyńska, Joanna; Ptasińska, Karolina; Walczak, Dominik A

2015-11-01

Wound dehiscence is a surgical complication in which the wound ruptures along the surgical suture with abdominal cavity bowel displacement. It is observed in 0.2-6% of operated patients. The extensive wound is a gateway for infection. Moreover, increased secretion of serous fluid induces a hygienic problem and may lead to secondary skin infections or bedsores. The negative pressure wound therapy (NPWT) system is an innovative therapeutic method. It perfectly executes the TIME strategy, receiving more and more recognition. The study presented a case of a 62-year old male patient after several consecutive wound dehiscence episodes who was primarily treated for rectal cancer by means of low anterior resection of the rectum. Due to acute respiratory insufficiency after several operations, wound necrosis with dehiscence was observed. Considering the high risk of perioperative death we abandoned surgical treatment and introduced conservative management using negative pressure wound therapy until the patient's health improved. Literature regarding the above-mentioned issue was also reviewed.

Coverage of Deep Cutaneous Wounds Using Dermal Template in Combination with Negative-pressure Therapy and Subsequent Skin Graft

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Chang, Alexandre A.; Lobato, Rodolfo C.; Nakamoto, Hugo A.; Tuma, Paulo; Ferreira, Marcus C.

2014-01-01

Background: We consider the use of dermal matrix associated with a skin graft to cover deep wounds in the extremities when tendon and bone are exposed. The objective of this article was to evaluate the efficacy of covering acute deep wounds through the use of a dermal regeneration template (Integra) associated with vacuum therapy and subsequent skin grafting. Methods: Twenty patients were evaluated prospectively. All of them had acute (up to 3 weeks) deep wounds in the limbs. We consider a deep wound to be that with exposure of bone, tendon, or joint. Results: The average area of integration of the dermal regeneration template was 86.5%. There was complete integration of the skin graft over the dermal matrix in 14 patients (70%), partial integration in 5 patients (25%), and total loss in 1 case (5%). The wound has completely closed in 95% of patients. Conclusions: The use of Integra dermal template associated with negative-pressure therapy and skin grafting showed an adequate rate of resolution of deep wounds with low morbidity. PMID:25289363

Stagnations of increasing trends in negative pressure with repeated cavitation in water/metal Berthelot tubes as a result of mechanical sealing

International Nuclear Information System (INIS)

Hiro, Kazuki; Ohde, Yoshihito; Tanzawa, Yasutoshi

2003-01-01

To investigate effects of mechanical sealing on negative pressures in water/metal tube Berthelot systems, trends in negative pressure are observed through runs of temperature cycles below 90 deg. C in two systems made of metals having small amounts of gas inclusions. The first system is a pre-degassed all-stainless-steel tube/plug system. The steel is a special product for vacuum engineering. The second is the same tube sealed with plugs made of silver solidified one-dimensionally in a vacuum furnace. A new type of trend, stagnation for intermediate cycles is found in both systems so long as sealing distortion of each plug is small in amount. The stagnation period for the first system is longer than that for the second one. A metallurgical mechanism of a gas-being-replenished crevice model is proposed: distorted parts of metals undergo heat-treatment during runs of temperature cycles, and the heat-treatment enhances the rates of impurity gas transports to crevices on the metal surface where cavitation occurs, and the transport causes the stagnation for cycles during which the rates are still high

Evidence for Negative Effects of Elevated Intra-Abdominal Pressure on Pulmonary Mechanics and Oxidative Stress

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I. Davarcı

2015-01-01

Full Text Available Objective. To compare the effects of pneumoperitoneum on lung mechanics, end-tidal CO2 (ETCO2, arterial blood gases (ABG, and oxidative stress markers in blood and bronchoalveolar lavage fluid (BALF during laparoscopic cholecystectomy (LC by using lung-protective ventilation strategy. Materials and Methods. Forty-six patients undergoing LC and abdominal wall hernia (AWH surgery were assigned into 2 groups. Measurements and blood samples were obtained before, during pneumoperitoneum, and at the end of surgery. BALF samples were obtained after anesthesia induction and at the end of surgery. Results. Peak inspiratory pressure, ETCO2, and pCO2 values at the 30th minute were significantly increased, while there was a significant decrease in dynamic lung compliance, pH, and pO2 values in LC group. In BALF samples, total oxidant status (TOS, arylesterase, paraoxonase, and malondialdehyde levels were significantly increased; the glutathione peroxidase levels were significantly decreased in LC group. The serum levels of TOS and paraoxonase were significantly higher at the end of surgery in LC group. In addition, arylesterase level in the 30th minute was increased compared to baseline. Serum paraoxonase level at the end of surgery was significantly increased when compared to AWH group. Conclusions. Our study showed negative effects of pneumoperitoneum in both lung and systemic levels despite lung-protective ventilation strategy.

Osteomyelitis beneath pressure sores

International Nuclear Information System (INIS)

Sugarman, B.; Hawes, S.; Musher, D.M.; Klima, M.; Young, E.J.; Pircher, F.

1983-01-01

Twenty-eight pressure sores were evaluated prospectively. Osteomyelitis was reported histologically in nine of 28 bones and pressure-related changes were reported in 14 bones. Roentgenograms suggested the presence of osteomyelitis in four instances of histologically proved osteomyelitis. Technetium Tc 99m medronate bone scans were highly sensitive, showing increased uptake in all cases of osteomyelitis; however, increased uptake also occurred commonly in uninfected bones due to pressure-related changes or other noninfectious causes. Cultures of bone biopsy samples usually disclosed anaerobic bacteria, gram-negative bacilli, or both. The diagnosis of osteomyelitis must be considered if a pressure sore does not respond to local therapy. If the technetium Tc 99m medronate uptake is increased in the involved area, or roentgenographic findings are abnormal, the diagnosis can only be made with certainty by histologic examination of bone. Antibacterial treatment should be selected based on the results of bone culture

Negative pressure wound treatment improves Acute Physiology and Chronic Health Evaluation II score in mediastinitis allowing a successful elective pectoralis muscle flap closure: six-year experience of a single protocol.

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Salica, Andrea; Weltert, Luca; Scaffa, Raffaele; Guerrieri Wolf, Lorenzo; Nardella, Saverio; Bellisario, Alessandro; De Paulis, Ruggero

2014-11-01

Optimal management of poststernotomy mediastinitis is controversial. Negative pressure wound treatment improves wound environment and sternal stability with low surgical invasiveness. Our protocol was based on negative pressure followed by delayed surgical closure. The aim of this study was to provide the results at early follow-up and to identify the risk factors for adverse outcome. In 5400 cardiac procedures, 44 consecutive patients with mediastinitis were enrolled in the study. Mediastinitis treatment was based on urgent debridement and negative pressure as the first-line approach. After wound sterilization, chest closure was achieved by elective pectoralis muscle advancement flap. Each patient's hospital data were collected prospectively. Variables included patient demographics and clinical and biological data. Acute Physiology and Chronic Health Evaluation (APACHE) II score was calculated at the time of diagnosis and 48 hours after debridement. Focus outcome measures were mediastinitis-related death and need for reintervention after pectoralis muscle closure. El Oakley type I and type IIIA mediastinitis were the most frequent types (63.6%). Methicillin-resistant Staphylococcus aureus was present in 25 patients (56.8%). Mean APACHE II score was 19.4±4 at the time of diagnosis, and 30 patients (68.2%) required intensive care unit transfer before surgical debridement. APACHE II score improved 48 hours after wound debridement and negative pressure application (mean value, 19.4±4 vs 7.2±2; P=.005) independently of any other variables included in the study. One patient in septic shock at the time of diagnosis died (2.2%). Negative pressure promotes a significant improvement in clinical status according to APACHE II score and allows a successful elective surgical closure. Copyright © 2014 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Novel cytokinin derivatives do not show negative effects on root growth and proliferation in submicromolar range.

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Kateřina Podlešáková

Full Text Available BACKGROUND: When applied to a nutrition solution or agar media, the non-substituted aromatic cytokinins caused thickening and shortening of the primary root, had an inhibitory effect on lateral root branching, and even showed some negative effects on development of the aerial part at as low as a 10 nanomolar concentration. Novel analogues of aromatic cytokinins ranking among topolins substituted on N9-atom of adenine by tetrahydropyranyl or 4-chlorobutyl group have been prepared and tested in standardized cytokinin bioassays [1]. Those showing comparable activities with N(6-benzylaminopurine were further tested in planta. METHODOLOGY/PRINCIPAL FINDINGS: The main aim of the study was to explain molecular mechanism of function of novel cytokinin derivatives on plant development. Precise quantification of cytokinin content and profiling of genes involved in cytokinin metabolism and perception in treated plants revealed several aspects of different action of m-methoxytopolin base and its substituted derivative on plant development. In contrast to standard cytokinins, N9- tetrahydropyranyl derivative of m-topolin and its methoxy-counterpart showed the negative effects on root development only at three orders of magnitude higher concentrations. Moreover, the methoxy-derivative demonstrates a positive effect on lateral root branching and leaf emerging in a nanomolar range of concentrations, in comparison with untreated plants. CONCLUSIONS/SIGNIFICANCE: Tetrahydropyranyl substitution at N9-position of cytokinin purine ring significantly enhances acropetal transport of a given cytokinins. Together with the methoxy-substitution, impedes accumulation of non-active cytokinin glucoside forms in roots, allows gradual release of the active base, and has a significant effect on the distribution and amount of endogenous isoprenoid cytokinins in different plant tissues. The utilization of novel aromatic cytokinin derivatives can distinctively improve expected

Non-existence of Normal Tokamak Equilibria with Negative Central Current

International Nuclear Information System (INIS)

Hammett, G.W.; Jardin, S.C.; Stratton, B.C.

2003-01-01

Recent tokamak experiments employing off-axis, non-inductive current drive have found that a large central current hole can be produced. The current density is measured to be approximately zero in this region, though in principle there was sufficient current-drive power for the central current density to have gone significantly negative. Recent papers have used a large aspect-ratio expansion to show that normal MHD equilibria (with axisymmetric nested flux surfaces, non-singular fields, and monotonic peaked pressure profiles) can not exist with negative central current. We extend that proof here to arbitrary aspect ratio, using a variant of the virial theorem to derive a relatively simple integral constraint on the equilibrium. However, this constraint does not, by itself, exclude equilibria with non-nested flux surfaces, or equilibria with singular fields and/or hollow pressure profiles that may be spontaneously generated

Tissue Oxygenation and Negative-Pressure Wound Therapy When Applied to the Feet of Persons With Diabetes Mellitus: An Observational Study.

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Lee, Ye-Na; Lee, Jong Seok; Han, Seung-Kyu; Jung, Hye-Kyung

Our group has reported that negative-pressure wound therapy (NPWT) decreases tissue oxygenation by 84% in the foot of diabetic patients because the pad of the connecting drainage tube and foam sponge of the NPWT system compress the wound bed. The purpose of this study was to determine whether an NPWT modified dressing application reduces tissue oxygenation in the feet of persons with diabetes mellitus. A prospective, clinical, observational study. We enrolled 30 patients with diabetic mellitus; their mean age was 63.9 ± 11.2 years (mean ± standard deviation). All were cared for at the diabetic wound center at an academic tertiary medical center in South Korea between 2014 and January 2015. Transcutaneous partial oxygen pressures (TcpO2) were measured to determine tissue oxygenation levels beneath modified NPWT dressings. A TcpO2 sensor was fixed at the tarsometatarsal area of the contralateral unwounded foot. A negative pressure of -125 mm Hg was applied until TcpO2 reached a plateau state; values were measured before, during, and after the modified NPWT. The Wilcoxon' and Mann-Whitney U tests were used to compare differences between these measurements. TcpO2 levels decreased by 26% during the modified NPWT. Mean TcpO2 values before, during, and after turning off the therapy were 54.3 ± 15.3 mm Hg, 41.6 ± 16.3 mm Hg, and 53.3 ± 15.6 mm Hg (P drainage tube significantly reduces the amount of tissue oxygenation loss beneath foam dressings on the skin of the foot dorsum in diabetic patients.

Intrarectal negative pressure system in the management of open abdomen with colorectal fistula: A case report☆

Science.gov (United States)

Yetişir, Fahri; Salman, A. Ebru; Mamedov, Ruslan; Aksoy, Mustafa; Yalcin, Abdussamet; Kayaalp, Cüneyt

2014-01-01

INTRODUCTION To present the management of open abdomen with colorectal fistula by application of intrarectal negative pressure system (NPS) in addition to abdominal NPS. PRESENTATION OF CASE Twenty-year old man had a history of injuries by a close-range gunshot to the abdomen eight days ago and he had been treated by bowel repairs, resections, jejunal anastomosis and Hartman's procedure. He was referred to our center after deterioration, evisceration with open abdomen and enteric fistula in septic shock. There were edematous, fibrinous bowels and large multiple fistulas from the edematous rectal stump. APACHE II, Mannheim Peritoneal Index and Björck scores were 18, 33 and 3, respectively (expected mortality 100%). After intensive care for 5 days, he was treated by abdominal and intrarectal NPS. NPS repeated for 5 times and the fistula was recovered on day 18 completely. Fascial closure was facilitated with a dynamic abdominal closure system (ABRA) and he was discharged on day 33 uneventfully. There was no herniation and any other problem after 12 months follow-up. DISCUSSION Management of fistula in OA can be extremely challenging. Floating stoma, fistula VAC, nipple VAC, ring and silo VAC, fistula intubation systems are used for isolation of the enteric effluent from OA. Several biologic dressings such as acellular dermal matrix, pedicled flaps have been used to seal the fistula opening with various success. Resection of the involved enteric loop and a new anastomosis of the intestine is very hard and rarely possible. In all of these reports, usually patients are left to heal with a giant hernia. In contrast to this, there is no hernia in our case during one year follow up period. CONCLUSION Combination of intra and extra luminal negative pressure systems and ABRA is a safe and successful method to manage open abdomen with colorectal fistula. PMID:24584042

Intrarectal negative pressure system in the management of open abdomen with colorectal fistula: A case report.

Science.gov (United States)

Yetişir, Fahri; Salman, A Ebru; Mamedov, Ruslan; Aksoy, Mustafa; Yalcin, Abdussamet; Kayaalp, Cüneyt

2014-01-01

To present the management of open abdomen with colorectal fistula by application of intrarectal negative pressure system (NPS) in addition to abdominal NPS. Twenty-year old man had a history of injuries by a close-range gunshot to the abdomen eight days ago and he had been treated by bowel repairs, resections, jejunal anastomosis and Hartman's procedure. He was referred to our center after deterioration, evisceration with open abdomen and enteric fistula in septic shock. There were edematous, fibrinous bowels and large multiple fistulas from the edematous rectal stump. APACHE II, Mannheim Peritoneal Index and Björck scores were 18, 33 and 3, respectively (expected mortality 100%). After intensive care for 5 days, he was treated by abdominal and intrarectal NPS. NPS repeated for 5 times and the fistula was recovered on day 18 completely. Fascial closure was facilitated with a dynamic abdominal closure system (ABRA) and he was discharged on day 33 uneventfully. There was no herniation and any other problem after 12 months follow-up. Management of fistula in OA can be extremely challenging. Floating stoma, fistula VAC, nipple VAC, ring and silo VAC, fistula intubation systems are used for isolation of the enteric effluent from OA. Several biologic dressings such as acellular dermal matrix, pedicled flaps have been used to seal the fistula opening with various success. Resection of the involved enteric loop and a new anastomosis of the intestine is very hard and rarely possible. In all of these reports, usually patients are left to heal with a giant hernia. In contrast to this, there is no hernia in our case during one year follow up period. Combination of intra and extra luminal negative pressure systems and ABRA is a safe and successful method to manage open abdomen with colorectal fistula. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Effects of Abrupt Variations of Solar Wind Dynamic Pressure on the High-Latitude Ionosphere

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Igino Coco

2011-01-01

Full Text Available We show the results of a statistical study on the effects in the high-latitude ionosphere of abrupt variations of solar wind dynamic pressure, using Super Dual Auroral Radar Network (SuperDARN data in both hemispheres. We find that, during periods of quiet ionospheric conditions, the amount of radar backscatter increases when a variation in the dynamic pressure occurs, both positive (increase of the pressure and negative (decrease of the pressure. We also investigate the behaviour of the Cross-Polar Cap Potential (CPCP during pressure variations and show preliminary results.

Combined pressure and cosolvent effects on enzyme activity - a high-pressure stopped-flow kinetic study on α-chymotrypsin.

Science.gov (United States)

Luong, Trung Quan; Winter, Roland

2015-09-21

We investigated the combined effects of cosolvents and pressure on the hydrolysis of a model peptide catalysed by α-chymotrypsin. The enzymatic activity was measured in the pressure range from 0.1 to 200 MPa using a high-pressure stopped-flow systems with 10 ms time resolution. A kosmotropic (trimethalymine-N-oxide, TMAO) and chaotropic (urea) cosolvent and mixtures thereof were used as cosolvents. High pressure enhances the hydrolysis rate as a consequence of a negative activation volume, ΔV(#), which, depending on the cosolvent system, amounts to -2 to -4 mL mol(-1). A more negative activation volume can be explained by a smaller compression of the ES complex relative to the transition state. Kinetic constants, such as kcat and the Michaelis constant KM, were determined for all solution conditions as a function of pressure. With increasing pressure, kcat increases by about 35% and its pressure dependence by a factor of 1.9 upon addition of 2 M urea, whereas 1 M TMAO has no significant effect on kcat and its pressure dependence. Similarly, KM increases upon addition of urea 6-fold. Addition of TMAO compensates the urea-effect on kcat and KM to some extent. The maximum rate of the enzymatic reaction increases with increasing pressure in all solutions except in the TMAO : urea 1 : 2 mixture, where, remarkably, pressure is found to have no effect on the rate of the enzymatic reaction anymore. Our data clearly show that compatible solutes can easily override deleterious effects of harsh environmental conditions, such as high hydrostatic pressures in the 100 MPa range, which is the maximum pressure encountered in the deep biosphere on Earth.

The effects of superimposed tilt and lower body negative pressure on anterior and posterior cerebral circulations.

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Tymko, Michael M; Rickards, Caroline A; Skow, Rachel J; Ingram-Cotton, Nathan C; Howatt, Michael K; Day, Trevor A

2016-09-01

Steady-state tilt has no effect on cerebrovascular reactivity to increases in the partial pressure of end-tidal carbon dioxide (PETCO2). However, the anterior and posterior cerebral circulations may respond differently to a variety of stimuli that alter central blood volume, including lower body negative pressure (LBNP). Little is known about the superimposed effects of head-up tilt (HUT; decreased central blood volume and intracranial pressure) and head-down tilt (HDT; increased central blood volume and intracranial pressure), and LBNP on cerebral blood flow (CBF) responses. We hypothesized that (a) cerebral blood velocity (CBV; an index of CBF) responses during LBNP would not change with HUT and HDT, and (b) CBV in the anterior cerebral circulation would decrease to a greater extent compared to posterior CBV during LBNP when controlling PETCO2 In 13 male participants, we measured CBV in the anterior (middle cerebral artery, MCAv) and posterior (posterior cerebral artery, PCAv) cerebral circulations using transcranial Doppler ultrasound during LBNP stress (-50 mmHg) in three body positions (45°HUT, supine, 45°HDT). PETCO2 was measured continuously and maintained at constant levels during LBNP through coached breathing. Our main findings were that (a) steady-state tilt had no effect on CBV responses during LBNP in both the MCA (P = 0.077) and PCA (P = 0.583), and (b) despite controlling for PETCO2, both the MCAv and PCAv decreased by the same magnitude during LBNP in HUT (P = 0.348), supine (P = 0.694), and HDT (P = 0.407). Here, we demonstrate that there are no differences in anterior and posterior circulations in response to LBNP in different body positions. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Electrical admittance for filling of the heart during lower body negative pressure in humans

DEFF Research Database (Denmark)

Cai, Yujia; Holm, S; Jenstrup, M

2000-01-01

To evaluate whether electrical admittance of intracellular water is applicable for monitoring filling of the heart, we determined the difference in intracellular water in the thorax (Thorax(ICW)), measured as the reciprocal value of the electrical impedance for the thorax at 1.5 and 100 kHz during...... lower body negative pressure (LBNP) in humans. Changes in Thorax(ICW) were compared with positron emission tomography-determined C(15)O-labeled erythrocytes over the heart. During -40 mmHg LBNP, the blood volume of the heart decreased by 21 +/- 3% as the erythrocyte volume was reduced by 20 +/- 2.......6 to 40.9 +/- 5.0 S. 10(-4); P = 0.08). The correlation between Thorax(ICW) and heart erythrocyte volume was 0.84 (P electrical admittance of intracellular water can be applied to evaluate changes in blood volume of the heart during LBNP in humans....

Method transfer from high-pressure liquid chromatography to ultra-high-pressure liquid chromatography. II. Temperature and pressure effects.

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Åsberg, Dennis; Samuelsson, Jörgen; Leśko, Marek; Cavazzini, Alberto; Kaczmarski, Krzysztof; Fornstedt, Torgny

2015-07-03

The importance of the generated temperature and pressure gradients in ultra-high-pressure liquid chromatography (UHPLC) are investigated and compared to high-pressure liquid chromatography (HPLC). The drug Omeprazole, together with three other model compounds (with different chemical characteristics, namely uncharged, positively and negatively charged) were used. Calculations of the complete temperature profile in the column at UHPLC conditions showed, in our experiments, a temperature difference between the inlet and outlet of 16 °C and a difference of 2 °C between the column center and the wall. Through van't Hoff plots, this information was used to single out the decrease in retention factor (k) solely due to the temperature gradient. The uncharged solute was least affected by temperature with a decrease in k of about 5% while for charged solutes the effect was more pronounced, with k decreases up to 14%. A pressure increase of 500 bar gave roughly 5% increase in k for the uncharged solute, while omeprazole and the other two charged solutes gave about 25, 20 and 15% increases in k, respectively. The stochastic model of chromatography was applied to estimate the dependence of the average number of adsorption/desorption events (n) and the average time spent by a molecule in the stationary phase (τs) on temperature and pressure on peak shape for the tailing, basic solute. Increasing the temperature yielded an increase in n and decrease in τs which resulted in less skew at high temperatures. With increasing pressure, the stochastic modeling gave interesting results for the basic solute showing that the skew of the peak increased with pressure. The conclusion is that pressure effects are more pronounced for both retention and peak shape than the temperature effects for the polar or charged compounds in our study. Copyright © 2015 Elsevier B.V. All rights reserved.

Negative Pressure Wound Therapy in Infected Wound following Posterior Spinal Instrumentation using Simple Self-assembled System: A Case Report

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CW Chang

2014-07-01

Full Text Available Postoperative wound infection in an instrumented spine patient is often disastrous. Management includes implant removal leading to spine instability. Negative pressure wound therapy (NPWT applied to the spine surgical wound is one of the wound care technique with successful results. We report a case of a man who sustained Chance fracture of Lumbar 1 (L1 vertebra treated with long segment posterior instrumentation, who unfortunately developed Extended-spectrum beta-lactamase (ESBL positive E. coli infection one month after the operation. After careful debridement of the wound, the implant became exposed. Three cycles of NPWT were applied and the wound healed with granulation tissue completely covering the implant, and thus negating the need to remove the implant. In conclusion, the NPWT is a good alternative in postoperative wound management especially in an instrumented spine patient.

The use of negative pressure wound therapy in the treatment of infected wounds. Case studies

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Daniel de Alcântara Jones

Full Text Available ABSTRACT OBJECTIVE: To evaluate the results and benefits obtained from the topical use of negative pressure wound therapy (NPWT in patients with infected wounds. METHODS: This was a retrospective study of 20 patients (17 males and three females, mean age 42 years with infected wounds treated using NPWT. The infected wounds were caused by trauma. The treatment system used was VAC.(r (Vacuum Assisted Closure, KCI, San Antonio, United States applied to the wound in continuous mode from 100 to 125 mmHg. The parameters related to the wounds (location, number of VAC changes, the size of the defects in the soft parts, and the evolution of the state of the wound, length of hospital stay, length of intravenous antibiotic therapy, and complications related to the use of this therapy were evaluated. RESULTS: The mean length of the hospital stay, use of NPWT, and antibacterial therapy were 41 days, 22.5 days, and 20 days respectively. The use of the VAC led to a mean reduction of 29% in the wound area (95.65-68.1 cm2; p < 0.05. Only one patient did not show any improvement in the final appearance of the wound with complete eradication of the infection. No complication directly caused by NPWT was observed. CONCLUSION: NPWT stimulates infection-free scar tissue formation in a short time, and is a quick and comfortable alternative to conventional infected wounds treatment methods.

Do Infants Show Distinct Negative Facial Expressions for Fear and Anger? Emotional Expression in 11-Month-Old European American, Chinese, and Japanese Infants

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Camras, Linda A.; Oster, Harriet; Bakeman, Roger; Meng, Zhaolan; Ujiie, Tatsuo; Campos, Joseph J.

2007-01-01

Do infants show distinct negative facial expressions for different negative emotions? To address this question, European American, Chinese, and Japanese 11-month-olds were videotaped during procedures designed to elicit mild anger or frustration and fear. Facial behavior was coded using Baby FACS, an anatomically based scoring system. Infants'…

Relationship quality: effects on ambulatory blood pressure and negative affect in a biracial sample of men and women.

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Grewen, Karen M; Girdler, Susan S; Light, Kathleen C

2005-06-01

Prospective studies link marriage to better cardiovascular health, but marital dissatisfaction and discord predict increased rates of hypertension, higher blood pressure (BP), greater reactivity to stress, and left ventricular mass. To determine and compare effects of partner status and relationship quality on 24-h BP, urinary norepinephrine and cortisol, and self-reported stress and negative affect. Ambulatory BP (ABP) and 24-h urine collections were obtained during a typical work day in 325 adults, including 139 African Americans (AAs). Participants cohabiting with a spouse or partner were classified into high, intermediate and low relationship quality (RQ) groups and compared to those without partners (Alone). Mean ABP was nearly identical in participants with versus without partners (125.7/76.9 versus 125.9/76.7 mmHg). High RQ subjects had lower mean waking ABP than intermediate/low RQ and Alone groups [systolic blood pressure (SBP), F=3.45; diastolic blood pressure (DBP), F=3.38, P-values affect and stress than all other groups (Paffect and stress than partner status. High RQ is linked to lower ABP across race and gender. This reduced ABP may be due, in part, to the stress buffering effects of better RQ and/or the stress enhancing effects of poor RQ.

DC negative corona discharge in atmospheric pressure helium: transition from the corona to the ‘normal’ glow regime

International Nuclear Information System (INIS)

Hasan, Nusair; Farouk, Bakhtier; Antao, Dion S

2014-01-01

Direct current (dc) negative corona discharges in atmospheric pressure helium are simulated via detailed numerical modeling. Simulations are conducted to characterize the discharges in atmospheric helium for a pin plate electrode configuration. A self-consistent two-dimensional hybrid model is developed to simulate the discharges and the model predictions are validated with experimental measurements. The discharge model considered consists of momentum and energy conservation equations for a multi-component (electrons, ions, excited species and neutrals) gas mixture, conservation equations for each component of the mixture and state relations. A drift–diffusion approximation for the electron and the ion fluxes is used. A model for the external circuit driving the discharge is also considered and solved along with the discharge model. Many of the key features of a negative corona discharge, namely non-linear current–voltage characteristics, spatially flat cathode current density and glow-like discharge in the high current regime are displayed in the predictions. A transition to the ‘normal’ glow discharge from the corona discharge regime is also observed. The transition is identified from the calculated current–voltage characteristic curve and is characterized by the radial growth of the negative glow and the engulfment of the cathode wire. (paper)

Stability of the geometrically frustrated magnetic state of Ca3CoRhO6 to applications of positive and negative pressure

International Nuclear Information System (INIS)

Mohapatra, Niharika; Iyer, Kartik K; Jammalamadaka, S Narayana; Sampathkumaran, E V; Rayaprol, Sudhindra

2008-01-01

The influence of negative chemical pressure induced by gradual replacement of Ca by Sr as well as of external pressure (up to 10 kbar) on the magnetism of Ca 3 CoRhO 6 has been investigated by magnetization studies. It is found that the solid solution, Ca 3-x Sr x CoRhO 6 , exists at least until about x = 1.0 without any change in the crystal structure. Apart from insensitivity of the spin-chain feature to volume expansion, the characteristic features of geometrical frustration interestingly appear at the same temperatures for all compositions, in sharp contrast to the response to Y substitution for Ca (reported previously). Interestingly, the huge frequency dependence of ac susceptibility known for the parent compound persists for all compositions. We do not find a change in the properties under external pressure. The stability of the magnetic anomalies of this compound to volume change (about 4%) is puzzling

A new low-cost negative-pressure wound therapy versus a commercially available therapy device widely used to treat complex traumatic injuries: a prospective, randomized, non-inferiority trial

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Fabio Kamamoto

Full Text Available OBJECTIVES: Negative-pressure wound therapy has been widely adopted to reduce the complexity of treating a broad range of acute and chronic wounds. However, its cost is high. The objective of this study was to evaluate the following two different methods of negative-pressure wound therapy in terms of healing time: a low-cost method of negative-pressure wound therapy (a pressure stabilizer device connected to a hospital wall-vacuum system with a gauze-sealed dressing, USP and the standard of care (vacuum-assisted closure, VAC. METHODS: This is a randomized, controlled, non-inferiority, unblinded trial. Patients admitted with complex injuries to a trauma center in a public referral hospital who were indicated for orthopedic surgery were randomized to a USP or VAC group. The primary outcome was the time required to achieve a “ready for surgery condition”, which was defined as a wound bed with healthy granulation tissue and without necrosis or purulent secretion. Wound bed area contraction, granulation tissue growth and the direct costs of the dressings were secondary outcomes. RESULTS: Variation in area and granulation tissue growth were essentially the same between the systems, and healing time was equal between the groups (p=0.379. In both systems, serial debridement increased wound area (p=0.934, and granulation tissue was also increased (p=0.408. The mean treatment cost was US$ 15.15 in the USP group and US$ 872.59 in the VAC group. CONCLUSIONS: For treating complex traumatic injuries, USP was non-inferior to and less expensive than VAC.

A new low-cost negative-pressure wound therapy versus a commercially available therapy device widely used to treat complex traumatic injuries: a prospective, randomized, non-inferiority trial.

Science.gov (United States)

Kamamoto, Fabio; Lima, Ana Lucia Munhoz; Rezende, Marcelo Rosa de; Mattar-Junior, Rames; Leonhardt, Marcos de Camargo; Kojima, Kodi Edson; Santos, Carla Chineze Dos

2017-12-01

Negative-pressure wound therapy has been widely adopted to reduce the complexity of treating a broad range of acute and chronic wounds. However, its cost is high. The objective of this study was to evaluate the following two different methods of negative-pressure wound therapy in terms of healing time: a low-cost method of negative-pressure wound therapy (a pressure stabilizer device connected to a hospital wall-vacuum system with a gauze-sealed dressing, USP) and the standard of care (vacuum-assisted closure, VAC). This is a randomized, controlled, non-inferiority, unblinded trial. Patients admitted with complex injuries to a trauma center in a public referral hospital who were indicated for orthopedic surgery were randomized to a USP or VAC group. The primary outcome was the time required to achieve a "ready for surgery condition", which was defined as a wound bed with healthy granulation tissue and without necrosis or purulent secretion. Wound bed area contraction, granulation tissue growth and the direct costs of the dressings were secondary outcomes. Variation in area and granulation tissue growth were essentially the same between the systems, and healing time was equal between the groups (p=0.379). In both systems, serial debridement increased wound area (p=0.934), and granulation tissue was also increased (p=0.408). The mean treatment cost was US$ 15.15 in the USP group and US$ 872.59 in the VAC group. For treating complex traumatic injuries, USP was non-inferior to and less expensive than VAC.

Incidence of Parental Support and Pressure on Their Children's Motivational Processes towards Sport Practice Regarding Gender.

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Amado, Diana; Sánchez-Oliva, David; González-Ponce, Inmaculada; Pulido-González, Juan José; Sánchez-Miguel, Pedro Antonio

2015-01-01

Grounded in Self-Determination Theory, structural equation modeling (SEM) with the aim of examining how parental support/pressure could influence their children´s motivational processes in sport was conducted, as well as the models´ differences in operability regarding gender. The sample size was 321 children ranging in age from 10 to 16 years old who were athletes from Extremadura, and 321 parents (included only the father or mother more involved with the sport of his or her child). 175 participants were male and 146 were female from individual (n = 130), and team sports (n=191). A questionnaire was conducted to assess parental perception of support/pressure and another questionnaire was conducted to measure satisfaction of basic psychological needs, type of motivation and enjoyment/boredom showed by their children towards sport practice. Results revealed that parental pressure negatively predicted satisfaction of the basic psychological needs. It also emerged as a strong positive predictor of intrinsic motivation and negative predictor of amotivation. Moreover, intrinsic motivation emerged as positive predictor of enjoyment and a negative predictor of boredom, whereas amotivation positively predicted boredom and negatively predicted enjoyment. Furthermore, results showed there were mean differences by gender: male athletes perceived greater parental pressure. Hence, it is necessary to decrease parental pressure towards their children in sport, with the aim of making them more motivated and enjoy, promoting positive consequences.

Incidence of Parental Support and Pressure on Their Children's Motivational Processes towards Sport Practice Regarding Gender.

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Diana Amado

Full Text Available Grounded in Self-Determination Theory, structural equation modeling (SEM with the aim of examining how parental support/pressure could influence their children´s motivational processes in sport was conducted, as well as the models´ differences in operability regarding gender. The sample size was 321 children ranging in age from 10 to 16 years old who were athletes from Extremadura, and 321 parents (included only the father or mother more involved with the sport of his or her child. 175 participants were male and 146 were female from individual (n = 130, and team sports (n=191. A questionnaire was conducted to assess parental perception of support/pressure and another questionnaire was conducted to measure satisfaction of basic psychological needs, type of motivation and enjoyment/boredom showed by their children towards sport practice. Results revealed that parental pressure negatively predicted satisfaction of the basic psychological needs. It also emerged as a strong positive predictor of intrinsic motivation and negative predictor of amotivation. Moreover, intrinsic motivation emerged as positive predictor of enjoyment and a negative predictor of boredom, whereas amotivation positively predicted boredom and negatively predicted enjoyment. Furthermore, results showed there were mean differences by gender: male athletes perceived greater parental pressure. Hence, it is necessary to decrease parental pressure towards their children in sport, with the aim of making them more motivated and enjoy, promoting positive consequences.

The Effect of Negative Pressure Wound Therapy With Antiseptic Instillation on Biofilm Formation in a Porcine Model of Infected Spinal Instrumentation.

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Singh, Devinder P; Gowda, Arvind U; Chopra, Karan; Tholen, Michael; Chang, Sarah; Mavrophilipos, Vasilios; Semsarzadeh, Nina; Rasko, Yvonne; Holton Iii, Luther

2017-06-01

This study evaluates the effect of negative pressure wound therapy with antiseptic instillation (NPWTi) in the clearance of infection and biofilm formation in an in vivo model of infected spinal implants compared to traditional treatment modalities. Five pigs underwent titanium rod implantation of their spinous processes followed by injection of 1 x 106 CFUs/100μL of methicillin-resistant Staphylococcus aureus through the fascia at each site. At 1 week postoperatively, an experimental arm of 3 pigs received NPWTi, and a control arm of 2 pigs received wet-to-dry dressings. The persistence of local infection in the experimental group was compared to the control group using tissue cultures. Biofilm development on spinal implants was evaluated using scanning electron microscopy. Mean bacterial count showed a statistical difference between the experimental and the control groups (P < .05). Scanning electron microscopy revealed the presence of uniform biofilm formation across the surface of control group instrumentation, whereas the experimental group showed interrupted areas between biofilm formations. The authors concluded that NPWTi is associated with decreased bacterial load and biofilm formation compared to wet-to-dry dressings in an in vivo porcine model of infected spinal instrumentation.

Measurement of negative ion mobility in O2 at high pressures using a point plate gap as an ion detector

International Nuclear Information System (INIS)

Okuyama, Y; Kimura, T; Suzuki, S; Itoh, H

2012-01-01

This paper describes the experimental results for negative ion mobility in O 2 at 0.5-2.0 atm. The ion mobility is observed using a high-pressure ion drift tube with a positive corona gap (Geiger counter), which is constructed from a point plate gap and acts as a negative ion detector. The variation of waveforms in the burst pulse is observed by varying the voltage applied to the ion detector to find the optimum voltage that must be applied across the ion detector in O 2 . This is investigated carefully to ensure the precise determination of mobility. The distortion of the electric field near the mesh electrode, which operates as the cathode of the ion detector and as the anode of the ion drift gap, is then examined to determine the optimum applied voltage to suppress its effect on the measurement of mobility. The mobility is subsequently measured at a reduced electric field intensity of 2.83 × 10 -3 to 2.83. The observed mobility of 2.31 ± 0.03 cm 2 V -1 s -1 in O 2 is concluded to be that of O 2 - . This value is also obtained in experiments over a wide range of gas pressures (0.5-2.0 atm) and drift lengths (1.00-9.00 cm). The mobilities of O 3 - and O - are also obtained experimentally. (paper)

Effect of Intracanal Cryotherapy and Negative Irrigation Technique on Postendodontic Pain.

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Al-Nahlawi, Talal; Hatab, Talaat Abo; Alrazak, Mahmoud Abd; Al-Abdullah, Ahmad

2016-12-01

To evaluate the effect of intracanal cryotherapy with negative pressure irrigation (EndoVac) on postendodontic pain after vital single-visit root canal treatment (RCT). A total of 75 single-rooted teeth with single root canal were treated endodontically. After root canal preparation with Protaper Universal rotary system and irrigation, teeth were divided randomly into three groups (n = 25) according to additional irrigation protocol as follows: Group I: No additional irrigation was applied (control); group II: A 20 mL of room temperature saline was irrigated during 5 minutes using EndoVac, and group III: A 20 mL of 2 to 4°C cold saline was irrigated during 5 minutes using EndoVac. Pain levels were assessed by visual analog scale (VAS) and verbal evaluation of pain questionnaire after 6, 12, 24, 48 hours, and 7 days of canal obturation. The data were then analyzed using Statistical Package for the Social Sciences (SPSS) 13.0 using Kruskal-Wallis and Mann-Whitney U tests at p-value of 0.05. The results showed that pain levels were high in groups I and II after 6 hours that decreased with time to almost diminish after 1 week, and on the other hand, group III showed no pain among different monitoring periods. Also pain levels in groups II were lower compared with group I after only 6 hours, with significance p cryotherapy eliminated postendodontic pain clinically. Negative pressure reduced postendodontic pain after 6 hours of treatment. The outcome of this study indicates that the use of intracanal cryotherapy technique with negative pressure irrigation eliminates postendodontic pain after single-visit RCTs.

Hydrostatic pressure mimics gravitational pressure in characean cells

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Staves, M. P.; Wayne, R.; Leopold, A. C.

1992-01-01

Hydrostatic pressure applied to one end of a horizontal Chara cell induces a polarity of cytoplasmic streaming, thus mimicking the effect of gravity. A positive hydrostatic pressure induces a more rapid streaming away from the applied pressure and a slower streaming toward the applied pressure. In contrast, a negative pressure induces a more rapid streaming toward and a slower streaming away from the applied pressure. Both the hydrostatic pressure-induced and gravity-induced polarity of cytoplasmic streaming respond identically to cell ligation, UV microbeam irradiation, external Ca2+ concentrations, osmotic pressure, neutral red, TEA Cl-, and the Ca2+ channel blockers nifedipine and LaCl3. In addition, hydrostatic pressure applied to the bottom of a vertically-oriented cell can abolish and even reverse the gravity-induced polarity of cytoplasmic streaming. These data indicate that both gravity and hydrostatic pressure act at the same point of the signal transduction chain leading to the induction of a polarity of cytoplasmic streaming and support the hypothesis that characean cells respond to gravity by sensing a gravity-induced pressure differential between the cell ends.

Incidence of Parental Support and Pressure on Their Children’s Motivational Processes towards Sport Practice Regarding Gender

Science.gov (United States)

Amado, Diana

2015-01-01

Grounded in Self-Determination Theory, structural equation modeling (SEM) with the aim of examining how parental support/pressure could influence their children´s motivational processes in sport was conducted, as well as the models´ differences in operability regarding gender. The sample size was 321 children ranging in age from 10 to 16 years old who were athletes from Extremadura, and 321 parents (included only the father or mother more involved with the sport of his or her child). 175 participants were male and 146 were female from individual (n = 130), and team sports (n=191). A questionnaire was conducted to assess parental perception of support/pressure and another questionnaire was conducted to measure satisfaction of basic psychological needs, type of motivation and enjoyment/boredom showed by their children towards sport practice. Results revealed that parental pressure negatively predicted satisfaction of the basic psychological needs. It also emerged as a strong positive predictor of intrinsic motivation and negative predictor of amotivation. Moreover, intrinsic motivation emerged as positive predictor of enjoyment and a negative predictor of boredom, whereas amotivation positively predicted boredom and negatively predicted enjoyment. Furthermore, results showed there were mean differences by gender: male athletes perceived greater parental pressure. Hence, it is necessary to decrease parental pressure towards their children in sport, with the aim of making them more motivated and enjoy, promoting positive consequences. PMID:26039062

A Unique Application of Negative Pressure Wound Therapy Used to Facilitate Patient Engagement in the Amputation Recovery Process.

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Wise, Jessica; White, Alicia; Stinner, Daniel J; Fergason, John R

2017-08-01

Amputation rates during recent military conflicts were at an all-time high, but medical treatment of those amputations and attitudes of service members to get back to duty are also surging ahead. We present the cases of an active duty rescue C130 pilot with an above-the-knee amputation and a retired army sergeant with a below-the-knee amputation. Successful rehabilitation was augmented in both cases by using negative pressure incorporated in a custom prosthetic socket to accelerate incision closure, improve self-efficacy in wound care, and self-management, ultimately leading to faster recovery times, full engagement of the rehabilitation process, and return to active duty.

Two-dimensional simulation of positive and negative streamers in air

International Nuclear Information System (INIS)

Babaeva, N.Yu.; Naidis, G.V.

1998-01-01

The paper deals with 2D numerical simulation of positive and negative streamers in air at atmospheric pressure. The dynamics of an axially symmetric streamer based on a charged sphere is described by a coupled system of equations for the electric field and the density of charged particles. The results of simulation show that the production rate of radicals in short sphere-plane gaps depends only weakly on the discharge conditions, that the streamer velocity in uniform field depends linearly on the streamer length, and the field corresponding to the negative streamer propagation with a constant velocity is 2-3 times greater than that obtained with a positive streamer. (J.U.)

Negative Pressure Wound Therapy Applied Before and After Split-Thickness Skin Graft Helps Healing of Fournier Gangrene

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Ye, Junna; Xie, Ting; Wu, Minjie; Ni, Pengwen; Lu, Shuliang

2015-01-01

Abstract Fournier gangrene is a rare but highly infectious disease characterized by fulminant necrotizing fasciitis involving the genital and perineal regions. Negative pressure wound therapy (NPWT; KCI USA Inc, San Antonio, TX) is a widely adopted technique in many clinical settings. Nevertheless, its application and effect in the treatment of Fournier gangrene are unclear. A 47-year-old male patient was admitted with an anal abscess followed by a spread of the infection to the scrotum, which was caused by Pseudomonas aeruginosa. NPWT was applied on the surface of the scrotal area and continued for 10 days. A split-thickness skin graft from the scalp was then grafted to the wound, after which, NPWT utilizing gauze sealed with an occlusive dressing and connected to a wall suction was employed for 7 days to secure the skin graft. At discharge, the percentage of the grafted skin alive on the scrotum was 98%. The wound beside the anus had decreased to 4 × 0.5 cm with a depth of 1 cm. Follow-up at the clinic 1 month later showed that both wounds had healed. The patient did not complain of any pain or bleeding, and was satisfied with the outcome. NPWT before and after split-thickness skin grafts is safe, well tolerated, and efficacious in the treatment of Fournier gangrene. PMID:25654376

Negative secondary ion emission from oxidized surfaces

International Nuclear Information System (INIS)

Gnaser, H.; Kernforschungsanlage Juelich G.m.b.H.

1984-01-01

The emission of negative secondary ions from 23 elements was studied for 10 keV O 2 + and 10 keV In + impact at an angle of incidence of 45 0 . Partial oxidation of the sample surfaces was achieved by oxygen bombardment and/or by working at a high oxygen partial pressure. It was found that the emission of oxide ions shows an element-characteristic pattern. For the majority of the elements investigated these features are largely invariant against changes of the surface concentration of oxygen. For the others admission of oxygen strongly changes the relative intensities of oxide ions: a strong increase of MO 3 - signals (M stands for the respective element) is accompanied by a decrease of MO - and M - intensities. Different primary species frequently induce changes of both the relative and the absolute negative ion intensities. Carbon - in contrast to all other elements - does not show any detectable oxide ion emission but rather intense cluster ions Csub(n) - (detected up to n=12) whose intensities oscillate in dependence on n. (orig./RK)

Double streamer phenomena in atmospheric pressure low frequency corona plasma

International Nuclear Information System (INIS)

Kim, Dan Bee; Jung, H.; Gweon, B.; Choe, Wonho

2010-01-01

Time-resolved images of an atmospheric pressure corona discharge, generated at 50 kHz in a single pin electrode source, show unique positive and negative corona discharge features: a streamer for the positive period and a glow for the negative period. However, unlike in previous reports of dc pulse and low frequency corona discharges, multistreamers were observed at the initial time stage of the positive corona. A possible physical mechanism for the multistreamers is suggested.

Effect of antioxidant rich diets on lipid profile and blood pressure in cardiovascular patients

International Nuclear Information System (INIS)

Akhtar, M.S.; Ashraf, S.; Bhatty, N.; Ahmad, N.

2006-01-01

A sample of 200 patients was randomly selected and interviewed. Various data related to their food consumption in previous weeks and other behavioral attitudes were recorded. Their blood pressure was measured and blood was analyzed for total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and triglycerides (TG). Spearman's correlation coefficient was worked out between blood pressure, serum lipid parameters and tea, vitamin C and fibre intake. Tea showed significant correlation with diastolic blood pressure (DBP) (-0.2373; P<0.02), systolic blood pressure (SBP) (-0.2299; P<0.02) and TC (-0.3454; P<0.01). Vitamin C showed a negatively significant correlation with TC (-0.4676; P<0.01), and LDL-C (-2661; P<0.01) and significant positive correlation with HDL-C (+0.2227; P < 0.05). The tea intake was found strongly correlated with blood pressure as compared to vitamin C, while vitamin C had stronger correlation with TC as compared to tea intake. Fibre was not found significantly correlated with any of the studied parameters. A 30-day control trial on 50 subjects revealed that antioxidant therapy during fat-restricted diet period significantly affected blood pressure and serum lipids. Comparative effect showed that lemon juice showed best results. Lemon juice decreased DBP, SBP, TC, TG and increased HDL-C, while tea added with lemon only significantly decreased DBP, SBP and TC. Salad, especially onion, only improved HDL-C and LDLC levels. Vitamin C supplement also significantly lowered DBP, SBP, TC, LDL-C and TG. Tea had negative correlation with blood pressure and TC, while vitamin C has showed relationship with TC, LDL-C and positive with HDL-C. It is conceivable, therefore, that dietary antioxidants cause a significant improvement in blood pressure and serum lipids than vitamin C supplement and simple fat-restricted diets. (author)

Management of the open abdomen using negative pressure wound therapy with instillation in severe abdominal sepsis: A review of 48 cases in Hospital Mexico, Costa Rica.

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Sibaja, Pablo; Sanchez, Alfredo; Villegas, Guillermo; Apestegui, Alvaro; Mora, Esteban

2017-01-01

Despite the numerous advances in recent years, severe abdominal sepsis (with associated organ failure associated with infection) remains a serious, life-threatening condition with a high mortality rate. OA is a viable alternative to the previously used scheduled repeat laparotomy or continuous peritoneal lavage. The use of Negative Pressure Wound Therapy (NPWT) has been described as a successful method of management of the open abdomen. Adding instillation of saline solution to NPWT in a programmed and controlled manner, could offer the clinician an additional tool for the management of complex septic abdomen. To explore if the concept of active two-way therapy (Negative pressure wound therapy with instillation or NPWT-I) yields superior control of underlying, life-threatening abdominal infections and its effects on survival and morbidity in patients with severe abdominal sepsis when management with an open abdomen is required. A retrospective review of 48 patients with severe abdominal sepsis, who were managed with and open abdomen and NPWT-I was performed. NPWT-I was initiated utilizing the same parameters on all patients, this consisted of cycles of instillation of saline solution, which was removed through negative pressure after a short dwell period. We observed the effects on primary fascia closure rate, mortality, hospital and SICU length of stay and associated complications. Our patient group consisted of 20 (42%) males and 28 (58%) females. Average age was 48 years. Mortality in these patients was attributed to pulmonary embolism (n=1), acute renal failure (n=2) and cardiopulmonary arrest (n=1). Average total hospital stay was 24days, and stay in the SICU (n=26) averaged 7.5days. No acute complications related to the NPWT-I. All patients presenting with abdominal compartment syndrome resolved after initiation of the NPWT-I. A total of 46 patients (96%) patients achieved fascia closure after NPWT-I therapy after an average of 6days. Four patients (8%) died

Ultra pressure liquid chromatography-negative electrospray ionization mass spectrometry determination of twelve halobenzoquinones at ng/L levels in drinking water.

Science.gov (United States)

Huang, Rongfu; Wang, Wei; Qian, Yichao; Boyd, Jessica M; Zhao, Yuli; Li, Xing-Fang

2013-05-07

We report here the characterization of twelve halobenzoquinones (HBQs) using electrospray ionization (ESI) high resolution quadrupole time-of-flight mass spectrometry. The high resolution negative ESI spectra of the twelve HBQs formed two parent ions, [M + H(+) + 2e(-)], and the radical M(-•). The intensities of these two parent ions are dependent on their chemical structures and on instrumental parameters such as the source temperature and flow rate. The characteristic ions of the HBQs were used to develop an ultra pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. At the UPLC flow rate (400 μL/min) and under the optimized ESI conditions, eleven HBQs showed the stable and abundant transitions [M + H(+) + 2e(-)] → X(-) (X(-) representing Cl(-), Br(-), or I(-)), while dibromo-dimethyl-benzoquinone (DBDMBQ) showed only the transition of M(-•) → Br(-). The UPLC efficiently separates all HBQs including some HBQ isomers, while the MS/MS offers exquisite limits of detection (LODs) at subng/mL levels for all HBQs except DBDMBQ. Combined with solid phase extraction (SPE), the method LOD is down to ng/L. The results from analysis of authentic samples demonstrated that the SPE-UPLC-MS/MS method is reliable, fast, and sensitive for the identification and quantification of the twelve HBQs in drinking water.

The effect of blood volume loss on cardiovascular response to lower body negative pressure using a mathematical model

Science.gov (United States)

Karam, E. H.; Srinivasan, R. S.; Charles, J. B.; Fortney, S. M.

1994-01-01

Different mathematical models of varying complexity have been proposed in recent years to study the cardiovascular (CV) system. However, only a few of them specifically address the response to lower body negative pressure (LBNP), a stress that can be applied in weightlessness to predict changes in orthostatic tolerance. Also, the simulated results produced by these models agree only partially with experimental observations. In contrast, the model proposed by Melchior et al., and modified by Karam et al. is a simple representation of the CV system capable of accurately reproducing observed LBNP responses up to presyncopal levels. There are significant changes in LBNP response due to a loss of blood volume and other alterations that occur in weightlessness and related one-g conditions such as bedrest. A few days of bedrest can cause up to 15% blood volume loss (BVL), with consequent decreases in both stroke volume and cardiac output, and increases in heart rate, mean arterial pressure, and total peripheral resistance. These changes are more pronounced at higher levels of LBNP. This paper presents the results of a simulation study using our CV model to examine the effect of BVL on LBNP response.

Comparison of compensatory reserve during lower-body negative pressure and hemorrhage in nonhuman primates

Science.gov (United States)

Howard, Jeffrey T.; Mulligan, Jane; Grudic, Greg Z.; Convertino, Victor A.

2016-01-01

Compensatory reserve was measured in baboons (n = 13) during hemorrhage (Hem) and lower-body negative pressure (LBNP) using a machine-learning algorithm developed to estimate compensatory reserve by detecting reductions in central blood volume during LBNP. The algorithm calculates compensatory reserve index (CRI) from normovolemia (CRI = 1) to cardiovascular decompensation (CRI = 0). The hypothesis was that Hem and LBNP will elicit similar CRI values and that CRI would have higher specificity than stroke volume (SV) in predicting decompensation. Blood was removed in four steps: 6.25%, 12.5%, 18.75%, and 25% of total blood volume. Four weeks after Hem, the same animals were subjected to four levels of LBNP that was matched on the basis of their central venous pressure. Data (mean ± 95% confidence interval) indicate that CRI decreased (P < 0.001) from baseline during Hem (0.69 ± 0.10, 0.57 ± 0.09, 0.36 ± 0.10, 0.16 ± 0.08, and 0.08 ± 0.03) and LBNP (0.76 ± 0.05, 0.66 ± 0.08, 0.36 ± 0.13, 0.23 ± 0.11, and 0.14 ± 0.09). CRI was not different between Hem and LBNP (P = 0.20). Linear regression analysis between Hem CRI and LBNP CRI revealed a slope of 1.03 and a correlation coefficient of 0.96. CRI exhibited greater specificity than SV in both Hem (92.3 vs. 82.1) and LBNP (94.8 vs. 83.1) and greater ROC AUC in Hem (0.94 vs. 0.84) and LBNP (0.94 vs. 0.92). These data support the hypothesis that Hem and LBNP elicited the same CRI response, suggesting that measurement of compensatory reserve is superior to SV as a predictor of cardiovascular decompensation PMID:27030667

Influence of ambient air pressure on impact pressure caused by breaking waves

NARCIS (Netherlands)

Moutzouris, C.

1979-01-01

Engineers are interested in the dynamics of the interface waterstructure. In case of breaking of water waves on a structure high positive and sometimes negative pressures of very short duration occur. Not only the maxima and minima of the pressures on the structure are important to a designing

Cardiovascular reactivity of younger and older adults to positive-, negative-, and mixed-emotion cognitive challenge.

Science.gov (United States)

Hogan, Michael J; James, Jack E; McCabe, Tadhg R; Kilmartin, Liam; Howard, Siobhán; Noone, Chris

2012-03-01

Although aging is associated with progressive increases in blood pressure level, previous research has been inconsistent as to whether older adults show greater or lesser cardiovascular reactivity (CVR) to emotion than do younger adults. There is reason to believe that these inconsistencies could be clarified by examining age-related differences in hemodynamic profile revealed by measuring the pattern of cardiac output and total peripheral resistance associated with changes in blood pressure reactivity. Accordingly, the present study examined the performance, CVR, and hemodynamic profile of younger and older adults during encoding and recognition of word pairs involving four valence types: positive, negative, mixed (positive/negative), and neutral word pairs. Results revealed higher baseline blood pressure, increased CVR characterized by a vascular hemodynamic profile, and more rapid recovery (especially during encoding) for older than for younger participants. Results are discussed in light of research and theory on the relationship between aging and cardiovascular health. Copyright © 2012 Elsevier B.V. All rights reserved.

Apical negative pressure irrigation versus syringe irrigation: a systematic review of cleaning and disinfection of the root canal system.

Science.gov (United States)

Konstantinidi, E; Psimma, Z; Chávez de Paz, L E; Boutsioukis, C

2017-11-01

The aim of this study was to systematically review and critically analyse the published data on the treatment outcome (primary outcome) and on the cleaning and disinfection of root canals (secondary outcomes) achieved by negative pressure irrigation as compared to syringe irrigation. An electronic search was conducted in EMBASE, LILACS, PubMed, SciELO, Scopus and Web of Knowledge using both free-text keywords and controlled vocabulary. Additional studies were sought through hand searching of endodontic journals and of the relevant chapters of endodontic textbooks. No language restriction was imposed. The retrieved studies were screened by two reviewers according to predefined criteria. Included studies were critically appraised and the extracted data were arranged in tables. The electronic search and hand search retrieved 489 titles. One clinical study and 14 in vitro studies were finally included in the review; none of these studies assessed treatment outcome, four studies assessed the antimicrobial effect, seven studies evaluated the removal of pulp tissue remnants, and four studies investigated the removal of hard tissue debris or both hard tissue debris and pulp tissue remnants. Poor standardization and description of the protocols was evident. Inconclusive results were reported about the cleaning and disinfection accomplished by the two irrigation methods. Negative pressure irrigation was more effective under certain conditions when compared to suboptimal syringe irrigation; however, the variability of the protocols hindered quantitative synthesis. There is insufficient evidence to claim general superiority of any one of these methods. The level of the available evidence is low, and the conclusions should be interpreted with caution. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

[Clinical analysis of 4 children with negative pressure pulmonary edema].

Science.gov (United States)

Chen, Jiehua; Wang, Shu; Ma, Hongling; Wang, Wenjian; Fu, Dan; Huang, Wenxian; Deng, Jikui; Tang, Huiying; He, Yanxia; Zheng, Yuejie

2014-02-01

To analyze the clinical characteristics of negative pressure pulmonary edema (NPPE). A retrospective investigation of the clinical manifestation, imageology, clinical course and outcome of 4 children with NPPE seen between June 2012 and July 2013 in a children's hospital. The causation of the airway obstruction was also explored. All the 4 cases were boys, the range of age was 40 days to 9 years. They had no history of respiratory and circulatory system disease. In 3 cases the disease had a sudden onset after the obstruction of airway, and in one the onset occurred 1.5 hours after removing the airway foreign body. All these cases presented with tachypnea, dyspnea, and cyanosis, none had fever. Three cases had coarse rales. Chest radiography was performed in 3 cases and CT scan was performed in 1 case, in all of them both lungs displayed diffuse ground-glass-like change and patchy consolidative infiltrates. Three cases were admitted to the ICU, duration of mechanical ventilation was less than 24 hours in 2 cases and 39 hours in one. Oxygen was given by mask to the remaining one in emergency department, whose symptoms were obviously improved in 10 hours. None was treated with diuretics, glucocorticoids or inotropic agents. Chest radiographs were taken within 24 hours of treatment in 2 cases and 24-48 hours in the other 2; almost all the pulmonary infiltrates were resolved. All the 4 cases were cured. The causes of airway obstruction were airway foreign bodies in two cases, laryngospasm in one and laryngomalacia in the other. NPPE is a life-threatening emergency, which is manifested by rapid onset of respiratory distress rapidly (usually in several minutes, but might be hours later) after relief of the airway obstruction, with findings of pulmonary edema in chest radiograph. The symptoms resolve rapidly by oxygen therapy timely with or without mechanical ventilation. In children with airway obstruction, NPPE should be considered.

Seasonal emanation of radon at Ghuttu, northwest Himalaya: Differentiation of atmospheric temperature and pressure influences.

Science.gov (United States)

Kamra, Leena

2015-11-01

Continuous monitoring of radon along with meteorological parameters has been carried out in a seismically active area of Garhwal region, northwest Himalaya, within the frame work of earthquake precursory research. Radon measurements are carried out by using a gamma ray detector installed in the air column at a depth of 10m in a 68m deep borehole. The analysis of long time series for 2006-2012 shows strong seasonal variability masked by diurnal and multi-day variations. Isolation of a seasonal cycle by minimising short-time by 31 day running average shows a strong seasonal variation with unambiguous dependence on atmospheric temperature and pressure. The seasonal characteristics of radon concentrations are positively correlated to atmospheric temperature (R=0.95) and negatively correlated to atmospheric pressure (R=-0.82). The temperature and pressure variation in their annual progressions are negatively correlated. The calculations of partial correlation coefficient permit us to conclude that atmospheric temperature plays a dominant role in controlling the variability of radon in borehole, 71% of the variability in radon arises from the variation in atmospheric temperature and about 6% of the variability is contributed by atmospheric pressure. The influence of pressure variations in an annual cycle appears to be a pseudo-effect, resulting from the negative correlation between temperature and pressure variations. Incorporation of these results explains the varying and even contradictory claims regarding the influence of the pressure variability on radon changes in the published literature. Temperature dependence, facilitated by the temperature gradient in the borehole, controls the transportation of radon from the deep interior to the surface. Copyright © 2015 Elsevier Ltd. All rights reserved.

Production of hydrogen and deuterium negative ions in an electron cyclotron resonance driven plasma

Energy Technology Data Exchange (ETDEWEB)

Dougar-Jabon, V.D. [Industrial Univ. of Santander, Bucaramanga (Colombia)

2001-04-01

An electron cyclotron resonance source with driven plasma rings for hydrogen isotope ion production is studied. Extracted currents of positive and negative ions depending on gas pressure, microwave power value and extraction voltage are obtained. The study shows that the negative ion yield is an order of magnitude higher than the yield of positive particles when a driven ring is in contact with the surface of the plasma electrode. The production of negative ions of deuterium, D{sup -}, is close to the production of negative ions of light hydrogen isotope, H{sup -}. The comparison of the experimental data with the calculated ones shows that the most probable process of the H{sup -} and D{sup -} ion formation in the electron cyclotron driven plasma is dissociative attachment of electrons to molecules in high Rydberg states. For hydrogen ions and ions of deuterium, the negative current at a microwave power of 200 W through a 3-mm aperture and 8 kV extraction voltage are 4.7 mA and 3.1 mA respectively. (orig.)

Production of hydrogen and deuterium negative ions in an electron cyclotron resonance driven plasma

International Nuclear Information System (INIS)

Dougar-Jabon, V.D.

2001-01-01

An electron cyclotron resonance source with driven plasma rings for hydrogen isotope ion production is studied. Extracted currents of positive and negative ions depending on gas pressure, microwave power value and extraction voltage are obtained. The study shows that the negative ion yield is an order of magnitude higher than the yield of positive particles when a driven ring is in contact with the surface of the plasma electrode. The production of negative ions of deuterium, D - , is close to the production of negative ions of light hydrogen isotope, H - . The comparison of the experimental data with the calculated ones shows that the most probable process of the H - and D - ion formation in the electron cyclotron driven plasma is dissociative attachment of electrons to molecules in high Rydberg states. For hydrogen ions and ions of deuterium, the negative current at a microwave power of 200 W through a 3-mm aperture and 8 kV extraction voltage are 4.7 mA and 3.1 mA respectively. (orig.)

Structures of Bordered Pits Potentially Contributing to Isolation of a Refilled Vessel from Negative Xylem Pressure in Stems of Morus australis Poir.: Testing of the Pit Membrane Osmosis and Pit Valve Hypotheses.

Science.gov (United States)

Ooeda, Hiroki; Terashima, Ichiro; Taneda, Haruhiko

2017-02-01

Two hypotheses have been proposed to explain the mechanism preventing the refilling vessel water from being drained to the neighboring functional vessels under negative pressure. The pit membrane osmosis hypothesis proposes that the xylem parenchyma cells release polysaccharides that are impermeable to the intervessel pit membranes into the refilling vessel; this osmotically counteracts the negative pressure, thereby allowing the vessel to refill. The pit valve hypothesis proposes that gas trapped within intervessel bordered pits isolates the refilling vessel water from the surrounding functional vessels. Here, using the single-vessel method, we assessed these hypotheses in shoots of mulberry (Morus australis Poir.). First, we confirmed the occurrence of xylem refilling under negative pressure in the potted mulberry saplings. To examine the pit membrane osmosis hypothesis, we estimated the semi-permeability of pit membranes for molecules of various sizes and found that the pit membranes were not semi-permeable to polyethylene glycol of molecular mass osmosis mechanism in mulberry would be unrealistically large. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

The concept of negative pressure wound therapy (NPWT) after poststernotomy mediastinitis--a single center experience with 54 patients.

Science.gov (United States)

Ennker, Ina C; Malkoc, Anita; Pietrowski, Detlef; Vogt, Peter M; Ennker, Juergen; Albert, Alexander

2009-01-12

Deep sternal infections, also known as poststernotomy mediastinitis, are a rare but often fatal complication in cardiac surgery. They are a cause of increased morbidity and mortality and have a significant socioeconomic aspect concerning the health system. Negative pressure wound therapy (NPWT) followed by muscular pectoralis plasty is a quite new technique for the treatment of mediastinitis after sternotomy. Although it could be demonstrated that this technique is at least as safe and reliable as other techniques for the therapy of deep sternal infections, complications are not absent. We report about our experiences and complications using this therapy in a set of 54 patients out of 3668 patients undergoing cardiac surgery in our institution between January 2005 and April 2007.

Combined effect of salt concentration and pressure gradients across charged membranes

DEFF Research Database (Denmark)

Benavente, Juana; Jonsson, Gunnar Eigil

2002-01-01

The combined effect of both concentration and pressure differences on electrical potential (Deltaphi) for two ion-exchanger membranes, one positively charged (AE) and another negatively charged (CE), measured with the membranes in contact with NaCl solutions was studied. Results show a linear dep...

Seasonal emanation of radon at Ghuttu, northwest Himalaya: Differentiation of atmospheric temperature and pressure influences

International Nuclear Information System (INIS)

Kamra, Leena

2015-01-01

Continuous monitoring of radon along with meteorological parameters has been carried out in a seismically active area of Garhwal region, northwest Himalaya, within the frame work of earthquake precursory research. Radon measurements are carried out by using a gamma ray detector installed in the air column at a depth of 10 m in a 68 m deep borehole. The analysis of long time series for 2006–2012 shows strong seasonal variability masked by diurnal and multi-day variations. Isolation of a seasonal cycle by minimising short-time by 31 day running average shows a strong seasonal variation with unambiguous dependence on atmospheric temperature and pressure. The seasonal characteristics of radon concentrations are positively correlated to atmospheric temperature (R=0.95) and negatively correlated to atmospheric pressure (R=−0.82). The temperature and pressure variation in their annual progressions are negatively correlated. The calculations of partial correlation coefficient permit us to conclude that atmospheric temperature plays a dominant role in controlling the variability of radon in borehole, 71% of the variability in radon arises from the variation in atmospheric temperature and about 6% of the variability is contributed by atmospheric pressure. The influence of pressure variations in an annual cycle appears to be a pseudo-effect, resulting from the negative correlation between temperature and pressure variations. Incorporation of these results explains the varying and even contradictory claims regarding the influence of the pressure variability on radon changes in the published literature. Temperature dependence, facilitated by the temperature gradient in the borehole, controls the transportation of radon from the deep interior to the surface. - Highlights: • Seasonal variability of radon in borehole. • Influence of atmospheric temperature and pressure on radon variability. • Partial correlation coefficient.

Atmospheric pressure ionization-tandem mass spectrometry of the phenicol drug family.

Science.gov (United States)

Alechaga, Élida; Moyano, Encarnación; Galceran, M Teresa

2013-11-01

In this work, the mass spectrometry behaviour of the veterinary drug family of phenicols, including chloramphenicol (CAP) and its related compounds thiamphenicol (TAP), florfenicol (FF) and FF amine (FFA), was studied. Several atmospheric pressure ionization sources, electrospray (ESI), atmospheric pressure chemical ionization and atmospheric pressure photoionization were compared. In all atmospheric pressure ionization sources, CAP, TAP and FF were ionized in both positive and negative modes; while for the metabolite FFA, only positive ionization was possible. In general, in positive mode, [M + H](+) dominated the mass spectrum for FFA, while the other compounds, CAP, TAP and FF, with lower proton affinity showed intense adducts with species present in the mobile phase. In negative mode, ESI and atmospheric pressure photoionization showed the deprotonated molecule [M-H](-), while atmospheric pressure chemical ionization provided the radical molecular ion by electron capture. All these ions were characterized by tandem mass spectrometry using the combined information obtained by multistage mass spectrometry and high-resolution mass spectrometry in a quadrupole-Orbitrap instrument. In general, the fragmentation occurred via cyclization and losses or fragmentation of the N-(alkyl)acetamide group, and common fragmentation pathways were established for this family of compounds. A new chemical structure for the product ion at m/z 257 for CAP, on the basis of the MS(3) and MS(4) spectra is proposed. Thermally assisted ESI and selected reaction monitoring are proposed for the determination of these compounds by ultra high-performance liquid chromatography coupled to tandem mass spectrometry, achieving instrumental detection limits down to 0.1 pg. Copyright © 2013 John Wiley & Sons, Ltd.

Pressure Induced Phase Transformations in Ceramics

Energy Technology Data Exchange (ETDEWEB)

Reimanis, Ivar [Colorado School of Mines, Golden, CO (United States); Cioabanu, Cristian [Colorado School of Mines, Golden, CO (United States)

2017-10-15

The study of materials with unusual properties offers new insight into structure-property relations as well as promise for the design of novel composites. In this spirit, the PIs seek to (1) understand fundamental mechanical phenomena in ceramics that exhibit pressure-induced phase transitions, negative coefficient of thermal expansion (CTE), and negative compressibility, and (2) explore the effect of these phenomena on the mechanical behavior of composites designed with such ceramics. The broad and long-term goal is to learn how to utilize these unusual behaviors to obtain desired mechanical responses. While the results are expected to be widely applicable to many ceramics, most of the present focus is on silicates, as they exhibit remarkable diversity in structure and properties. Eucryptite, a lithium aluminum silicate (LiAlSiO₄), is specifically targeted because it exhibits a pressure-induced phase transition at a sufficiently low pressure to be accessible during conventional materials processing. Thus, composites with eucryptite may be designed to exhibit a novel type of transformation toughening. The PIs have performed a combination of activities that encompass synthesis and processing to control structures, atomistic modeling to predict and understand structures, and characterization to study mechanical behavior. Several materials behavior discoveries were made. It was discovered that small amounts of Zn (as small as 0.1 percent by mol) reverse the sign of the coefficient of thermal expansion of beta-eucryptite from negative to slightly positive. The presence of Zn also significantly mitigates microcracking that occurs during thermal cycling of eucryptite. It is hypothesized that Zn disrupts the Li ordering in beta-eucryptite, thereby altering the thermal expansion behavior. A nanoindentation technique developed to characterize incipient plasticity was applied to examine the initial stages of the pressure induced phase transformation from beta to

Effect of negative pressure wound therapy on molecular markers in diabetic foot ulcers.

Science.gov (United States)

Karam, Rehab A; Rezk, Noha A; Abdel Rahman, Tamer M; Al Saeed, Mohamed

2018-08-15

Diabetic foot ulcers are one of the most common complications of diabetes with high morbidity and mortality. Negative pressure wound therapy (NPWT) is one of the treatment modalities that facilitates the wound healing process; however, its molecular mechanism remains unclear. The aim of this study was to investigate the mechanism of action of NPWT in the treatment of diabetic foot ulcers via measuring the tissue expression of genes related to the wound healing process. The study included 40 patients with diabetic foot ulceration, 20 of them received NPWT and the other 20 were a control group treated with advanced moist therapy. Granulation tissue biopsies were obtained before and 10 days after treatment in both groups and subjected to real-time polymerase chain reaction to measure the mRNA expression of TGF-β1, VEGF, TNF-α, IL-1β, MMP-1, MMP-9 and TIMP-1 which are involved in the wound healing pathway. After 10 days of treatment with NPWT, the mRNA levels of IL-1β, TNF-α, MMP-1, and MMP-9 were significantly downregulated, while the levels of VEGF, TGF-β1 and TIMP-1 were significantly increased. Our study demonstrated that NPWT promotes wound healing in diabetic foot ulcers possibly by affecting growth factors, inflammatory cytokines, and matrix metalloproteinases. Copyright © 2018 Elsevier B.V. All rights reserved.

Cost analysis of Topical Negative Pressure (TNP Therapy for traumatic acquired wounds

Directory of Open Access Journals (Sweden)

Freytag, Sebastian

2010-01-01

Full Text Available Extended traumatic wounds require extended reconstructive operations and are accompanied by long hospitalizations and risks of infection, thrombosis and flap loss. In particular, the frequently used Topical Negative Pressure (TNP Therapy is regarded as cost-intensive. The costs of TNP in the context of traumatic wounds is analyzed using the method of health economic evaluation.All patients (n=67: 45 male, 22 female; average age 54 y with traumatically acquired wounds being treated with TNP at the university hospital of Goettingen in the period 01/01/2005–31/12/2007 comprise the basis for this analysis. The concept of activity-based costing based on clinical pathways according to InEK (National Institute for the Hospital Remuneration System systematic calculations was chosen for cost accounting. In addition, a special module system adaptable for individual courses of disease was developed. The treated wounds were located on a lower extremity in 83.7% of cases (n=56 and on an upper extremity in 16.3% of cases (n=11. The average time of hospitalization of the patients was 54 days. Twenty-five patients (37.31% exceeded the „maximum length of stay“ of their associated DRG (Diagnosis Related Groups. The total PCCL (patient clinical complexity level = patient severity score of 2.99 reflects the seriousness of disease. For the treatment of the 67 patients, total costs were $1,729,922.32 (1,249,176.91 €. The cost calculation showed a financial deficit of $–210,932.50 (–152,314.36 €. Within the entire treatment costs of $218,848.07 (158,030.19 €, 12.65% per case were created by TNP with material costs of $102,528.74 (74,036 €, representing 5.92% of entire costs. The cost of TNP per patient averaged $3,266.39 (2,358.66 €. The main portion of the costs was not – as is often expected – due to high material costs of TNP but instead to long-term treatments. Because of their complexity, the cases are insufficiently represented in the

Experience with the vacuum assisted closure negative pressure technique in the treatment of non-healing diabetic and dysvascular wounds.

Science.gov (United States)

Clare, Michael P; Fitzgibbons, Timothy C; McMullen, Scott T; Stice, R Colleen; Hayes, Dennis F; Henkel, Loree

2002-10-01

The purpose of this study is to report our experience with the Vacuum Assisted Closure (VAC) negative pressure technique in patients with non-healing wounds of the foot, ankle, and lower limb. We retrospectively reviewed 17 patients with non-healing wounds of the lower extremity who underwent treatment using the Vacuum Assisted Closure (VAC) device. Thirteen of 17 (76%) had diabetes mellitus, nine of whom were insulin-dependent, and 10 of whom had associated peripheral neuropathy. Eight of 17 (47%) had severe peripheral vascular disease. All had failed previous management with serial wound debridements and dressing changes; 15 of 17 (88%) had previously completed at least one course of oral antibiotics. Thirteen of 17 (76%) had previously undergone operative irrigation and debridement of the wounds; six of 17 (35%) had previously undergone revascularization procedures of the involved extremity. Five of 17 (29%) had wounds necessitating an amputation procedure prior to the present treatment; seven of 17 (41%) had failed treatment with local growth factors prior to the present treatment. Average length of treatment with the VAC device was 8.2 weeks. Fourteen of 17 (82%) wounds successfully healed; four underwent split-thickness skin grafting for wound closure; four were briefly treated with local growth factors; six were treated with only dressing changes following VAC treatment. Three of 17 (18%) wounds failed VAC treatment; all three patients had diabetes and had wounds located in the midfoot or forefoot; two of three had severe peripheral vascular disease. Our results indicate that the Vacuum Assisted Closure negative pressure technique is emerging as an acceptable option for wound care of the lower extremity. Not all patients are candidates for such treatment; those patients with severe peripheral vascular disease or smaller forefoot wounds may be best treated by other modalities. Larger wounds seem to be better suited for skin grafting or two-stage primary

Mobility of negative ions in superfluid 3He

International Nuclear Information System (INIS)

Ahonen, A.I.; Kokko, J.; Lounasmaa, O.V.; Paalanen, M.A.; Richardson, R.C.; Schoepe, W.; Takano, Y.

1977-01-01

The mobility of negative ions is shown to increase rapidly below T/sub c/ in both superfluid 3 He phases. The ratio μ/μ/sub N/ of superfluid to normal mobility is larger in the B phase than in the A phase. A critical velocity consistent in magnitude with the Landau limit for pair breaking has also been observed. In the normal fluid we find a temperature independent mobility between 40 mK and T/sub c/ for all pressures between 0 and 28 bar. The increase of μ/sub N/ with increasing pressure is in agreement with the bubble model for the negative ion

Pentaclethra macroloba tannins fractions active against methicillin-resistant staphylococcal and Gram-negative strains showing selective toxicity

Directory of Open Access Journals (Sweden)

Ivana Correa Ramos Leal

2011-12-01

Full Text Available The ethanol extract of the vegetal species Pentaclethra macroloba (Willd. Kuntze, Fabaceae, was fractioned and the antibacterial activity was determined. The active ethyl acetate (ea fraction showed activity against Gram-positive (Staphylococcus spp. and Enterococcus spp. and Gram-negative (Pseudomonas aeruginosa, Acinetobacter spp. and Klebsiella pneumoniae multiresistant bacteria. Gallic acid derivatives were identified as the main compounds in inactive subfractions from the ea fraction, while the active one afforded ellagic acid as the major constituent when submitted to acid hydrolysis reaction, which suggests the presence of hydrolysable tannins. The minimum bactericidal concentration analysis showed a bactericide mechanism of action for the tannin subfraction found. The antibacterial mechanism of action of the active tannin subfraction against S. aureus reference strains (ATCC 29213 e 33591 was proposed adopting an in vitro assay of protein synthesis inhibition. For this, bacterial cells were labeled with [35S] methionine in the presence of the subfraction. The protein synthesis inhibition was observed at 256 µg/mL of this subfraction. At this concentration it did not present cytotoxicity in eukaryotic cells by the neutral red technique, suggesting selective toxicity. The present study is the first in vitro investigation of the antibacterial properties of tannin fractions obtained from a polar extract of P. macroloba.

Pentaclethra macroloba tannins fractions active against methicillin-resistant staphylococcal and Gram-negative strains showing selective toxicity

Directory of Open Access Journals (Sweden)

Ivana Correa Ramos Leal

2011-08-01

Full Text Available The ethanol extract of the vegetal species Pentaclethra macroloba (Willd. Kuntze, Fabaceae, was fractioned and the antibacterial activity was determined. The active ethyl acetate (ea fraction showed activity against Gram-positive (Staphylococcus spp. and Enterococcus spp. and Gram-negative (Pseudomonas aeruginosa, Acinetobacter spp. and Klebsiella pneumoniae multiresistant bacteria. Gallic acid derivatives were identified as the main compounds in inactive subfractions from the ea fraction, while the active one afforded ellagic acid as the major constituent when submitted to acid hydrolysis reaction, which suggests the presence of hydrolysable tannins. The minimum bactericidal concentration analysis showed a bactericide mechanism of action for the tannin subfraction found. The antibacterial mechanism of action of the active tannin subfraction against S. aureus reference strains (ATCC 29213 e 33591 was proposed adopting an in vitro assay of protein synthesis inhibition. For this, bacterial cells were labeled with [35S] methionine in the presence of the subfraction. The protein synthesis inhibition was observed at 256 µg/mL of this subfraction. At this concentration it did not present cytotoxicity in eukaryotic cells by the neutral red technique, suggesting selective toxicity. The present study is the first in vitro investigation of the antibacterial properties of tannin fractions obtained from a polar extract of P. macroloba.

Magnetic field and pressure dependant resistivity behaviour of MnAs

Science.gov (United States)

Satya, A. T.; Amaladass, E. P.; Mani, Awadhesh

2018-04-01

The studies on the effect of magnetic field and external pressure on temperature dependant electrical resistivity behaviour of polycrystalline MnAs have been reported. At ambient pressure, ρ(T) shows a first order magnetic transition associated with change in sign of the temperature coefficient of resistivity from positive in the ferromagnetic (FM) phase to negative in the paramagnetic (PM) phase. The magneto resistance is negative and shows a peak at the FM transition temperature (T C ). The first order hysteresis width decreases with increase in magnetic field and the intersection of extrapolated linear variations of T C with field for the cooling and warming cycles enabled determination of the tricritical point. At high pressures, ρ(T) displays non monotonic variation exhibiting a low temperature minimum ({T}\\min L) and a high temperature maximum ({T}\\max H) accompanying broad thermal hysteresis above {T}\\min L. It is surmised that spin disorder scattering is responsible for the resistivity behaviour above {T}\\min L and the essential features of ρ(T) are qualitatively explained using Kasuya theoretical model. Below the {T}\\min L, ρ(T) follows linear logarithmic temperature dependence similar to the effect occurring due to Kondo type of scattering of conduction electrons with localised moments.

Structural and optical high-pressure study of spinel-type MnIn2S4

International Nuclear Information System (INIS)

Manjon, F.J.; Segura, A.; Pellicer-Porres, J.; Sanchez-Royo, J.F.; Amboage, M.; Itie, J.P.; Flank, A.M.; Lagarde, P.; Polian, A.; Ursaki, V.V.; Tiginyanu, I.M.

2007-01-01

We report a combined study of the structural and electronic properties of the spinel-type semiconductor MnIn 2 S 4 under high pressures by means of X-ray diffraction (ADXRD), X-ray absorption (XAS), and optical absorption measurements. The three techniques evidence a reversible structural phase transition near 7 GPa, that according to ADXRD measurements is to a double-NaCl structure. XAS measurements evidence predominant tetrahedral coordination for Mn in the spinel phase that does not noticeably change with increasing pressure up to the phase transition. XAS measurements indicate that the static disorder increases considerably when the sample reverts from the double-NaCl phase to the spinel phase. Optical absorption measurements show that the direct gap of MnIn 2 S 4 exhibits a nonlinear behaviour with a positive pressure coefficient at pressures below 2.5 GPa and a negative pressure coefficient between 2.5 and 7 GPa. The pressure behavior of the bandgap seems to be affected by the defect concentration. The double-NaCl phase also exhibits a bandgap with a negative pressure coefficient. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Numerical simulation of the pressure pulses produced by a pressure screen foil rotor

International Nuclear Information System (INIS)

Feng, M.; Ollivier-Gooch, C.; Gooding, R.W.; Olson, J.A.

2003-01-01

Pressure screening is the most industrially efficient and effective means of removing contaminants that degrade the appearance and strength of paper and fractionating fibres for selective treatments and specialty products. A critical design component of a screen is the rotor which produces pressure pulses on the screen cylinder surface to keep the screening apertures clear. To understand the effect of the key design and operating variables for a NACA 0012 foil rotor, a computational fluid dynamic (CFD) simulation tool was developed with FLUENT software, and the numerical results were compared with experimental measurements. The computational results of pressure pulses were shown to be in good agreement with experimental pressure measurements over a wide range of foil tip-speeds, clearances and angles of attack. In addition, it was shown that the magnitude of the pressure pulse peak increases as the rotating speed increases linearly with the square of tip-speed for all the angles of attack studied. The maximum negative pressure pulse occurred for the foil at 5 degrees angle of attack. Flow began to separate from foil surface near the screen plate beyond 10 degrees angle of attack. The positive pressure peak near the leading edge of the foil is completely eliminated for foils operating at a positive angle of attack. The magnitude of the negative pressure peak increased as clearance decreased. In addition to, and more important than, these specific results, we have shown that CFD is a viable tool for the optimal design and operation of rotors in industrial pressure screens. (author)

A 10-Day Developmental Voyage: Converging Evidence from Three Studies Showing that Self-Esteem May Be Elevated and Maintained without Negative Outcomes

Science.gov (United States)

Kafka, S.; Hunter, J. A.; Hayhurst, J.; Boyes, M.; Thomson, R. L.; Clarke, H.; Grocott, A. M.; Stringer, M.; O'Brien, K. S.

2012-01-01

Empirical evidence shows that educational experiences in the context of the outdoors lead to elevated self-esteem. Although elevated self-esteem is widely assumed to promote beneficial outcomes, recent evidence suggests that elevated self-esteem may also facilitate a variety of negative outcomes (i.e., increased prejudice, aggression, drug and…

Effect of cesium seeding on hydrogen negative ion volume production

International Nuclear Information System (INIS)

Bacal, M.; Balghiti-Sube, F. El; Elizarov, L. I.; Tontegode, A. J.

1998-01-01

The effect of cesium vapor partial pressure on the plasma parameters has been studied in the dc hybrid negative ion source ''CAMEMBERT III.'' The cesium vapor pressure was varied up to 10 -5 Torr and was determined by a surface ionization gauge in the absence of the discharge. The negative ion relative density measured by laser photodetachment in the center of the plasma extraction region increases by a factor of four when the plasma is seeded with cesium. However the plasma density and the electron temperature (determined using a cylindrical electrostatic probe) are reduced by the cesium seeding. As a result, the negative ion density goes up by a factor of two at the lowest hydrogen pressure studied. The velocity of the directed negative ion flow to the plasma electrode, determined from two-laser beam photodetachment experiments, appears to be affected by the cesium seeding. The variation of the extracted negative ion and electron currents versus the plasma electrode bias will also be reported for pure hydrogen and cesium seeded plasmas. The cesium seeding leads to a dramatic reduction of the electron component, which is consistent with the reduced electron density and temperature. The negative ion current is enhanced and a goes through a maximum at plasma electrode bias lower than 1 V. These observations lead to the conclusion that the enhancement of pure volume production occurs in this type of plasma. Possible mechanisms for this type of volume process will be discussed

An exposition on Friedmann cosmology with negative energy densities

International Nuclear Information System (INIS)

Nemiroff, Robert J.; Joshi, Ravi; Patla, Bijunath R.

2015-01-01

How would negative energy density affect a classic Friedmann cosmology? Although never measured and possibly unphysical, certain realizations of quantum field theories leaves the door open for such a possibility. In this paper we analyze the evolution of a universe comprising varying amounts of negative energy forms. Negative energy components have negative normalized energy densities, Ω < 0. They include negative phantom energy with an equation of state parameter w < −1, negative cosmological constant: w=−1, negative domain walls: w = −2/3, negative cosmic strings: w=−1/3, negative mass: w = 0, negative radiation: w = 1/3 and negative ultralight: w > 1/3. Assuming that such energy forms generate pressure like perfect fluids, the attractive or repulsive nature of negative energy components are reviewed. The Friedmann equation is satisfied only when negative energy forms are coupled to a greater magnitude of positive energy forms or positive curvature. We show that the solutions exhibit cyclic evolution with bounces and turnovers.The future and fate of such universes in terms of curvature, temperature, acceleration, and energy density are reviewed. The end states are dubbed ''big crunch,' '' big void,' or ''big rip' and further qualified as ''warped',''curved', or ''flat',''hot' versus ''cold', ''accelerating' versus ''decelerating' versus ''coasting'. A universe that ends by contracting to zero energy density is termed ''big poof.' Which contracting universes ''bounce' in expansion and which expanding universes ''turnover' into contraction are also reviewed

A high pressure x-ray diffraction study of titanium disulfide

International Nuclear Information System (INIS)

Aksoy, Resul; Selvi, Emre; Knudson, Russell; Ma Yanzhang

2009-01-01

A high pressure angle dispersive synchrotron x-ray diffraction study of titanium disulfide (TiS 2 ) was carried out to pressures of 45.5 GPa in a diamond-anvil cell. We observed a phase transformation of TiS 2 beginning at about 20.7 GPa. The structure of the high pressure phase needs further identification. By fitting the pressure-volume data to the third-order Birch-Murnaghan equation of state, the bulk modulus, K 0T , was determined to be 45.9 ± 0.7 GPa with its pressure derivative, K' 0T , being 9.5 ± 0.3 at pressures lower than 17.8 GPa. It was found that the compression behavior of TiS 2 is anisotropic along the different axes. The compression ratio of the c-axis is about nine times larger than the a-axis when pressures are lower than 1 GPa. It suddenly decreases to three times larger at pressures of about 3 GPa. This ratio shows a linear decrease with a slope of negative 0.048 at pressures below phase transformation.

Hydrostatic pressure effects on the dielectric response of potassium cyanide

International Nuclear Information System (INIS)

Ortiz Lopez, J.

1992-01-01

The complex dielectric constant of crystalline KCN was measured under hydrostatic pressures up to 6.1 kbar in the temperature and frequency ranges of 50-300 K and 10-10 5 Hz, respectively. It is found that the pressure derivative of the real part of the dielectric constant at all measured temperatures is negative. From these results we obtain estimates for the pressure and volume derivatives of polarizabilities. The anomaly in the real part of the dielectric constant at the elastic order-disorder transition shifts to higher temperatures with increasing pressure at a rate of 2.05 K/kbar. By carefully avoiding thermal cycling through this transition we find no evidence of the monoclinic phase reported to exist in the P-T phase diagram of KCN at relatively low pressures. Dielectric loss measurements show thermally-activated CN - reorientation rates in the elastically ordered phase with pressure-independent reorientational barriers and decreasing attempt frequencies for increasing pressures. Additional pressure effects on dielectric loss allow to obtain the pressure derivative of the antiferroelectric transition temperature as 1.97 K/kbar. (Author)

The concept of negative pressure wound therapy (NPWT after poststernotomy mediastinitis – a single center experience with 54 patients

Directory of Open Access Journals (Sweden)

Vogt Peter M

2009-01-01

Full Text Available Abstract Deep sternal infections, also known as poststernotomy mediastinitis, are a rare but often fatal complication in cardiac surgery. They are a cause of increased morbidity and mortality and have a significant socioeconomic aspect concerning the health system. Negative pressure wound therapy (NPWT followed by muscular pectoralis plasty is a quite new technique for the treatment of mediastinitis after sternotomy. Although it could be demonstrated that this technique is at least as safe and reliable as other techniques for the therapy of deep sternal infections, complications are not absent. We report about our experiences and complications using this therapy in a set of 54 patients out of 3668 patients undergoing cardiac surgery in our institution between January 2005 and April 2007.

Cost study of dermal substitutes and topical negative pressure in the surgical treatment of burns.

Science.gov (United States)

Hop, M Jenda; Bloemen, Monica C T; van Baar, Margriet E; Nieuwenhuis, Marianne K; van Zuijlen, Paul P M; Polinder, Suzanne; Middelkoop, Esther

2014-05-01

A recently performed randomised controlled trial investigated the clinical effectiveness of dermal substitutes (DS) and split skin grafts (SSG) in combination with topical negative pressure (TNP) in the surgical treatment of burn wounds. In the current study, medical and non-medical costs were investigated, to comprehensively assess the benefits of this new treatment. The primary outcome was mean total costs of the four treatment strategies: SSG with or without DS, and with or without TNP. Costs were studied from a societal perspective. Findings were evaluated in light of the clinical effects on scar elasticity. Eighty-six patients were included. Twelve months post-operatively, highest elasticity was measured in scars treated with DS and TNP (p=0.027). The initial cost price of treatment with DS and TNP was €2912 compared to treatment with SSG alone €1703 (ptreatment contributed maximal 7% to the total costs and total costs varied widely within and between groups, but were not significantly different. Therefore, in the selection of the most optimal type of surgical intervention, cost considerations should not play an important role. Copyright © 2013 Elsevier Ltd and ISBI. All rights reserved.

Comparing negative pressure wound treatment with honey dressing in healing of foot ulcers in diabetics

International Nuclear Information System (INIS)

Bashir, U.; Maqsood, R.; Shabbir, H.

2018-01-01

To evaluate and compare the effectiveness of vacuum assisted treatment with that of honey dressing in duration of healing of foot ulcers in diabetics. Study Design: Randomized control study. Place and Duration of Study: Combined Military Hospital Multan and Nishtar Hospital Multan, from Aug 2016 till Feb 2017. Patients and Methods: A total of 95 patients with ages between 30-60 years of both sexes, who presented with diabetic ulcers of foot involving subcutaneous tissue and skin. Patients were divided randomly into two groups; Group V and H. Group V was subjected to Vacuum Pack closure (negative pressure wound treatment) and group H was treated with honey dressing, follow up was done till the appearance of healthy tissue after initial debridement, suitable for STSG (Split Thickness Skin Graft) or primary closure. Results: Healthy tissue appeared much faster in Vacuum assisted treatment, then with honey dressing with mean of 18.2 days for V.A.C and 28.8 days for honey dressing. Conclusion: Vacuum assisted closure was more effective in the treatment of foot ulcers in diabetics. It promotes healthy granulation tissue in the wound bed at a faster rate in comparison to honey dressing. (author)

Kinetics on the reaction of substituted quinolines and p-substituted benzoylchlorides under various pressures

International Nuclear Information System (INIS)

Kim, Young Cheul; Lim, Jong Wan; Choi, Sung Yong; Kim, Se Kyong

1999-01-01

The reaction rates of substituted quinolines(6-CH 3 C 9 H 7 N, C 9 H 7 N) with p-substituted benzoylchlorides(p-CH 3 , p-H, p-NO 2 ) have been measured by conductometry in acetonitrile, and the rate constants are determined at various temperatures (10,15, 20, 25 .deg. C) and pressures(1, 200, 500, 1000bar). From the values of rate constants, the activation parameters(Ea, ΔV ≠ , ΔS ≠ , and ΔG ≠ ) and the pressure dependence of Hammett ρ values were determined. The rate constants increase as a function of temperatures and pressures, and are further increase by introduction the electron donor substituents in nucleophile(p-CH 3 ) or electron acceptor(p-NO 2 ) substituents in substrate. The activation volume, and the activation entropy are all negative. Hammett ρ values are also negative for nucleophile (ρ X ) and positive for the substrate (ρ Y ) over the pressure range studied. The results of kinetic studies for pressure and substituent show that these reactions proceed in typical S N 2 reaction mechanism and 'associative S N 2' in which bond formation favored with increasing pressures

Effects of Solvent and Ion Source Pressure on the Analysis of Anabolic Steroids by Low Pressure Photoionization Mass Spectrometry.

Science.gov (United States)

Liu, Chengyuan; Zhu, Yanan; Yang, Jiuzhong; Zhao, Wan; Lu, Deen; Pan, Yang

2017-04-01

Solvent and ion source pressure were two important factors relating to the photon induced ion-molecule reactions in low pressure photoionization (LPPI). In this work, four anabolic steroids were analyzed by LPPI mass spectrometry. Both the ion species present and their relative abundances could be controlled by switching the solvent and adjusting the ion source pressure. Whereas M •+ , MH + , [M - H 2 O] + , and solvent adducts were observed in positive LPPI, [M - H] - and various oxidation products were abundant in negative LPPI. Changing the solvent greatly affected formation of the ion species in both positive and negative ion modes. The ion intensities of the solvent adduct and oxygen adduct were selectively enhanced when the ion source pressure was elevated from 68 to 800 Pa. The limit of detection could be decreased by increasing the ion source pressure. Graphical Abstract ᅟ.

Effects of Solvent and Ion Source Pressure on the Analysis of Anabolic Steroids by Low Pressure Photoionization Mass Spectrometry

Science.gov (United States)

Liu, Chengyuan; Zhu, Yanan; Yang, Jiuzhong; Zhao, Wan; Lu, Deen; Pan, Yang

2017-04-01

Solvent and ion source pressure were two important factors relating to the photon induced ion-molecule reactions in low pressure photoionization (LPPI). In this work, four anabolic steroids were analyzed by LPPI mass spectrometry. Both the ion species present and their relative abundances could be controlled by switching the solvent and adjusting the ion source pressure. Whereas M•+, MH+, [M - H2O]+, and solvent adducts were observed in positive LPPI, [M - H]- and various oxidation products were abundant in negative LPPI. Changing the solvent greatly affected formation of the ion species in both positive and negative ion modes. The ion intensities of the solvent adduct and oxygen adduct were selectively enhanced when the ion source pressure was elevated from 68 to 800 Pa. The limit of detection could be decreased by increasing the ion source pressure.

Susceptibility to social pressure following ventromedial prefrontal cortex damage.

Science.gov (United States)

Chen, Kuan-Hua; Rusch, Michelle L; Dawson, Jeffrey D; Rizzo, Matthew; Anderson, Steven W

2015-11-01

Social pressure influences human behavior including risk taking, but the psychological and neural underpinnings of this process are not well understood. We used the human lesion method to probe the role of ventromedial prefrontal cortex (vmPFC) in resisting adverse social pressure in the presence of risk. Thirty-seven participants (11 with vmPFC damage, 12 with brain damage outside the vmPFC and 14 without brain damage) were tested in driving simulator scenarios requiring left-turn decisions across oncoming traffic with varying time gaps between the oncoming vehicles. Social pressure was applied by a virtual driver who honked aggressively from behind. Participants with vmPFC damage were more likely to select smaller and potentially unsafe gaps under social pressure, while gap selection by the comparison groups did not change under social pressure. Participants with vmPFC damage also showed prolonged elevated skin conductance responses (SCR) under social pressure. Comparison groups showed similar initial elevated SCR, which then declined prior to making left-turn decisions. The findings suggest that the vmPFC plays an important role in resisting explicit and immediately present social pressure with potentially negative consequences. The vmPFC appears to contribute to the regulation of emotional responses and the modulation of decision making to optimize long-term outcomes. © The Author (2015). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Cocaine users with comorbid Cluster B personality disorders show dysfunctional brain activation and connectivity in the emotional regulation networks during negative emotion maintenance and reappraisal.

Science.gov (United States)

Albein-Urios, Natalia; Verdejo-Román, Juan; Soriano-Mas, Carles; Asensio, Samuel; Martínez-González, José Miguel; Verdejo-García, Antonio

2013-12-01

Cocaine dependence often co-occurs with Cluster B personality disorders. Since both disorders are characterized by emotion regulation deficits, we predicted that cocaine comorbid patients would exhibit dysfunctional patterns of brain activation and connectivity during reappraisal of negative emotions. We recruited 18 cocaine users with comorbid Cluster B personality disorders, 17 cocaine users without comorbidities and 21 controls to be scanned using functional magnetic resonance imaging (fMRI) during performance on a reappraisal task in which they had to maintain or suppress the emotions induced by negative affective stimuli. We followed region of interest (ROI) and whole-brain approaches to investigate brain activations and connectivity associated with negative emotion experience and reappraisal. Results showed that cocaine users with comorbid personality disorders had reduced activation of the subgenual anterior cingulate cortex during negative emotion maintenance and increased activation of the lateral orbitofrontal cortex and the amygdala during reappraisal. Amygdala activation correlated with impulsivity and antisocial beliefs in the comorbid group. Connectivity analyses showed that in the cocaine comorbid group the subgenual cingulate was less efficiently connected with the amygdala and the fusiform gyri and more efficiently connected with the anterior insula during maintenance, whereas during reappraisal the left orbitofrontal cortex was more efficiently connected with the amygdala and the right orbitofrontal cortex was less efficiently connected with the dorsal striatum. We conclude that cocaine users with comorbid Cluster B personality disorders have distinctive patterns of brain activation and connectivity during maintenance and reappraisal of negative emotions, which correlate with impulsivity and dysfunctional beliefs. Copyright © 2013 Elsevier B.V. and ECNP. All rights reserved.

High negative pressure subcutaneous suction drain for managing debilitating subcutaneous emphysema secondary to tube thoracostomy for an iatrogenic post computed tomography guided transthoracic needle biopsy pneumothorax: Case report and review of literature.

Science.gov (United States)

Ahmed, Zeeshan; Patel, Pinakin; Singh, Suresh; Sharma, Raj Govind; Somani, Pankaj; Gouri, Abdul Rauf; Singh, Shiv

2016-01-01

Subcutaneous emphysema is a common complication of tube thoracostomy. Though self-limiting, it should be treated when it causes palpebral closure, dyspnea, dysphagia or undue disfigurement resulting in anxiety and distress to the patient. A 72year old man who was a known case of COPD on bronchodilators developed a large pneumothorax and respiratory distress after a CT guided transthoracic lung biopsy done for a lung opacity (approx. 3×3cm) at the right hilar region on Chest X-ray. Within 24h of an urgent tube thoracostomy, patient developed intractable subcutaneous emphysema with closure of palpebral fissure and dyspnea unresponsive to increasing suction on chest tube. A subcutaneous fenestrated drain was placed mid-way between the nipple and clavicle in the mid-clavicular line bilaterally. Continuous negative suction (-150mmHg) resulted in immediate, sustained relief and complete resolution within 5days. Extensive and debilitating SE (subcutaneous emphysema) has to be treated promptly to relieve patient discomfort, dysphagia or imminent respiratory compromise. A variety of treatment have been tried including infraclavicular blow-hole incisions, subcutaneous drains +/- negative pressure suction, fenestrated angiocatheters, Vacuum assisted dressings and increasing suction on a pre-existing chest tube. We describe a high negative pressure subcutaneous suction drain which provides immediate and sustained relief in debilitating SE. Debilitating subcutaneous emphysema which causes distress, anxiety, palpebral closure, dyspnoea or dysphagia requires intervention. High negative pressure subcutaneous suction drain provides immediate and sustained relief in extensive and debilitating SE. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Association between ambient temperature and blood pressure and blood pressure regulators: 1831 hypertensive patients followed up for three years.

Directory of Open Access Journals (Sweden)

Qing Chen

Full Text Available Several studies have suggested an association between ambient air temperature and blood pressure. However, this has not been reliably confirmed by longitudinal studies. Also, whether the reaction to temperature stimulation is modified by other factors such as antihypertensive medication is rarely investigated. The present study explores the relationship between ambient temperature and blood pressure, without and with antihypertensive medication, in a study of 1,831 hypertensive patients followed up for three years, in two or four weekly check ups, accumulating 62,452 follow-up records. Both baseline and follow-up blood pressure showed an inverse association with ambient temperature, which explained 32.4% and 65.6% of variation of systolic blood pressure and diastolic blood pressure (P<0.05 respectively. The amplitude of individual blood pressure fluctuation with temperature throughout a year (a 29 degrees centigrade range was 9.4/7.3 mmHg. Medication with angiotensin converting enzyme inhibitor benazepril attenuated the blood pressure fluctuation by 2.4/1.3 mmHg each year, though the inverse association of temperature and blood pressure remained. Gender, drinking behavior and body mass index were also found to modify the association between temperature and diastolic blood pressure. The results indicate that ambient temperature may negatively regulate blood pressure. Hypertensive patients should monitor and treat blood pressure more carefully in cold days, and it could be especially important for the males, thinner people and drinkers.

A case report of locally advanced triple negative breast cancer showing pathological complete response to weekly paclitaxel with bevacizumab treatment following disease progression during anthracycline-based neoadjuvant chemotherapy

Directory of Open Access Journals (Sweden)

Hideo Shigematsu

2017-01-01

Conclusions: Although the addition of bevacizumab to standard adjuvant chemotherapy is not recommended in unselected triple negative breast cancer, the potent effect on tumor shrinkage should be considered in the treatment of locally advanced triple negative breast cancer showing disease progression during standard NAC.

High negative pressure subcutaneous suction drain for managing debilitating subcutaneous emphysema secondary to tube thoracostomy for an iatrogenic post computed tomography guided transthoracic needle biopsy pneumothorax: Case report and review of literature

Directory of Open Access Journals (Sweden)

Zeeshan Ahmed

2016-01-01

Conclusion: Debilitating subcutaneous emphysema which causes distress, anxiety, palpebral closure, dyspnoea or dysphagia requires intervention. High negative pressure subcutaneous suction drain provides immediate and sustained relief in extensive and debilitating SE.

Blood pressure responses to LBNP in nontrained and trained hypertensive rats

Science.gov (United States)

Bedford, T. G.; Tipton, C. M.

1992-01-01

To study the influences of 16 wk of endurance training on the reflex regulation of resting blood pressure, nontrained (NT) and trained (T) female hypertensive rats (SHR) were subjected to conditions of lower body negative pressure (LBNP). Measurements of muscle cytochrome oxidase activity and run time to exhaustion indicated that the animals were endurance trained. The rats (NT = 6, T = 7) were tranquilized with 300-600 micrograms.kg-1 diazepam (IV) before heart rates and blood pressures were measured over a range of 2.5-10.0 mm Hg of negative pressure. When subjected to conditions of LBNP, the reflex tachycardia of the T group was greater than the NT at the lower (-2.5 and -5.0 mm Hg) negative pressures. Although arterial pressure declines were similar in both groups, the T group experienced significantly less of a decline in central venous pressure than the NT animals. When chlorisondamine was used as a ganglionic blocker (2.5 mg.kg-1, IV), the fall in CVP at 10 mm Hg negative pressure was greater for the NT group while the fall in the initial systemic arterial pressure was more for the T group. From these results we concluded that training had altered the interaction between cardiopulmonary and arterial baroreflexes in these hypertensive rats and a nonneural component had been altered such as cardiac function.

Negative pressure driven valence instability of Eu in cubic Eu0.4La0.6Pd3

International Nuclear Information System (INIS)

Pandey, Abhishek; Mazumdar, Chandan; Ranganathan, R

2009-01-01

We report the change in the valency of Eu-ions in the binary intermetallic cubic compound EuPd 3 induced by La doping at rare-earth sites. Doping of La generates negative chemical pressure in the lattice, resulting in a significant increase of the lattice parameter without altering the simple-cubic structure of the compound. Results of dc-magnetic measurements suggest that this increase in the lattice parameter is associated with the valence transition of Eu-ions from Eu 3+ to a mixed-valent state. As Eu 2+ -ions possess a large magnetic moment, this valence transition significantly modifies the magnetic behavior of the compound. In contrast to introducing boron at the vacant body center site of the unit cell to change the valency of Eu-ions, as in the case of EuPd 3 B, our results suggest it can also be altered by doping a rare-earth ion of larger size at the lattice site of Eu in EuPd 3 .

Predicting burst pressure of radiofrequency-induced colorectal anastomosis by bio-impedance measurement.

Science.gov (United States)

Zhao, Lingxi; Zhou, Yu; Song, Chengli; Wang, Zhigang; Cuschieri, Alfred

2017-03-01

The present study investigates the relationship between bio-impedance and burst pressure of colorectal anastomosis created by radiofrequency (RF)-induced tissue fusion. Colorectal anastomosis were created with ex vivo porcine colorectal segments, during which 5 levels of compression pressure were applied by a custom-made bipolar prototype, with 5 replicate experiments at each compression pressure. Instant anastomotic tensile strength was assessed by burst pressure. Bio-impedance of fused tissue was measured by Impedance Analyzer across frequency that 100 Hz to 3 MHz. Statistical analysis shows only a weak correlation between bio-impedance modulus and burst pressures at frequency of 445 kHz ([Formula: see text]  =  -0.426, P  =  0.099  >  0.05). In contrast, results demonstrated a highly significant negative correlation between reactance modulus and burst pressures ([Formula: see text]  =  -0.812, P  =  0.000  <  0.05). The decrease in mean reactance modulus with increasing burst pressures was highly significant (P  =  0.019  <  0.05). The observed strong negative correlation between reactance modulus and burst pressures at frequency of 445 kHz indicates that reactance is likely to be a good index for tensile strength of RF-induced colorectal anastomosis, and should be considered for inclusion in a feedback loops in devices design.

Results of a retrospective comparative study: material cost for managing a series of large wounds in subjects with serious morbidity with a hydrokinetic fiber dressing or negative pressure wound therapy.

Science.gov (United States)

Hermans, Michel H E; Kwon Lee, S; Ragan, Mitzie R; Laudi, Pam

2015-03-01

This retrospective observational study analyzed lesions with regard to healing trends and cost of materials. The observed lesions were mostly postsurgical or stage IV pressure ulcers in patients with serious morbidity. The wounds were treated with a hydrokinetic fiber dressing (sorbion Sachet S, sorbion Gmbh & Co, a BSN medical company, Senden, Germany) (n = 26) or negative pressure wound therapy (NPWT) (n = 16). Primary healing trends (ie, reduction of wound size, change from necrosis to granulation tissue, and change from granulation tissue to epithelium) and secondary healing trends (ie, periwound conditions) were similar for wounds treated with the hydrokinetic dressing when compared to wounds treated with NPWT. Cost of materials was substantially lower for wounds treated with the hydrokinetic fiber dressing compared to the NPWT, with cost reductions of $1,640 (348%) to $2,242 (1794%) per wound, depending on the criteria used for the analysis. In this set of wounds, the hydrokinetic fiber dressing was shown to lead to similar healing results while providing substantial reductions of the cost of materials. For the types of wounds presented in this observational study, the hydrokinetic fiber dressing seems to be an effective substitution for negative pressure wound therapy.

The SNaP™ Wound Care System: A Case Series Using a Novel Ultraportable Negative Pressure Wound Therapy Device for the Treatment of Diabetic Lower Extremity Wounds

Science.gov (United States)

Lerman, Bruce; Oldenbrook, Leslie; Ryu, Justin; Fong, Kenton D.; Schubart, Peter J.

2010-01-01

Although there is significant evidence supporting the use of negative pressure wound therapy (NPWT) for the treatment of lower extremity diabetic ulcers, currently available electrically powered NPWT systems are not ideally suited for treating smaller diabetic foot ulcers. The Smart Negative Pressure (SNaP™) Wound Care System is a novel, ultraportable device that delivers NPWT without the use of an electrically powered pump. It was specifically designed to meet the wound care needs of patients with diabetes. The SNaP System is compact, silent, mobile, easy-to-use, and available off-the-shelf. It is fully disposable and may offer other important benefits over electrically powered systems to both the clinician and patient. We review the evidence for use of NPWT for the treatment of diabetic wounds and discuss the potential benefits of this new NPWT technology for patients with diabetes. We also present a case series of four difficult lower extremity diabetic ulcers that were successfully treated with the SNaP System. This study suggests that the SNaP System may be a useful addition to the armamentarium of the diabetic wound care clinician. PMID:20663444

Changes in subcutaneous blood flow during locally applied negative pressure to the skin

DEFF Research Database (Denmark)

Skagen, K; Henriksen, O

1983-01-01

The effect of locally applied subatmospheric pressure on subcutaneous blood flow was studied in 12 healthy subjects. Blood flow was measured on the forearm by the local 133Xe wash-out technique. Air suction between 10 mmHg and 250 mmHg was applied to the skin. Subatmospheric pressure of 20 mm...

Betterment, undermining, support and distortion: A heuristic model for the analysis of pressure on evaluators.

Science.gov (United States)

Pleger, Lyn; Sager, Fritz

2016-09-18

Evaluations can only serve as a neutral evidence base for policy decision-making as long as they have not been altered along non-scientific criteria. Studies show that evaluators are repeatedly put under pressure to deliver results in line with given expectations. The study of pressure and influence to misrepresent findings is hence an important research strand for the development of evaluation praxis. A conceptual challenge in the area of evaluation ethics research is the fact that pressure can be not only negative, but also positive. We develop a heuristic model of influence on evaluations that does justice to this ambivalence of influence: the BUSD-model (betterment, undermining, support, distortion). The model is based on the distinction of two dimensions, namely 'explicitness of pressure' and 'direction of influence'. We demonstrate how the model can be applied to understand pressure and offer a practical tool to distinguish positive from negative influence in the form of three so-called differentiators (awareness, accordance, intention). The differentiators comprise a practical component by assisting evaluators who are confronted with influence. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fundamental Studies of Transient, Atmospheric-Pressure, Small-Scale Plasmas

Science.gov (United States)

2017-01-23

C. Jiang, R. Heller, J. Lane, and K. H. Schoenbach, " Ozone -free nitric oxide production using an atmospheric pressure surface discharge – a way to...Electrostatic modeling and energy-dependent studies showed that the direct and indirect electron-induced processes in the pulsed plasma jet are responsible for...Coupled sliding discharges : a scalable nonthermal plasma system utilizing positive and negative streamers on DISTRIBUTION A: Distribution

Negative muon capture in noble gas mixtures

International Nuclear Information System (INIS)

Hutson, R.L.; Knight, J.D.; Leon, M.; Schillaci, M.E.; Knowles, H.B.; Reidy, J.J.

1980-01-01

We have determined the probabilities of atomic negative muon capture in binary mixtures of the gases He, Ne, Ar, and Kr at partial pressures near five atmospheres. Relative capture rates were deduced from measured muonic X-ray yields. (orig.)

Efficacy of Negative Pressure Wound Treatment in Preventing Surgical Site Infections after Whipple Procedures.

Science.gov (United States)

Gupta, Ryan; Darby, Geoffrey C; Imagawa, David K

2017-10-01

Surgical site infections (SSIs) occur at an average rate of 21.1 per cent after Whipple procedures per NSQIP data. In the setting of adherence to standard National Surgery Quality Improvement Program (NSQIP) Hepatopancreatobiliary recommendations including wound protector use and glove change before closing, this study seeks to evaluate the efficacy of using negative pressure wound treatment (NPWT) over closed incision sites after a Whipple procedure to prevent SSI formation. We retrospectively examined consecutive patients from January 2014 to July 2016 who met criteria of completing Whipple procedures with full primary incision closure performed by a single surgeon at a single institution. Sixty-one patients were included in the study between two cohorts: traditional dressing (TD) (n = 36) and NPWT dressing (n = 25). There was a statistically significant difference (P = 0.01) in SSI formation between the TD cohort (n = 15, SSI rate = 0.41) and the NPWT cohort (n = 3, SSI rate = 0.12). The adjusted odds ratio (OR) of SSI formation was significant for NPWT use [OR = 0.15, P = 0.036] and for hospital length of stay [OR = 1.21, P = 0.024]. Operative length, operative blood loss, units of perioperative blood transfusion, intraoperative gastrojejunal tube placement, preoperative stent placement, and postoperative antibiotic duration did not significantly impact SSI formation (P > 0.05).

Pressure-induced positive electrical resistivity coefficient in Ni-Nb-Zr-H glassy alloy

Science.gov (United States)

Fukuhara, M.; Gangli, C.; Matsubayashi, K.; Uwatoko, Y.

2012-06-01

Measurements under hydrostatic pressure of the electrical resistivity of (Ni0.36Nb0.24Zr0.40)100-xHx (x = 9.8, 11.5, and 14) glassy alloys have been made in the range of 0-8 GPa and 0.5-300 K. The resistivity of the (Ni0.36Nb0.24Zr0.40)86H14 alloy changed its sign from negative to positive under application of 2-8 GPa in the temperature range of 300-22 K, coming from electron-phonon interaction in the cluster structure under pressure, accompanied by deformation of the clusters. In temperature region below 22 K, the resistivity showed negative thermal coefficient resistance by Debye-Waller factor contribution, and superconductivity was observed at 1.5 K.

Negative pressure wound therapy for Gustilo Anderson grade IIIb open tibial fractures.

Science.gov (United States)

Park, Chul Hyun; Shon, Oog Jin; Kim, Gi Beom

2016-09-01

Traditionally, Gustilo Anderson grade IIIb open tibial fractures have been treated by initial wide wound debridement, stabilization of fracture with external fixation, and delayed wound closure. The purpose of this study is to evaluate the clinical and radiological results of staged treatment using negative pressure wound therapy (NPWT) for Gustilo Anderson grade IIIb open tibial fractures. 15 patients with Gustilo Anderson grade IIIb open tibial fractures, treated using staged protocol by a single surgeon between January 2007 and December 2011 were reviewed in this retrospective study. The clinical results were assessed using a Puno scoring system for severe open fractures of the tibia at the last followup. The range of motion (ROM) of the knee and ankle joints and postoperative complication were evaluated at the last followup. The radiographic results were assessed using time to bone union, coronal and sagittal angulations and a shortening at the last followup. The mean score of Puno scoring system was 87.4 (range 67-94). The mean ROM of the knee and ankle joints was 121.3° (range 90°-130°) and 37.7° (range 15°-50°), respectively. Bone union developed in all patients and the mean time to union was 25.3 weeks (range 16-42 weeks). The mean coronal angulation was 2.1° (range 0-4°) and sagittal was 2.7° (range 1-4°). The mean shortening was 4.1 mm (range 0-8 mm). Three patients had partial flap necrosis and 1 patient had total flap necrosis. There was no superficial and deep wound infection. Staged treatment using NPWT decreased the risks of infection and requirement of flap surgeries in Gustilo Anderson grade IIIb open tibial fractures. Therefore, staged treatment using NPWT could be a useful treatment option for Gustilo Anderson grade IIIb open tibial fractures.

Mechanisms of lower body negative pressure-induced syncope

Science.gov (United States)

Davrath, Linda Ruble

Although extensively investigated, the mechanisms of post-spaceflight orthostatic intolerance have not been elucidated. The working hypothesis was that a markedly reduced left ventricular end-systolic volume (LVESV) would be achieved during progressive, presyncopal-limited LBNP and would cause bradycardia and a fall in blood pressure, thus triggering syncope. Eight healthy men, age 25.1 ± 1.3 years, volunteered for the study. Subjects were exposed to graded levels of LBNP on two separate occasions. Changes in left ventricular end-diastolic volume and LVESV were measured, using two-dimensional echocardiography, at each stage of LBNP from rest to presyncope. Plasma venous blood samples were withdrawn at the end of each stage of the LBNP protocol for the measurement of plasma venous catecholamines and plasma renin activity (PRA). Catecholamines were analyzed by HPLC with electro-chemical detection, and PRA was determined by radioimmunoassay. All subjects reached presyncope during the LBNP. LVESV decreased by 28% at presyncope with no evidence of ventricular cavity obliteration. Norepinephrine (NE) increased by 44% from rest to presyncope, but no epinephrine surge was detected (35% increase from rest to presyncope). These data indicate that it is possible to initiate syncope with only a 28% decrease in LVESV, and that sympatho-inhibition and bradycardia are not required elements for syncope to occur. To investigate the effect of moderate sodium restriction on cardiovascular hemodynamics and orthostatic tolerance, presyncopal LBNP testing was performed. Urinary sodium excretion was significantly higher on the normal-sodium diet when compared with the sodium-restricted diet, but urinary potassium was not different. Cumulative stress index (655 ± 460 on normal-sodium diet vs. 639 ± 388 on sodium-restricted diet) scores were not different. Cardiac volumes, blood pressure and total peripheral resistance were not different at any stage of the LBNP between the diets, nor

Effect of Negative Pressure Wound Therapy on Cellular Fibronectin and Transforming Growth Factor-β1 Expression in Diabetic Foot Wounds.

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Yang, Shao Ling; Zhu, Lv Yun; Han, Rui; Sun, Lei Lei; Dou, Jing Tao

2017-08-01

Chronic diabetic foot wounds are a leading cause of amputation, morbidity, and hospitalization for patients with diabetes. Negative-pressure wound therapy (NPWT) can putatively facilitate wound healing, but the underlying mechanisms remain unclear. Cellular fibronectin (cFN) and transforming growth factor-β1 (TGF-β1) play an important role in wound healing. This prospective randomized controlled trial evaluated the effects of NPWT on the production of cFN and the expression of TGF-β1 in diabetic foot wounds of patients. From January 2012 to January 2015, 40 patients with diabetic foot wounds were randomly and equally apportioned to receive either NPWT or advanced moist wound therapy (control) for 7 days. Granulation tissue was harvested before and after treatment. Immunohistochemistry and Western blot were performed to evaluate protein levels of cFN and TGF-β1, and real-time polymerase chain reaction (PCR) to measure corresponding mRNA expressions. NPWT facilitated the expression of cFN and TGF-β1 in diabetic foot wounds. Immunohistochemical analysis revealed higher levels of cFN and TGF-β1 in the NPWT group than in the control group. Western blot and real-time PCR analysis further showed that protein and mRNA levels of cFN or TGF-β1 were higher in the NPWT group than that in the control group ( P diabetic foot ulcers. Level I, randomized controlled study.

Electromagnetic forces in negative-refractive-index metamaterials: A first-principles study

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Yannopapas, Vassilios; Galiatsatos, Pavlos G.

2008-04-01

According to the theory of Veselago, when a particle immersed within a metamaterial with negative refractive index is illuminated by plane wave, it experiences a reversed radiation force due to the antiparallel directions of the phase velocity and energy flow. By employing an ab initio method, we show that, in the limit of zero losses, the effect of reversed radiation pressure is generally true only for the specular beam. Waves generated by diffraction of the incident light at the surface of the slab of the metamaterial can produce a total force which is parallel to the radiation flow. However, when the actual losses of the materials are taken into account, the phenomenon of reversed radiation force is evident within the whole range of a negative refractive index band.

Use of a risk assessment method to improve the safety of negative pressure wound therapy.

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Lelong, Anne-Sophie; Martelli, Nicolas; Bonan, Brigitte; Prognon, Patrice; Pineau, Judith

2014-06-01

To conduct a risk analysis of the negative pressure wound therapy (NPWT) care process and to improve the safety of NPWT, a working group of nurses, hospital pharmacists, physicians and hospital managers performed a risk analysis for the process of NPWT care. The failure modes, effects and criticality analysis (FMECA) method was used for this analysis. Failure modes and their consequences were defined and classified as a function of their criticality to identify priority actions for improvement. By contrast to classical FMECA, the criticality index (CI) of each consequence was calculated by multiplying occurrence, severity and detection scores. We identified 13 failure modes, leading to 20 different consequences. The CI of consequences was initially 712, falling to 357 after corrective measures were implemented. The major improvements proposed included the establishment of 6-monthly training cycles for nurses, physicians and surgeons and the introduction of computerised prescription for NPWT. The FMECA method also made it possible to prioritise actions as a function of the criticality ranking of consequences and was easily understood and used by the working group. This study is, to our knowledge, the first to use the FMECA method to improve the safety of NPWT. © 2012 The Authors. International Wound Journal © 2012 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Recurring pressure ulcers: identifying the definitions. A National Pressure Ulcer Advisory Panel white paper.

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Tew, Cindy; Hettrick, Heather; Holden-Mount, Sarah; Grigsby, Rebekah; Rhodovi, Julie; Moore, Lyn; Ghaznavi, Amir M; Siddiqui, Aamir

2014-01-01

Currently, there is a lack of consensus regarding the accepted terminology pertaining to the pressure ulcer healing progression and recidivism. This lack of uniformity can negatively impact initiation of treatment pathways, completion of appropriate interventions, clinical documentation, medical coding, patient education, discharge planning and healthcare revenue through out the healthcare system. The purpose of this paper is to introduce a standard nomenclature as it pertains to pressure ulcer healing progression and any recidivism that may occur. The National Pressure Ulcer Advisory Panel has formulated a framework of terms regarding pressure ulcer progression. We also developed a clearer nomenclature for lack of progress and recidivism of pressure ulcers. This document should serve as a starting point for the discussion of the pressure ulcer care, research, and terminology. © 2014 by the Wound Healing Society.

The effect of pressure and shear on tissue viability of human skin in relation to the development of pressure ulcers: a systematic review.

Science.gov (United States)

Hoogendoorn, Iris; Reenalda, Jasper; Koopman, Bart F J M; Rietman, Johan S

2017-08-01

Pressure ulcers are a significant problem in health care, due to high costs and large impact on patients' life. In general, pressure ulcers develop as tissue viability decreases due to prolonged mechanical loading. The relation between load and tissue viability is highly influenced by individual characteristics. It is proposed that measurements of skin blood flow regulation could provide good assessment of the risk for pressure ulcer development, as skin blood flow is essential for tissue viability. . Therefore, the aim of this systematic review is to gain insight in the relation between mechanical load and the response of the skin and underlying tissue to this loading measured in-vivo with non-invasive techniques. A systematic literature search was performed to identify articles analysing the relation between mechanical load (pressure and/or shear) and tissue viability measured in-vivo. Two independent reviewers scored the methodological quality of the 22 included studies. Methodological information as well as tissue viability parameters during load application and after load removal were extracted from the included articles and used in a meta-analysis. Pressure results in a decrease in skin blood flow parameters, compared to baseline; showing a larger decrease with higher magnitudes of load. The steepness of the decrease is mostly dependent on the anatomical location. After load removal the magnitude of the post-reactive hyperaemic peak is related to the magnitude of pressure. Lastly, shear in addition to pressure, shows an additional negative effect, but the effect is less apparent than pressure on skin viability. Copyright © 2017 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

Seaweed intake and blood pressure levels in healthy pre-school Japanese children

Directory of Open Access Journals (Sweden)

Yamamoto Keiko

2011-08-01

Full Text Available Abstract Background Few studies have examined whether dietary factors might affect blood pressure in children. We purposed to investigate whether seaweed intake is associated with blood pressure level among Japanese preschool children. Methods The design of the study was cross-sectional and it was conducted in autumn 2006. Subjects were healthy preschoolers aged 3-6 years in Aichi, Japan. Blood pressure and pulse were measured once by an automated sphygmomanometer, which uses oscillometric methods. Dietary data, including seaweed intake, were assessed using 3-day dietary records covering 2 consecutive weekdays and 1 weekend day. Of a total of 533 children, 459 (86.1 percent agreed to be enrolled in our study. Finally, blood pressure measurement, complete dietary records and parent-reported height and weight were obtained for 223 boys and 194 girls. Results When we examined Spearman's correlation coefficients, seaweed intake was significantly negatively related to systolic blood pressure in girls (P = 0.008. In the one-way analysis of covariance for blood pressure and pulse after adjustments for age and BMI, the boys with the lowest, middle and highest tertiles of seaweed intake had diastolic blood pressure readings of 62.8, 59.3 and 59.6 mmHg, respectively (P = 0.11, trend P = 0.038. Girls with higher seaweed intake had significantly lower systolic blood pressure readings (102.4, 99.2 and 96.9 mmHg for girls with the lowest, middle and highest tertiles of seaweed intake, respectively; P = 0.037, trend P = 0.030. Conclusion Our study showed that seaweed intake was negatively related to diastolic blood pressure in boys and to systolic blood pressure in girls. This suggests that seaweed might have beneficial effects on blood pressure among children.

Association between Macronutrients Intake, Visceral Obesity and Blood Pressure in a Sample of Obese Egyptian Women.

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Hassan, Nayera E; El Shebini, Salwa M; Ahmed, Nihad H; Selim Mostafa, Mohamed

2015-03-15

Study the association between the total caloric intake, protein, lipid, and some classes of fatty acids of the diet, and their effects on blood pressure in a sample of Egyptian obese women with and without visceral obesity. Five hundred forty-nine obese women were included in the study with mean age of 38.1 ± 11.56 years and mean Body mass index [BMI] of 36.17 ± 7.23. They enrolled in a program for losing weight. Visceral fat was determined using ultrasound. Blood pressure was measured 3 times and the mean was recorded. Twenty four hours dietary recall was reported. Thirty point four percentages of samples has visceral obesity ≥ 7cm; they were the older, showed higher values of BMI, visceral obesity and blood pressure. Significant difference was found between groups regarding mean value of BMI, visceral obesity, both systolic blood pressure SBP and diastolic blood pressure DBP and most of the daily macronutrients intake. In groups (2&3) positive significant correlation was recorded between (SBP) & (DBP) and total daily intake of total calories, carbohydrate, total fat, saturated fatty acids and cholesterol, and negative significant correlation with total daily intake of total protein, animal and vegetable protein, linolenic and linoleic fatty acids, while oleic fatty acid showed negative correlation with SBP&DBP in all groups. This study emphasizes the hypothesis that the macronutrients composition of diet influences blood pressure in different ways, in obese patients with visceral obesity.

A prospective randomized evaluation of negative-pressure wound dressings for diabetic foot wounds.

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Eginton, Mark T; Brown, Kellie R; Seabrook, Gary R; Towne, Jonathan B; Cambria, Robert A

2003-11-01

Optimal treatment for large diabetic foot wounds is ill defined. The purpose of this study was to compare the rate of wound healing with the Vacuum Assisted Closure device trade mark (VAC) to conventional moist dressings in the treatment of large diabetic foot wounds. Diabetics with significant soft tissue defects of the foot were considered for enrollment. Patients were randomized to receive either moist gauze dressings or VAC treatments for 2 weeks, after which they were treated with the alternative dressing for an additional 2 weeks. Wounds were photographed weekly and wound dimensions calculated in a blinded fashion with spatial analysis software. Percent change in wound dimensions were calculated and compared for each weekly assessment and over 2 weeks of therapy with each dressing type. Ten patients were enrolled in the trial, but two were lost to follow-up and two were withdrawn. Complete data were available for analysis on seven wounds in six patients. Average length, width, and depth of the wounds at initiation of the trial was 7.7, 3.5, and 3.1 cm, respectively. Only the wound depth was significantly decreased over the weeks of the trial to 1.2 cm ( p VAC dressings decreased the wound volume and depth significantly more than moist gauze dressings (59% vs. 0% and 49% vs. 8%, respectively). VAC dressings were associated with a decrease in all wound dimensions while wound length and width increased with moist dressings. In summary, over the first several weeks of therapy, VAC dressings decreased wound depth and volume more effectively than moist gauze dressings. Negative-pressure wound treatment may accelerate closure of large foot wounds in the diabetic patient.

Fundamentals of negative refractive index optical trapping: forces and radiation pressures exerted by focused Gaussian beams using the generalized Lorenz-Mie theory.

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Ambrosio, Leonardo A; Hernández-Figueroa, Hugo E

2010-11-04

Based on the generalized Lorenz-Mie theory (GLMT), this paper reveals, for the first time in the literature, the principal characteristics of the optical forces and radiation pressure cross-sections exerted on homogeneous, linear, isotropic and spherical hypothetical negative refractive index (NRI) particles under the influence of focused Gaussian beams in the Mie regime. Starting with ray optics considerations, the analysis is then extended through calculating the Mie coefficients and the beam-shape coefficients for incident focused Gaussian beams. Results reveal new and interesting trapping properties which are not observed for commonly positive refractive index particles and, in this way, new potential applications in biomedical optics can be devised.

Body indices and basic vital signs in Helicobacter pylori positive and negative persons

International Nuclear Information System (INIS)

Kopacova, Marcela; Bures, Jan; Koupil, Ilona; Rejchrt, Stanislav; Vorisek, Viktor; Seifert, Bohumil; Pozler, Oldrich; Zivny, Pavel; Douda, Tomas; Palicka, Vladimir; Holcik, Jan

2007-01-01

It has been hypothesized that Helicobacter pylori (Hp) infection may contribute to reduced stature, risk of hypertension or obesity. The aim was to evaluate body indices in Hp positive and negative persons. A total of 2436 subjects (4-100 years old) were tested for Hp status by 13 C-urea breath test. Data on height and weight were collected for 84%, and blood pressure for 80% of the study subjects. The prevalence of Hp infection was 41.6%. The odds ratio for a 10-year increase in age was 1.21 (95% CI 1.17-1.25, p-value <0.001). Statistically significant negative association of Hp positivity with body height was most pronounced in the younger age groups, while a positive association of Hp positivity with body mass index was only seen in those aged 15+ years. There was a negative effect of Hp positivity on systolic and diastolic blood pressure in subjects below 25 and a relatively strong positive effect on blood pressure in subjects over 65 years. Residual confounding by social characteristics as a possible explanation for the associations of Hp positivity with height and blood pressure cannot be excluded. Unmeasured factors related to social and family environment may cause the apparent association between Hp positivity and children's growth and blood pressure

Influence of operating conditions and atomizer design on circumferential liquid distribution from small pressure-swirl atomizer

Science.gov (United States)

Malý, Milan; Janáčková, Lada; Jedelský, Jan; Jícha, Miroslav

The spray symmetry is an important aspect in most practical applications. However, it is often an overlooked parameter. A measurement of circumferential distribution was carried out by a circular-sectored vessel on several pressure-swirl atomizers with spill-line over a wide range of injection pressure. The obtained results show that the spray uniformity improves markedly with the injection pressure. The increase in a number of tangential entry ports has only a minor effect on the spray uniformity. Even a small mechanical corruption of the atomizer internal parts negatively affects the spray patternation.

Effect of negative bias voltage on CrN films deposited by arc ion plating. I. Macroparticles filtration and film-growth characteristics

International Nuclear Information System (INIS)

Wang Qimin; Kim, Kwang Ho

2008-01-01

Chromium nitride (CrN) films were deposited on Si wafers by arc ion plating (AIP) at various negative bias voltages and several groups of N 2 /Ar gas flux ratios and chamber gas pressures. The authors systematically investigated the influence of negative bias voltage on the synthesis, composition, microstructure, and properties of the AIP CrN films. In this part (Part I), the investigations were mainly focused on the macroparticle distributions and film-growth characteristics. The results showed that macroparticle densities on the film surfaces decreased greatly by applying negative bias voltage, which can be affected by partial pressure of N 2 and Ar gases. From the statistical analysis of the experimental results, they proposed a new hybrid mechanism of ion bombardment and electrical repulsion. Also, the growth of the AIP CrN films was greatly altered by applying negative bias voltage. By increasing the bias voltage, the film surfaces became much smoother and the films evolved from apparent columnar microstructures to an equiaxed microstructure. The impinging high-energy Cr ions accelerated by negative bias voltages were deemed the inherent reason for the evolution of growth characteristics

Comparison of measured and modelled negative hydrogen ion densities at the ECR-discharge HOMER

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Rauner, D.; Kurutz, U.; Fantz, U.

2015-04-01

As the negative hydrogen ion density nH- is a key parameter for the investigation of negative ion sources, its diagnostic quantification is essential in source development and operation as well as for fundamental research. By utilizing the photodetachment process of negative ions, generally two different diagnostic methods can be applied: via laser photodetachment, the density of negative ions is measured locally, but only relatively to the electron density. To obtain absolute densities, the electron density has to be measured additionally, which induces further uncertainties. Via cavity ring-down spectroscopy (CRDS), the absolute density of H- is measured directly, however LOS-averaged over the plasma length. At the ECR-discharge HOMER, where H- is produced in the plasma volume, laser photodetachment is applied as the standard method to measure nH-. The additional application of CRDS provides the possibility to directly obtain absolute values of nH-, thereby successfully bench-marking the laser photodetachment system as both diagnostics are in good agreement. In the investigated pressure range from 0.3 to 3 Pa, the measured negative hydrogen ion density shows a maximum at 1 to 1.5 Pa and an approximately linear response to increasing input microwave powers from 200 up to 500 W. Additionally, the volume production of negative ions is 0-dimensionally modelled by balancing H- production and destruction processes. The modelled densities are adapted to the absolute measurements of nH- via CRDS, allowing to identify collisions of H- with hydrogen atoms (associative and non-associative detachment) to be the dominant loss process of H- in the plasma volume at HOMER. Furthermore, the characteristic peak of nH- observed at 1 to 1.5 Pa is identified to be caused by a comparable behaviour of the electron density with varying pressure, as ne determines the volume production rate via dissociative electron attachment to vibrationally excited hydrogen molecules.

Rate of rise in diastolic blood pressure influences vascular sympathetic response to mental stress.

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El Sayed, Khadigeh; Macefield, Vaughan G; Hissen, Sarah L; Joyner, Michael J; Taylor, Chloe E

2016-12-15

Research indicates that individuals may experience a rise (positive responders) or fall (negative responders) in muscle sympathetic nerve activity (MSNA) during mental stress. In this study, we examined the early blood pressure responses (including the peak, time of peak and rate of rise in blood pressure) to mental stress in positive and negative responders. Negative MSNA responders to mental stress exhibit a more rapid rise in diastolic pressure at the onset of the stressor, suggesting a baroreflex-mediated suppression of MSNA. In positive responders there is a more sluggish rise in blood pressure during mental stress, which appears to be MSNA-driven. This study suggests that whether MSNA has a role in the pressor response is dependent upon the reactivity of blood pressure early in the task. Research indicates that individuals may experience a rise (positive responders) or fall (negative responders) in muscle sympathetic nerve activity (MSNA) during mental stress. The aim was to examine the early blood pressure response to stress in positive and negative responders and thus its influence on the direction of change in MSNA. Blood pressure and MSNA were recorded continuously in 21 healthy young males during 2 min mental stressors (mental arithmetic, Stroop test) and physical stressors (cold pressor, handgrip exercise, post-exercise ischaemia). Participants were classified as negative or positive responders according to the direction of the mean change in MSNA during the stressor tasks. The peak changes, time of peak and rate of changes in blood pressure were compared between groups. During mental arithmetic negative responders experienced a significantly greater rate of rise in diastolic blood pressure in the first minute of the task (1.3 ± 0.5 mmHg s -1 ) compared with positive responders (0.4 ± 0.1 mmHg s -1 ; P = 0.03). Similar results were found for the Stroop test. Physical tasks elicited robust parallel increases in blood pressure and MSNA across

Giant negative linear compression positively coupled to massive thermal expansion in a metal-organic framework.

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Cai, Weizhao; Katrusiak, Andrzej

2014-07-04

Materials with negative linear compressibility are sought for various technological applications. Such effects were reported mainly in framework materials. When heated, they typically contract in the same direction of negative linear compression. Here we show that this common inverse relationship rule does not apply to a three-dimensional metal-organic framework crystal, [Ag(ethylenediamine)]NO3. In this material, the direction of the largest intrinsic negative linear compression yet observed in metal-organic frameworks coincides with the strongest positive thermal expansion. In the perpendicular direction, the large linear negative thermal expansion and the strongest crystal compressibility are collinear. This seemingly irrational positive relationship of temperature and pressure effects is explained and the mechanism of coupling of compressibility with expansivity is presented. The positive coupling between compression and thermal expansion in this material enhances its piezo-mechanical response in adiabatic process, which may be used for designing new artificial composites and ultrasensitive measuring devices.

Suture Technique to Prevent Air Leakage during Negative-Pressure Wound Therapy in Fournier Gangrene.

Science.gov (United States)

Chang, Feng-Shu; Chou, Chieh; Hu, Chuan-Yu; Huang, Shu-Hung

2018-01-01

The use of negative-pressure wound therapy (NPWT) for Fournier gangrene management is well documented; however, it is difficult to fixate GranuFoam dressings and maintain an airtight seal over the perineum area. We developed a simple method to facilitate GranuFoam fixation and improve airtight sealing. The Fournier's gangrene severity index (FGSI) score less than 9 was collected in from January 2015 to October 2016. All 13 patients underwent fasciotomy, and NPWT was applied directly on fasciotomy wounds after the debridement of infected tissue. Partial wound closure was performed, and a portion of GranuFoam was inserted to facilitate fixation. The seal check was converted to a 0-10 scale score that was recorded every 4 hours during NPWT. Patient profiles including medical history, FGSI, method of wound closure, and length of stay were collected in this study. The median age of the patients was 62 (38-76) years. The mean FGSI score was 4.3 ± 3.1. The average duration of NPWT was 17.5 ± 11.5 days, and the average seal check score was 0.8 ± 0.5. No seal check alarms were noted during the study. Successful wound closure was achieved in all patients without using additional reconstruction methods such as skin grafting or muscle flap coverage. The present results suggest that partial wound-edge closure and in situ GranuFoam fixation improve the NPWT leaks in Fournier gangrene wounds. Furthermore, this method is simple to learn and can be useful in applying NPWT to anatomically difficult areas.

Cost-effectiveness analysis alongside a pilot study of prophylactic negative pressure wound therapy.

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Heard, Christopher; Chaboyer, Wendy; Anderson, Vinah; Gillespie, Brigid M; Whitty, Jennifer A

2017-02-01

Negative pressure wound therapy (NPWT) is increasingly used prophylactically following surgery despite limited evidence of clinical or cost-effectiveness. To evaluate whether NPWT is cost-effective compared to standard care, for the prevention of surgical site infection (SSI) in obese women undergoing elective caesarean section, and inform development of a larger trial. An economic evaluation was conducted alongside a pilot randomised controlled trial at one Australian hospital, in which women were randomised to NPWT (n = 44) or standard care (n = 43). A public health care provider perspective and time horizon to four weeks post-discharge was adopted. Cost-effectiveness assessment was based on incremental cost per SSI prevented and per quality-adjusted life year (QALY) gained. Patients receiving NPWT each received health care costing AU$5887 (±1038) and reported 0.069 (±0.010) QALYs compared to AU$5754 (±1484) and 0.066 (±0.010) QALYs for patients receiving standard care. NPWT may be slightly more costly and more effective than standard care, with estimated incremental cost-effectiveness ratios (ICERs) of AU$1347 (95%CI dominant- $41,873) per SSI prevented and AU$42,340 (95%CI dominant- $884,019) per QALY gained. However, there was considerable uncertainty around these estimates. NPWT may be cost-effective in the prophylactic treatment of surgical wounds following elective caesarean section in obese women. Larger trials could clarify the cost-effectiveness of NPWT as a prophylactic treatment for SSI. Sensitive capture of QALYs and cost offsets will be important given the high level of uncertainty around the point estimate cost-effectiveness ratio which was close to conventional thresholds. ACTRN12612000171819. Copyright © 2016 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

In-flight Assessment of Lower Body Negative Pressure as a Countermeasure for Post-flight Orthostatic Intolerance

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Charles, J. B.; Stenger, M. B.; Phillips, T. R.; Arzeno, N. M.; Lee, S. M. C.

2009-01-01

Introduction. We investigated the efficacy of combining fluid loading with sustained lower body negative pressure (LBNP) to reverse orthostatic intolerance associated with weightlessness during and immediately after Space Shuttle missions. Methods. Shuttle astronauts (n=13) underwent 4 hours of LBNP at -30 mm(Hg) and ingested water and salt ( soak treatment) during flight in two complementary studies. In the first study (n=8), pre-flight heart rate (HR) and blood pressure (BP) responses to an LBNP ramp (5-min stages of -10 mm(Hg) steps to -50 mm(Hg) were compared to responses in-flight one and two days after LBNP soak treatment. In the second study (n=5), the soak was performed 24 hr before landing, and post-flight stand test results of soak subjects were compared with those of an untreated cohort (n=7). In both studies, the soak was scheduled late in the mission and was preceded by LBNP ramp tests at approximately 3-day intervals to document the in-flight loss of orthostatic tolerance. Results. Increased HR and decreased BP responses to LBNP were evident early in-flight. In-flight, one day after LBNP soak, HR and BP responses to LBNP were not different from pre-flight, but the effect was absent the second day after treatment. Post-flight there were no between-group differences in HR and BP responses to standing, but all 5 treatment subjects completed the 5-minute stand test whereas 2 of 7 untreated cohort subjects did not. Discussion. Exaggerated HR and BP responses to LBNP were evident within the first few days of space flight, extending results from Skylab. The combined LBNP and fluid ingestion countermeasure restored in-flight LBNP HR and BP responses to pre-flight levels and provided protection of post-landing orthostatic function. Unfortunately, any benefits of the combined countermeasure were offset by the complexity of its implementation, making it inappropriate for routine application during Shuttle flights.

Martian Atmospheric Pressure Static Charge Elimination Tool

Science.gov (United States)

Johansen, Michael R.

2014-01-01

A Martian pressure static charge elimination tool is currently in development in the Electrostatics and Surface Physics Laboratory (ESPL) at NASA's Kennedy Space Center. In standard Earth atmosphere conditions, static charge can be neutralized from an insulating surface using air ionizers. These air ionizers generate ions through corona breakdown. The Martian atmosphere is 7 Torr of mostly carbon dioxide, which makes it inherently difficult to use similar methods as those used for standard atmosphere static elimination tools. An initial prototype has been developed to show feasibility of static charge elimination at low pressure, using corona discharge. A needle point and thin wire loop are used as the corona generating electrodes. A photo of the test apparatus is shown below. Positive and negative high voltage pulses are sent to the needle point. This creates positive and negative ions that can be used for static charge neutralization. In a preliminary test, a floating metal plate was charged to approximately 600 volts under Martian atmospheric conditions. The static elimination tool was enabled and the voltage on the metal plate dropped rapidly to -100 volts. This test data is displayed below. Optimization is necessary to improve the electrostatic balance of the static elimination tool.

Experimental Evaluation of a Negative Ion Source for a Heavy Ion Fusion Negative Ion Driver

International Nuclear Information System (INIS)

Grisham, L.R.; Hahto, S.K.; Hahto, S.T.; Kwan, J.W.; Leung, K.N.

2004-01-01

Negative halogen ions have recently been proposed as a possible alternative to positive ions for heavy ion fusion drivers because electron accumulation would not be a problem in the accelerator, and if desired, the beams could be photo-detached to neutrals. To test the ability to make suitable quality beams, an experiment was conducted at Lawrence Berkeley National Laboratory using chlorine in an RF-driven ion source. Without introducing any cesium (which is required to enhance negative ion production in hydrogen ion sources) a negative chlorine current density of 45 mA/cm 2 was obtained under the same conditions that gave 57 45 mA/cm 2 of positive chlorine, suggesting the presence of nearly as many negative ions as positive ions in the plasma near the extraction plane. The negative ion spectrum was 99.5% atomic chlorine ions, with only 0.5% molecular chlorine, and essentially no impurities. Although this experiment did not incorporate the type of electron suppression technology that i s used in negative hydrogen beam extraction, the ratio of co-extracted electrons to Cl - was as low as 7 to 1, many times lower than the ratio of their mobilities, suggesting that few electrons are present in the near-extractor plasma. This, along with the near-equivalence of the positive and negative ion currents, suggests that the plasma in this region was mostly an ion-ion plasma. The negative chlorine current density was relatively insensitive to pressure, and scaled linearly with RF power. If this linear scaling continues to hold at higher RF powers, it should permit current densities of 100 45 mA/cm 2 , sufficient for present heavy ion fusion injector concepts. The effective ion temperatures of the positive and negative ions appeared to be similar and relatively low for a plasma source

Crucial role of rho-kinase in pressure overload-induced right ventricular hypertrophy and dysfunction in mice.

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Ikeda, Shohei; Satoh, Kimio; Kikuchi, Nobuhiro; Miyata, Satoshi; Suzuki, Kota; Omura, Junichi; Shimizu, Toru; Kobayashi, Kenta; Kobayashi, Kazuto; Fukumoto, Yoshihiro; Sakata, Yasuhiko; Shimokawa, Hiroaki

2014-06-01

Right ventricular (RV) failure is the leading cause of death in various cardiopulmonary diseases, including pulmonary hypertension. It is generally considered that the RV is vulnerable to pressure overload as compared with the left ventricle (LV). However, as compared with LV failure, the molecular mechanisms of RV failure are poorly understood, and hence therapeutic targets of the disorder remain to be elucidated. Thus, we aimed to identify molecular therapeutic targets for RV failure in a mouse model of pressure overload. To induce pressure overload to respective ventricles, we performed pulmonary artery constriction or transverse aortic constriction in mice. We first performed microarray analysis and found that the molecules related to RhoA/Rho-kinase and integrin pathways were significantly upregulated in the RV with pulmonary artery constriction compared with the LV with transverse aortic constriction. Then, we examined the responses of both ventricles to chronic pressure overload in vivo. We demonstrated that compared with transverse aortic constriction, pulmonary artery constriction caused greater extents of mortality, Rho-kinase expression (especially ROCK2 isoform), and oxidative stress in pressure-overloaded RV, reflecting the weakness of the RV in response to pressure overload. Furthermore, mice with myocardial-specific overexpression of dominant-negative Rho-kinase showed resistance to pressure overload-induced hypertrophy and dysfunction associated with reduced oxidative stress. Finally, dominant-negative Rho-kinase mice showed a significantly improved long-term survival in both pulmonary artery constriction and transverse aortic constriction as compared with littermate controls. These results indicate that the Rho-kinase pathway plays a crucial role in RV hypertrophy and dysfunction, suggesting that the pathway is a novel therapeutic target of RV failure in humans. © 2014 American Heart Association, Inc.

The effects of intermittent negative pressure on the lower extremities' peripheral circulation and wound healing in four patients with lower limb ischemia and hard-to-heal leg ulcers: a case report.

Science.gov (United States)

Sundby, Øyvind H; Høiseth, Lars Ø; Mathiesen, Iacob; Jørgensen, Jørgen J; Sundhagen, Jon O; Hisdal, Jonny

2016-10-01

Peripheral circulation is severely compromised in the advanced stages of peripheral arterial disease. Recently, it was shown that the application of -40 mmHg intermittent negative pressure (INP) to the lower leg and foot enhances macro- and microcirculation in healthy volunteers. In this case report, we describe the effects of INP treatment on four patients with lower limb ischemia and hard-to-heal leg and foot ulcers. We hypothesized that INP therapy may have beneficial hemodynamic and clinical effects in the patients. Four patients (age range: 61-79 years) with hard-to-heal leg and foot ulcers (6-24 months) and ankle-brachial pressure indices of ≤0.60 on the affected side were included. They were treated with an 8-week intervention period of -40 mmHg INP (10 sec negative pressure and 7 sec atmospheric pressure) on the lower limbs. A custom-made vacuum chamber was used to apply INP to the affected lower leg and foot for 2 h per day. After 8 weeks of INP therapy, one ulcer healed completely, while the other three ulcers were almost completely healed. These cases suggest that INP may facilitate wound healing. The theoretical foundation is that INP assists wound healing by improving blood flow to the small blood vessels in the affected limb, increasing the flow of oxygen and nutrients to the cells. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Inelastic neutron scattering an ab-initio calculation of negative thermal expansion in Ag2O

International Nuclear Information System (INIS)

Gupta, M.K.; Mittal, R.; Rols, S.; Chaplot, S.L.

2012-01-01

The compound Ag 2 O undergoes large and isotropic negative thermal expansion over 0-500 K. We report temperature dependent inelastic neutron scattering measurements and ab-initio calculations of the phonon spectrum. The temperature dependence of the experimental phonon spectrum shows strong anharmonic nature of phonon modes of energy around 2.4 meV. The ab-initio calculations reveal that the maximum negative Grüneisen parameter, which is a measure of the relevant anharmonicity, occurs for the transverse phonon modes that involve bending motions of the Ag 4 O tetrahedra. The thermal expansion is evaluated from the ab-initio calculation of the pressure dependence of the phonon modes, and found in good agreement with available experimental data.

Negative pressure wound therapy using polyvinyl alcohol foam to bolster full-thickness mesh skin grafts in dogs.

Science.gov (United States)

Or, Matan; Van Goethem, Bart; Kitshoff, Adriaan; Koenraadt, Annika; Schwarzkopf, Ilona; Bosmans, Tim; de Rooster, Hilde

2017-04-01

To report the use of negative pressure wound therapy (NPWT) with polyvinyl alcohol (PVA) foam to bolster full-thickness mesh skin grafts in dogs. Retrospective case series. Client-owned dogs (n = 8). Full-thickness mesh skin graft was directly covered with PVA foam. NPWT was maintained for 5 days (in 1 or 2 cycles). Grafts were evaluated on days 2, 5, 10, 15, and 30 for graft appearance and graft take, granulation tissue formation, and complications. Firm attachment of the graft to the recipient bed was accomplished in 7 dogs with granulation tissue quickly filling the mesh holes, and graft take considered excellent. One dog had bandage complications after cessation of the NPWT, causing partial graft loss. The PVA foam did not adhere to the graft or damage the surrounding skin. The application of NPWT with a PVA foam after full-thickness mesh skin grafting in dogs provides an effective method for securing skin grafts, with good graft acceptance. PVA foam can be used as a primary dressing for skin grafts, obviating the need for other interposing materials to protect the graft and the surrounding skin. © 2017 The American College of Veterinary Surgeons.

Influence of operating conditions and atomizer design on circumferential liquid distribution from small pressure-swirl atomizer

Directory of Open Access Journals (Sweden)

Malý Milan

2017-01-01

Full Text Available The spray symmetry is an important aspect in most practical applications. However, it is often an overlooked parameter. A measurement of circumferential distribution was carried out by a circular-sectored vessel on several pressure-swirl atomizers with spill-line over a wide range of injection pressure. The obtained results show that the spray uniformity improves markedly with the injection pressure. The increase in a number of tangential entry ports has only a minor effect on the spray uniformity. Even a small mechanical corruption of the atomizer internal parts negatively affects the spray patternation.

Insomnia complaints in lean patients with obstructive sleep apnea negatively affect positive airway pressure treatment adherence.

Science.gov (United States)

Eysteinsdottir, Bjorg; Gislason, Thorarinn; Pack, Allan I; Benediktsdottir, Bryndís; Arnardottir, Erna S; Kuna, Samuel T; Björnsdottir, Erla

2017-04-01

The objective of this study was to evaluate the determinants of long-term adherence to positive airway pressure treatment among patients with obstructive sleep apnea, with special emphasis on patients who stop positive airway pressure treatment within 1 year. This is a prospective long-term follow-up of subjects in the Icelandic Sleep Apnea Cohort who were diagnosed with obstructive sleep apnea between 2005 and 2009, and started on positive airway pressure treatment. In October 2014, positive airway pressure adherence was obtained by systematically evaluating available clinical files (n = 796; 644 males, 152 females) with moderate to severe obstructive sleep apnea (apnea-hypopnea index ≥15 events per h). The mean follow-up time was 6.7 ± 1.2 years. In total, 123 subjects (15.5%) returned their positive airway pressure device within the first year, 170 (21.4%) returned it later and 503 (63.2%) were still using positive airway pressure. The quitters within the first year had lower body mass index, milder obstructive sleep apnea, less sleepiness, and more often had symptoms of initial and late insomnia compared with long-term positive airway pressure users at baseline. Both initial and late insomnia were after adjustment still significantly associated with being an early quitter among subjects with body mass index insomnia are associated with early quitting on positive airway pressure among non-obese subjects. © 2016 European Sleep Research Society.

The use of isoprene as a novel dopant in negative ion atmospheric pressure photoionization mass spectrometry coupled to high-performance liquid chromatography.

Science.gov (United States)

Dousty, Faezeh; O'Brien, Rob

2015-06-15

As in the case with positive ion atmospheric pressure photoionization (PI-APPI), the addition of dopants significantly improves the sensitivity of negative ion APPI (NI-APPI). However, the research on dopant-assisted-NI-APPI has been quite limited compared to the studies on dopant-assisted PI-APPI. This work presents the potential of isoprene as a novel dopant for NI-APPI. Thirteen compounds, possessing suitable gas-phase ion energetic properties in order to make stable negative ions, were selected. Dopants were continuously introduced into a tee junction prior to the ion source through a fused-silica capillary, while analytes were directly injected into the same tee. Then both were mixed with the continuous solvent from high-performance liquid chromatography (HPLC), nebulized, and entered the source. The nebulized stream was analyzed by APPI tandem quadrupole mass spectrometry in the negative ion mode. The results obtained using isoprene were compared with those obtained by using toluene as a dopant and dopant-free NI-APPI. Isoprene enhanced the ionization intensities of the studied compounds, which were found to be comparable and, in some cases, more effective than toluene. The mechanisms leading to the observed set of negative analyte ions were also discussed. Because in NI-APPI, thermal electrons, which are produced during the photoionization of a dopant, are considered the main reagent ions, both isoprene and toluene promoted the ionization of analytes through the same mechanisms, as expected. Isoprene was shown to perform well as a novel dopant for NI-APPI. Isoprene has a high photoabsorption cross section in the VUV region; therefore, its photoionization leads to a highly effective production of thermal electrons, which further promotes the ionization of analytes. In addition, isoprene is environmentally benign and less toxic compared to currently used dopants. Copyright © 2015 John Wiley & Sons, Ltd.

Negative pressure wound therapy in complex cranio-maxillofacial and cervical wounds.

Science.gov (United States)

Novelli, Giorgio; Daleffe, Francesco; Birra, Gisella; Canzi, Gabriele; Mazzoleni, Fabio; Boni, Pietro; Maino, Clara; Giussani, Carlo; Sozzi, Davide; Bozzetti, Alberto

2018-02-01

The care and the management of the healing of difficult wounds at the level of the skull-facial face many problems related to patient compliance and the need to perform multiple dressings, with long periods of healing and, occasionally, a very long hospitalisation period. The introduction and evolution of negative pressure wound therapy (NPWT) in the treatment of difficult wounds has resulted in better healing, with a drastic reduction in terms of time and biological costs to the patient and cost to the health care system. The main aim of this study is to describe and discuss, using out our experience, the usefulness of NPWT in the cranial-facial-cervical region. We studied 16 patients with complex wounds of the cranial-facial-cervical region treated with NPWT. We divided clinical cases in four groups: cervicofacial infectious disease, healing complications in oncological-reconstructive surgery, healing complications of injury with exposure of bone and/or internal fixations and healing complications in traumatic injury with loss of substance. We evaluated complete or incomplete wound healing; application time, related also to hospitalisation time; days of intensive care unit (ICU) stay; management of the upper airways; timing of medication renewal; and patient comfort and compliance (on a scale of 1-5). Depression values were always between -75 and -125 mmHg in a continuous aspiration pattern. For every patient, we used the ActiVAC Therapy Unit, derived from the vacuum-assisted closure system (Kinetic Concepts Inc., San Antonio, TX). Medication renewals were performed every 48-72 hours. The NPWT application time ranged from 4 to 22 days (mean of 11·57 day). Therapy was effective to gain a complete restitutio ad integrum in every patient included in the group of cervicofacial infectious disease. Therapy has, however, been well tolerated in our series; this is probably due to the decreased number of applications, the ease of use and the comfort of the system

Comparative Autoignition Trends in Butanol Isomers at Elevated Pressure

KAUST Repository

Weber, Bryan W.

2013-03-21

Autoignition experiments of stoichiometric mixtures of s-, t-, and i-butanol in air have been performed using a heated rapid compression machine (RCM). At compressed pressures of 15 and 30 bar and for compressed temperatures in the range 715-910 K, no evidence of a negative temperature coefficient region in terms of ignition delay response is found. The present experimental results are also compared with previously reported RCM data of n-butanol in air. The order of reactivity of the butanols is n-butanol > s-butanol ≈ i-butanol > t-butanol at the lower pressure but changes to n-butanol > t-butanol > s-butanol > i-butanol at higher pressure. In addition, t-butanol shows preignition heat release behavior, which is especially evident at higher pressures. To help identify the controlling chemistry leading to this preignition heat release, off-stoichiometric experiments are further performed at 30 bar compressed pressure, for t-butanol at φ = 0.5 and φ = 2.0 in air. For these experiments, higher fuel loading (i.e., φ = 2.0) causes greater preignition heat release (as indicated by greater pressure rise) than the stoichiometric or φ = 0.5 cases. Comparison of the experimental ignition delays with the simulated results using two literature kinetic mechanisms shows generally good agreement, and one mechanism is further used to explore and compare the fuel decomposition pathways of butanol isomers. Using this mechanism, the importance of peroxy chemistry in the autoignition of the butanol isomers is highlighted and discussed. © 2013 American Chemical Society.

If you negate, you may forget: negated repetitions impair memory compared with affirmative repetitions.

Science.gov (United States)

Mayo, Ruth; Schul, Yaacov; Rosenthal, Meytal

2014-08-01

One of the most robust laws of memory is that repeated activation improves memory. Our study shows that the nature of repetition matters. Specifically, although both negated repetition and affirmative repetition improve memory compared with no repetition, negated repetition hinders memory compared with affirmative repetition. After showing participants different entities, we asked them about features of these entities, leading to either "yes" or "no" responses. Our findings show that correctly negating an incorrect feature of an entity elicits an active forgetting effect compared with correctly affirming its true features. For example, after seeing someone drink a glass of white wine, answering "no" to "was it red wine?" may lead one to greater memory loss of the individual drinking wine at all compared with answering "yes" to "was it white wine?" We find this negation-induced forgetting effect in 4 experiments that differ in (a) the meaning given for the negation, (b) the type of stimuli (visual or verbal), and (c) the memory measure (recognition or free recall). We discuss possible underlying mechanisms and offer theoretical and applied implications of the negation-induced forgetting effect in relation to other known inhibition effects. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Pressure ulcer prevention in frail older people.

Science.gov (United States)

Barry, Maree; Nugent, Linda

2015-12-16

Pressure ulcers are painful and cause discomfort, have a negative effect on quality of life, and are costly to treat. The incidence and severity of preventable pressure ulcers is an important indicator of quality of care; it is essential that healthcare providers monitor prevalence and incidence rates to ensure that care strategies implemented are effective. Frail older people are at increased risk of developing pressure ulcers. This article discusses the complexities of preventing pressure ulcers in frail older people and emphasises the importance of structured educational programmes that incorporate effective clinical leadership and multidisciplinary teamwork.

Negative and Positive Peer Influence: Relations to Positive and Negative Behaviors for African American, European American, and Hispanic Adolescents

Science.gov (United States)

Padilla-Walker, Laura M.; Bean, Roy A.

2009-01-01

The purpose of the current study was to examine adolescents' perceptions of negative and positive peer influence (i.e., indirect peer association and direct peer pressure) as they related to adolescent behavior. Regression analyses were conducted using a sample of African American, European American, and Hispanic adolescents (N=1659, M age=16.06,…

Investigations on Cs-free alternative materials for negative hydrogen ion formation

Energy Technology Data Exchange (ETDEWEB)

Kurutz, Uwe

2017-01-19

Neutral beam injection (NBI) represents a main auxiliary heating and current drive system for thermonuclear fusion devices. For ITER, a total heating power of up to 33 MW will be delivered for up to one hour pulses at particle energies of up to 1 MeV by two NBI systems. The respective ion sources will therefore have to allow for the extraction and acceleration of negative hydrogen ions at a current density of 200 A/m{sup 2} from a low pressure low temperature hydrogen plasma. Also for the succeeding demonstration reactor DEMO the application of NBI is currently discussed. Respective systems will, however, have to fulfil even higher demands, like higher powers (up to 135 MW), longer pulse lengths (2 h or even cw operation), and more restrictive constrains regarding the reliability and stability. Today efficient NBI negative hydrogen ion sources are based mainly on the conversion of positive hydrogen ions and/or hydrogen atoms at a grid surface coated with caesium. Cs is used for reducing the grid's work function which significantly enhances the particle conversion probability. However, the alkali metal is chemically very reactive and easily forms compounds with residual gas impurities. Furthermore, complex redistribution dynamics of the deposited Cs layer is given. This inherently links the application of Cs with a temporal and spatial non-stability of the negative ion yield, which contradicts the required reliability of a DEMO NBI system. Thus, for DEMO, Cs-free alternative materials for negative ion formation are investigated within this work at a flexible laboratory experiment. An ECR discharge is used which provides comparable parameters (pressure, densities, particle fluxes and -energies) to the NBI ion sources. Negative ion formation is measured above different material samples via laser photodetachment together with global plasma parameters using a Langmuir probe and optical emission spectroscopy. The plasma parameters are used for modelling the

Investigations on Cs-free alternative materials for negative hydrogen ion formation

International Nuclear Information System (INIS)

Kurutz, Uwe

2017-01-01

Neutral beam injection (NBI) represents a main auxiliary heating and current drive system for thermonuclear fusion devices. For ITER, a total heating power of up to 33 MW will be delivered for up to one hour pulses at particle energies of up to 1 MeV by two NBI systems. The respective ion sources will therefore have to allow for the extraction and acceleration of negative hydrogen ions at a current density of 200 A/m 2 from a low pressure low temperature hydrogen plasma. Also for the succeeding demonstration reactor DEMO the application of NBI is currently discussed. Respective systems will, however, have to fulfil even higher demands, like higher powers (up to 135 MW), longer pulse lengths (2 h or even cw operation), and more restrictive constrains regarding the reliability and stability. Today efficient NBI negative hydrogen ion sources are based mainly on the conversion of positive hydrogen ions and/or hydrogen atoms at a grid surface coated with caesium. Cs is used for reducing the grid's work function which significantly enhances the particle conversion probability. However, the alkali metal is chemically very reactive and easily forms compounds with residual gas impurities. Furthermore, complex redistribution dynamics of the deposited Cs layer is given. This inherently links the application of Cs with a temporal and spatial non-stability of the negative ion yield, which contradicts the required reliability of a DEMO NBI system. Thus, for DEMO, Cs-free alternative materials for negative ion formation are investigated within this work at a flexible laboratory experiment. An ECR discharge is used which provides comparable parameters (pressure, densities, particle fluxes and -energies) to the NBI ion sources. Negative ion formation is measured above different material samples via laser photodetachment together with global plasma parameters using a Langmuir probe and optical emission spectroscopy. The plasma parameters are used for modelling the inherently

Roller pressure algometry as a new tool for assessing dynamic pressure sensitivity in migraine

DEFF Research Database (Denmark)

Guerrero-Peral, Ángel L.; Ruíz, Marina; Barón, Johanna

2018-01-01

from 500 to 5300 g. Each roller was moved at a speed of 0.5 cm/sec over a 60 mm horizontal line covering the temporalis muscle. The dynamic pain threshold (the pressure level of the first painful roller) and pain elicited during the pain threshold (roller evoked pain) were determined. Static pressure...... pain thresholds were assessed over the temporalis muscle, C5/C6 joint, second metacarpal, and tibialis anterior. Results Side-to-side consistency between dynamic pain threshold (rs = 0.769, p ... was slightly stronger in chronic migraine. Pain during dynamic pain threshold was negatively associated with widespread pressure pain thresholds (-0.336 

The impact of blood pressure on hippocampal glutamate and mnestic function.

Science.gov (United States)

Westhoff, T H; Schubert, F; Wirth, C; Joppke, M; Klär, A A; Zidek, W; Gallinat, J

2011-04-01

Hypertension is associated with an increased risk of cognitive decline, which is generally regarded as a consequence of advanced cerebral atherosclerosis. Many hypertensive patients, however, suffer from cognitive decline long before they have any signs of cerebrovascular disease. Therefore, this study examines direct effects of blood pressure on neurotransmitter status in the hippocampus, a vulnerable cerebral structure relevant for memory consolidation. Absolute glutamate concentration and N-acetylaspartate (NAA) concentration as an alternative marker of neuronal integrity were determined in the hippocampus and the cerebral cortex (anterior cingulate cortex; ACC) by 3-T proton magnetic resonance spectroscopy in 16 probands without any history of cerebrovascular disease. Memory function was tested by the auditory verbal learning test (AVLT) and the rivermead behavioural memory test (RBMT). Arterial stiffness was assessed by augmentation index (AI). Mean arterial pressure showed a significant negative age-adjusted correlation to absolute glutamate concentrations in the hippocampus (R=-0.655, P=0.011), but not in the ACC. There was no significant correlation of mean arterial pressure and NAA in either hippocampus or ACC. AI did not affect hippocampal glutamate. Moreover, there was a significant negative correlation between mean arterial pressure and AVLT (r=-0.558, P=0.025) and RBMT score (r=-0.555, P=0.026). There is an inverse relation between blood pressure and the concentration of hippocampal glutamate. Glutamate is essential for long-term potentiation, the neurobiological correlate for memory formation in the hippocampus. Thus, hypertension-associated cognitive decline may not only be mediated by structural atherosclerotic wall changes, but also by functional changes in neurotransmission.

System for keeping atmospheric pressure in nuclear facility and its peripheral equipments

International Nuclear Information System (INIS)

Matsumoto, Hatsuo

1993-02-01

The design to keep radioactive materials in the facility and not to make them spread inside the facility and into the environments is an essential issue in the construction of nuclear facilities. One reason of the contamination is due to the diffusion with air flow, therefore, negative pressure for the ambients has been utilized to keep gaseous radioactivities inside the facility of interest. The pressure difference is not so large, though, the atmospheric pressure level of the contaminated and possibly contaminated areas are always kept to be lower than those of the ambient one to prevent the dissemination of radioactivity from the defined area. The technique using negative pressure, at present, is employed widely in nuclear facilities, and the basic system is the same as that of JRR-1 built as the first nuclear facility in Japan. In the present work, the conventional system with negative pressure was reexamined on the sate-of-art of the regulations for the nuclear facilities, and consequently some shortages of the system has been found. Thus, an advanced system with an excellent performance keeping the negative pressure has been developed to cover the shortage. In this report, the new system is introduced with a couple of comments, acquired from the author's experience, to the design and the maintenance of the composite equipments of the system. (author)

Bacterial and Archaeal Communities Variability Associated with Upwelling and Anthropogenic Pressures in the Protection Area of Arraial do Cabo (Cabo Frio region - RJ).

Science.gov (United States)

Coelho-Souza, Sergio A; Araújo, Fábio V; Cury, Juliano C; Jesus, Hugo E; Pereira, Gilberto C; Guimarães, Jean R D; Peixoto, Raquel S; Dávila, Alberto M R; Rosado, Alexandre S

2015-09-01

Upwelling systems contain a high diversity of pelagic microorganisms and their composition and activity are defined by factors like temperature and nutrient concentration. Denaturing gradient gel electrophoresis (DGGE) technique was used to verify the spatial and temporal genetic variability of Bacteria and Archaea in two stations of the Arraial do Cabo coastal region, one under upwelling pressure and another under anthropogenic pressure. In addition, biotic and abiotic variables were measured in surface and deep waters from three other stations between these stations. Six samplings were done during a year and adequately represented the degrees of upwelling and anthropogenic pressures to the system. Principal Component Analysis (PCA) showed negative correlations between the concentrations of ammonia and phosphorous with prokaryotic secondary production and the total heterotrophic bacteria. PCA also showed negative correlation between temperature and the abundance of prokaryotic cells. Bacterial and archaeal compositions were changeable as were the oceanographic conditions, and upwelling had a regional pressure while anthropogenic pressure was punctual. We suggest that the measurement of prokaryotic secondary production was associated with both Bacteria and Archaea activities, and that substrate availability and temperature determine nutrients cycling.

Negative pressure wound therapy applied before and after split-thickness skin graft helps healing of Fournier gangrene: a case report (CARE-Compliant).

Science.gov (United States)

Ye, Junna; Xie, Ting; Wu, Minjie; Ni, Pengwen; Lu, Shuliang

2015-02-01

Fournier gangrene is a rare but highly infectious disease characterized by fulminant necrotizing fasciitis involving the genital and perineal regions. Negative pressure wound therapy (NPWT; KCI USA Inc, San Antonio, TX) is a widely adopted technique in many clinical settings. Nevertheless, its application and effect in the treatment of Fournier gangrene are unclear. A 47-year-old male patient was admitted with an anal abscess followed by a spread of the infection to the scrotum, which was caused by Pseudomonas aeruginosa. NPWT was applied on the surface of the scrotal area and continued for 10 days. A split-thickness skin graft from the scalp was then grafted to the wound, after which, NPWT utilizing gauze sealed with an occlusive dressing and connected to a wall suction was employed for 7 days to secure the skin graft. At discharge, the percentage of the grafted skin alive on the scrotum was 98%. The wound beside the anus had decreased to 4 × 0.5 cm with a depth of 1 cm. Follow-up at the clinic 1 month later showed that both wounds had healed. The patient did not complain of any pain or bleeding, and was satisfied with the outcome. NPWT before and after split-thickness skin grafts is safe, well tolerated, and efficacious in the treatment of Fournier gangrene.

Benchtop evaluation of pressure barrier insufflator and standard insufflator systems.

Science.gov (United States)

Nepple, Kenneth G; Kallogjeri, Dorina; Bhayani, Sam B

2013-01-01

Previous experimental research has reported minimal differences in pressure maintenance between different versions of standard insufflators (SI). However, a recent report identified potential clinical benefits with a valveless pressure barrier insufflator (PBI). We sought to perform a benchtop objective evaluation of SI and PBI systems. A rigid box system with continuous pressure manometry was used to evaluate a PBI (Surgiquest Airseal) and two SIs (SI1 = Stryker PneumoSure High Flow Insufflator and SI2 = Storz SCB Thermoflator). Pressure maintenance of 15 mmHg was evaluated during experimental conditions of leakage from a 5 mm port site, leakage from a 12 mm port site, and continuous suction. With leakage from the 5 mm port site, the PBI maintained pressure of >13 mmHg whereas the pressures dropped moderately with the SI1 (7-13 mmHg) and SI2 insufflators (3-7 mmHg) and did not regain goal pressure until leakage was stopped. With leakage from 12 mm port site, the PBI pressure decreased to 9-11 mmHg, whereas the SI1 and SI2 lost insufflation pressures completely. The PBI maintained pressure of >11 mmHg during continuous suction while the SI1 and SI2 lost pressure entirely, and actually showed negative pressure from air suction into the rigid box system. When evaluated statistically with the mixed model repeated measures ANOVA, the SI1 and SI2 performed similarly while the PBI maintained increased pressure. In the experimental rigid box system, the PBI more successfully maintained pressure in response to leakage and suction than SIs.

Hypertension in diabetes as related to nephropathy. Early blood pressure changes

DEFF Research Database (Denmark)

Feldt-Rasmussen, B; Borch-Johnsen, K; Mathiesen, E R

1985-01-01

We measured the blood pressure under standardized conditions in three groups of patients with type I (insulin-dependent) diabetes: group 1, patients with Albustix-negative urine and normal urinary albumin excretion rate below 20 micrograms/min; group 2, patients with Albustix-negative urine and e...... that arterial hypertension is an early feature in the developing of diabetic nephropathy, with blood pressure rising before the presence of clinical proteinuria.......We measured the blood pressure under standardized conditions in three groups of patients with type I (insulin-dependent) diabetes: group 1, patients with Albustix-negative urine and normal urinary albumin excretion rate below 20 micrograms/min; group 2, patients with Albustix-negative urine...... and elevated urinary albumin excretion rate 20 to 200 micrograms/min; and group 3, patients with Albustix-positive urine at the time of diagnosis of diabetic nephropathy, that is, proteinuria greater than 0.5 g/24 hr on four consecutive visits with an interval of more than 1 month. We also studied blood...

Pressure exerted by a vesicle on a surface

International Nuclear Information System (INIS)

Owczarek, A L; Prellberg, T

2014-01-01

Several recent works have considered the pressure exerted on a wall by a model polymer. We extend this consideration to vesicles attached to a wall, and hence include osmotic pressure. We do this by considering a two-dimensional directed model, namely that of area-weighted Dyck paths. Not surprisingly, the pressure exerted by the vesicle on the wall depends on the osmotic pressure inside, especially its sign. Here, we discuss the scaling of this pressure in the different regimes, paying particular attention to the crossover between positive and negative osmotic pressure. In our directed model, there exists an underlying Airy function scaling form, from which we extract the dependence of the bulk pressure on small osmotic pressures. (paper)

Mass spectrometric analysis of small negative ions (e/m < 100) produced by Trichel pulse negative corona discharge fed by ozonised air

OpenAIRE

Skalny, J.D.; Horvath, G.; Mason, N.

2007-01-01

Mass spectrometric analysis of small negative ions (e/m < 100) produced by DC negative corona discharge in ozonised wet air both in flow and flow-stopped regimes was conducted at pressure of 30 kPa. The point-to-plain electrode system has been used. The yield of individual ions is strongly affected by trace concentrations of ozone in both regimes. Ozone concentration greater than 25 ppm is sufficient to completely suppress the appearance of O2- and a NO2- ion as well as theirs clusters in the...

Wind Tunnel Tests for Wind Pressure Distribution on Gable Roof Buildings

Science.gov (United States)

2013-01-01

Gable roof buildings are widely used in industrial buildings. Based on wind tunnel tests with rigid models, wind pressure distributions on gable roof buildings with different aspect ratios were measured simultaneously. Some characteristics of the measured wind pressure field on the surfaces of the models were analyzed, including mean wind pressure, fluctuating wind pressure, peak negative wind pressure, and characteristics of proper orthogonal decomposition results of the measured wind pressure field. The results show that extremely high local suctions often occur in the leading edges of longitudinal wall and windward roof, roof corner, and roof ridge which are the severe damaged locations under strong wind. The aspect ratio of building has a certain effect on the mean wind pressure coefficients, and the effect relates to wind attack angle. Compared with experimental results, the region division of roof corner and roof ridge from AIJ2004 is more reasonable than those from CECS102:2002 and MBMA2006.The contributions of the first several eigenvectors to the overall wind pressure distributions become much bigger. The investigation can offer some basic understanding for estimating wind load distribution on gable roof buildings and facilitate wind-resistant design of cladding components and their connections considering wind load path. PMID:24082851

Diagnosing and alleviating the impact of performance pressure on mathematical problem solving.

Science.gov (United States)

DeCaro, Marci S; Rotar, Kristin E; Kendra, Matthew S; Beilock, Sian L

2010-08-01

High-pressure academic testing situations can lead people to perform below their actual ability levels by co-opting working memory (WM) resources needed for the task at hand (Beilock, 2008). In the current work we examine how performance pressure impacts WM and design an intervention to alleviate pressure's negative impact. Specifically, we explore the hypothesis that high-pressure situations trigger distracting thoughts and worries that rely heavily on verbal WM. Individuals performed verbally based and spatially based mathematics problems in a low-pressure or high-pressure testing situation. Results demonstrated that performance on problems that rely heavily on verbal WM resources was less accurate under high-pressure than under low-pressure tests. Performance on spatially based problems that do not rely heavily on verbal WM was not affected by pressure. Moreover, the more people reported worrying during test performance, the worse they performed on the verbally based (but not spatially based) maths problems. Asking some individuals to focus on the problem steps by talking aloud helped to keep pressure-induced worries at bay and eliminated pressure's negative impact on performance.

Psychomotor performance during a 28 day head-down tilt with and without lower body negative pressure

Science.gov (United States)

Traon, A. Pavy-le; de Feneyrols, A. Rous; Cornac, A.; Abdeseelam, R.; N'uygen, D.; Lazerges, M.; Güell, A.; Bes, A.

Several factors may affect psychomotor performance in space: sensory-motor changes, sleep disturbances, psychological modifications induced by the social isolation and confinement. However, psychomotor performance is difficult to assess. A battery of standardized and computerized tests, so-called "Automated Portable Test System" (APTS) was devised to ascertain the cognitive, perceptive and motor abilities and their possible fluctuations according to environmental effects. Antiorthostatic bedrest, often used to simulate weightlessness, (particularly cardiovascular modifications) also constitutes a situation of social confinement and isolation. During two bedrest experiments (with head-down tilt of -6°) of 28 days each, we intended to assess psychomotor performance of 6 males so as to determine whether: —on the one hand, it could be altered by remaining in decubitus; —on the other, the Lower Body Negative Pressure sessions, designed to prevent orthostatic intolerance back on Earth, could improve the performance. To accomplish this, part of the APTS tests as well as an automated perceptive attention test were performed. No downgrading of psychomotor performance was observed. On the contrary, the tasks were more accurately performed over time. In order to assess the experimental conditions on the acquisition phase, the learning curves were modelled. A beneficial effect of the LBNP sessions on simple tests involving the visual-motor coordination and attention faculties can only be regarded as a mere trend. Methods used in this experiment are also discussed.

[Treatment of pubic osteomyelitis secondary to pressure sores].

Science.gov (United States)

Brunel, Anne-Sophie; Téot, Luc; Lamy, Brigitte; Masson, Raphaël; Morquin, David; Reynes, Jacques; Le Moing, Vincent

2014-01-01

There is no consensus regarding the diagnostic and therapeutic strategy for pubic osteomyelitis secondary to pelvic pressure sores. Diagnosis is often difficult and bone biopsies with microbiological and anatomical-pathological examination remain the gold standard. The rate of cicatrisation of pressure sores is low. Cleansing and negative pressure treatment are key elements of the treatment. Optimising the care management with medical-surgical collaboration is being studied in the Ostear protocol.

Gram positive and Gram negative bacteria differ in their sensitivity to cold plasma

Science.gov (United States)

Mai-Prochnow, Anne; Clauson, Maryse; Hong, Jungmi; Murphy, Anthony B.

2016-12-01

Cold atmospheric-pressure plasma (CAP) is a relatively new method being investigated for antimicrobial activity. However, the exact mode of action is still being explored. Here we report that CAP efficacy is directly correlated to bacterial cell wall thickness in several species. Biofilms of Gram positive Bacillus subtilis, possessing a 55.4 nm cell wall, showed the highest resistance to CAP, with less than one log10 reduction after 10 min treatment. In contrast, biofilms of Gram negative Pseudomonas aeruginosa, possessing only a 2.4 nm cell wall, were almost completely eradicated using the same treatment conditions. Planktonic cultures of Gram negative Pseudomonas libanensis also had a higher log10 reduction than Gram positive Staphylococcus epidermidis. Mixed species biofilms of P. aeruginosa and S. epidermidis showed a similar trend of Gram positive bacteria being more resistant to CAP treatment. However, when grown in co-culture, Gram negative P. aeruginosa was more resistant to CAP overall than as a mono-species biofilm. Emission spectra indicated OH and O, capable of structural cell wall bond breakage, were present in the plasma. This study indicates that cell wall thickness correlates with CAP inactivation times of bacteria, but cell membranes and biofilm matrix are also likely to play a role.

Research on pipeline leak detection method based on pressure and dynamic pressure

Energy Technology Data Exchange (ETDEWEB)

Wang, Likun; Xiong, Min; Zhao, Jinyun; Wang, Hongchao; Xu, Bin; Yu, DongLiang; Sun, Yi; Cai, Yongjun [RnD center of PetroChina Pipeline Company, Langfang, Hebei, (China)

2010-07-01

Pipeline leakages are very frequent and need to be detected as fast as possible to avoid safety and environment issues. Many leakage detection processes have been developed. Acoustic wave methods based on static pressure and dynamic pressure are both used for pipeline leakage detection. This study investigated a new pipeline leak detection method based on joint pressure and dynamic pressure. A dynamic pressure transmitter was designed based on a piezoelectric dynamic pressure sensor. The study showed that the dynamic pressure signal should be used for pipeline leak detection with a quick-change in pipeline internal pressure, while the static pressure signal provides better results with a slow-change of pipeline internal pressure. The in-field results showed that the location error of dynamic pressure is reduced to 80 m with a leakage ratio of 0.6 % pipeline throughput.

Relationships between fluid pressure and capillary pressure in ...

African Journals Online (AJOL)

In this work, the Bower's and Gardner's technique of velocity-to fluid pressure gradient methods were applied on seismic reflection data in order to predict fluid pressure of an X- oil field in Niger Delta Basin. Results show significant deflection common with fluid pressure zones . With average connate water saturation Swc ...

Effect of Large Negative Phase of Blast Loading on Structural Response of RC Elements

Directory of Open Access Journals (Sweden)

Syed Zubair Iman

2016-01-01

Full Text Available Structural response of reinforced concrete (RC elements for analysis and design are often obtained using the positive phase of the blast pressure curve disregarding the negative phase assuming insignificant contribution from the negative phase of the loading. Although, some insight on the effect of negative phase of blast pressure based on elastic single-degree-of-freedom (SDOF analysis was presented before, the influence of negative phase on different types of resistance functions of SDOF models and on realistic finite element analysis has not been explored. In this study, the effects of inclusion of pulse negative phase on structural response of RC elements from SDOF analysis and from more detailed finite element analysis have been investigated. Investigation of SDOF part has been conducted using MATLAB code that utilizes non-linear resistance functions of SDOF model. Detailed numerical investigation using finite element code DIANA was conducted on the significance of the negative phase on structural response. In the FE model, different support stiffness was used to explore the effect of support stiffness on the structural response due to blast negative phase. Results from SDOF and FE analyses present specific situations where the effect of large negative phase was found to be significant on the structural response of RC elements.

Investigation of a large volume negative hydrogen ion source

International Nuclear Information System (INIS)

Courteille, C.; Bruneteau, A.M.; Bacal, M.

1995-01-01

The electron and negative ion densities and temperatures are reported for a large volume hybrid multicusp negative ion source. Based on the scaling laws an analysis is made of the plasma formation and loss processes. It is shown that the positive ions are predominantly lost to the walls, although the observed scaling law is n + ∝I 0.57 d . However, the total plasma loss scales linearly with the discharge current, in agreement with the theoretical model. The negative ion formation and loss is also discussed. It is shown that at low pressure (1 mTorr) the negative ion wall loss becomes a significant part of the total loss. The dependence of n - /n e versus the electron temperature is reported. When the negative ion wall loss is negligible, all the data on n - /n e versus the electron temperatures fit a single curve. copyright 1995 American Institute of Physics

Pressure tube reactor

International Nuclear Information System (INIS)

Susuki, Akira; Murata, Shigeto; Minato, Akihiko.

1993-01-01

In a pressure tube reactor, a reactor core is constituted by arranging more than two units of a minimum unit combination of a moderator sealing pipe containing a calandria tube having moderators there between and a calandria tube and moderators. The upper header and a lower header of the calandria tank containing moderators are communicated by way of the moderator sealing tube. Further, a gravitationally dropping mechanism is disposed for injecting neutron absorbing liquid to a calandria gas injection portion. A ratio between a moderator volume and a fuel volume is defined as a function of the inner diameter of the moderator sealing tube, the outer diameter of the calandria tube and the diameter of fuel pellets, and has no influence to intervals of a pressure tube lattice. The interval of the pressure tube lattice is enlarged without increasing the size of the pressure tube, to improve production efficiency of the reactor and set a coolant void coefficient more negative, thereby enabling to improve self controllability and safety. Further, the reactor scram can be conducted by injecting neutron absorbing liquid. (N.H.)

Edema pulmonar por pressão negativa após extubação traqueal: relato de caso Negative pressure pulmonary edema after tracheal extubation: case report

Directory of Open Access Journals (Sweden)

Fabiano Timbó Barbosa

2007-03-01

Full Text Available JUSTIFICATIVA E OBJETIVOS: O edema pulmonar por pressão negativa após obstrução de via aérea é atualmente uma entidade bem descrita, porém pouco diagnosticada e com poucos casos relatados. O objetivo deste artigo foi relatar um caso de edema pulmonar por pressão negativa (EPPN após extubação traqueal com sucesso terapêutico, após uso de ventilação mecânica não-invasiva com pressão positiva. RELATO DO CASO: Paciente do sexo feminino, 22 anos, foi submetida à colecistectomia aberta. Os exames pré-operatórios encontravam-se sem alterações. Imediatamente após extubação a paciente apresentou dispnéia súbita e crepitações pulmonares. Foi iniciado tratamento para edema agudo de pulmão com oxigenoterapia sob máscara de Venturi, elevação do tórax e diurético. A paciente foi encaminhada a UTI devido a falha no tratamento. Ao chegar a UTI foi iniciada ventilação mecânica não-invasiva (VMNI com pressão de suporte (15 cmH2O e pressão expiratória final positiva (5 cmH2O com resolução dos sintomas. A paciente foi mantida em observação por mais 24 horas depois do evento com boas condições e recebeu alta para o quarto sem sintomas. CONCLUSÕES: O EPPN é uma entidade de difícil diagnóstico e deverá ser observada sempre que os pacientes evoluem com sinais e sintomas de insuficiência respiratória pós-extubação. Esta paciente se beneficiou de VMNI, mas caso haja falha terapêutica, a intubação traqueal e o suporte ventilatório mecânico invasivo deverão ser instituídos para melhor oxigenação dos pacientes.BACKGROUND AND OBJECTIVES: Negative pressure pulmonary edema after acute upper airway obstruction is a well-described event, thought infrequently diagnosed and reported. This report aimed at presenting a case of postextubation negative pressure pulmonary edema refractory to use of diuretics and with successful therapeutic after using positive pressure noninvasive mechanic ventilation. CASE REPORT: A

Comparison of measured and modelled negative hydrogen ion densities at the ECR-discharge HOMER

Energy Technology Data Exchange (ETDEWEB)

Rauner, D.; Kurutz, U.; Fantz, U. [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); AG Experimentelle Plasmaphysik, Universität Augsburg, 86135 Augsburg (Germany)

2015-04-08

As the negative hydrogen ion density n{sub H{sup −}} is a key parameter for the investigation of negative ion sources, its diagnostic quantification is essential in source development and operation as well as for fundamental research. By utilizing the photodetachment process of negative ions, generally two different diagnostic methods can be applied: via laser photodetachment, the density of negative ions is measured locally, but only relatively to the electron density. To obtain absolute densities, the electron density has to be measured additionally, which induces further uncertainties. Via cavity ring-down spectroscopy (CRDS), the absolute density of H{sup −} is measured directly, however LOS-averaged over the plasma length. At the ECR-discharge HOMER, where H{sup −} is produced in the plasma volume, laser photodetachment is applied as the standard method to measure n{sub H{sup −}}. The additional application of CRDS provides the possibility to directly obtain absolute values of n{sub H{sup −}}, thereby successfully bench-marking the laser photodetachment system as both diagnostics are in good agreement. In the investigated pressure range from 0.3 to 3 Pa, the measured negative hydrogen ion density shows a maximum at 1 to 1.5 Pa and an approximately linear response to increasing input microwave powers from 200 up to 500 W. Additionally, the volume production of negative ions is 0-dimensionally modelled by balancing H{sup −} production and destruction processes. The modelled densities are adapted to the absolute measurements of n{sub H{sup −}} via CRDS, allowing to identify collisions of H{sup −} with hydrogen atoms (associative and non-associative detachment) to be the dominant loss process of H{sup −} in the plasma volume at HOMER. Furthermore, the characteristic peak of n{sub H{sup −}} observed at 1 to 1.5 Pa is identified to be caused by a comparable behaviour of the electron density with varying pressure, as n{sub e} determines

Cavitation inception by the backscattering of pressure waves from a bubble interface

Energy Technology Data Exchange (ETDEWEB)

Takahira, Hiroyuki, E-mail: takahira@me.osakafu-u.ac.jp; Ogasawara, Toshiyuki, E-mail: oga@me.osakafu-u.ac.jp; Mori, Naoto, E-mail: su101064@edu.osakafu-u.ac.jp; Tanaka, Moe [Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531 (Japan)

2015-10-28

The secondary cavitation that occurs by the backscattering of focused ultrasound from a primary cavitation bubble caused by the negative pressure part of the ultrasound (Maxwell, et al., 2011) might be useful for the energy exchange due to bubble oscillations in High Intensity Focused Ultrasound (HIFU). The present study is concerned with the cavitation inception by the backscattering of ultrasound from a bubble. In the present experiment, a laser-induced bubble which is generated by a pulsed focused laser beam with high intensity is utilized as a primary cavitation bubble. After generating the bubble, focused ultrasound is emitted to the bubble. The acoustic field and the bubble motion are observed with a high-speed video camera. It is confirmed that the secondary cavitation bubble clouds are generated by the backscattering from the laser-induced bubble. The growth of cavitation bubble clouds is analyzed with the image processing method. The experimental results show that the height and width of the bubble clouds grow in stepwise during their evolution. The direct numerical simulations are also conducted for the backscattering of incident pressure waves from a bubble in order to evaluate a pressure field near the bubble. It is shown that the ratio of a bubble collapse time t{sub 0} to a characteristic time of wave propagation t{sub S}, η = t{sub 0}/t{sub s}, is an important determinant for generating negative pressure region by backscattering. The minimum pressure location by the backscattering in simulations is in good agreement with the experiment.

On the pressure evolution of dynamic properties of supercooled liquids

Energy Technology Data Exchange (ETDEWEB)

Drozd-Rzoska, Aleksandra; Rzoska, Sylwester J [Institute of Physics, Silesian University, ulica Uniwersytecka 4, 40-007 Katowice (Poland); Roland, C Michael [Naval Research Laboratory, Chemistry Division, Code 6120, Washington, DC 20375-5342 (United States); Imre, Attila R [KFKI Atomic Energy Research Institute, 1525 Budapest, POB 49 (Hungary)

2008-06-18

A pressure counterpart of the Vogel-Fulcher-Tammann (VFT) equation for representing the evolution of dielectric relaxation times or related dynamic properties is discussed: {tau}(P) = {tau}{sub 0}{sup P}exp[D{sub P}{delta}P(P{sub 0}-{delta}P)], where {delta}P = P-P{sub SL}, P{sub 0} is the ideal glass pressure estimation, D{sub P} is the pressure fragility strength coefficient, and the prefactor {tau}{sub 0}{sup P} is related to the relaxation time at the stability limit (P{sub SL}) in the negative pressure domain. The discussion is extended to the Avramov model (AvM) relation {tau}(T,P) = {tau}{sub 0}exp[{epsilon}(T{sub g}(P)/T){sup D}], supplemented with a modified Simon-Glatzel-type equation for the pressure dependence of the glass temperature (T{sub g}(P)), enabling an insight into the negative pressure region. A recently postulated (Dyre 2006 Rev. Mod. Phys. 78 953) comparison between the VFT and the AvM-type descriptions is examined, for both the temperature and the pressure paths. Finally, we address the question 'Does fragility depend on pressure?' from the title of Paluch M et al (2001 J. Chem. Phys. 114 8048) and propose a pressure counterpart for the 'Angell plot'.

Stability of negative central magnetic shear discharges in the DIII-D tokamak

International Nuclear Information System (INIS)

Strait, E.J.; Chu, M.S.; Ferron, J.R.

1996-12-01

Discharges with negative central magnetic shear (NCS) hold the promise of enhanced fusion performance in advanced tokamaks. However, stability to long wavelength magnetohydrodynamic modes is needed to take advantage of the improved confinement found in NCS discharges. The stability limits seen in DIII-D experiments depend on the pressure and current density profiles and are in good agreement with stability calculations. Discharges with a strongly peaked pressure profile reach a disruptive limit at low beta, β N = β (I/aB) -1 ≤ 2.5 (% m T/MA), caused by an n = 1 ideal internal kink mode or a global resistive instability close to the ideal stability limit. Discharges with a broad pressure profile reach a soft beta limit at significantly higher beta, β N = 4 to 5, usually caused by instabilities with n > 1 and usually driven near the edge of the plasma. With broad pressure profiles, the experimental stability limit is independent of the magnitude of negative shear but improves with the internal inductance, corresponding to lower current density near the edge of the plasma. Understanding of the stability limits in NCS discharges has led to record DIII-D fusion performance in discharges with a broad pressure profile and low edge current density

Path-integral simulation of ice Ih: The effect of pressure

Science.gov (United States)

Herrero, Carlos P.; Ramírez, Rafael

2011-12-01

The effect of pressure on structural and thermodynamic properties of ice Ih has been studied by means of path-integral molecular dynamics simulations at temperatures between 50 and 300 K. Interatomic interactions were modeled by using the effective q-TIP4P/F potential for flexible water. Positive (compression) and negative (tension) pressures have been considered, which allowed us to approach the limits for the mechanical stability of this solid water phase. We have studied the pressure dependence of the crystal volume, bulk modulus, interatomic distances, atomic delocalization, and kinetic energy. The spinodal point at both negative and positive pressures is derived from the vanishing of the bulk modulus. For P300 K. At positive pressure the spinodal is associated with ice amorphization, and at low temperatures it is found to be between 1.1 and 1.3 GPa. Quantum nuclear effects cause a reduction of the metastability region of ice Ih.

Effect of flow rate and temperature on transmembrane blood pressure drop in an extracorporeal artificial lung.

Science.gov (United States)

Park, M; Costa, E L V; Maciel, A T; Barbosa, E V S; Hirota, A S; Schettino, G de P; Azevedo, L C P

2014-11-01

Transmembrane pressure drop reflects the resistance of an artificial lung system to blood transit. Decreased resistance (low transmembrane pressure drop) enhances blood flow through the oxygenator, thereby, enhancing gas exchange efficiency. This study is part of a previous one where we observed the behaviour and the modulation of blood pressure drop during the passage of blood through artificial lung membranes. Before and after the induction of multi-organ dysfunction, the animals were instrumented and analysed for venous-venous extracorporeal membrane oxygenation, using a pre-defined sequence of blood flows. Blood flow and revolutions per minute (RPM) of the centrifugal pump varied in a linear fashion. At a blood flow of 5.5 L/min, pre- and post-pump blood pressures reached -120 and 450 mmHg, respectively. Transmembrane pressures showed a significant spread, particularly at blood flows above 2 L/min; over the entire range of blood flow rates, there was a positive association of pressure drop with blood flow (0.005 mmHg/mL/minute of blood flow) and a negative association of pressure drop with temperature (-4.828 mmHg/(°Celsius). These associations were similar when blood flows of below and above 2000 mL/minute were examined. During its passage through the extracorporeal system, blood is exposed to pressure variations from -120 to 450 mmHg. At high blood flows (above 2 L/min), the drop in transmembrane pressure becomes unpredictable and highly variable. Over the entire range of blood flows investigated (0-5500 mL/min), the drop in transmembrane pressure was positively associated with blood flow and negatively associated with body temperature. © The Author(s) 2014.

Negative pressure wound therapy after partial diabetic foot amputation: a multicentre, randomised controlled trial.

Science.gov (United States)

Armstrong, David G; Lavery, Lawrence A

2005-11-12

Diabetic foot wounds, particularly those secondary to amputation, are very complex and difficult to treat. We investigated whether negative pressure wound therapy (NPWT) improves the proportion and rate of wound healing after partial foot amputation in patients with diabetes. We enrolled 162 patients into a 16-week, 18-centre, randomised clinical trial in the USA. Inclusion criteria consisted of partial foot amputation wounds up to the transmetatarsal level and evidence of adequate perfusion. Patients who were randomly assigned to NPWT (n=77) received treatment with dressing changes every 48 h. Control patients (n=85) received standard moist wound care according to consensus guidelines. NPWT was delivered through the Vacuum Assisted Closure (VAC) Therapy System. Wounds were treated until healing or completion of the 112-day period of active treatment. Analysis was by intention to treat. This study has been registered with , number NCT00224796. More patients healed in the NPWT group than in the control group (43 [56%] vs 33 [39%], p=0.040). The rate of wound healing, based on the time to complete closure, was faster in the NPWT group than in controls (p=0.005). The rate of granulation tissue formation, based on the time to 76-100% formation in the wound bed, was faster in the NPWT group than in controls (p=0.002). The frequency and severity of adverse events (of which the most common was wound infection) were similar in both treatment groups. NPWT delivered by the VAC Therapy System seems to be a safe and effective treatment for complex diabetic foot wounds, and could lead to a higher proportion of healed wounds, faster healing rates, and potentially fewer re-amputations than standard care.

Clinical Features of Patients with Diffuse Alveolar Hemorrhage due to Negative-Pressure Pulmonary Edema.

Science.gov (United States)

Contou, Damien; Voiriot, Guillaume; Djibré, Michel; Labbé, Vincent; Fartoukh, Muriel; Parrot, Antoine

2017-08-01

Diffuse alveolar hemorrhage (DAH) with negative-pressure pulmonary edema (NPPE) is an uncommon yet life-threatening condition. We aimed at describing the circumstances, clinical, radiological, and bronchoscopic features, as well as the outcome of patients with NPPE-related DAH. We performed a retrospective, observational cohort study, using data prospectively collected over 35 years in an intensive care unit (ICU). Of the 149 patients admitted for DAH, we identified 18 NPPE episodes in 15 patients, one admitted four times for recurrent NPPE-related DAH. The patients were primarily young, male, and athletic. The NPPE setting was postoperative (n = 12/18, 67%) or following generalized tonic-clonic seizures (n = 6/18, 33%). Hemoptysis was almost constant (n = 17/18, 94%), yet rarely massive (>200 cc, n = 1/18, 6%), with anemia observed in 10 (56%) episodes. The DAH triad (hemoptysis, anemia, and pulmonary infiltrates) was observed in 50% of episodes (n = 9/18), and acute respiratory failure in 94% (n = 17/18). Chest computed tomography revealed diffuse bilateral ground glass opacities (n = 10/10, 100%), while bronchoscopy detected bilateral hemorrhage (n = 12/12, 100%) and macroscopically bloody bronchoalveolar lavage, with siderophage absence in most (n = 7/8, 88%), indicating acute DAH. While one episode proved fatal, the other 17 recovered rapidly, with a mean ICU stay lasting 4.6 (2-15) days. Typically, the evolution was rapidly favorable under supportive care. NPPE-related DAH is a rare life-threatening condition occurring primarily after tonic-clonic generalized seizure or generalized anesthesia. Clinical circumstances are a key to its diagnosis. Early diagnosis and recognition likely allow for successful management of this potentially serious complication, whereas ictal-DAH appears ominous in epileptic patients.

Tratamiento mediante terapia de presión negativa VAC® de herida infectada tras artrodesis raquídea Treatment of infected wound secondary to spinal arthrodesis with negative pressure therapy VAC®

Directory of Open Access Journals (Sweden)

V. Yuste Benavente

2011-12-01

Full Text Available Las complicaciones cutáneas secundarias a artrodesis raquídea son un problema frecuente que requiere la colaboración de los Servicios de Cirugía Plástica y en cuyo tratamiento la terapia de presión negativa puede resultar útil. En este artículo presentamos el caso de un paciente afectado por metástasis vertebrales de adenocarcinoma gástrico que requirió artrodesis raquídea y desarrolló posteriormente una úlcera por presión dorsal debido al material implantado. El sistema VAC® permitió la limpieza y disminución de tamaño de la lesión, siendo posible la cobertura posterior de la misma con un colgajo miocutáneo de dorsal ancho. En este artículo discutimos la utilidad de la terapia de presión negativa en este tipo de lesiones.Cutaneous complications secondary to spinal fusion are a common problem that requires the collaboration of the Department of Plastic Surgery and in which negative pressure therapy treatment may be useful. In this paper we present the case of a patient with spinal metastases secondary to gastric adenocarcinoma that required spinal fusion and developed a dorsal pressure ulcer secondary to the implanted material. VAC® therapy system allowed cleaning the wound and decreasing the size of the injury, thus making it possible subsequently to cover it with a latissimus dorsi myocutaneous flap. In this paper we discuss the usefulness of negative pressure therapy in this type of injury.

Negative corona discharges modelling. Application to the electrostatic precipitation

International Nuclear Information System (INIS)

Gaychet, S.

2010-01-01

Electrostatic precipitation presents many advantages from the nuclear wastes treatment's point of view. Indeed, this kind of process can capture submicron particles without producing secondary wastes (no filter media) and without pressure looses in the exhaust circuit. The work presented in this thesis concerns the study of negative corona discharges in air at atmospheric pressure occurring in an electrostatic precipitator (ESP) developed by the CEA (Atomic Energy Committee). The aim of this study is to determine how the electrostatic precipitation dedicated phenomena, especially the specific high voltage generator, the gas temperature and the fact that particles are flowing through the gap then collapsing on the electrodes, modify the discharge to improve the efficiency of ESPs. This work is based on a fundamental experimental study of the negative corona discharge and on numerical simulations of this discharge under conditions close to those of the lab scale ESP developed by the CEA. (author) [fr

Fluid Redistribution and Heart Rate in Humans During Whole-Body Tilting, G(z) Centrifugation, and Lower Body Negative Pressure

Science.gov (United States)

Watenpaugh, D. E.; Breit, G. A.; Ballard, R. E.; Murthy, G.; Hargens, A. R.

1994-01-01

Gravity creates blood pressure gradients which redistribute body fluids towards the feet. Positive G(z) centrifugation and lower body negative pressure (LBNP) have been proposed to simulate these and other effects of gravity during long-term existence in microgravity. We hypothesized that the magnitude of upper-to-lower body fluid redistribution would increase according to the following order: short-arm centrifugation (SAC), long-arm centrifugation (LAC), head-up tilt (HUT), and LBNP. To test this hypothesis, we employed strain gauge plethysmography of the neck, thigh and calf during HUT and supine SAC and LAC up to lG(z) at the feet, and during supine LBNP to 100 mm Hg. Supine 100 mm Hg LBNP generates footward force and produces transmural blood pressures in the foot approximately equal to 1 G(z) (90 deg) HUT. Heart rate was measured via cardiotachometry. Control measurements were made while supine. SAC and LAC elicited similar increases in thigh volume at 1 G(z) (2.3 +/- 0.4 and 2.1 +/- 0.1%, respectively; mean +/- se, n greater than or equal to 7). At 100 mm Hg LBNP, thigh volume increased (3.4 +/- 0.3%) significantly more than during l G(z) centrifugation (p less than 0.05). Surprisingly, due to a paradoxical 0.6% reduction of thigh volume between 0.8 and 1.0 G(z) HUT, thigh volume was increased only 0.6 +/- 0.3% at 1 G(z) HUT. The calf demonstrated similar, although less definitive, responses to the various gravitational stimuli. Neck volume tended to decrease less during HUT than during the other stimuli. Heart rate increased similarly during HUT (18 +/- 2 beats/min) and LAC (12 +/- 2 beats/min), and exhibited still greater elevation during LBNP (29 +/- 4 beats/min), yet did not increase during SAC. These results suggest upright posture activates mechanisms that counteract footward fluid redistribution which are not activated during supine applications of simulated gravity. LAC more closely approximated effects of normal gravity (HUT) than LBNP. Therefore

Negative pressure wound therapy literature review of efficacy, cost effectiveness, and impact on patients' quality of life in chronic wound management and its implementation in the United kingdom.

Science.gov (United States)

Othman, Diaa

2012-01-01

This is a paper reviewing the National Health Service (NHS) agenda in relation to the use of Negative Pressure Wound Therapy (NPWT) in chronic wound management and assesses the evidence behind it, its cost effectiveness and the outcome it has on patients' satisfaction and life style. Multiple studies over the last 10 years looking at clinical efficacy of NPWT with its cost effectiveness and the implementation of this service in the UK were reviewed. NPWT has showed a reasonable body of evidence to support its usage in chronic wounds with potential positive outcomes on finance and patients' satisfaction. However, the NHS system shows significant variations in the availability and implementation of this useful tool, depending on care providers and resources availabilities. The paper concluded that the NPWT can be a useful source of cutting down costs of chronic wound managements and saving money by its effect on expediting wound healing, which can address a part of the financial crises facing the NHS, however, has to be considered according to specific case needs. There should also be a national standard for the availability and indication of this tool to assure equal opportunities for different patients in different areas in the country.

Negative Pressure Wound Therapy Literature Review of Efficacy, Cost Effectiveness, and Impact on Patients' Quality of Life in Chronic Wound Management and Its Implementation in the United Kingdom

Directory of Open Access Journals (Sweden)

Diaa Othman

2012-01-01

Full Text Available This is a paper reviewing the National Health Service (NHS agenda in relation to the use of Negative Pressure Wound Therapy (NPWT in chronic wound management and assesses the evidence behind it, its cost effectiveness and the outcome it has on patients’ satisfaction and life style. Multiple studies over the last 10 years looking at clinical efficacy of NPWT with its cost effectiveness and the implementation of this service in the UK were reviewed. NPWT has showed a reasonable body of evidence to support its usage in chronic wounds with potential positive outcomes on finance and patients’ satisfaction. However, the NHS system shows significant variations in the availability and implementation of this useful tool, depending on care providers and resources availabilities. The paper concluded that the NPWT can be a useful source of cutting down costs of chronic wound managements and saving money by its effect on expediting wound healing, which can address a part of the financial crises facing the NHS, however, has to be considered according to specific case needs. There should also be a national standard for the availability and indication of this tool to assure equal opportunities for different patients in different areas in the country.

Counteracting negative venous line pressures to avoid arterial air bubbles: an experimental study comparing two different types of miniaturized extracorporeal perfusion systems.

Science.gov (United States)

Aboud, Anas; Mederos-Dahms, Hendrikje; Liebing, Kai; Zittermann, Armin; Schubert, Harald; Murray, Edward; Renner, Andre; Gummert, Jan; Börgermann, Jochen

2015-05-29

Because of its low rate of clinical complications, miniaturized extracorporeal perfusion systems (MEPS) are frequently used in heart centers worldwide. However, many recent studies refer to the higher probability of gaseous microemboli formation by MEPS, caused by subzero pressure values. This is the main reason why various de-airing devices were developed for today's perfusion systems. In the present study, we investigated the potential benefits of a simple one-way-valve connected to a volume replacement reservoir (OVR) for volume and pressure compensation. In an experimental study on 26 pigs, we compared MEPS (n = 13) with MEPS plus OVR (n = 13). Except OVR, perfusion equipment was identical in both groups. Primary endpoints were pressure values in the venous line and the right atrium as well as the number and volume of air bubbles. Secondary endpoints were biochemical parameters of systemic inflammatory response, ischemia, hemodilution and hemolysis. One animal was lost in the MEPS + OVR group. In the MEPS + OVR group no pressure values below -150 mmHg in the venous line and no values under -100 mmHg in right atrium were noticed. On the contrary, nearly 20% of venous pressure values in the MEPS group were below -150 and approximately 10% of right atrial pressure values were below -100 mmHg. Compared with the MEPS group, the bubble counter device showed lower numbers of arterial air bubbles in the MEPS + OVR group (mean ± SD: 13444 ± 5709 vs. 1 ± 2, respectively; p pressures and to reduce the number and volume of arterial air bubbles. This approach may lead to a lower rate of neurological complications.

Sensitivity enhancement using annealed polymer optical fibre based sensors for pressure sensing applications

DEFF Research Database (Denmark)

Pospori, A.; Marques, C. A. F.; Saez-Rodriguez, D.

2016-01-01

for that investigation was an unexpected behaviour observed in an array of sensors which were used for liquid level monitoring. One sensor exhibited much lower pressure sensitivity and that was the only one that was not annealed. To further investigate the phenomenon, additional sensors were photo...... sensitivity of the devices. This can provide better performing sensors for use in stress, force and pressure sensing applications.......Thermal annealing can be used to induce a permanent negative Bragg wavelength shift for polymer fibre grating sensors and it was originally used for multiplexing purposes. Recently, researchers showed that annealing can also provide additional benefits, such as strain and humidity sensitivity...

Social Stress Induced Pressure Breathing and Consequent Blood Pressure Oscillation

NARCIS (Netherlands)

Fokkema, Dirk S.; Koolhaas, Jaap M.; Meulen, Jan van der; Schoemaker, Regien

1986-01-01

A large amplitude blood pressure oscillation occurs during social defeat in a territorial fight between male rats, and during the application of a psychosocial stimulus associated with this defeat. Synchronous recording of blood pressure, intrathoracic pressure and diaphragm activity shows that the

Negative Knudsen force on heated microbeams

KAUST Repository

Zhu, Taishan

2011-11-18

Knudsen force acting on a heated microbeam adjacent to a cold substrate in a rarefied gas is a mechanical force created by unbalanced thermal gradients. The measured force has its direction pointing towards the side with a lower thermal gradient and its magnitude vanishes in both continuum and free-molecule limits. In our previous study, negative Knudsen forces were discovered at the high Knudsen regime before diminishing in the free-molecule limit. Such a phenomenon was, however, neither observed in experiment [A. Passian et al., Phys. Rev. Lett. 90, 124503 (2003)], nor captured in the latest numerical study [J. Nabeth et al., Phys. Rev. E 83, 066306 (2011)]. In this paper, the existence of such a negative Knudsen force is further confirmed using both numerical simulation and theoretical analysis. The asymptotic order of the Knudsen force near the collisionless limit is analyzed and the analytical expression of its leading term is provided, from which approaches for the enhancement of negative Knudsen forces are proposed. The discovered phenomenon could find its applications in novel mechanisms for pressure sensing and actuation.

Acute effects of capsaicin on energy expenditure and fat oxidation in negative energy balance.

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Pilou L H R Janssens

Full Text Available BACKGROUND: Addition of capsaicin (CAPS to the diet has been shown to increase energy expenditure; therefore capsaicin is an interesting target for anti-obesity therapy. AIM: We investigated the 24 h effects of CAPS on energy expenditure, substrate oxidation and blood pressure during 25% negative energy balance. METHODS: Subjects underwent four 36 h sessions in a respiration chamber for measurements of energy expenditure, substrate oxidation and blood pressure. They received 100% or 75% of their daily energy requirements in the conditions '100%CAPS', '100%Control', '75%CAPS' and '75%Control'. CAPS was given at a dose of 2.56 mg (1.03 g of red chili pepper, 39,050 Scoville heat units (SHU with every meal. RESULTS: An induced negative energy balance of 25% was effectively a 20.5% negative energy balance due to adapting mechanisms. Diet-induced thermogenesis (DIT and resting energy expenditure (REE at 75%CAPS did not differ from DIT and REE at 100%Control, while at 75%Control these tended to be or were lower than at 100%Control (p = 0.05 and p = 0.02 respectively. Sleeping metabolic rate (SMR at 75%CAPS did not differ from SMR at 100%CAPS, while SMR at 75%Control was lower than at 100%CAPS (p = 0.04. Fat oxidation at 75%CAPS was higher than at 100%Control (p = 0.03, while with 75%Control it did not differ from 100%Control. Respiratory quotient (RQ was more decreased at 75%CAPS (p = 0.04 than at 75%Control (p = 0.05 when compared with 100%Control. Blood pressure did not differ between the four conditions. CONCLUSION: In an effectively 20.5% negative energy balance, consumption of 2.56 mg capsaicin per meal supports negative energy balance by counteracting the unfavorable negative energy balance effect of decrease in components of energy expenditure. Moreover, consumption of 2.56 mg capsaicin per meal promotes fat oxidation in negative energy balance and does not increase blood pressure significantly. TRIAL REGISTRATION

The face of appearance-related social pressure: gender, age and body mass variations in peer and parental pressure during adolescence.

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Helfert, Susanne; Warschburger, Petra

2013-05-17

Appearance-related social pressure plays an important role in the development of a negative body image and self-esteem as well as severe mental disorders during adolescence (e.g. eating disorders, depression). Identifying who is particularly affected by social pressure can improve targeted prevention and intervention, but findings have either been lacking or controversial. Thus the aim of this study is to provide a detailed picture of gender, weight, and age-related variations in the perception of appearance-related social pressure by peers and parents. 1112 German students between grades 7 and 9 (mean age: M = 13.38, SD = .81) filled in the Appearance-Related Social Pressure Questionnaire (German: FASD), which considers different sources (peers, parents) as well as various kinds of social pressure (e.g. teasing, modeling, encouragement). Girls were more affected by peer pressure, while gender differences in parental pressure seemed negligible. Main effects of grade-level suggested a particular increase in indirect peer pressure (e.g. appearance-related school and class norms) from early to middle adolescence. Boys and girls with higher BMI were particularly affected by peer teasing and exclusion as well as by parental encouragement to control weight and shape. The results suggest that preventive efforts targeting body concerns and disordered eating should bring up the topic of appearance pressure in a school-based context and should strengthen those adolescents who are particularly at risk - in our study, girls and adolescents with higher weight status. Early adolescence and school transition appear to be crucial periods for these efforts. Moreover, the comprehensive assessment of appearance-related social pressure appears to be a fruitful way to further explore social risk-factors in the development of a negative body image.

Glassy selenium at high pressure: Le Chatelier's principle still works

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Brazhkin, V. V.; Tsiok, O. B.

2017-10-01

Selenium is the only easily vitrified elementary substance. Numerous experimental studies of glassy Se (g -Se) at high pressures show a large spread in the data on the compressibility and electrical resistivity of g -Se. Furthermore, H. Liu et al. [Proc. Natl. Acad. Sci. USA 105, 13229 (2008), 10.1073/pnas.0806857105] have arrived at the surprising conclusion that the volume of glass increases during pressure-induced crystallization. We have performed high-precision measurements of the specific volume and electrical resistivity of glassy selenium (g -Se) at high hydrostatic pressures up to 9 GPa. The measured bulk modulus at normal pressure is B =(9.0 5 ±0.15 ) GPa and its pressure derivative is BP'=6.4 ±0.2 . In the pressure range P <3 GPa, glassy selenium has an anomalously large negative second derivative of the bulk modulus. The electrical resistivity of g -Se decreases almost exponentially with increasing pressure and reaches 20 Ω cm at a pressure of 8.75 GPa. The inelastic behavior and weak relaxation of the volume for g -Se begin at pressures above 3.5 GPa; the volume and logarithm of the electrical resistivity relax significantly (logarithmically with the time) at pressures above 8 GPa. Bulk measurements certainly indicate that the volume of g -Se glass in the crystallization pressure range is larger than the volumes of both appearing crystalline phases (by 2% and 4%). Therefore, the "volume expansion phenomenon" suggested in [H. Liu et al., Proc. Natl. Acad. Sci. USA 105, 13229 (2008), 10.1073/pnas.0806857105] is not observed, and the pressure-induced crystallization of glassy selenium is consistent with the laws of thermodynamics.

[Blood pressure was associated with body mass but no with pre- and postnatal growth in Mexican school-children].

Science.gov (United States)

Cruz Angeles, Laura Isabel; Ortiz-Hernández, Luis

2006-01-01

1) To know the prevalence of malnourishment and high values of arterial blood pressure in schoolchildren of Xochimilco county, Mexico. 2) To analyze the association of pre- and postnatal growth and the body mass with high values of blood pressure. It is a cross-sectional, observational and analytic study. During the elective year 2003-2004, 972 students of Xochimilco county was studied. The independent variables was age, sex, intrauterine and infant growth, body mass, body fat and socioeconomic status. It was assessed the relationship between the independent variables and the values of blood pressure by a logistic regression model. The indicators of intrauterine (birth weight and length) and infantile (head circumference and height-for-age index) growth were not associated with the high levels of systolic and diastolic blood pressure. After adjusted other variables, women had more risk to show high levels of systolic blood pressure, as the overweight children had more risk to show high blood pressure systolic and diastolic levels. In the students the overweight and obesity increase the probability to show high blood pressure values therefore it is necessary to implement programs to promote an adequate nutritional status. In this study was not observed empiric support to the Barker hypothesis according to the intrauterine and infantile growth could have negative effects in the blood pressure levels.

Age Differences in Affective and Cardiovascular Responses to a Negative Social Interaction: The Role of Goals, Appraisals, and Emotion Regulation

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Luong, Gloria; Charles, Susan T.

2014-01-01

Older adults often report less affective reactivity to interpersonal tensions than younger individuals, but few studies have directly investigated mechanisms explaining this effect. The current study examined whether older adults’ differential endorsement of goals, appraisals, and emotion regulation strategies (i.e., conflict avoidance/de-escalation, self-distraction) during a controlled negative social interaction may explain age differences in affective and cardiovascular responses to the conflict discussion. Participants (N=159; 80 younger adults, 79 older adults) discussed hypothetical dilemmas with disagreeable confederates. Throughout the laboratory session, participants’ subjective emotional experience, blood pressure, and pulse rate were assessed. Older adults generally exhibited less reactivity (negative affect reactivity, diastolic blood pressure reactivity, and pulse rate reactivity) to the task, and more pronounced positive and negative affect recovery following the task, than did younger adults. Older adults appraised the task as more enjoyable and the confederate as more likeable, and more strongly endorsed goals to perform well on the task, which mediated age differences in negative affect reactivity, pulse rate reactivity, and positive affect recovery (i.e., increases in post-task positive affect), respectively. In addition, younger adults showed increased negative affect reactivity with greater use of self-distraction, whereas older adults did not. Together, findings suggest that older adults respond less negatively to unpleasant social interactions than younger adults, and these responses are explained in part by older adults’ pursuit of different motivational goals, less threatening appraisals of the social interaction, and more effective use of self-distraction, compared to younger adults. PMID:24773101

When negation is not negation

OpenAIRE

Milicevic, Nataša

2008-01-01

In this paper I will discuss the formation of different types of yes/no questions in Serbian (examples in (1)), focusing on the syntactically and semantically puzzling example (1d), which involves the negative auxiliary inversion. Although there is a negative marker on the fronted auxiliary, the construction does not involve sentential negation. This coincides with the fact that the negative quantifying NPIs cannot be licensed. The question formation and sentential negation have similar synta...

Delay Pressure Detection Method to Eliminate Pump Pressure Interference on the Downhole Mud Pressure Signals

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Yue Shen

2013-01-01

Full Text Available The feasibility of applying delay pressure detection method to eliminate mud pump pressure interference on the downhole mud pressure signals is studied. Two pressure sensors mounted on the mud pipe in some distance apart are provided to detect the downhole mud continuous pressure wave signals on the surface according to the delayed time produced by mud pressure wave transmitting between the two sensors. A mathematical model of delay pressure detection is built by analysis of transmission path between mud pump pressure interference and downhole mud pressure signals. Considering pressure signal transmission characteristics of the mud pipe, a mathematical model of ideal low-pass filter for limited frequency band signal is introduced to study the pole frequency impact on the signal reconstruction and the constraints of pressure sensor distance are obtained by pole frequencies analysis. Theoretical calculation and numerical simulation show that the method can effectively eliminate mud pump pressure interference and the downhole mud continuous pressure wave signals can be reconstructed successfully with a significant improvement in signal-to-noise ratio (SNR in the condition of satisfying the constraints of pressure sensor distance.

Thermal conductivity and diffusivity of Permian Basin bedded salt at elevated pressure and temperature

International Nuclear Information System (INIS)

Durham, W.B.; Boro, C.O.; Beiriger, J.M.; Montan, D.N.

1983-10-01

Measurements of thermal conductivity and diffusivity were made on five core samples of bedded rock salt from the Permian Basin in Texas to determine its suitability as an underground nuclear waste repository. The sample size was 100 mm in diameter by 250 mm in length. Measurements were conducted under confining pressures ranging from 3.8 to 31.0 MPa and temperatures from room temperature to 473 K. Conductivity showed no dependence on confining pressure but evidenced a monotonic, negative temperature dependence. Four of the five samples showed conductivities clustered in a range of 5.6 +- 0.5 W/m.K at room temperature, falling to 3.6 +- 0.3 W/m.K at 473 K. These values are approximately 20% below those for pure halite, reflecting perhaps the 5 to 20%-nonhalite component of the samples. Diffusivity also showed a monotonic, negative temperature dependence, with four of the five samples clustered in a range of 2.7 +- 0.4 x 10 -6 m 2 /s at room temperature, and 1.5 +- 0.3 x 10 -6 m 2 /s at 473 K, all roughly 33% below the values for pure halite. One sample showed an unusually high conductivity (it also had the highest diffusivity), about 20% higher than the others; and one sample showed an unusually low diffusivity (it also had the lowest conductivity), roughly a factor of 2 lower than the others. 27 references, 8 figures, 4 tables

Is the negative glow plasma of a direct current glow discharge negatively charged?

International Nuclear Information System (INIS)

Bogdanov, E. A.; Saifutdinov, A. I.; Demidov, V. I.; Kudryavtsev, A. A.

2015-01-01

A classic problem in gas discharge physics is discussed: what is the sign of charge density in the negative glow region of a glow discharge? It is shown that traditional interpretations in text-books on gas discharge physics that states a negative charge of the negative glow plasma are based on analogies with a simple one-dimensional model of discharge. Because the real glow discharges with a positive column are always two-dimensional, the transversal (radial) term in divergence with the electric field can provide a non-monotonic axial profile of charge density in the plasma, while maintaining a positive sign. The numerical calculation of glow discharge is presented, showing a positive space charge in the negative glow under conditions, where a one-dimensional model of the discharge would predict a negative space charge

Kinetics on the reaction of 6-chloroquinoline and p-substituted benzoylchlorides under high pressures

International Nuclear Information System (INIS)

Kim, Eung Ryul; Lim, Jong Wan; Kim, Se Kyong; Ko, Young Shin

2002-01-01

The reactions rates of substituted 6-chloroquinoline, with p-substituted benzoyichlorides (p-CH 3 , p-H, p-NO 2 ) have been measured by conductometry in acetonitrile, and the rate constants are determined at various temperatures (10,15,20,25 .deg. C) and pressures (1, 200, 500, 1000 bar). From the values of rate constants, the activation parameters (Ea, ΔV ≠ , ΔH ≠ , ΔS ≠ , and ΔG ≠ ) and the pressure dependence of Hammett ρ values were determined. The rate constants increased with increasing temperatures and pressures, and are further increased to introduction to the electron donor substituents in substrate (p-NO 2 ) with 6-chloroquinoline. When, the activation volume and the activation entropy are all negative. And the Hammett ρ values are positive for the substrate over the pressure and temperature range studied. The results of kinetic studies for pressure and substituent show that thease reactions proceed in typical S N 2 reaction mechanism and 'associative S N 2' in bond formation favored with increasing pressures

Comparison of natural drainage group and negative drainage groups after total thyroidectomy: prospective randomized controlled study.

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Woo, Seung Hoon; Kim, Jin Pyeong; Park, Jung Je; Shim, Hyun Seok; Lee, Sang Ha; Lee, Ho Joong; Won, Seong Jun; Son, Hee Young; Kim, Rock Bum; Son, Young-Ik

2013-01-01

The aim of this study was to compare a negative pressure drain with a natural drain in order to determine whether a negative pressure drainage tube causes an increase in the drainage volume. Sixty-two patients who underwent total thyroidectomy for papillary thyroid carcinoma (PTC) were enrolled in the study between March 2010 and August 2010 at Gyeongsang National University Hospital. The patients were prospectively and randomly assigned to two groups, a negative pressure drainage group (n=32) and natural drainage group (n=30). Every 3 hours, the volume of drainage was checked in the two groups until the tube was removed. The amount of drainage during the first 24 hours postoperatively was 41.68 ± 3.93 mL in the negative drain group and 25.3 ± 2.68 mL in the natural drain group (pdrain group was 35.19 ± 4.26 mL and natural drain groups 21.53 ± 2.90 mL (pdrain may increase the amount of drainage during the first 24-48 hours postoperatively. Therefore, it is not necessary to place a closed suction drain when only a total thyroidectomy is done.

Cost-Utility Analysis: Sartorius Flap versus Negative Pressure Therapy for Infected Vascular Groin Graft Managment.

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Chatterjee, Abhishek; Macarios, David; Griffin, Leah; Kosowski, Tomasz; Pyfer, Bryan J; Offodile, Anaeze C; Driscoll, Daniel; Maddali, Sirish; Attwood, John

2015-11-01

Sartorius flap coverage and adjunctive negative pressure wound therapy (NPWT) have been described in managing infected vascular groin grafts with varying cost and clinical success. We performed a cost-utility analysis comparing sartorius flap with NPWT in managing an infected vascular groin graft. A literature review compiling outcomes for sartorius flap and NPWT interventions was conducted from peer-reviewed journals in MEDLINE (PubMed) and EMBASE. Utility scores were derived from expert opinion and used to estimate quality-adjusted life years (QALYs). Medicare current procedure terminology and diagnosis-related groups codes were used to assess the costs for successful graft salvage with the associated complications. Incremental cost-effectiveness was assessed at $50,000/QALY, and both univariate and probabilistic sensitivity analyses were conducted to assess robustness of the conclusions. Thirty-two studies were used pooling 384 patients (234 sartorius flaps and 150 NPWT). NPWT had better clinical outcomes (86.7% success rate, 0.9% minor complication rate, and 13.3% major complication rate) than sartorius flap (81.6% success rate, 8.0% minor complication rate, and 18.4% major complication rate). NPWT was less costly ($12,366 versus $23,516) and slightly more effective (12.06 QALY versus 12.05 QALY) compared with sartorius flap. Sensitivity analyses confirmed the robustness of the base case findings; NPWT was either cost-effective at $50,000/QALY or dominated sartorius flap in 81.6% of all probabilistic sensitivity analyses. In our cost-utility analysis, use of adjunctive NPWT, along with debridement and antibiotic treatment, for managing infected vascular groin graft wounds was found to be a more cost-effective option when compared with sartorius flaps.

The potential for health risks from intrusion of contaminants into the distribution system from pressure transients.

Science.gov (United States)

LeChevallier, Mark W; Gullick, Richard W; Karim, Mohammad R; Friedman, Melinda; Funk, James E

2003-03-01

The potential for public health risks associated with intrusion of contaminants into water supply distribution systems resulting from transient low or negative pressures is assessed. It is shown that transient pressure events occur in distribution systems; that during these negative pressure events pipeline leaks provide a potential portal for entry of groundwater into treated drinking water; and that faecal indicators and culturable human viruses are present in the soil and water exterior to the distribution system. To date, all observed negative pressure events have been related to power outages or other pump shutdowns. Although there are insufficient data to indicate whether pressure transients are a substantial source of risk to water quality in the distribution system, mitigation techniques can be implemented, principally the maintenance of an effective disinfectant residual throughout the distribution system, leak control, redesign of air relief venting, and more rigorous application of existing engineering standards. Use of high-speed pressure data loggers and surge modelling may have some merit, but more research is needed.

Parent-Pressure

DEFF Research Database (Denmark)

Jensen, Helle Strandgaard

2016-01-01

of parents as co-consumers prevailed despite radical changes in views on children’s media consumption. In particular, I examine the shared inter-Scandinavian socio-cultural contexts that structured the changing professional and political groups’ pressure on parents to perform according to their norms......In this article, I examine change and continuity in conceptions of parental agency in public debates about children’s media consumption in Scandinavia, 1945-1975. During this period, public debates about the various kinds of media products children consumed were dominated by different groups....... However, a strong continuity in the debates was the negative influence parents were seen as having on children’s media consumption due to their lack of insight and interest in the topic. Drawing upon recent works on children’s media, consumption and enculturation, I analyse why the negative description...

Nurses' attitude and perceived barriers to pressure ulcer prevention.

Science.gov (United States)

Etafa, Werku; Argaw, Zeleke; Gemechu, Endalew; Melese, Belachew

2018-01-01

The presence or absence of pressure ulcers has been generally regarded as a performance measure of quality nursing care and overall patient health. The aim of this study- wasto explorenurses' attitude about pressure ulcer prevention'and to identify staff nurses' perceived barriers to pressure ulcer prevention public hospitals in Addis Ababa, Ethiopia. A self-reported multi-center institutional based cross sectional study design was employed to collect data from staff nurses ( N  = 222) working in six (6) selected public hospitals in Addis Ababa, from April 01-28/2015. Majority of the nurses had ( n  = 116, 52.2%) negative attitude towards pressure ulcer prevention. The mean scores of the test for all participants was 3.09out of 11(SD =0.92, range = 1-5). Similarly, the study revealed several barriers need to be resolved to put in to practice the strategies of pressure ulcer prevention; Heavy workload and inadequate staff (lack of tie) (83.1%), shortage of resources/equipment (67.7%) and inadequate training (63.2%) were among the major barriers identified in the study. The study finding suggests that Addis Ababa nurses have negative attitude to pressure ulcer prevention. Also several barriers exist for implementing pressure ulcer prevention protocols in public hospitals in Addis Ababa, Ethiopia. Suggestion for improving this situation is attractive.

The pressure dependence of structural, electronic, mechanical, vibrational, and thermodynamic properties of palladium-based Heusler alloys

Energy Technology Data Exchange (ETDEWEB)

Coban, Cansu [Balikesir Univ. (Turkey). Dept. of Physics

2017-07-01

The pressure dependent behaviour of the structural, electronic, mechanical, vibrational, and thermodynamic properties of Pd{sub 2}TiX (X=Ga, In) Heusler alloys was investigated by ab initio calculations. The lattice constant, the bulk modulus and its first pressure derivative, the electronic band structure and the density of states (DOS), mechanical properties such as elastic constants, anisotropy factor, Young's modulus, etc., the phonon dispersion curves and phonon DOS, entropy, heat capacity, and free energy were obtained under pressure. It was determined that the calculated lattice parameters are in good agreement with the literature, the elastic constants obey the stability criterion, and the phonon dispersion curves have no negative frequency which shows that the compounds are stable. The band structures at 0, 50, and 70 GPa showed valence instability at the L point which explains the superconductivity in Pd{sub 2}TiX (X=Ga, In).

The Influence of Time Pressure and Case Complexity on Physicians׳ Diagnostic Performance

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Dalal A. ALQahtani

2016-12-01

Conclusions: Time pressure did not impact the diagnostic performance, whereas the complexity of the clinical case negatively influenced the diagnostic accuracy. Further studies with the enhanced experimental manipulation of time pressure are needed to reveal the effect of time pressure, if any, on a physician׳s diagnostic performance.

[Investigation on the gas temperature of a plasma jet at atmospheric pressure by emission spectrum].

Science.gov (United States)

Li, Xue-chen; Yuan, Ning; Jia, Peng-ying; Niu, Dong-ying

2010-11-01

A plasma jet of a dielectric barrier discharge in coaxial electrode was used to produce plasma plume in atmospheric pressure argon. Spatially and temporally resolved measurement was carried out by photomultiplier tubes. The light emission signals both from the dielectric barrier discharge and from the plasma plume were analyzed. Furthermore, emission spectrum from the plasma plume was collected by high-resolution optical spectrometer. The emission spectra of OH (A 2sigma + --> X2 II, 307.7-308.9 nm) and the first negative band of N2+ (B2 sigma u+ --> X2 IIg+, 390-391.6 nm) were used to estimate the rotational temperature of the plasma plume by fitting the experimental spectra to the simulated spectra. The rotational temperature obtained is about 443 K by fitting the emission spectrum from the OH, and that from the first negative band of N2+ is about 450 K. The rotational temperatures obtained by the two method are consistent within 5% error band. The gas temperature of the plasma plume at atmospheric pressure was obtained because rotational temperature equals to gas temperature approximately in gas discharge at atmospheric pressure. Results show that gas temperature increases with increasing the applied voltage.

Treatment of hardware infection after osteosynthesis of lower leg using negative pressure wound therapy and transforming powder dressing.

Science.gov (United States)

Marinović, Marin; Ivandcić, Aldo; Spanjol, Josip; Pina, Maja; Bakota, Bore; Bandalović, Ante; Cukeljs, Fabijan

2014-12-01

Fractures of the distal part of the lower leg are more common in everyday practice and traumatology. In young and active patients these injuries are mainly caused by high energy trauma. They are treated with external fixator in first step, and in second step, after sanation of the soft tissue, with open reduction and internal fixation (ORIF). It is very safe and effective method of treatment. Treatment of the infections that occur in the early postoperative period after open reduction and internal fixation represents a great problem and challenge for surgeons. It is widely accepted that the presence of deep infection can't be cured in the presence of hardware. However, removal of hardware in the presence of unhealed fractures significantly complicates sanation of infection and fracture itself We have decided to present a 35-years-old patient with a hardware infection with present chronic wound with hardware exposed eight months after the first operation and six months after second operation. The wound measured one centimeter in diameter with cell detritus and bad granulations tissue inside the wound. Hardwre was exposed in the depth of the wound.The secretion was minimal. Negative Pressure Wound Therapy (NPWT) was applicated after debridemet and lavage performed in ambulatory conditions. The starting therapy was continuously -125 mm Hg of vacuum. After five days of NPWT the defect was partially filled with granula- tion tissue. For another five days we continue with NPWT with the same values of-125 mm Hg pressure but in the inter- mitent mode. After that period we used transforming powder dressing for covering and protection of the wound with was filled with granulation tissue. Five days later, wound was completely healed with epithelisation. After four months of patient follow-up, we found the wound is completely repaired. The patient denies pain and has continued orderly flow of fracture healing, with no signs of infection.

Sagittal abdominal diameter shows better correlation with cardiovascular risk factors than waist circumference and BMI.

Science.gov (United States)

de Souza, Natalia Cavalheri; de Oliveira, Erick Prado

2013-01-01

Obesity (abdominal adiposity) is a risk factor for cardiovascular diseases and the most used methods to measure the adiposity are body mass index (BMI), waist circumference (WC), and sagittal abdominal diameter (SAD). To correlate BMI, WC, and SAD with biochemical parameters and blood pressure in adults. A non-experimental exploratory/descriptive and cross sectional study was developed and it was assessed 133 subjects (59 men and 74 women) aging between 18 and 87 years. It was registered the patients' weight (kg), height (m), BMI (kg/m(2)), WC (cm) and SAD (cm), and these parameters were correlated with glycemia, triglycerides, total cholesterol, HDL-c, LDL-c and blood pressure. After adjustment for gender and age, it was observed a positive correlation between SAD and systolic arterial blood pressure (r = 0.20), glycemia (r = 0.20), triglycerides (r = 0.32), LDL (r = 0.26), total cholesterol (TC) (r = 0.33), and a negative correlation with HDL-c (r = -0.21) (p correlation between WC and systolic arterial blood pressure (r = 0.14), triglycerides (r = 0.31), total cholesterol (r = 0.21), and a negative correlation with HDL-c (r = -0.24) (p correlation with systolic arterial blood pressure (r = 0.22), total cholesterol (r = 0.20), and triglycerides (r = 0.23) (p correlated with almost all the cardiovascular risk factors analyzed and it might be considered the best predictor of abdominal fat and cardiovascular risk.

Pressure-aided transfusion of platelets: does it affect the platelets?

DEFF Research Database (Denmark)

Fischer-Nielsen, Anne; Stissing, Trine; Maansson, Charlotte

2010-01-01

In massively bleeding patients, pressure infusers are used for transfusion of red blood cells and plasma but not for platelets (PLTs) due to an assumed negative effect on the PLTs. This study examined whether pressure-aided in vitro transfusion affected the number, activation state, and/or function...

RESTING SYMPATHETIC BAROREFLEX SENSITIVITY IN SUBJECTS WITH LOW AND HIGH TOLERANCE TO CENTRAL HYPOVOLEMIA INDUCED BY LOWER BODY NEGATIVE PRESSURE

Directory of Open Access Journals (Sweden)

Carmen eHinojosa-Laborde

2014-06-01

Full Text Available Central hypovolemia elicited by orthostasis or hemorrhage triggers sympathetically-mediated baroreflex responses to maintain organ perfusion; these reflexes are less sensitive in patients with orthostatic intolerance, and during conditions of severe blood loss, may result in cardiovascular collapse (decompensatory or circulatory shock. The ability to tolerate central hypovolemia is variable and physiological factors contributing to tolerance are emerging. We tested the hypothesis that resting muscle sympathetic nerve activity (MSNA and sympathetic baroreflex sensitivity (BRS are attenuated in male and female subjects who have low tolerance (LT to central hypovolemia induced by lower body negative pressure (LBNP. MSNA and diastolic arterial pressure (DAP were recorded in 47 human subjects who subsequently underwent LBNP to tolerance (onset of presyncopal symptoms. LT subjects experienced presyncopal symptoms prior to completing LBNP of -60 mm Hg, and subjects with high tolerance (HT experienced presyncopal symptoms after completing LBNP after -60 mmHg. Contrary to our hypothesis, resting MSNA burst incidence was not different between LT and HT subjects, and was not related to time to presyncope. BRS was assessed as the slope of the relationship between spontaneous fluctuations in DAP and MSNA during 5 min of supine rest. MSNA burst incidence/DAP correlations were greater than or equal to 0.5 in 37 subjects (LT: n= 9; HT: n=28, and BRS was not different between LT and HT (-1.8 ± 0.3 vs. -2.2 ± 0.2 bursts•(100 beats-1•mmHg-1, p=0.29. We conclude that tolerance to central hypovolemia is not related to either resting MSNA or sympathetic BRS.

Dynamic Leg Exercise Improves Tolerance to Lower Body Negative Pressure

Science.gov (United States)

Watenpaugh, D. E.; Ballard, R. E.; Stout, M. S.; Murthy, G.; Whalen, R. T.; Hargens, A. R.

1994-01-01

These results clearly demonstrate that dynamic leg exercise against the footward force produced by LBNP substantially improves tolerance to LBNP, and that even cyclic ankle flexion without load bearing also increases tolerance. This exercise-induced increase of tolerance was actually an underestimate, because subjects who completed the tolerance test while exercising could have continued for longer periods. Exercise probably increases LBNP tolerance by multiple mechanisms. Tolerance was increased in part by skeletal muscle pumping venous blood from the legs. Rosenhamer and Linnarsson and Rosenhamer also deduced this for subjects cycling during centrifugation, although no measurements of leg volume were made in those studies: they found that male subjects cycling at 98 W could endure 3 Gz centrifugation longer than when they remained relaxed during centrifugation. Skeletal muscle pumping helps maintain cardiac filling pressure by opposing gravity-, centrifugation-, or LBNP-induced accumulation of blood and extravascular fluid in the legs.

Automated electronic monitoring of circuit pressures during continuous renal replacement therapy: a technical report.

Science.gov (United States)

Zhang, Ling; Baldwin, Ian; Zhu, Guijun; Tanaka, Aiko; Bellomo, Rinaldo

2015-03-01

Automated electronic monitoring and analysis of circuit pressures during continuous renal replacement therapy (CRRT) has the potential to predict failure and allow intervention to optimise function. Current CRRT machines can measure and store pressure readings for downloading into databases and for analysis. We developed a procedure to obtain such data at intervals of 1 minute and analyse them using the Prismaflex CRRT machine, and we present an example of such analysis. We obtained data on pressures obtained at intervals of 1 minute in a patient with acute kidney injury and sepsis treated with continuous haemofiltration at 2 L/hour of ultrafiltration and a blood flow of 200 mL/minute. Data analysis identified progressive increases in transmembrane pressure (TMP) and prefilter pressure (PFP) from time 0 until 33 hours or clotting. TMP increased from 104 mmHg to 313 mmHg and PFP increased from from 131 mmHg to 185 mmHg. Effluent pressure showed a progressive increase in the negative pressure applied to achieve ultrafiltration from 0 mmHg to -168 mmHg. The inflection point for such changes was also identified. Blood pathway pressures for access and return remained unchanged throughout. Automated electronic monitoring of circuit pressure during CRRT is possible and provides useful information on the evolution of circuit clotting.

Negative pressure driven valence instability of Eu in cubic Eu{sub 0.4}La{sub 0.6}Pd{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Pandey, Abhishek [S N Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata-700098 (India); Mazumdar, Chandan; Ranganathan, R [Experimental Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata-700064 (India)], E-mail: abhishek.phy@gmail.com, E-mail: chandan.mazumar@saha.ac.in

2009-05-27

We report the change in the valency of Eu-ions in the binary intermetallic cubic compound EuPd{sub 3} induced by La doping at rare-earth sites. Doping of La generates negative chemical pressure in the lattice, resulting in a significant increase of the lattice parameter without altering the simple-cubic structure of the compound. Results of dc-magnetic measurements suggest that this increase in the lattice parameter is associated with the valence transition of Eu-ions from Eu{sup 3+} to a mixed-valent state. As Eu{sup 2+}-ions possess a large magnetic moment, this valence transition significantly modifies the magnetic behavior of the compound. In contrast to introducing boron at the vacant body center site of the unit cell to change the valency of Eu-ions, as in the case of EuPd{sub 3}B, our results suggest it can also be altered by doping a rare-earth ion of larger size at the lattice site of Eu in EuPd{sub 3}.

Lactotripeptides Show No Effect on Human Blood Pressure: Results from a double-blind randomized controlled trial

NARCIS (Netherlands)

Engberink, M.F.; Schouten, E.G.; Kok, F.J.; Mierlo, van L.A.J.; Brouwer, I.A.; Geleijnse, J.M.

2008-01-01

Milk-derived peptides with ACE-inhibiting properties may have antihypertensive effects in humans. We conducted a randomized double-blind placebo-controlled trial to examine the blood pressure lowering potential of 2 ACE-inhibiting lactotripeptides, ie, Isoleucine-Proline-Proline and

Movement of the lacrimal canalicular wall under intracanalicular pressure changes observed with dacryoendoscopy.

Science.gov (United States)

Kakizaki, Hirohiko; Takahashi, Yasuhiro; Mito, Hidenori; Nakamura, Yasuhisa

2015-01-01

Movement of the lacrimal canalicular wall has been speculated to occur during blinking. Movement of the common internal ostium has been observed under nasal endoscopy, and pressure changes in the lacrimal canalicular cavity have been observed with a pressure sensor; however, lacrimal canalicular wall movement under pressure changes has not been observed. To examine movement of the lacrimal canalicular wall under intracanalicular pressure changes using dacryoendoscopy. The authors examined 20 obstruction-free lacrimal canaliculi in 10 patients. A dacryoendoscope was inserted, and water was poured into the intracanalicular cavity via the dacryoendoscope's water channel. The water was then poured or suctioned to cause positive or negative pressure changes in the intracanalicular cavity, and movement of the lacrimal canalicular wall was examined. The lacrimal canalicular wall moved flexibly with pressure changes. Under positive pressure, the intracanalicular cavity was dilated; however, it narrowed under negative pressure. The extent of movement was more dramatic in the common canalicular portion than the proximal canalicular portion. Intracanalicular pressure changes cause movement of the lacrimal canalicular wall. There was a consistent relationship between intracanalicular cavity changes and pressure changes, possibly contributing to lacrimal drainage of the canaliculus.

Perceiving social pressure not to feel negative predicts depressive symptoms in daily life

NARCIS (Netherlands)

Dejonckheere, E.; Bastian, B.; Fried, E.I.; Murphy, S.C.; Kuppens, P.

Background Western societies often overemphasize the pursuit of happiness, and regard negative feelings such as sadness or anxiety as maladaptive and unwanted. Despite this emphasis on happiness, the amount of people suffering from depressive complaints is remarkably high. To explain this apparent

Effects of the imposed pressure differential conditions on duoplasmatron performance

International Nuclear Information System (INIS)

Oztarhan, A.

1988-01-01

The duoplasmatron plasma source (D.P.T.) was modified to allow access to the arc discharge (to measure the discharge properties) and to vary independently the pressures in different volumes of the arc with the aim of seeing if this freedom would help in optimising the output. The duoplasmatron plasma source was operated under normal running condition (N.R.C.), positive imposed pressure differential condition (P.I.P.D.C.) and negative imposed pressure differential condition (N.I.P.D.C.) and the corresponding properties of the plasma output were measured. Running the duoplasmatron under P.I.P.D. condition did not seem to improve the output as compared to that under N.R.C. However, running the duoplasmatron under N.I.P.D. condition seemed to be advantageous as the output increased by about 30%. It was observed that the back pressure was critical in maintaining the arc and the gap pressure could be lowered much below the normal minimum (while the arc was on) if back pressure was kept above a critical value. The results showed that the effects of varying the dimensions of the intermediate electrode nozzle on the output could be understood in terms of the effect of changes in these dimensions on the relative pressures. An empirical expression for the effect of the pressure ratio was developed from the observations and compared with the experimental results. The reasons for various results can be related to the plasma emission mechanism. (author). 8 refs, 6 figs, 1 tab

Pressure Dependence of Komatiite Liquid Viscosity and Implications for Magma Ocean Rheology

Science.gov (United States)

O'Dwyer Brown, L.; Lesher, C. E.; Terasaki, H. G.; Yamada, A.; Sakamaki, T.; Shibazaki, Y.; Ohtani, E.

2009-12-01

The viscosities of komatiite liquids at high pressures and temperatures were investigated using the in-situ falling sphere technique at BL04B1, SPring-8. Komatiites are naturally occurring magmas, rich in network modifying cations. Despite the refractory and fluid nature of komatiite, we successfully measured the viscosity of molten komatiites from Gorgona Island, Colombia (MgO = 17.8 wt.%; NBO/T = 1.5) between 11 and 13 GPa at 2000 C, and from Belingwe, Zimbabwe (MgO = 28.14 wt.%; NBO/T = 2.1) from 12 to 14 GPa at 2000 C. Under isothermal conditions, the viscosity of Gorgona Island komatiite melt increased with pressure, consistent with our previous measurements at lower pressures for this composition. We interpreted this positive pressure dependence as the result of reductions in interatomic space diminishing the free volume of the liquid when compressed. The viscosity of molten komatiite from Belingwe also increased up to 12 GPa, however between 12 and 14 GPa the viscosity is nearly constant. In previous studies of depolymerized silicate liquids, the pressure dependence of viscosity has been shown to reverse from positive to negative between 8 and 10 GPa with corresponding changes in activation volume [1] [2]. In contrast, the activation volume for Belingwe liquid decreases to near zero, but does not become negative above 11 GPa. Similarly, the activation volume for Gorgona Island komatiite remains positive throughout the pressure range investigated. Molecular dynamics simulations of simple MgO-SiO2 liquids with NBO/T > 2 also show a positive pressure dependence, reflecting the dominant control of free-volume reduction on the viscosity of depolymerized melts. However, the more rapid reduction in activation volume with pressure in komatiite liquids may be related to the presence of Al, Ti and other cations that interact and undergo coordination changes unavailable in simple silicate liquids. Along Hadean and post-Hadean mantle adiabats the net effect of

Pressure derivatives of elastic moduli of fused quartz to 10 kb

Science.gov (United States)

Peselnick, L.; Meister, R.; Wilson, W.H.

1967-01-01

Measurements of the longitudinal and shear moduli were made on fused quartz to 10 kb at 24??5??C. The anomalous behavior of the bulk modulus K at low pressure, ???K ???P 0, at higher pressures. The pressure derivative of the rigidity modulus ???G ???P remains constant and negative for the pressure range covered. A 15-kb hydrostatic pressure vessel is described for use with ultrasonic pulse instrumentation for precise measurements of elastic moduli and density changes with pressure. The placing of the transducer outside the pressure medium, and the use of C-ring pressure seals result in ease of operation and simplicity of design. ?? 1967.

The influence of defects on the transport properties of AgSbPb18Te20 prepared at high pressure and high temperature

International Nuclear Information System (INIS)

Wang Yi; Zhu Pinwen; Jiao Hujun; Chen Haiyong; Ma Yanming; Niu Yingli; Li Yingai; Zhang Lijun; Zhang Tiechen; Gao Chunxiao; Zou Guangtian

2007-01-01

We synthesized polycrystal AgSbPb 18 Te 20 by using the method of high pressure and high temperature, and found that the defects produced by high pressure and high temperature caused the changes of transport properties. X-ray diffraction patterns showed that the cell parameters did not change obviously with synthesis at high pressure, apart from a small fluctuation. The electrical resistivity first increased, and then decreased to one quarter of the original value, as the synthesis pressure changed from low to high. The Seebeck coefficient decreased with the increase of synthesis pressure, and then changed from positive to negative. High pressure and high temperature could cause AgSbPb 18 Te 20 to change from a p-type to n-type semiconductor, increase the carrier concentration at maximum by two orders of magnitude, and shift the infrared absorption edge to a higher energy range. All of these phenomena were regarded as showing that high pressure and high temperature favored the formation of certain defects which could change the band structure and thereby change the transport properties

Zero-truncated negative binomial - Erlang distribution

Science.gov (United States)

Bodhisuwan, Winai; Pudprommarat, Chookait; Bodhisuwan, Rujira; Saothayanun, Luckhana

2017-11-01

The zero-truncated negative binomial-Erlang distribution is introduced. It is developed from negative binomial-Erlang distribution. In this work, the probability mass function is derived and some properties are included. The parameters of the zero-truncated negative binomial-Erlang distribution are estimated by using the maximum likelihood estimation. Finally, the proposed distribution is applied to real data, the number of methamphetamine in the Bangkok, Thailand. Based on the results, it shows that the zero-truncated negative binomial-Erlang distribution provided a better fit than the zero-truncated Poisson, zero-truncated negative binomial, zero-truncated generalized negative-binomial and zero-truncated Poisson-Lindley distributions for this data.

Longitudinal Associations between Maternal Work Stress, Negative Work-Family Spillover, and Depressive Symptoms.

Science.gov (United States)

Goodman, W Benjamin; Crouter, Ann C

2009-07-01

The current study examined associations over an 18-month period between maternal work stressors, negative work-family spillover, and depressive symptoms in a sample of 414 employed mothers with young children living in six predominantly nonmetropolitan counties in the Eastern United States. Results from a one-group mediation model revealed that a less flexible work environment and greater work pressure predicted higher levels of depressive symptoms, and further, that these associations were mediated by perceptions of negative work-family spillover. Additionally, results from a two-group mediation model suggested that work pressure predicted greater perceptions of spillover only for mothers employed full-time. Findings suggest the need for policies that reduce levels of work stress and help mothers manage their work and family responsibilities.

Extraction of negative lithium ions from a lithium-containing hydrogen plasma

International Nuclear Information System (INIS)

Wada, M.; Sasao, M.

1996-01-01

Negative lithium ions (Li - ) were extracted from a 6-cm-diam 7-cm-long negative hydrogen ion (H - ) source to simulate the condition of Li - extraction from a Li vapor introduced ion source for the neutral beam heating. The amount of the Li - current extracted from a hydrogen plasma with Li vapor was comparable to that extracted from a pure Li plasma. However, the amount of the H - current decreased as the H 2 gas pressure in the source decreased due to a getter-pump effect of Li during the introduction of Li vapor. A heat shield installed to keep a high wall temperature was effective in mitigating the pressure decrease. However, the H - current extracted from the ion source equipped with the heat shield became 20% of the original value, as Li vapor was injected into the ion source. copyright 1996 American Institute of Physics

Female Emotional Eaters Show Abnormalities in Consummatory and Anticipatory Food Reward

Science.gov (United States)

Bohon, Cara; Stice, Eric; Spoor, Sonja

2009-01-01

Objective To test the hypothesis that emotional eaters show greater neural activation in response to food intake and anticipated food intake than nonemotional eaters and whether these differences are amplified during a negative versus neutral mood state. Method Female emotional eaters and nonemotional eaters (N = 21) underwent functional magnetic resonance imaging (fMRI) during receipt and anticipated receipt of chocolate milkshake and a tasteless control solution while in a negative and neutral mood. Results Emotional eaters showed greater activation in the parahippocampal gyrus and anterior cingulate (ACC) in response to anticipated receipt of milkshake and greater activation in the pallidum, thalamus, and ACC in response to receipt of milkshake during a negative relative to a neutral mood. In contrast, nonemotional eaters showed decreased activation in reward regions during a negative versus a neutral mood. Discussion Results suggest that emotional eating is related to increased anticipatory and consummatory food reward, but only during negative mood. PMID:19040270

Pressure dependence of resistivity and magnetic properties in a Mn1.9Cr0.1Sb alloy

Directory of Open Access Journals (Sweden)

D. V. Maheswar Repaka

2017-12-01

Full Text Available We report magnetic-field and hydrostatic pressure dependent electrical resistivity and magnetic properties of a Mn1.9Cr0.1Sb alloy. Upon cooling, the magnetization of Mn1.9Cr0.1Sb exhibits a first-order ferrimagnetic to antiferromagnetic transition at the exchange inversion temperature, TS = 261 K under a 0.1 T magnetic field. Our experimental results show that TS decreases with increasing magnetic field but increase with increasing hydrostatic pressure. The pressure induced transition is accompanied by a large positive baro-resistance of 30.5% for a hydrostatic pressure change of 0.69 GPa. These results show that the lattice parameters as well as the bond distance between Mn-Mn atoms play a crucial role in the magnetic and electronic transport properties of Mn1.9Cr0.1Sb. This sample also exhibits a large inverse magnetocaloric effect with a magnetic entropy change of ΔSm = +6.75 J/kg.K and negative magnetoresistance (44.5% for a field change of 5 T at TS in ambient pressure which may be useful for magnetic cooling and spintronics applications.

Reef fish communities in the central Red Sea show evidence of asymmetrical fishing pressure

KAUST Repository

Kattan, Alexander; Coker, Darren James; Berumen, Michael L.

2017-01-01

In order to assess human impacts and develop rational restoration goals for corals reefs, baseline estimates of fish communities are required. In Saudi Arabian waters of the Red Sea, widespread unregulated fishing is thought to have been ongoing for decades, but there is little direct evidence of the impact on reef communities. To contextualize this human influence, reef-associated fish assemblages on offshore reefs in Saudi Arabia and Sudan in the central Red Sea were investigated. These reefs have comparable benthic environments, experience similar oceanographic influences, and are separated by less than 300 km, offering an ideal comparison for identifying potential anthropogenic impacts such as fishing pressure. This is the first study to assess reef fish biomass in both these regions, providing important baselines estimates. We found that biomass of top predators on offshore Sudanese reefs was on average almost three times that measured on comparable reefs in Saudi Arabia. Biomass values from some of the most remote reefs surveyed in Sudan’s far southern region even approach those previously reported in the Northwestern Hawaiian Islands, northern Line Islands, Pitcairn Islands, and other isolated Pacific islands and atolls. The findings suggest that fishing pressure has significantly altered the fish community structure of Saudi Arabian Red Sea reefs, most conspicuously in the form of top predator removal. The results point towards the urgent need for enhanced regulation and enforcement of fishing practices in Saudi Arabia, while making a strong case for protection in the form of no-take marine protected areas to maintain preservation of the relatively intact southern Sudanese Red Sea.

Reef fish communities in the central Red Sea show evidence of asymmetrical fishing pressure

KAUST Repository

Kattan, Alexander

2017-03-09

In order to assess human impacts and develop rational restoration goals for corals reefs, baseline estimates of fish communities are required. In Saudi Arabian waters of the Red Sea, widespread unregulated fishing is thought to have been ongoing for decades, but there is little direct evidence of the impact on reef communities. To contextualize this human influence, reef-associated fish assemblages on offshore reefs in Saudi Arabia and Sudan in the central Red Sea were investigated. These reefs have comparable benthic environments, experience similar oceanographic influences, and are separated by less than 300 km, offering an ideal comparison for identifying potential anthropogenic impacts such as fishing pressure. This is the first study to assess reef fish biomass in both these regions, providing important baselines estimates. We found that biomass of top predators on offshore Sudanese reefs was on average almost three times that measured on comparable reefs in Saudi Arabia. Biomass values from some of the most remote reefs surveyed in Sudan’s far southern region even approach those previously reported in the Northwestern Hawaiian Islands, northern Line Islands, Pitcairn Islands, and other isolated Pacific islands and atolls. The findings suggest that fishing pressure has significantly altered the fish community structure of Saudi Arabian Red Sea reefs, most conspicuously in the form of top predator removal. The results point towards the urgent need for enhanced regulation and enforcement of fishing practices in Saudi Arabia, while making a strong case for protection in the form of no-take marine protected areas to maintain preservation of the relatively intact southern Sudanese Red Sea.

A model for negative ion extraction and comparison of negative ion optics calculations to experimental results

International Nuclear Information System (INIS)

Pamela, J.

1990-10-01

Negative ion extraction is described by a model which includes electron diffusion across transverse magnetic fields in the sheath. This model allows a 2-Dimensional approximation of the problem. It is used to introduce electron space charge effects in a 2-D particle trajectory code, designed for negative ion optics calculations. Another physical effect, the stripping of negative ions on neutral gas atoms, has also been included in our model; it is found to play an important role in negative ion optics. The comparison with three sets of experimental data from very different negative ion accelerators, show that our model is able of accurate predictions

Demonstration of high performance negative central magnetic shear discharges on the DIII-D tokamak

International Nuclear Information System (INIS)

Rice, B.W.; Burrell, K.H.; Lao, L.L.

1996-01-01

Reliable operation of discharges with negative central magnetic shear has led to significant increases in plasma performance and reactivity in both low confinement, L-mode, and high confinement, H-mode, regimes in the DIII-D tokamak. Using neutral beam injection early in the initial current ramp, a large range of negative shear discharges have been produced with durations lasting up to 3.2 s. The total non- inductive current (beam plus bootstrap) ranges from 50% to 80% in these discharges. In the region of shear reversal, significant peaking of the toroidal rotation [f φ ∼ 30-60 kHz] and ion temperature [T i (0) ∼ 15-22 keV] profiles are observed. In high power discharges with an L-mode edge, peaked density profiles are also observed. Confinement enhancement factors up to H ≡ τ E /τ ITER-89P ∼ 2.5 with an L-mode edge, and H ∼ 3.3 in an Edge Localized Mode (ELM)-free H-mode, are obtained. Transport analysis shows both ion thermal diffusivity and particle diffusivity to be near or below standard neoclassical values in the core. Large pressure peaking in L- mode leads to high disruptivity with Β N ≡ Β T /(I/aB) ≤ 2.3, while broader pressure profiles in H- mode gives low disruptivity with Β N ≤ 4.2

Magnetization and Hall effect under high pressure in NaV 6O 11

Science.gov (United States)

Naka, T.; Matsumoto, T.; Kanke, Y.; Murata, K.

1995-02-01

We have investigated the pressure dependences of magnetization and the Hall coefficient in the ferromagnetic vanadium oxide NaV 6O 11 up to 1.2 GPa. Structural transitions (hexagonal-hexagonal-orthorhombic) occur at TH = 245 K and TL = 35 K at ambient pressure. Meanwhile, the susceptibility obeys the Curie-Weiss law X = C/( T - θ) with antiferromagnetic correlation of θ TH, with ferromagnetic correlation of θ TH. The spontaneous magnetization appears below Tc = 64.2 K. With increasing pressure, Tc and magnetization M( T TH increases. The sign of the Hall coefficient changes continuously (negative-positive-negative) at around T ≈ 170 K and 75 K.

Non-expert listeners show decreased heart rate and increased blood pressure (fear bradycardia) in response to atonal music.

Science.gov (United States)

Proverbio, Alice M; Manfrin, Luigi; Arcari, Laura A; De Benedetto, Francesco; Gazzola, Martina; Guardamagna, Matteo; Lozano Nasi, Valentina; Zani, Alberto

2015-01-01

Previous studies suggested that listening to different types of music may modulate differently psychological mood and physiological responses associated with the induced emotions. In this study the effect of listening to instrumental classical vs. atonal contemporary music was examined in a group of 50 non-expert listeners. The subjects' heart rate and diastolic and systolic blood pressure values were measured while they listened to music of different style and emotional typologies. Pieces were selected by asking a group of composers and conservatory professors to suggest a list of the most emotional music pieces (from Renaissance to present time). A total of 214 suggestions from 20 respondents were received. Then it was asked them to identify which pieces best induced in the listener feelings of agitation, joy or pathos and the number of suggested pieces per style was computed. Atonal pieces were more frequently indicated as agitating, and tonal pieces as joyful. The presence/absence of tonality in a musical piece did not affect the affective dimension of pathos (being touching). Among the most frequently cited six pieces were selected that were comparable for structure and style, to represent each emotion and style. They were equally evaluated as unfamiliar by an independent group of 10 students of the same cohort) and were then used as stimuli for the experimental session in which autonomic parameters were recorded. Overall, listening to atonal music (independent of the pieces' emotional characteristics) was associated with a reduced heart rate (fear bradycardia) and increased blood pressure (both diastolic and systolic), possibly reflecting an increase in alertness and attention, psychological tension, and anxiety. This evidence fits with the results of the esthetical assessment showing how, overall, atonal music is perceived as more agitating and less joyful than tonal one.

Non-expert listeners show decreased heart rate and increased blood pressure (fear bradycardia in response to atonal music

Directory of Open Access Journals (Sweden)

Alice Mado eProverbio

2015-10-01

Full Text Available Previous studies suggested that listening to different types of music may modulate differently psychological mood and physiological responses associated with the induced emotions. In this study the effect of listening to instrumental classical vs. atonal contemporary music was examined in a group of 50 non-expert listeners. The subjects’ heart rate and diastolic and systolic blood pressure values were measured while they listened to music of different style and emotional typologies. Pieces were selected by asking a group of composers and conservatory professors to suggest a list of the most emotional music pieces (from Renaissance to present time. A total of 214 suggestions from 20 respondents was received. Then it was asked them to identify which pieces best induced in the listener feelings of agitation, joy or pathos and the number of suggested pieces per style was computed. Atonal pieces were more frequently indicated as agitating, and tonal pieces as joyful. The presence/absence of tonality in a musical piece did not affect the affective dimension of pathos (being touching. Among the most frequently cited six pieces were selected that were comparable for structure and style, to represent each emotion and style. They were equally evaluated as unfamiliar by an independent group of 10 students of the same cohort and were then used as stimuli for the experimental session in which autonomic parameters were recorded. Overall, listening to atonal music (independent of the pieces’ emotional characteristics was associated with a reduced heart rate (fear bradycardia and increased blood pressure (both diastolic and systolic, possibly reflecting an increase in alertness and attention, psychological tension, and anxiety. This evidence fits with the results of the aesthetical assessment showing how, overall, atonal music is perceived as more agitating and less joyful than tonal one.

Non-expert listeners show decreased heart rate and increased blood pressure (fear bradycardia) in response to atonal music

Science.gov (United States)

Proverbio, Alice M.; Manfrin, Luigi; Arcari, Laura A.; De Benedetto, Francesco; Gazzola, Martina; Guardamagna, Matteo; Lozano Nasi, Valentina; Zani, Alberto

2015-01-01

Previous studies suggested that listening to different types of music may modulate differently psychological mood and physiological responses associated with the induced emotions. In this study the effect of listening to instrumental classical vs. atonal contemporary music was examined in a group of 50 non-expert listeners. The subjects’ heart rate and diastolic and systolic blood pressure values were measured while they listened to music of different style and emotional typologies. Pieces were selected by asking a group of composers and conservatory professors to suggest a list of the most emotional music pieces (from Renaissance to present time). A total of 214 suggestions from 20 respondents were received. Then it was asked them to identify which pieces best induced in the listener feelings of agitation, joy or pathos and the number of suggested pieces per style was computed. Atonal pieces were more frequently indicated as agitating, and tonal pieces as joyful. The presence/absence of tonality in a musical piece did not affect the affective dimension of pathos (being touching). Among the most frequently cited six pieces were selected that were comparable for structure and style, to represent each emotion and style. They were equally evaluated as unfamiliar by an independent group of 10 students of the same cohort) and were then used as stimuli for the experimental session in which autonomic parameters were recorded. Overall, listening to atonal music (independent of the pieces’ emotional characteristics) was associated with a reduced heart rate (fear bradycardia) and increased blood pressure (both diastolic and systolic), possibly reflecting an increase in alertness and attention, psychological tension, and anxiety. This evidence fits with the results of the esthetical assessment showing how, overall, atonal music is perceived as more agitating and less joyful than tonal one. PMID:26579029

Affective reactions and context-dependent processing of negations

Directory of Open Access Journals (Sweden)

Enrico Rubaltelli

2008-12-01

Full Text Available Three experiments demonstrate how the processing of negations is contingent on the evaluation context in which the negative information is presented. In addition, the strategy used to process the negations induced different affective reactions toward the stimuli, leading to inconsistency of preference. Participants were presented with stimuli described by either stating the presence of positive features (explicitly positive alternative or negating the presence of negative features (non-negative alternative. Alternatives were presented for either joint (JE or separate evaluation (SE. Experiment 1 showed that the non-negative stimuli were judged less attractive than the positive ones in JE but not in SE. Experiment 2 revealed that the non-negative stimuli induced a less clear and less positive feeling when they were paired with explicitly positive stimuli rather than evaluated separately. Non-negative options were also found less easy to judge than the positive ones in JE but not in SE. Finally, Experiment 3 showed that people process negations using two different models depending on the evaluation mode. Through a memory task, we found that in JE people process the non-negative attributes as negations of negative features, whereas in SE they directly process the non-negative attributes as positive features.

Human gallbladder pressure and volume

DEFF Research Database (Denmark)

Borly, L; Højgaard, L; Grønvall, S

1996-01-01

volume with only slight changes in intraluminal pressure (n = 4). Except for the zero drift, this piece of equipment seemed to fulfil the requirements of being able to measure pressure in the GB. In vivo measurements showed a good clinical reproducibility of the method, and also that respiration...... influenced by respiration (n = 8) and the pressure seems to be higher in the sitting position than in the supine position (n = 5). Cystic duct opening pressure was 10.4, 11.2 and 16.8 mmHg (n = 3). Pressure-volume responses showed that the GB up to a certain volume could accommodate increases in intraluminal...... and patient posture influenced the pressure measurements. Further, a GB pressure-volume relationship was demonstrated, and the possibility of a cystic duct opening pressure was described....

24-hour aortic blood pressure variability showed a stronger association with carotid damage than 24-hour brachial blood pressure variability: The SAFAR study.

Science.gov (United States)

Yu, Shikai; Chi, Chen; Protogerou, Athanase D; Safar, Michel E; Blacher, Jacques; Argyris, Antonis A; Nasothimiou, Efthimia G; Sfikakis, Petros P; Papaioannou, Theodore G; Xu, Henry; Zhang, Yi; Xu, Yawei

2018-03-01

We aim to compare 24-hour aortic blood pressure variability (BPV) with brachial BPV in relation to carotid damage as estimated by carotid intima-media thickness (CIMT) and cross-sectional area (CCSA). Four hundred and forty five individuals received brachial and aortic 24-hour ambulatory BP monitoring with a validated device (Mobil-O-Graph). Systolic BPV was estimated by average real variability (ARV) and time-weighted standard deviation (wSD). In multiple logistic regression analysis, CIMT > 900 μm was significantly and independently associated with aortic ARV (OR = 1.38; 95% CI: 1.04-1.84), aortic wSD (OR = 1.65; 95% CI: 1.19-2.29) and brachial ARV (OR = 1.53; 95% CI: 1.07-2.18), but not with brachial wSD. CCSA > 90th percentile was significantly and independently associated with aortic ARV (OR = 1.50; 95% CI: 1.07-2.10) and wSD (OR = 1.70; 95% CI: 1.12-2.56), but not with brachial BPVs. In receiver operator characteristics curve analysis, aortic wSD identified CCSA > 90th percentile better than brachial wSD (AUC: 0.73 vs 0.68, P < .01). In conclusion, aortic 24-hour systolic BPV showed a slightly stronger association with carotid damage than brachial BPV. ©2018 Wiley Periodicals, Inc.

Hyperbolic spaces are of strictly negative type

DEFF Research Database (Denmark)

Hjorth, Poul G.; Kokkendorff, Simon L.; Markvorsen, Steen

2002-01-01

We study finite metric spaces with elements picked from, and distances consistent with, ambient Riemannian manifolds. The concepts of negative type and strictly negative type are reviewed, and the conjecture that hyperbolic spaces are of strictly negative type is settled, in the affirmative....... The technique of the proof is subsequently applied to show that every compact manifold of negative type must have trivial fundamental group, and to obtain a necessary criterion for product manifolds to be of negative type....

First-principles investigations on structural, elastic, electronic properties and Debye temperature of orthorhombic Ni3Ta under pressure

Science.gov (United States)

Li, Pan; Zhang, Jianxin; Ma, Shiyu; Jin, Huixin; Zhang, Youjian; Zhang, Wenyang

2018-06-01

The structural, elastic, electronic properties and Debye temperature of Ni3Ta under different pressures are investigated using the first-principles method based on density functional theory. Our calculated equilibrium lattice parameters at 0 GPa well agree with the experimental and previous theoretical results. The calculated negative formation enthalpies and elastic constants both indicate that Ni3Ta is stable under different pressures. The bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν are calculated by the Voigt-Reuss-Hill method. The bigger ratio of B/G indicates Ni3Ta is ductile and the pressure can improve the ductility of Ni3Ta. In addition, the results of density of states and the charge density difference show that the stability of Ni3Ta is improved by the increasing pressure. The Debye temperature ΘD calculated from elastic modulus increases along with the pressure.

Impact of microarousal associated with increased negative esophageal pressure in sleep-disordered breathing.

Science.gov (United States)

Sukegawa, Mayo; Noda, Akiko; Yasuda, Yoshinari; Nakata, Seiichi; Sugiura, Tatsuki; Miyata, Seiko; Honda, Kumiko; Hasegawa, Yoshinori; Nakashima, Tsutomu; Koike, Yasuo

2009-11-01

"Microarousals" during sleep have not been analyzed systematically. We investigated the importance of "microarousals" (lasting 1.5-3 s). Standard polysomnography including esophageal pressure (Pes) assessment was performed on ten patients (aged 54.0 +/- 5.0 years) with respiratory effort-related arousal > or =5/h. We measured the number of arousals per hour (American Sleep Disorders Association (ASDA) arousal index) and the number of microarousals lasting 1.5-3 s per hour (mASDA arousal index). On the night after the baseline sleep study, we performed overnight continuous positive airway pressure (CPAP) titration. mASDA arousals, characterized by lower Pes values, were observed more frequently in patients with sleep-disordered breathing. The Pes results did not differ significantly between ASDA and mASDA arousals (-15.6 +/- -5.0 vs -15.0 +/- -4.4 cmH(2)O). mASDA arousals were significantly improved by CPAP treatment (mASDA arousals, 82.6 +/- 60.1 vs 6.0 +/- 1.4/h). mASDA arousals were characterized by an increase in Pes. mASDA arousals are thus key to our understanding of clinical manifestations in patients with sleep-disordered breathing.

Monitoring pressure profiles across an airfoil with a fiber Bragg grating sensor array

Science.gov (United States)

Papageorgiou, Anthony W.; Parkinson, Luke A.; Karas, Andrew R.; Hansen, Kristy L.; Arkwright, John W.

2018-02-01

Fluid flow over an airfoil section creates a pressure difference across the upper and lower surfaces, thus generating lift. Successful wing design is a combination of engineering design and experience in the field, with subtleties in design and manufacture having significant impact on the amount of lift produced. Current methods of airfoil optimization and validation typically involve computational fluid dynamics (CFD) and extensive wind tunnel testing with pressure sensors embedded into the airfoil to measure the pressure over the wing. Monitoring pressure along an airfoil in a wind tunnel is typically achieved using surface pressure taps that consist of hollow tubes running from the surface of the airfoil to individual pressure sensors external to the tunnel. These pressure taps are complex to configure and not ideal for in-flight testing. Fiber Bragg grating (FBG) pressure sensing arrays provide a highly viable option for both wind tunnel and inflight pressure measurement. We present a fiber optic sensor array that can detect positive and negative pressure suitable for validating CFD models of airfoil profile sections. The sensing array presented here consists of 6 independent sensing elements, each capable of a pressure resolution of less than 10 Pa over the range of 70 kPa to 120 kPa. The device has been tested with the sensor array attached to a 90mm chord length airfoil section subjected to low velocity flow. Results show that the arrays are capable of accurately detecting variations of the pressure profile along the airfoil as the angle of attack is varied from zero to the point at which stall occurs.

Nonlinear transient dynamic response of pressure relief valves for a negative containment system

International Nuclear Information System (INIS)

Aziz, T.S.; Duff, C.G.; Tang, J.H.K.

1979-01-01

The response of the piston for the postulated simultaneous effect of pressure and an earthquake is obtained for different parameters and accident conditions. Response quantities such as accelerations, displacements, rotations, diaphragm forces as well as opening time during a design basis earthquake are obtained. The results of the different analyses, as related to the functional operability of the valves, are evaluated and discussed. (orig.)

[Invasive arterial blood pressure measurement using an aneroid pressure system in cattle].

Science.gov (United States)

Mosing, M; Franz, S; Iff, I; Schwendenwein, I

2009-06-01

The aim of this study was to compare the results of invasive arterial blood pressure measurement using an electronic pressure transducer (EPT) or an aneroid pressure system (APS) in cattle. A catheter was placed in the auricular artery of 11 adult cattle and connected to a pressure transducer via pressure line. The aneroid system was connected to the same catheter using a three-way stop-cock in the pressure line. On five occasions three consecutive measurements were performed with the APS. The mean blood pressure values of the EPT were recorded before each individual measurement. Values from each device were compared using Passing and Bablok regression of agreement and a Bland and Altman difference plot. One hundred and forty-seven paired measurements were analysed. The average bias between the two methods (EPT vs. APS) was -1.6 mmHg (95 % confidence interval [CI]: -3.0 to -0.2 mmHg). The coefficient of correlation was 1.0084. The aneroid system showed an almost perfect agreement with the EPT. This study shows that it can be used in a clinical setting as well as under field conditions to measure arterial blood pressure in cattle.

Geometrical Model of Solar Radiation Pressure Based on High-Performing Galileo Clocks - First Geometrical Mapping of the Yarkowsky effect

Science.gov (United States)

Svehla, Drazen; Rothacher, Markus; Hugentobler, Urs; Steigenberger, Peter; Ziebart, Marek

2014-05-01

Solar radiation pressure is the main source of errors in the precise orbit determination of GNSS satellites. All deficiencies in the modeling of Solar radiation pressure map into estimated terrestrial reference frame parameters as well as into derived gravity field coefficients and altimetry results when LEO orbits are determined using GPS. Here we introduce a new approach to geometrically map radial orbit perturbations of GNSS satellites using highly-performing clocks on board the first Galileo satellites. Only a linear model (time bias and time drift) needs to be removed from the estimated clock parameters and the remaining clock residuals map all radial orbit perturbations along the orbit. With the independent SLR measurements, we show that a Galileo clock is stable enough to map radial orbit perturbations continuously along the orbit with a negative sign in comparison to SLR residuals. Agreement between the SLR residuals and the clock residuals is at the 1 cm RMS for an orbit arc of 24 h. Looking at the clock parameters determined along one orbit revolution over a period of one year, we show that the so-called SLR bias in Galileo and GPS orbits can be explained by the translation of the determined orbit in the orbital plane towards the Sun. This orbit translation is due to thermal re-radiation and not accounting for the Sun elevation in the parameterization of the estimated Solar radiation pressure parameters. SLR ranging to GNSS satellites takes place typically at night, e.g. between 6 pm and 6 am local time when the Sun is in opposition to the satellite. Therefore, SLR observes only one part of the GNSS orbit with a negative radial orbit error that is mapped as an artificial bias in SLR observables. The Galileo clocks clearly show orbit translation for all Sun elevations: the radial orbit error is positive when the Sun is in conjuction (orbit noon) and negative when the Sun is in opposition (orbit midnight). The magnitude of this artificial negative SLR bias

Negative pressure wound therapy using a portable single-use device for free skin grafts on the distal extremity in seven dogs.

Science.gov (United States)

Miller, A J; Cashmore, R G; Marchevsky, A M; Havlicek, M; Brown, P M; Fearnside, S M

2016-09-01

Retrospective study to describe clinical experience with a portable single-use negative pressure wound therapy device after application of full-thickness meshed skin grafts to wounds on the distal extremities of seven dogs. Seven dogs were treated with portable NPWT after receiving skin grafts; six as the result of tumour resection and one for traumatic injury. Medical records were reviewed and data recorded on patient signalment, cause and location of wound, surgical technique, application and maintenance of portable NPWT, graft survival and outcome, and complications encountered with the system. NPWT was provided for between 4 and 7 days. Five patients were discharged from hospital during the treatment period. Application and maintenance of the portable device was technically easy and no major complications were encountered. Minor complications consisted of fluid accumulation in the evacuation tubing. All dogs achieved 100% graft survival. Application and maintenance of the portable device was technically straightforward. All dogs receiving portable NPWT after transfer of a free skin graft to the distal extremity had a successful outcome. © 2016 Australian Veterinary Association.

Hydrogen storage in insulated pressure vessels

Energy Technology Data Exchange (ETDEWEB)

Aceves, S.M.; Garcia-Villazana, O. [Lawrence Livermore National Lab., CA (United States)

1998-08-01

Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen (LH{sub 2}) or ambient-temperature compressed hydrogen (CH{sub 2}). Insulated pressure vessels offer the advantages of liquid hydrogen tanks (low weight and volume), with reduced disadvantages (lower energy requirement for hydrogen liquefaction and reduced evaporative losses). This paper shows an evaluation of the applicability of the insulated pressure vessels for light-duty vehicles. The paper shows an evaluation of evaporative losses and insulation requirements and a description of the current analysis and experimental plans for testing insulated pressure vessels. The results show significant advantages to the use of insulated pressure vessels for light-duty vehicles.

What happens at work stays at work? Workplace supervisory social interactions and blood pressure outcomes.

Science.gov (United States)

Wong, Jennifer H K; Kelloway, E Kevin

2016-04-01

We investigated the relationship between workplace supervisory social interactions and blood pressure outcomes using hourly diary entries and ambulatory blood pressure data from an experience sampling study of 55 long-term care employees. After accounting for relevant cardiovascular controls, significant effects of supervisory interactions on cardiovascular reactivity and recovery were found. Multilevel analyses revealed that negatively perceived supervisory interactions predicted higher systolic blood pressure at work (B = -1.59, p pressure recovery after work (B = -14.52, p < .05, N = 33). Specifically, negatively perceived supervisory interactions at work predicted poorer cardiovascular recovery after work. Suggestions for improving practices in organizations and in experience sampling research are discussed. (c) 2016 APA, all rights reserved).

[The influence of oxygen partial pressure change and vascularization of rabbit wound through negative pressure wound therapy].

Science.gov (United States)

Yang, Fan; Hu, Duan; Bai, Xiang-jun; Zhang, Kun; Li, Ren-jie; Xue, Chen-chen

2012-07-01

To investigate the effect of vacuum sealing drainage (VSD) on variation of oxygen partial pressure (PtO2) and vascularization. The 12 cases of rabbit's wound models were undergoing the VSD (vacuum group, n = 6) or conventional therapy (conventional group, n = 6). Variation of PtO2 was measured by oxygen partial pressure admeasuring apparatus, expression of hypoxia inducible factor 1α (HIF-1α) mRNA was measured by real-time fluorescent quantitative PCR, content of vascular endothelial growth factor (VEGF) was measured by ELISA after tissue homogenate in 7 days. Vascular endothelial cell (VEC) and new blood capillary (NBC) of hematoxylin-eosin slice of tissue were counted by using light microscope. Average value of PtO2 of vacuum group was significant lower than conventional group (t = -99.780 to -5.305, P < 0.01). Expression of HIF-1α (30 minutes, 1, 6, 12 hours were 3.11 ± 0.07, 3.68 ± 0.26, 4.16 ± 0.13 and 3.91 ± 0.26 respectively) and content of VEGF (30 minutes, 1, 6, 12 hours were 103.3 ± 2.4, 134.2 ± 9.0, 167.8 ± 3.8 and 232.1 ± 9.5 respectively) of vacuum group were increased after 30 minutes and significant lower than conventional group (t = 13.038 - 80.208, P < 0.01), and both of them were reduced after 24 hours (P < 0.05). Counting numbers of VEC (2.47 ± 0.45 to 4.70 ± 0.38) and NBC (1.33 ± 0.49 to 4.33 ± 0.68) of vacuum group were increased at the same time-point and significant higher than conventional group (t = -0.670 to 16.500, P < 0.05). PtO2 of wound surface could be reduced significantly by VSD. Expression of HIF-1α and content of VEGF were increased by VSD for enhancing differentiated state of VEC and construction of NBC, which were better for vascularization and wound healing.

Evaluation of Negative-Ion-Beam Driver Concepts for Heavy Ion Fusion

International Nuclear Information System (INIS)

Grisham, Larry R.

2002-01-01

We evaluate the feasibility of producing and using atomically neutral heavy ion beams produced from negative ions as drivers for an inertial confinement fusion reactor. Bromine and iodine appear to be the most attractive elements for the driver beams. Fluorine and chlorine appear to be the most appropriate feedstocks for initial tests of extractable negative ion current densities. With regards to ion sources, photodetachment neutralizers, and vacuum requirements for accelerators and beam transport, this approach appears feasible within existing technology, and the vacuum requirements are essentially identical to those for positive ion drivers except in the target chamber. The principal constraint is that this approach requires harder vacuums in the target chamber than do space-charge-neutralized positive ion drivers. With realistic (but perhaps pessimistic) estimates of the total ionization cross section, limiting the ionization of a neutral beam to less than 5% while traversing a four -meter path would require a chamber pressure of no more than 5 x 10 -5 torr. Alternatively, even at chamber pressures that are too high to allow propagation of atomically neutral beams, the negative ion approach may still have appeal, since it precludes the possibly serious problem of electron contamination of a positive ion beam during acceleration, drift compression, and focusing

Profiles of plasma parameters and density of negative hydrogen ions by laser detachment measurements in RF-driven ion sources

International Nuclear Information System (INIS)

Christ-Koch, Sina

2007-01-01

This work shows the application of the Laserdetachment method for spatially resolved measurements of negative Hydrogen/Deuterium ion density. It was applied on a high power low pressure RF-driven ion source. The Laser detachment method is based on the measurement of electron currents on a positively biased Langmuir probe before and during/after a laser pulse. The density ratio of negative ions to electrons can be derived from the ratio of currents to the probe. The absolute density of negative ions can be obtained when the electron density is measured with the standard Langmuir probe setup. Measurements with the Langmuir probe additionally yield information about the floating and plasma potential, the electron temperature and the density of positive ions. The Laser detachment setup had to be adapted to the special conditions of the RF-driven source. In particular the existence of RF fields (1 MHz), high source potential (-20 kV), magnetic fields (∝ 7 mT) and caesium inside the source had to be considered. The density of negative ions could be identified in the range of n(H - )=1.10 17 1/m 3 , which is in the same order of magnitude as the electron density. Only the application of the Laser detachment method with the Langmuir probe measurements will yield spatially resolved plasma parameters and H- density profiles. The influence of diverse external parameters, such as pressure, RF-power, magnetic fields on the plasma parameters and their profiles were studied and explained. Hence, the measurements lead to a detailed understanding of the processes inside the source. (orig.)

Application of adaptive fuzzy control technology to pressure control of a pressurizer

Institute of Scientific and Technical Information of China (English)

YANG Ben-kun; BIAN Xin-qian; GUO Wei-lai

2005-01-01

A pressurizer is one of important equipment in a pressurized water reactor plant. It is used to maintain the pressure of primary coolant within allowed range because the sharp change of coolant pressure affects the security of reactor,therefor,the study of pressurizer's pressure control methods is very important. In this paper, an adaptive fuzzy controller is presented for pressure control of a pressurizer in a nuclear power plant. The controller can on-line tune fuzzy control rules and parameters by self-learning in the actual control process, which possesses the way of thinking like human to make a decision. The simulation results for a pressurized water reactor plant show that the adaptive fuzzy controller has optimum and intelligent characteristics, which prove the controller is effective.

Swelling pressure in compacted bentonite below 0°C

International Nuclear Information System (INIS)

Birgersson, Martin; Karnland, Ola; Nilsson, Ulf

2010-01-01

Document available in extended abstract form only. Bentonite is a common component in many concepts for underground storage of high level radioactive waste. During its lifetime, an underground repository will be subject to various ambient temperatures. Backfilled tunnels, shafts and investigation bore holes closest to ground level will experience periods of temperature below 0 deg. C. From a safety assessment perspective, it is therefore essential to investigate and understand the behavior of bentonite below 0 deg. C. A large set of laboratory tests have been performed where fully water saturated samples of bentonites have been exposed to temperatures in the range -10 deg. C - +25 deg. C. The swelling pressure response has been recorded continuously. The samples have been varied with respect to bentonite type (e.g. calcium or sodium dominated), smectite content and density. The general observation is that the pressure of the bentonite lowers in a temperature range between 0 deg. C and a specific (negative) temperature T c , which is strongly correlated to the swelling pressure measured above 0 deg. C. Consequently, Tc decreases (i.e. becomes more negative) with increased density or smectite content. At T c , swelling pressure is completely lost. Furthermore, a very weak pressure dependence is observed at temperatures above 0 deg. C. This dependence is however strictly dependent on sample density. For any type of bentonite at high enough densities above 0 deg. C, the slope of the P-T curve is negative and becomes more negative with increasing density. For Na-dominated bentonites at lower densities, on the other hand, the slope is positive. An important observation is that no pressure increase was observed for any of the tested bentonite samples as the transition to temperatures below 0 deg. C was made. Since water expands as it freezes, this observation indicates that no ice is formed in compacted bentonite as the 0 deg. C level is passed. The observed swelling

Hydrostatic pressure promotes the proliferation and osteogenic/chondrogenic differentiation of mesenchymal stem cells: The roles of RhoA and Rac1

Directory of Open Access Journals (Sweden)

Yin-Hua Zhao

2015-05-01

Full Text Available Our previous studies have shown that hydrostatic pressure can serve as an active regulator for bone marrow mesenchymal stem cells (BMSCs. The current work further investigates the roles of cytoskeletal regulatory proteins Ras homolog gene family member A (RhoA and Ras-related C3 botulinum toxin substrate 1 (Rac1 in hydrostatic pressure-related effects on BMSCs. Flow cytometry assays showed that the hydrostatic pressure promoted cell cycle initiation in a RhoA- and Rac1-dependent manner. Furthermore, fluorescence assays confirmed that RhoA played a positive and Rac1 displayed a negative role in the hydrostatic pressure-induced F-actin stress fiber assembly. Western blots suggested that RhoA and Rac1 play central roles in the pressure-inhibited ERK phosphorylation, and Rac1 but not RhoA was involved in the pressure-promoted JNK phosphorylation. Finally, real-time polymerase chain reaction (PCR experiments showed that pressure promoted the expression of osteogenic marker genes in BMSCs at an early stage of osteogenic differentiation through the up-regulation of RhoA activity. Additionally, the PCR results showed that pressure enhanced the expression of chondrogenic marker genes in BMSCs during chondrogenic differentiation via the up-regulation of Rac1 activity. Collectively, our results suggested that RhoA and Rac1 are critical to the pressure-induced proliferation and differentiation, the stress fiber assembly, and MAPK activation in BMSCs.

Hydrostatic pressure promotes the proliferation and osteogenic/chondrogenic differentiation of mesenchymal stem cells: The roles of RhoA and Rac1.

Science.gov (United States)

Zhao, Yin-Hua; Lv, Xin; Liu, Yan-Li; Zhao, Ying; Li, Qiang; Chen, Yong-Jin; Zhang, Min

2015-05-01

Our previous studies have shown that hydrostatic pressure can serve as an active regulator for bone marrow mesenchymal stem cells (BMSCs). The current work further investigates the roles of cytoskeletal regulatory proteins Ras homolog gene family member A (RhoA) and Ras-related C3 botulinum toxin substrate 1 (Rac1) in hydrostatic pressure-related effects on BMSCs. Flow cytometry assays showed that the hydrostatic pressure promoted cell cycle initiation in a RhoA- and Rac1-dependent manner. Furthermore, fluorescence assays confirmed that RhoA played a positive and Rac1 displayed a negative role in the hydrostatic pressure-induced F-actin stress fiber assembly. Western blots suggested that RhoA and Rac1 play central roles in the pressure-inhibited ERK phosphorylation, and Rac1 but not RhoA was involved in the pressure-promoted JNK phosphorylation. Finally, real-time polymerase chain reaction (PCR) experiments showed that pressure promoted the expression of osteogenic marker genes in BMSCs at an early stage of osteogenic differentiation through the up-regulation of RhoA activity. Additionally, the PCR results showed that pressure enhanced the expression of chondrogenic marker genes in BMSCs during chondrogenic differentiation via the up-regulation of Rac1 activity. Collectively, our results suggested that RhoA and Rac1 are critical to the pressure-induced proliferation and differentiation, the stress fiber assembly, and MAPK activation in BMSCs. Copyright © 2015. Published by Elsevier B.V.

The effects of stereotypes and observer pressure on athletic performance.

Science.gov (United States)

Krendl, Anne; Gainsburg, Izzy; Ambady, Nalini

2012-02-01

Although the effects of negative stereotypes and observer pressure on athletic performance have been well researched, the effects of positive stereotypes on performance, particularly in the presence of observers, is not known. In the current study, White males watched a video either depicting Whites basketball players as the best free throwers in the NBA (positive stereotype), Black basketball players as the best free throwers in the NBA (negative stereotype), or a neutral sports video (control). Participants then shot a set of free throws, during which half the participants were also videotaped (observer condition), whereas the other half were not (no observer condition). Results demonstrated that positive stereotypes improved free throw performance, but only in the no observer condition. Interestingly, observer pressure interacted with the positive stereotype to lead to performance decrements. In the negative stereotype condition, performance decrements were observed both in the observer and no observer conditions.

Toxicological assessment and management options for boat pressure-washing wastewater.

Science.gov (United States)

Gerić, Marko; Gajski, Goran; Oreščanin, Višnja; Kollar, Robert; Franekić, Jasna; Garaj-Vrhovac, Vera

2015-04-01

Boats are washed periodically for maintenance in order to remove biofoulants from hulls, which results in the generation of wastewater. This study aimed at evaluating the cyto/genotoxic and mutagenic properties of wastewater produced by pressure washing of boats. The chemical characterisation of this wastewater showed that Cu, Zn, V, Cr, Fe, Pb, and select organic contaminants exceeded the maximum allowable values from 1.7 up to 96 times. The wastewater produced negative effects on human lymphocytes resulting in decreased cell viability after 4 and 24h of exposure. Chromosome aberration, micronucleus, and comet assay parameters were significantly higher after 24h of exposure. At the same time, the Salmonella typhimurium test showed negative for both TA98 and TA100 strains at all of the concentrations tested. After the treatment of wastewater using electrochemical methods/ozonation during real scale treatment plant, removal rates of colour, turbidity and heavy metals ranged from 99.4% to 99.9%, while the removal of total organic carbon (TOC) and chemical oxygen demand (COD) was above 85%. This was reflected in the removal of the wastewater's cyto/genotoxicity, which was comparable to negative controls in all of the conducted tests, suggesting that such plants could be implemented in marinas to minimise human impact on marine systems. Copyright © 2015 Elsevier Inc. All rights reserved.

Vortex, ULF wave and Aurora Observation after Solar Wind Dynamic Pressure Change

Science.gov (United States)

Shi, Q.

2017-12-01

Here we will summarize our recent study and show some new results on the Magnetosphere and Ionosphere Response to Dynamic Pressure Change/disturbances in the Solar Wind and foreshock regions. We study the step function type solar wind dynamic pressure change (increase/decrease) interaction with the magnetosphere using THEMIS satellites at both dayside and nightside in different geocentric distances. Vortices generated by the dynamic pressure change passing along the magnetopause are found and compared with model predictions. ULF waves and vortices are excited in the dayside and nightside plasma sheet when dynamic pressure change hit the magnetotail. The related ionospheric responses, such as aurora and TCVs, are also investigated. We compare Global MHD simulations with the observations. We will also show some new results that dayside magnetospheric FLRs might be caused by foreshock structures.Shi, Q. Q. et al. (2013), THEMIS observations of ULF wave excitation in the nightside plasma sheet during sudden impulse events, J. Geophys. Res. Space Physics, 118, doi:10.1029/2012JA017984. Shi, Q. Q. et al. (2014), Solar wind pressure pulse-driven magnetospheric vortices and their global consequences, J. Geophys. Res. Space Physics, 119, doi:10.1002/2013JA019551. Tian, A.M. et al.(2016), Dayside magnetospheric and ionospheric responses to solar wind pressure increase: Multispacecraft and ground observations, J. Geophys. Res., 121, doi:10.1002/2016JA022459. Shen, X.C. et al.(2015), Magnetospheric ULF waves with increasing amplitude related to solar wind dynamic pressure changes: THEMIS observations, J. Geophys. Res., 120, doi:10.1002/2014JA020913Zhao, H. Y. et al. (2016), Magnetospheric vortices and their global effect after a solar wind dynamic pressure decrease, J. Geophys. Res. Space Physics, 121, doi:10.1002/2015JA021646. Shen, X. C., et al. (2017), Dayside magnetospheric ULF wave frequency modulated by a solar wind dynamic pressure negative impulse, J. Geophys. Res

Contextual Risk, Maternal Negative Emotionality, and the Negative Emotion Dysregulation of Preschool Children from Economically Disadvantaged Families

Science.gov (United States)

Brown, Eleanor D.; Ackerman, Brian P.

2011-01-01

Research Findings: This study examined relations between contextual risk, maternal negative emotionality, and preschool teacher reports of the negative emotion dysregulation of children from economically disadvantaged families. Contextual risk was represented by cumulative indexes of family and neighborhood adversity. The results showed a direct…

(Pressure + volume + temperature) properties for binary oligomeric solutions of poly(ethylene glycol mono-4-octylphenyl ether) with 1-octanol or acetophenone at pressures up to 50 MPa

International Nuclear Information System (INIS)

Lee, M.-J.; Ku, T.-J.; Lin Homu

2009-01-01

Densities were measured with a high-pressure densitometer for two binary oligomeric systems of poly(ethylene glycol mono-4-octylphenyl ether) (PEGOPE) with 1-octanol or acetophenone at temperatures from 298.15 K to 348.15 K and pressures up to 50 MPa. While the excess volumes are negative in (acetophenone + PEGOPE) over the entire composition range, those are found to change from positive to negative with increasing mole fraction of the solvent in (1-octanol + PEGOPE). The pressure-effect on the liquid densities can be represented accurately by the Tait equation. Moreover, an empirical equation with two characteristic parameters correlates well the PVT data over the entire experimental conditions for each binary system. The experimental specific volumes were also correlated with the Flory-Orwoll-Vrij (FOV) and the Schotte equations of state to within the experimental uncertainty.

Boiling point of volatile liquids at various pressures

Directory of Open Access Journals (Sweden)

Luisa Maria Valencia

2017-07-01

Full Text Available Water, under normal conditions, tends to boil at a “normal boiling temperature” at which the atmospheric pressure fixes the average amount of kinetic energy needed to reach its boiling point. Yet, the normal boiling temperature of different substances varies depending on their nature, for which substances like alcohols, known as volatile, boil faster than water under same conditions. In response to this phenomenon, an investigation on the coexistence of both gas and liquid phases of a volatile substance in a closed system was made, establishing vapor pressure as the determining tendency of a substance to vaporize, which increases exponentially with temperature until a critical point is reached. Since atmospheric pressure is fixed, the internal pressure of the system was varied to determine its relationship with vapor pressure and thus with the boiling point of the substance, concluding that the internal pressure and boiling point of a volatile liquid in a closed system are negatively proportional.

A 1MeV, 1A negative ion accelerator test facility

International Nuclear Information System (INIS)