bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of O-Rings as an Example of Passive Adaptive Structures
Authors: Klamecki Barney E. , Sefkow Ryan B. , Maciejewski Nicholas J.
Published: July 2009

The use of material design to overcome time-dependent material deformation resulting in loss of sealing effectiveness of elastomeric seals was considered. O-ring sections with different stress-strain behavior in different regions of the section were studied. Experimentally validated finite element models were used to characterize the strain energy density distribution and seal-housing contact pressure for various section designs. The design rules extracted from experimental and numerical studies indicate that o-ring sections with lower elastic modulus, softening material located at regions of high strain energy will result in slower growth of permanent seal deformation and so improved seal performance over time. O-ring sections based on this material design were evaluated numerically and improved seal life predicted.
Hydraulically Amplified Magnetostrictive Actuator for Active Engine Mounts
Authors: Chakrabarti Suryarghya , Dapino Marcelo J.
Published: July 2009

A bidirectional magnetostrictive actuator with millimeter stroke and a blocked force of ± 22 N has been developed based on a simple hydraulic magnification mechanism. The purpose of the actuator is to replace the electromagnetic actuator in active engine mounts. The Terfenol-D actuator has a flat free displacement response up to 200 Hz and a flat blocked force response over a frequency range of at least 10 to 500 Hz. The actuator promises to deliver a much broader frequency bandwidth than commercial electromagnetic actuators.
Performance Analysis of Single Crystal PMN-PZT Unimorphs for Piezoelectric Energy Harvesting
Authors: Erturk Alper , Bilgen Onur , Inman Daniel J.
Published: July 2009

This paper presents the performance analysis of the single crystal piezoelectric ceramic PMN-PZT (where PMN stands for lead magnesium niobate and PZT stands for lead zirconate titanate) for piezoelectric energy harvesting. Unimorph cantilevers using PMN-PZT layers with Al (aluminum) and SS (stainless steel) substrates are tested under base excitation for a wide range of load resistance (from 10 ohms to 2.2 Mohms). Electrical power generation performance of the unimorphs using PMN-PZT is compared against that of the unimorphs using the conventional piezoelectric ceramic PZT-5H with Al and SS substrates. For both substrates, it is observed that the power density (power output per device volume) and the specific power (power output per device mass) results of the unimorphs using PMN-PZT are about two orders of magnitude larger than those of the unimorphs using PZT-5H. Outstanding power generation performance of the unimorphs with PMN-PZT is associated with stronger resistive shunt damping effect compared to unimorphs with PZT-5H. In addition to the experimental analyses and comparisons, power generation and shunt damping results of a single crystal unimorph are successfully predicted by using a distributed parameter electromechanical model. Results show that single crystal PMN-PZT is a very strong interface for piezoelectric energy harvesting and shunt damping. However, the improved power generation and shunt damping performance of PMN-PZT comes with reduced robustness due to the brittle nature of the single crystalline structure.
Broadband Vibration Suppression Assessment of Negative Impedance Shunts
Authors: Beck Benjamin , Cunefare Kenneth A. , Ruzzene Massimo
Published: July 2009

Piezoelectric materials allow for the manipulation of stiffness and damping properties of host structures by the application of electrical shunting networks. The use of piezoelectric patches for broadband control of vibration using a negative impedance shunt has been shown to be an effective active control solution. The wave-tuning and minimization of reactive input power shunt selection methodologies require the use a negative capacitance. This paper shows that the two theories are comparative and obtain the same shunt parameters. The results of the theoretical shunt selection and simulation are compared to experimental results of tip vibration suppression, spatial average vibration, and reactive input power minimization.
Modeling and Vibration Suppression of Pressurized Optical Membrane
Authors: Tarazaga Pablo A. , Johnson Marty E. , Inman Daniel J.
Published: July 2009

Optical membranes are being pursued for their ability to replace the conventional mirrors that are used to correct wave front aberration and space based telescopes. Among some of the many benefits of using optical membranes, is their ability to considerably reduce the weight of the structure. As a secondary effect, the cost of transportation, which is of great interest in space applications, is reduced as well. Another interesting advantage is the ability to have a continuous surface for the attenuation of wave front aberrations, instead of a discrete grid of rigid mirrors that have to be individually controlled. The effects of adding a pressurized cavity behind an optical membrane are examined in this paper by coupling an acoustic cylindrical cavity to a cylindrical membrane at the top boundary. This paper also looks at using a positive position feedback controller for vibration suppression of the membrane. This is done by using a centralized acoustic source in the cavity as the method of actuation. The acoustic actuation is of great interest since it does not mass load the membrane in the conventional way, as most methods of actuation would.
Multifunctional Adhesive Joints for Composites Using Aligned Carbon Nanotube Nanofoam Films
Authors: Gudapati Vamshi M. , Ghasemi-Nejhad Mehrdad N.
Published: July 2009

In this study, the effects of using aligned multi-walled carbon nanotube (MWCNT) nanofoam films as adhesive reinforcements to enhance the shear strength of composite joints are examined. The MWCNT reinforced adhesive nanofoam films are used to bond carbon/epoxy composite adherends. Mechanical characterization of the samples is performed using single lap joint samples to measure average shear strengths experimentally. Shear strength and other multifunctional properties of such nano-adhesives are discussed employing the results obtained in this work.
Nonlocal Continuum Theory Based Modeling of Carbon Nanotube Composites
Authors: Alavinasab Ali , Ahmadi Goodarz , Jha Ratneshwar
Published: July 2009

Analytical modeling of Carbon Nanotube (CNT) composite based on the nonlocal continuum theory is investigated. This approach accounts for nonlocal stress-strain relationships, that is, stress at any point in a structure is a function of strain in the entire structure. Finite element analysis of a representative volume element (RVE) of CNT composite is used to evaluate unknown constant in the nonlocal theory based solution. Stress distributions are obtained from finite element method (FEM), nonlocal theory, and standard (local) elasticity. Nonlocal theory and FEM stress distributions yield the same total force and first moment, whereas standard elasticity gives less accurate results.
Induced Magnetic Anisotropy in Stress-Annealed Galfenol Laminated Rods
Authors: Yoo Jin-Hyeong , Restorff James B. , Wun-Fogle Marilyn , Flatau Alison B.
Published: July 2009

The recent discovery of Iron-Gallium alloy (Galfenol) as a “large” magnetostrictive material (as high as 400 ppm) offers a particularly promising transducer material that combines largely desirable mechanical attributes with superior magnetic properties [1]. The high permeability of this material makes it easy to magnetize, however it also causes a relatively low cutoff frequency in dynamic applications, above which eddy currents form and introduce significant power losses. To reduce the eddy current losses, magnetostrictive drivers used in dynamic applications are commonly laminated. A second transducer design consideration is the introduction of an initial alignment of domains inside of the material to maximize the magnetostriction performance. It is common to achieve this by imposing an external compressive prestress to align magnetic moments perpendicular to the direction of actuation. An alternative to the application of an external prestress is to build-in a uniaxial magnetic anisotropy through stress annealing [2]. Stress annealing is a high temperature process with simultaneous application of an external load and subsequent cooling under load in which the magnetic moment alignment developed at temperature is retained upon removal from the stress annealing fixture. The external load needed to build in a useful uniaxial magnetic anisotropy in Galfenol is greater than the buckling load for Galfenol laminae sized for use in high frequency dynamic applications. In this study, prior work on stress annealing of solid rods of single and polycrystalline samples of Galfenol is successfully extended to thin laminae of Galfenol by introducing fixtures to avoid buckling of the laminae under compression during the heat treatment process. Values of the uniaxial anisotropy, cubic anisotropy, saturation magnetic induction, and saturation magnetostriction were obtained from measurements of the magnetization and magnetostriction of stress-annealed Galfenol strip as a function of compressive and tensile stress. These values were derived from fitting magnetization and magnetostriction curves to the energy expression formula [3]. Data are presented that demonstrate the magnetic uniaxial anisotropy developed by stress annealing of laminated Galfenol rods. An annealing temperature of 500 °C and a compressive stress of 200 MPa produced a uniaxial anisotropy of 11.3 kJ/m3 in this study.
Overview of Boeing’s Shape Memory Alloy Based Morphing Aerostructures
Authors: Calkins F. T. , Mabe J. H. , Ruggeri R. T.
Published: July 2009

The Boeing Company has a goal of creating aircraft that are capable of continuous optimization for all flight conditions. Toward this goal we have developed morphing-capable, adaptive structures based on Shape Memory Alloy (SMA) technology that enable component and system level optimization at multiple flight conditions. The SAMPSON Smart Inlet program showed that fully integrated SMA wire bundles could provide a fighter aircraft with a Variable Engine Inlet capability. The Reconfigurable Rotor Blade program demonstrated the ability of highly robust, controlled 55-Nitinol tube actuators to twist a rotor blade in a spin stand test to optimize aerodynamic characteristics. The Variable Geometry Chevrons program, which was the first use of 60-Nitinol for a major aerospace application, included a flight test and static engine test of GE90–115B engine fitted with controlled morphing chevrons that reduced noise and increased engine efficiency. The Deployable Rotor Tab employed tube actuators to deploy and retract small fences which are capable of significantly reducing blade vortex interaction generated noise on a rotorcraft. Most recently, the Variable Geometry Fan Nozzle program has built on the VGC technology to demonstrate improved jet engine performance. The Boeing Company continues to mature SMA technology in order to develop innovative applications and support their commercialization.
Flexible Learning of Multiple Speech Structures in Bilingual Infants
Authors: Kovács Ágnes Melinda , Mehler Jacques
Published: July 2009

Young and Flexible

How an infant learns to understand and speak a language remains a deep scientific mystery even though millions of kids accomplish these feats each year. Furthermore, this learning capacity is apparently not even taxed to its utmost; children who grow up in bilingual families learn two languages just as rapidly as those who learn only one.
Kovács and Mehler
(p.
611
, published online 9 July) have assessed the cognitive flexibility of preverbal 1-year-old children raised in monolingual versus bilingual households and find that the bilingual group displays an impressive facility in handling inconsistent, language-like, inputs. That is, the kids exposed to two distinct languages since birth were able to associate two distinct syllabic structures—AAB and ABA—with looking leftward and rightward, whereas the monolinguals could only do so only with the simpler AAB structure.
LARGE TIME DECAY OF SOLUTIONS TO ISENTROPIC GAS DYNAMICS WITH SPHERICAL SYMMETRY
Authors: TSUGE NAOKI
Published: July 2009

We consider the large time behavior of solutions to isentropic gas dynamics with spherical symmetry. In the present paper, we show the decay of the pressure in particular. To do this, we investigate approximate solutions constructed by a difference scheme.
Mimicking natural systems: methane hydrate formation-decomposition in depleted sediments
Authors: Eaton M. W. , Jones K. W. , Mahajan Devinder
Published: July 2009

We have initiated a systematic study of sediment–hydrate interaction under subsurface-mimic conditions to initially focus on marine hydrates. A major obstacle to studying natural hydrate systems has been the absence of a sophisticated mimic apparatus in which the hydrate formation phenomenon can be reproduced with precision. We have designed and constructed a bench-top unit, namely flexible integrated study of hydrates (FISH), for this purpose. The unit is fully instrumented to precisely record temperatures, pressures and changes in gas volume during absorption/evolution. The Labview software allows rapid and continuous data collection during the hydrate formation/dissociation cycle. In our integrated approach, several host sediments collected from Blake Ridge, a well-researched hydrate site, were characterized using the computed microtomography technique at Beamline X-26A of the National Synchrotron Light Source at Brookhaven National Laboratory. The characterized depleted sediments were then used to study the hydrate formation/decomposition kinetics under various pressures in the FISH unit. We report two hydrate formation methods: one under continuous methane gas-flow conditions (dynamic mode) and the other in which hydrates are formed from the dissolved gas phase by diffusion (static mode). Also reported is a depressurization method, namely the step-down pressure method, to yield gas evolution data. Data from such runs with host sediment from the deepest site (667 metres) is presented. During hydrate formation, the data reveals a temperature signature that is consistent with an exothermic hydrate formation event. In the decomposition cycle, data at various pressures was analysed to yield curves with similar slopes, suggesting a zero-order dependence. The capabilities of the FISH unit and the implications of these runs in establishing a database of sediment–hydrate kinetics and pore saturation are discussed.
Effects of solid surfaces on hydrate kinetics and stability
Authors: Kvamme B. , Graue A. , Buanes T. , Kuznetsova T. , Ersland G.
Published: July 2009

Reservoirs of clathrate hydrates of natural gases (hydrates), found worldwide and containing huge amounts of bound natural gases (mostly methane), represent potentially vast and yet untapped energy resources. Since CO
2
‐containing hydrates are considerably more stable thermodynamically than methane hydrates, if we find a way to replace the original hydrate-bound hydrocarbons with the CO
2
, two goals can be accomplished at the same time: safe storage of carbon dioxide in hydrate reservoirs, and
in situ
release of hydrocarbon gas. We have applied the techniques of magnetic resonance imaging as a tool to visualize the conversion of CH
4
hydrate within Bentheim sandstone matrix into the CO
2
hydrate. Corresponding model systems have been simulated using the phase field theory approach. Our theoretical studies indicate that the kinetic behaviour of the systems closely resembles that of CO
2
transport through an aqueous solution. We have interpreted this to mean that the hydrate and the matrix mineral surfaces are separated by liquid-containing channels. These channels will serve as escape routes for released natural gas, as well as distribution channels for injected CO
2
.
Gas hydrate growth and dissociation in narrow pore networks: capillary inhibition and hysteresis phenomena
Authors: Anderson R. , Tohidi B. , Webber J. B. W.
Published: July 2009

Marine sediments hosting gas hydrates are commonly fine-grained (silts, muds, clays) with very narrow mean pore diameters (∼0.1 µm). This has led to speculation that capillary phenomena could play an important role in controlling hydrate distribution in the seafloor, and may be in part responsible for discrepancies between observed and predicted (from bulk phase equilibria) hydrate stability zone (HSZ) thicknesses. Numerous recent laboratory studies have confirmed a close relationship between hydrate inhibition and pore size, stability being reduced in narrow pores; however, to date the focus has been hydrate
dissociation
conditions in porous media, with capillary controls on the equally important process of hydrate
growth
being largely neglected. Here, we present experimental methane hydrate growth and dissociation conditions for synthetic mesoporous silicas over a range of pressure–temperature (
PT
) conditions (273–293 K, to 20 MPa) and pore size distributions. Results demonstrate that hydrate formation and decomposition in narrow pore networks is characterized by a distinct hysteresis: solid growth occurs at significantly lower temperatures (or higher pressures) than dissociation. Hysteresis takes the form of repeatable, irreversible closed primary growth and dissociation
PT
loops, within which various characteristic secondary ‘scanning’ curve pathways may be followed. Similar behaviour has recently been observed for ice–water systems in porous media, and is characteristic of liquid–vapour transitions in mesoporous materials. The causes of such hysteresis are still not fully understood; our results suggest pore blocking during hydrate growth as a primary cause.
Can CO
2
hydrate assist in the underground storage of carbon dioxide?
Authors: Rochelle C. A. , Camps A. P. , Long D. , Milodowski A. , Bateman K. , Gunn D. , Jackson P. , Lovell M. A. , Rees J.
Published: July 2009

The sequestration of CO
2
in the deep geosphere is one potential method for reducing anthropogenic emissions to the atmosphere without necessarily incurring a significant change in our energy-producing technologies. Containment of CO
2
as a liquid and an associated hydrate phase, under cool conditions, offers an alternative underground storage approach compared with conventional supercritical CO
2
storage at higher temperatures. We briefly describe conventional approaches to underground storage, review possible approaches for using CO
2
hydrate in CO
2
storage generally, and comment on the important role CO
2
hydrate could play in underground storage. Cool underground storage appears to offer certain advantages in terms of physical, chemical and mineralogical processes, which may usefully enhance trapping of the stored CO
2
. This approach also appears to be potentially applicable to large areas of sub-seabed sediments offshore Western Europe.
Hydrocarbon gas hydrates in sediments of the Mississippi Canyon area, Northern Gulf of Mexico
Authors: McGee T. , Macelloni L. , Lutken C. , Bosman A. , Brunner C. , Rogers R. , Dearman J. , Sleeper K. , Woolsey J. R.
Published: July 2009

The Gulf of Mexico Hydrates Research Consortium has begun installing a seafloor observatory to monitor gas hydrate outcrops and the hydrate stability zone in Mississippi Canyon Area Lease Block 118. Relevant background information concerning the Mississippi Canyon Area and gas hydrate occurrences in the northern Gulf of Mexico is presented. Microbial influences and possible scenarios of hydrate accumulation are considered. The design of the observatory was based on field data recorded in the Mississippi Canyon Area, principally lease block 118 (MC118) and the vicinity of lease block 798 (MC798). Swath bathymetry by autonomous underwater vehicle played a large part, as did seismic imaging within the hydrate stability zone and core sampling. These data and the results of their analyses are discussed in detail. Discussion and interim conclusions are presented.
The pore-scale distribution of sediment-hosted hydrates: evidence from effective medium modelling of laboratory and borehole seismic data
Authors: Minshull T. A. , Chand S.
Published: July 2009

Much of our knowledge on hydrate distribution in the subsurface comes from interpretations of remote seismic measurements. A key step in such interpretations is an effective medium theory that relates the seismic properties of a given sediment to its hydrate content. A variety of such theories have been developed; these theories generally give similar results if the same assumptions are made about the extent to which hydrate contributes to the load-bearing sediment frame. We have further developed and modified one such theory, the self-consistent approximation/differential effective medium approach, to incorporate additional empirical parameters describing the extent to which both the sediment matrix material (clay or quartz) and the hydrate are load-bearing. We find that a single choice of these parameters allows us to match well both
P
and
S
wave velocity measurements from both laboratory and
in situ
datasets, and that the inferred proportion of hydrate that is load-bearing varies approximately linearly with hydrate saturation. This proportion appears to decrease with increasing hydrate saturation for gas-rich laboratory environments, but increases with hydrate saturation when hydrate is formed from solution and for an
in situ
example.
On the Biomechanics of Vaginal Birth and Common Sequelae
Authors: Ashton-Miller James A. , DeLancey John O.L.
Published: July 2009

Approximately 11% of U.S. women undergo surgery for pelvic floor dysfunction, including genital organ prolapse and urinary and fecal incontinence. The major risk factor for developing these conditions is giving vaginal birth. Vaginal birth is a remarkable event about which little is known from a biomechanical perspective. We first review the functional anatomy of the female pelvic floor, the normal loads acting on the pelvic floor in activities of daily living, and the functional capacity of the pelvic floor muscles. Computer models show that the stretch ratio in the pelvic floor muscles can reach an extraordinary 3.26 by the end of the second stage of labor. Magnetic resonance images provide evidence that show that the pelvic floor regions experiencing the most stretch are at the greatest risk for injury, especially in forceps deliveries. A conceptual model suggests how these injuries may lead to the most common form of pelvic organ prolapse, a cystocele.
Probiotic Lactobacillus casei strain Shirota prevents indomethacin-induced small intestinal injury: involvement of lactic acid
Authors: Watanabe Toshio , Nishio Hikaru , Tanigawa Tetsuya , Yamagami Hirokazu , Okazaki Hirotoshi , Watanabe Kenji , Tominaga Kazunari , Fujiwara Yasuhiro , Oshitani Nobuhide , Asahara Takashi , Nomoto Koji , Higuchi Kazuhide , Takeuchi Koji , Arakawa Tetsuo
Published: July 2009

Inflammatory responses triggered by activation of the lipopolysaccharide (LPS)/Toll-like receptor (TLR) 4 signaling pathway are a key mechanism in nonsteroidal anti-inflammatory drug-induced enteropathy. The aim of this study was to investigate the probiotic effect of Lactobacillus casei strain Shirota (LcS) on indomethacin-induced small intestinal injury. Rats pretreated with viable LcS or heat-killed LcS once or once daily for a week were administered indomethacin by gavage to induce injury. Anti-inflammatory effects of l-lactic acid (1–15 mM) were evaluated in vitro by use of THP-1 cells. One-week treatment with viable LcS prevented indomethacin-induced intestinal injury with increase in the concentration of lactic acid in small intestinal content and inhibited increases in myeloperoxidase activity and expression of mRNA for tumor necrosis factor-α (TNF-α) while affecting neither TLR4 expression nor the number of gram-negative bacteria in intestinal content, whereas neither heat-killed LcS nor a single dose of viable LcS inhibited intestinal injury. Prevention of this injury was also observed in rats given l-lactic acid in drinking water. Both l-lactic acid and LcS culture supernatant containing 10 mM lactic acid inhibited NF-κB activation and increases in TNF-α mRNA expression and TNF-α protein secretion in THP-1 cells treated with LPS. Western blot analyses showed that both l-lactic acid and LcS culture supernatants suppressed phosphorylation and degradation of I-κB-α induced by LPS without affecting expression of TLR4. These findings suggest that LcS exhibits a prophylactic effect on indomethacin-induced enteropathy by suppressing the LPS/TLR4 signaling pathway and that this probiotic effect of LcS may be mediated by l-lactic acid.
Robust passive dynamics of the musculoskeletal system compensate for unexpected surface changes during human hopping
Authors: van der Krogt Marjolein M. , de Graaf Wendy W. , Farley Claire T. , Moritz Chet T. , Richard Casius L. J. , Bobbert Maarten F.
Published: July 2009

When human hoppers are surprised by a change in surface stiffness, they adapt almost instantly by changing leg stiffness, implying that neural feedback is not necessary. The goal of this simulation study was first to investigate whether leg stiffness can change without neural control adjustment when landing on an unexpected hard or unexpected compliant (soft) surface, and second to determine what underlying mechanisms are responsible for this change in leg stiffness. The muscle stimulation pattern of a forward dynamic musculoskeletal model was optimized to make the model match experimental hopping kinematics on hard and soft surfaces. Next, only surface stiffness was changed to determine how the mechanical interaction of the musculoskeletal model with the unexpected surface affected leg stiffness. It was found that leg stiffness adapted passively to both unexpected surfaces. On the unexpected hard surface, leg stiffness was lower than on the soft surface, resulting in close-to-normal center of mass displacement. This reduction in leg stiffness was a result of reduced joint stiffness caused by lower effective muscle stiffness. Faster flexion of the joints due to the interaction with the hard surface led to larger changes in muscle length, while the prescribed increase in active state and resulting muscle force remained nearly constant in time. Opposite effects were found on the unexpected soft surface, demonstrating the bidirectional stabilizing properties of passive dynamics. These passive adaptations to unexpected surfaces may be critical when negotiating disturbances during locomotion across variable terrain.
Influence of Obesity on Progression of Non-Diabetic Chronic Kidney Disease: A Retrospective Cohort Study
Authors: Othman Muftah , Kawar Bisher , El Nahas A. Meguid
Published: July 2009

Background: There is increasing awareness of the impact of obesity on chronic diseases including chronic kidney disease (CKD). Until recently, a limited number of epidemiologic studies have examined the association between obesity and CKD. We conducted a retrospective cohort study to evaluate whether obesity impacts on the rate of non-diabetic CKD progression. Methods: The medical records of 125 non-diabetic CKD patients in the Sheffield Kidney Institute, Sheffield, UK, who have been followed-up for around 10 years, were reviewed. Various socio-demographic, clinical and biochemical parameters were retrospectively collected from the patients’ database. Participants were categorized into normal weight, overweight and obese groups. Multivariate regression analysis was used for modelling with estimated glomerular filtration rate (eGFR) reduction per year as the dependent variable to evaluate the impact of obesity (BMI) on CKD progression. Results: Patients studied were mostly CKD stage 3 with a mean GFR of 36.2 ml/min/1.73 m2 for the control group and 44.3 ml/min/1.73 m2 for those who were overweight or obese. Baseline diastolic and mean arterial blood pressure were significantly higher in overweight than normal weight CKD patients (p = 0.009 and p = 0.014 respectively). On follow-up, systolic, diastolic and mean arterial blood pressure were significantly higher in overweight (p = 0.03, p = 0.005 and p = 0.003, respectively) and obese (p = 0.008, p = 0.022 and p = 0.003, respectively) compared to normal weight CKD patients. Mean follow-up triglycerides level was significantly higher in obese than normal weight patients (p = 0.042). The frequency of CKD progression based on eGFR fall per year (>1 ml/min/1.73 m2/year) was 62.5% in overweight and 79.5% in obese compared to 44.7% in normal weight CKD patients (p = 0.007). However, no significant difference in the rate of progression (fall of eGFR ml/min/1.73 m2/year) was observed between the three groups. On multivariate regression analysis, adjusted for other covariates (age, BP and proteinuria), baseline BMI was an independent predictor of CKD progression (fall in eGFR, ml/min/1.73 m2/year) (R2 = 0.122 and p < 0.001). Percentage changes in BMI over the observation period did not affect the rate of eGFR decline. Young age also predicted a faster CKD progression. Conclusions: Baseline BMI and young age are strongly and independently associated with faster CKD progression based on the annual rate of eGFR fall. Prospective studies to investigate the relationship between BMI and CKD and its complications are warranted.
Interdialytic Weight Gain in Diabetic Haemodialysis Patients and Diabetic Control as Assessed by Glycated Haemoglobin
Authors: Davenport Andrew
Published: July 2009

Background: Cardiovascular morbidity and mortality is increased in diabetic haemodialysis patients. Diabetic subjects may suffer greater thirst and thereby be predisposed to increased interdialytic weight gains and hypertension. Methods: 175 established adult diabetic haemodialysis patients attending outpatient haemodialysis thrice weekly were audited during a 1-week interval. Results: Despite fewer patients prescribed antihypertensive medications (46%), the mean pre-dialysis systolic blood pressure was lowest in those patients with the lowest HbA1c values (≤6%; 146 ± 27 mm Hg), versus 154 ± 25 mm Hg for the highest group, with a HbA1c of >8%, of whom 70% were prescribed antihypertensive medications (p < 0.05). Both absolute and percentage interdialytic weight gain was lowest in the group with the best diabetic control: 2.0 ± 1 kg and 2.76 ± 1.5% versus 2.5 ± 1.1 kg and 3.3 ± 1.3%, respectively (p < 0.05). Conclusions: Poor diabetic control may increase thirst and salt intake, leading to increased interdialytic weight gains, associated with systolic hypertension, and as such, diabetic control is an important facet in the management of the diabetic haemodialysis patient.
Association of Secondary Hyperparathyroidism with CKD Progression, Health Care Costs and Survival in Diabetic Predialysis CKD Patients
Authors: Schumock Glen T. , Andress Dennis L. , Marx Steven E. , Sterz Raimund , Joyce Amie T. , Kalantar-Zadeh Kamyar
Published: July 2009

Background/Aims: The objective of this study was to examine health care costs and utilization and the risks of dialysis or mortality among diabetic predialysis chronic kidney disease (CKD) patients with and without secondary hyperparathyroidism (SHPT). Methods: This retrospective, matched cohort study examined insurance claims from 703 adult diabetic predialysis CKD patients with and without SHPT during a 72-month follow-up period. Annualized estimates of health care service utilization, costs and disease progression to dialysis or death following index CKD diagnosis were compared. Results: Preindex (baseline) characteristics were similar between the cohorts. Postindex numbers of prescription utilization, outpatient service utilization and hospitalizations were all higher (p < 0.0001) in diabetic CKD patients with SHPT compared to those without SPHT in both unadjusted and adjusted analyses even after multivariate adjustment for known confounders. The rate of progression to dialysis or death was higher for diabetic CKD patients with SHPT compared to those without SPHT. Those with SHPT were at higher risk of requiring dialysis treatment [hazard ratio (HR) = 6.7; 95% confidence interval (CI) = 4.3–10.6] and death (HR = 2.3; 95% CI = 1.1–4.9) compared to those without SHPT. Conclusion: In diabetic predialysis CKD patients, the presence of SHPT is associated with significantly greater health care resource utilization and costs, and a faster rate of disease progression.
Aldosterone Induces Apoptosis in Rat Podocytes: Role of PI3-K/Akt and p38MAPK Signaling Pathways
Authors: Chen Cheng , Liang Wei , Jia Junya , van Goor Harry , Singhal Pravin C. , Ding Guohua
Published: July 2009

Background: Podocytes play a critical role in the pathogenesis of glomerulosclerosis. Increasing evidence suggests that aldosterone (ALD) is involved in the initiation and progression of glomerular damage. It is, however, unknown whether there is a direct injurious effect of ALD on podocytes. Therefore, in the present study, we evaluated the effect of ALD on podocyte apoptosis and studied the role of phosphatidylinositol 3-kinase/Akt (PI3-K/Akt) and p38 mitogen-activated protein kinase (p38MAPK) signaling pathways in this process. Methods: Podocytes were incubated in media containing either buffer or increasing concentrations of ALD (10–9∼10–5M) for variable time periods. The cells were also treated with either wortmannin (inhibitor of PI3-K, 100 nM), SB202190 (SB20, inhibitor of p38MAPK, 10 μM) or buffer. All treatments were performed with or without ALD (10–7M) for 24 h. At the end of the incubation period, apoptosis was evaluated by cell nucleus staining and flow cytometric analyses. Activation of PI3-K/Akt and p38MAPK phosphorylation of cultured rat podocytes was evaluated by performing Akt kinase assay and Western blot, respectively. Results: Apoptosis of cultured rat podocytes was induced by ALD in a dose- and time-dependent manner. ALD inhibited the activity of PI3-K/Akt and increased the activation of p38MAPK. PI3-K/Akt activity was further inhibited by the addition of wortmannin to the cells in the presence of ALD. This was accompanied by a significant increase in apoptosis. ALD-induced p38MAPK phosphorylation and apoptosis were inhibited when the cells were pretreated with SB20. Furthermore, treatment with spironolactone not only attenuated the proapoptotic effect of ALD, but also significantly reversed its effects on PI3-K/Akt and p38MAPK signaling pathways. Conclusion: ALD induces apoptosis in rat podocytes through inhibition of PI3-K/Akt and stimulation of p38 MAPK signaling pathways. Spironolactone attenuates ALD-induced podocyte apoptosis, thereby positioning this compound as a potential promising target of intervention in human renal damage.
Risk Factors for Post-Pancreaticoduodenectomy Bleeding and Finding an Innovative Approach to Treatment
Authors: Wei Hung-Kuang , Wang Shin-E , Shyr Yi-Ming , Tseng Hsiuo-Shan , Tsai Wan-Chen , Chen Tien-Hua , Su Cheng-Hsi , Wu Chew-Wun , Lui Wing-Yiu
Published: July 2009

Background: This study is to determine the risk factors and outcome for post-pancreaticoduodenectomy bleeding, and to assess the roles of surgery and intravascular intervention in its management. Methods: Post-pancreaticoduodenectomy data of 628 patients were analyzed with regards to post-pancreaticoduodenectomy bleeding. Results: Post-pancreaticoduodenectomy bleeding occurred in 58 patients (9.2%) and led to death in 23 patients. Pancreatic leakage and intra-abdominal abscess were independent risk factors for both extraluminal and intraluminal post-pancreaticoduodenectomy bleeding. The most common source of bleeding was the gastroduodenal artery (n = 9, 24.3%), and 8 of these patients (88.9%) experienced gastroduodenal artery bleeding in late post-pancreaticoduodenectomy bleeding. Hemostasis for post-pancreaticoduodenectomy bleeding was achieved by surgery in 22 patients (78.6%) and intravascular intervention in 7 patients (58.3%). Transarterial embolization for gastroduodenal artery bleeding did not deteriorate liver function in most patients except for 1 who died of hepatic failure. Conclusions: The placement of metallic clips on the gastroduodenal artery stump during a pancreaticoduodenectomy is helpful in identifying overlooked intermittent sentinel bleeding during angiography. Transarterial embolization for gastroduodenal artery bleeding could not guarantee against hepatic failure. The intravascular placement of a covered stent is the preferred procedure to avoid the complete interruption of arterial blood supply to the liver.
The Selection and Design of Control Conditions for Randomized Controlled Trials of Psychological Interventions
Authors: Mohr David C. , Spring Bonnie , Freedland Kenneth E. , Beckner Victoria , Arean Patricia , Hollon Steven D. , Ockene Judith , Kaplan Robert
Published: July 2009

The randomized controlled trial (RCT) provides critical support for evidence-based practice using psychological interventions. The control condition is the principal method of removing the influence of unwanted variables in RCTs. There is little agreement or consistency in the design and construction of control conditions. Because control conditions have variable effects, the results of RCTs can depend as much on control condition selection as on the experimental intervention. The aim of this paper is to present a framework for the selection and design of control conditions for these trials. Threats to internal validity arising from modern RCT methodology are reviewed and reconsidered. The strengths and weaknesses of several categories of control conditions are examined, including the ones that are under experimental control, the ones that are under the control of clinical service providers, and no-treatment controls. Considerations in the selection of control conditions are discussed and several recommendations are proposed. The aim of this paper is to begin to define principles by which control conditions can be selected or developed in a manner that can assist both investigators and grant reviewers.
Nutrigenetics in the Light of Human Evolution
Authors: Verginelli Fabio , Aru Federica , Battista Pasquale , Mariani-Costantini Renato
Published: July 2009

Bio-cultural adaptations to new foods played a key role in human evolution. The fossil record and sequence differences between human and chimpanzee genes point to a major dietary shift at the stem of human evolution. The earliest representatives of the human lineage diverged from the ancestors of chimpanzees because of their better adaptation to hard and abrasive foods. Bipedalism and modifications of the hand, which allowed tool manufacture and use, impacted on dietary flexibility, facilitating access to foods of animal origin. This promoted major anatomic, physiologic and metabolic adaptations. Encephalization, which requires high-quality diet, characterizes the evolutionary sequence that, through the Homo ergaster/erectus stages, led to our species, Homo sapiens, which originated in Africa about 200,000 years ago. At the end of the Ice Age, climatic changes and human impact determined a major food crisis, which triggered the agricultural revolution. This affected nutrition and health, with rapid evolutionary adaptations through the selection of genetic variants that allowed better utilization of new foods, different in relation to geography and culture. Today population growth, globalization and economic pressure powerfully affect diets worldwide. We must take into account our evolutionary past to meet the present nutritional challenges.
Crime, Hysteria and Belle Époque Hypnotism: The Path Traced by Jean-Martin Charcot and Georges Gilles de la Tourette
Authors: Bogousslavsky Julien , Walusinski Olivier , Veyrunes Denis
Published: July 2009

Hysteria and hypnotism became a favorite topic of studies in the fin de siècle neurology that emerged from the school organized at La Salpêtrière by Jean-Martin Charcot, where he had arrived in 1861. Georges Gilles de la Tourette started working with Charcot in 1884 and probably remained his most faithful student, even after his mentor’s death in 1893. This collaboration was particularly intense on ‘criminal hypnotism’, an issue on which Hippolyte Bernheim and his colleagues from the Nancy School challenged the positions taken by the Salpêtrière School. Bernheim claimed that hypnotism was not a diagnostic feature of hysteria and that there were real-life examples of murders suggested under hypnosis, while hypnosis susceptibility was identified with hysteria by Charcot and Gilles de la Tourette, who saw rape as the only crime associated with hypnotism. The quarrel was particularly virulent during a series of famous criminal cases which took place between 1888 and 1890. At the time, it was considered that La Salpêtrière had succeeded over Nancy, since the role of hypnotism was discarded during these famous trials. However, the theories of Charcot and Gilles de la Tourette were also damaged by the fight, which probably triggered the conceptual evolution leading to Joseph Babinski’s revision of hysteria in 1901. Gilles de la Tourette’s strong and public interest in hypnotism nearly cost him his life, when a young woman who claimed to have been hypnotized against her will shot him in the head at his own home in 1893. It was subsequently shown that hypnotism had nothing to do with it. The delusional woman was interned at Sainte-Anne for mental disturbance, thus escaping trial. Ironically, Gilles de la Tourette may have been partly responsible, since he had been one of the strongest proponents of placing mentally-ill criminals in asylums instead of prisons.
Increased Risk for Falling Associated with Subtle Cognitive Impairment: Secondary Analysis of a Randomized Clinical Trial
Authors: Gleason Carey E. , Gangnon Ronald E. , Fischer Barbara L. , Mahoney Jane E.
Published: July 2009

Background/Aims: Having dementia increases patients’ risk for accidental falls. However, it is unknown if having mild cognitive deficits also elevates a person’s risk for falls. This study sought to clarify the relationship between subtle cognitive impairment, measured with a widely-used, clinic-based assessment, the Mini Mental State Exam (MMSE), and risk for falls. Methods: In a secondary analysis of the Kenosha County Falls Prevention Study, a randomized controlled trial targeting older adults at risk for falls, we examined the association between baseline MMSE and prospective rate of falls over 12 months in 172 subjects randomized to control group. Results: Using univariate analysis, the rate of falls increased with each unit decrease in MMSE score down to at least 22 (rate ratio 1.25, 95% confidence interval (CI) 1.09–1.45, p = 0.0026). Using stepwise multivariate regression, controlling for ability to perform activities of daily living, use of assistive device, current exercise, and arthritis, the association between MMSE score and falls rate persisted (rate ratio 1.20, 95% CI 1.03–1.40, p = 0.021). Conclusion: Minimal decrements on the MMSE were associated with elevations in rate of falls, suggesting that subtle cognitive deficits reflected in MMSE scores above a cut-off consistent with a diagnosis of dementia, can influence risk for falls.
Association between Plasma Homocysteine Levels and Mortality in Elderly Patients with Mental Illness
Authors: Nilsson Karin , Gustafson Lars , Hultberg Björn
Published: July 2009

Background/Method: Total plasma homocysteine (tHcy) concentration is elevated in elderly patients with mental illness. Plasma tHcy is known to be associated with cardiovascular disease, renal impairment and negative lifestyle factors, and has been shown to predict mortality in human subjects. Epidemiological data on this topic in elderly patients with mental illness are missing. We therefore investigated the association between plasma tHcy levels and mortality in these patients. Results: The group of deceased patients showed higher age, higher plasma tHcy, lower renal function and lower serum folate than patients who were still alive. Only age, plasma tHcy and the presence of vascular disease significantly influenced mortality. Conclusion: The association between plasma tHcy level and mortality risk was probably explained in part by the two plasma tHcy determinants age and presence of vascular disease. The determination of plasma tHcy in elderly patients with mental illness may help to identify patients in need of more intensive treatment.
‘Les ictus amnésiques’ and Transient Global Amnesia
Authors: Pearce J.M.S. , Bogousslavsky Julien
Published: July 2009

In March 1909, R. Benon was probably the first to report a typical case of what we now call transient global amnesia. In 1956, Bender, and independently, Guyotat and Courjon described clinical and epidemiological features of transient amnesic attacks. The condition achieved general recognition after the term transient global amnesia (TGA) was introduced by Fisher and Adams in 1958. Their historic work is the main focus of this review. They reported 17 patients, with an abrupt anterograde amnesia of short duration. Classification and criteria are outlined. Various aetiologies have been postulated, but although TGA remains a clinically distinct syndrome, usually with a good prognosis, evidence of neither ischaemia nor epilepsy is demonstrable in most patients. Theories of jugular venous reflux may be relevant in some but probably not in most cases of this heterogeneous disorder.
Patterns of Hospital Performance in Acute Myocardial Infarction and Heart Failure 30-Day Mortality and Readmission
Authors: Krumholz Harlan M. , Merrill Angela R. , Schone Eric M. , Schreiner Geoffrey C. , Chen Jersey , Bradley Elizabeth H. , Wang Yun , Wang Yongfei , Lin Zhenqiu , Straube Barry M. , Rapp Michael T. , Normand Sharon-Lise T. , Drye Elizabeth E.
Published: July 2009

Background—

In 2009, the Centers for Medicare & Medicaid Services is publicly reporting hospital-level risk-standardized 30-day mortality and readmission rates after acute myocardial infarction (AMI) and heart failure (HF). We provide patterns of hospital performance, based on these measures.

Methods and Results—

We calculated the 30-day mortality and readmission rates for all Medicare fee-for-service beneficiaries ages 65 years or older with a primary diagnosis of AMI or HF, discharged between July 2005 and June 2008. We compared weighted risk-standardized mortality and readmission rates across Hospital Referral Regions and hospital structural characteristics. The median 30-day mortality rate was 16.6% for AMI (range, 10.9% to 24.9%; 25th to 75th percentile, 15.8% to 17.4%; 10th to 90th percentile, 14.7% to 18.4%) and 11.1% for HF (range, 6.6% to 19.8%; 25th to 75th percentile, 10.3% to 12.0%; 10th to 90th percentile, 9.4% to 13.1%). The median 30-day readmission rate was 19.9% for AMI (range, 15.3% to 29.4%; 25th to 75th percentile, 19.5% to 20.4%; 10th to 90th percentile, 18.8% to 21.1%) and 24.4% for HF (range, 15.9% to 34.4%; 25th to 75th percentile, 23.4% to 25.6%; 10th to 90th percentile, 22.3% to 27.0%). We observed geographic differences in performance across the country. Although there were some differences in average performance by hospital characteristics, there were high and low hospital performers among all types of hospitals.

Conclusions—

In a recent 3-year period, 30-day risk-standardized mortality rates for AMI and HF varied among hospitals and across the country. The readmission rates were particularly high.