bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow Analysis in Francis Water Turbines
Authors: Jansen W.
Published: March 2013

It is the intent of this study to investigate the flow field in Francis water turbines operated at various guidevane settings with the use of analytical techniques. The flow fluid is analyzed with a streamline-curvature method and the underlying theory is discussed briefly. With the analysis, certain lower and upper limits for the guidevane settings can be defined. Within these limits only a small drop-off in efficiency at the extreme settings can be expected. Outside these limits severe cavitation and flow reversals are shown to take place. In the Appendix, it is shown how the analysis can be used to evaluate the effects of different passage and blade geometry on the flow field.
Some Vibration Characteristics of Pin-Fixed Compressor Blades
Authors: Goatham J. I. , Smailes G. T.
Published: March 2013

The nature of some of the modes of vibration of blades having a free-pin attachment is discussed, with particular reference to expected positions of failure, bending-stress distribution, and calculation of natural frequencies. Some aspects of aerodynamic damping and prediction of amplitudes in distorted flow are also treated, and a critical direction of blade vibration is indicated and shown to exist in a particular mode of a compressor blade.
Analysis and Solution of a Draft-Tube Water Depression Problem
Authors: Eyden B. , Slack J. R.
Published: March 2013

A compressed air system which initially failed to depress draft-tube water for synchronous condensing operation on a propeller turbine-driven hydroelectric generating unit was tested to determine cause of failure and formulate corrective measures. A hypothesis and certain assumptions concerning air and water action in the draft tube were essentially verified by further testing. Final testing of the modified evacuation air system demonstrated ample capability to attain a synchronous condensing condition. Several conclusions were drawn from the testing and modification work.
Transient Analysis of Variable-Pitch Pump Turbines
Authors: DeFazio F. G.
Published: March 2013

A method of analyzing the transient behavior of a pump turbine with variable-pitch blades is presented. A series of equations that describe the behavior of the unit during the transient period is found by interpolation of the unit’s characteristic. These equations are combined with the method of characteristic solution to the waterhammer equations to describe the behavior of an entire system during a transient period. A complete performance characteristic of a variable-pitch pump turbine is presented. Example problems which utilize this characteristic illustrate the method of analysis. The examples prove that the variation in pitch of a unit’s blades is very important in predicting the head across the unit, the discharge through the unit, and the speed of the unit during a transient period.
Analysis of Single- and Two-Phase Flows in Turbopump Inducers
Authors: Cooper P.
Published: March 2013

A model is developed for analytically determining pump inducer performance in both the single-phase and cavitating flow regimes. An equation of state for vaporizing flow is used in an approximate, three-dimensional analysis of the flow field. The method accounts for losses and yields internal distributions of fluid pressure, velocity, and density together with the resulting overall efficiency and pressure rise. The results of calculated performance of two sample inducers are presented. Comparison with recent theory for fluid thermal effects on suction head requirements is made with the aid of a resulting dimensionless vaporization parameter.
Cost Effectiveness in Pumping System Design and Operation
Authors: Benz Glen
Published: March 2013

A technique for numerically evaluating pumping system effectiveness on the basis of statistical analysis is presented. The technique is applied to a hypothetical substitution of stainless pump wear rings for bronze to find if the probable increase in quantity of water delivered annually compares favorably with the operational cost difference between the materials. Other applications for this decision-making device are briefly described.
Effect of Groove Geometry on Viscoseal Performance
Authors: Stair W. K.
Published: March 2013

An experimental investigation of the effect of groove geometry on the performance of the grooved-shaft viscoseal is being conducted. Using distilled water as the sealed fluid, the concentric and eccentric performance of ten seals has been determined under laminar and turbulent conditions. An approximate method is devised to predict the empirical factors in the turbulent sealing equation. The findings reveal that the optimum seal geometry for laminar operation is not optimum for turbulent conditions, the seal eccentricity has slight effect on performance, and the phenomenon of air ingestion may present a major problem in the application of the viscoseal.
Waterhammer Analysis of Pump Discharge Line With Several One-Way Surge Tanks
Authors: Miyashiro H.
Published: March 2013

In some pumping plants several one-way surge tanks are installed to prevent water-column separation in the discharge line caused by failure of power to pumps. This paper describes a method of analysis of waterhammer in a pump system of this type. The analysis is carried out by solving the fundamental equations by a digital computer. An example is calculated and the results are compared with the measurements.
Optimization of a Phase Change Thermal Storage Unit
Authors: Bonadies Monica F. , Ricklick Mark , Kapat J. S.
Published: March 2013

Several options exist to collect thermal energy from the sun for domestic use. This study examines a system integrating evacuated tube collectors with heat pipes with a storage unit using melted paraffin wax to store thermal energy. A shell-and-tube heat exchanger is embedded within the paraffin wax storage with a volume of 0.23 m3. The heat exchanger includes two loops: one for glycol to transfer heat to the paraffin and one for water to extract heat from the melted paraffin. Although the paraffin has the benefit of being inexpensive and nontoxic, it has low thermal conductivity. Therefore, the heat exchanger has large brazed copper fins to extend areas of high thermal conductivity into the wax reservoir. To determine the benefit of the fins, wax and working fluid temperature data are taken from a constructed thermal energy storage unit and then used to verify a finite-difference one-dimensional analytical model of the unit. The maximum operating temperature of the glycol/water mix heat transfer fluid was approximately 65 °C when the fluid flowed at 3.78 l/min. City water at approximately 11.34 l/min was used to test the water heating capabilities of the unit. The one dimensional model proved useful in predicting the heat storage mode of the system. Due to its form, which was specifically developed for the unit in the study, the model could be adjusted to calculate thermal performance of similarly constructed thermal storage units.
Experimental and Numerical Analyses of a Pressurized Air Receiver for Solar-Driven Gas Turbines
Authors: Hischier I. , Leumann P. , Steinfeld A.
Published: March 2013

A high-temperature pressurized air-based receiver for power generation via solar-driven gas turbines is experimentally examined and numerically modeled. It consists of an annular reticulate porous ceramic (RPC) foam concentric with an inner cylindrical cavity-receiver exposed to concentrated solar radiation. Absorbed heat is transferred by combined conduction, radiation, and convection to the pressurized air flowing across the RPC. The governing steady-state mass, momentum, and energy conservation equations are formulated and solved numerically by coupled finite volume and Monte Carlo techniques. Validation is accomplished with experimental results using a 3 kW solar receiver prototype subjected to average solar radiative fluxes at the CPC outlet in the range 1870–4360 kW m−2. Experimentation was carried out with air and helium as working fluids, heated from ambient temperature up to 1335 K at an absolute operating pressure of 5 bars. The validated model is then applied to optimize the receiver design for maximum solar energy conversion efficiency and to analyze the thermal performance of 100 kW and 1 MW scaled-up versions of the solar receiver.
Array of Thermoelectric Coolers for On-Chip Thermal Management
Authors: Sullivan Owen , Gupta Man Prakash , Mukhopadhyay Saibal , Kumar Satish
Published: March 2013

Site-specific on-demand cooling of hot spots in microprocessors can reduce peak temperature and achieve a more uniform thermal profile on chip, thereby improve chip performance and increase the processor’s life time. An array of thermoelectric coolers (TECs) integrated inside an electronic package has the potential to provide such efficient cooling of hot spots on chip. This paper analyzes the potential of using multiple TECs for hot spot cooling to obtain favorable thermal profile on chip in an energy efficient way. Our computational analysis of an electronic package with multiple TECs shows a strong conductive coupling among active TECs during steady-state operation. Transient operation of TECs is capable of driving cold-side temperatures below steady-state values. Our analysis on TEC arrays using current pulses shows that the effect of TEC coupling on transient cooling is weak. Various pulse profiles have been studied to illustrate the effect of shape of current pulse on the operation of TECs considering crucial parameters such as total energy consumed in TECs peak temperature on the chip, temperature overshoot at the hot spot and settling time during pulsed cooling of hot spots. The square root pulse profile is found to be the most effective with maximum cooling and at half the energy expenditure in comparison to a constant current pulse. We analyze the operation of multiple TECs for cooling spatiotemporally varying hot spots. The analysis shows that the transient cooling using high amplitude current pulses is beneficial for short term infrequent hot spots, but high amplitude current pulse cannot be used for very frequent or long lasting hot spots.
Minimization of the Local Residual Stress in 3D Flip Chip Structures by Optimizing the Mechanical Properties of Electroplated Materials and the Alignment Structure of TSVs and Fine Bumps
Authors: Nakahira Kota , Tago Hironori , Endo Fumiaki , Suzuki Ken , Miura Hideo
Published: March 2013

Since the thickness of stacked silicon chips in 3D integration has been thinned to less than 100 μm, the local thermal deformation of the chips has increased drastically because of the decrease of the flexural rigidity of the thinned chips. The clear periodic thermal deformation and thus, the local distribution of thermal residual stress appears in the stacked chips due to the periodic alignment of metallic bumps, and they sometimes deteriorate mechanical and electrical reliability of electronic products. In this paper, the dominant structural factors of the local residual stress in a silicon chip are investigated quantitatively based on the results of a three-dimensional finite element analysis and the measurement of the local residual stress in a chip using stress sensor chips. The piezoresistive strain gauges were embedded in the sensor chips. The length of each gauge was 2 μm, and an unit cell consisted of four gauges with different crystallographic directions. This alignment of the strain gauges enables us to measure the tensor component of three-dimensional stress fields separately. Test flip chip substrates were made of silicon chip on which the area-arrayed tin/copper bumps were electroplated. The width of a bump was fixed at 200 μm, and the bump pitch was varied from 400 μm to 1000 μm. The thickness of the copper bump was about 40 μm and that of tin layer was about 10 μm. This tin layer was used for the formation of rigid joint by alloying it with copper interconnection formed on a stress sensing chip. The measured amplitude of the residual stress increased from about 30 MPa to 250 MPa depending on the combination of materials such as bump, underfill, and interconnections. It was confirmed that both the material constant of underfill and the alignment structure of fine bumps are the dominant factors of the local deformation and stress of a silicon chip mounted on area-arrayed metallic bumps. It was also confirmed that not only the control of mechanical properties of electroplated copper thin films, but also the hound’s-tooth alignment of a through silicon via and a bump are indispensable for minimizing the packaging-induced stress in the three-dimensionally mounted chips. This test chip is very effective for evaluating the packaging-process-induced stress in 3D stacked chips quantitatively.
Multiobjective Optimization of a Pin-Fin Heat Sink Using Evolutionary Algorithms
Authors: Kanyakam Siwadol , Bureerat Sujin
Published: March 2013

This paper presents the use of multiobjective evolutionary algorithms for the optimal geometrical design of a pin-fin heat sink. The multiobjective design problem is posed to minimize two conflicting objectives: the junction temperature and the fan pumping power of the heat sink. The design variables are mixed integer/continuous. The encoding/decoding process for this mixed integer/continuous design variables is detailed. The multiobjective optimizers employed to solve the design problem are population-based incremental learning, strength Pareto evolutionary algorithm, particles swarm optimization, and archived multiobjective simulated annealing. The approximate Pareto fronts obtained from using the various optimizers are compared based upon the hypervolume and generational distance indicators. From the results, population-based incremental learning (PBIL) outperforms the others. The new design approach is said to be superior to a classical design approach. It is also illustrated that the proposed multiobjective design process leads to better design compared to the current commercial pin-fin heat sinks.
40 μm Copper–Silver Composite Flip-Chip Interconnect Technology Using Solid-State Bonding
Authors: Sha Chu-Hsuan , Lin Wen P. , Lee Chin C.
Published: March 2013

Copper–silver (Cu–Ag) composite flip-chip interconnect between silicon (Si) chips and Cu substrates is demonstrated. Array of Cu–Ag columns, each 28 μm in height and 40 μm in diameter, is electroplated on 2-in. Si wafers coated with chromium (Cr)/gold (Au) dual layer. The Si wafers are diced into 6 mm × 6 mm chips, each containing 50 × 50 Cu–Ag columns. The Si chip with Cu–Ag columns is bonded to Cu substrates at 260 °C in 80 mTorr vacuum. A bonding force of only 1.8 kg is applied, corresponding to 0.71 g per Cu–Ag column. During bonding, Ag atoms in Cu–Ag columns deform and their surfaces conform to and mate with the surface of Cu substrate. Solid-state bonding incurs when Ag atoms in Cu–Ag columns and Cu atoms in Cu substrates are brought within atomic distance so that they share conduction electrons. The Cu–Ag columns are indeed bonded to the Cu. No molten phase is involved in the bonding. The joint consists of 60% Cu section and 40% Ag section. The ductile Ag is able to accommodate the thermal expansion mismatch between Si and Cu. The Cu–Ag joints do not contain any intermetallic compound (IMC). This interconnect technology avoids all reliability issues associated with IMC growth in conventional soldering processes. Compared to tin-based lead-free solder joints, Cu–Ag composite joints have superior electrical and thermal properties.
Prognostication Based on Resistance-Spectroscopy and Phase-Sensitive Detection for Electronics Subjected to Shock-Impact
Authors: Lall Pradeep , Lowe Ryan , Goebel Kai
Published: March 2013

Leading indicators of failure have been developed based on high-frequency characteristics, and system-transfer function derived from resistance spectroscopy measurements during shock and vibration. The technique is intended for condition-monitoring in high-reliability applications where the knowledge of impending failure is critical and the risks in terms of loss-of-functionality are too high to bear. Previously, resistance spectroscopy measurements have been used during thermal cycling tests to monitor damage progression due to thermomechanical stresses. The development of resistance spectroscopy based damage precursors for prognostication under shock and vibration is new. In this paper, the high-frequency characteristics and system-transfer function based on resistance spectroscopy measurements have been correlated to the damage progression in electronics during shock and vibration. Packages being examined include ceramic area-array packages. Second level interconnect technologies examined include copper-reinforced solder column, SAC305 solder ball, and 90Pb10Sn high-lead solder ball. Assemblies have been subjected to 1500 g, 0.5 ms pulse (JESD-B2111). Continuity has been monitored in situ during the shock test for identification of part-failure. Resistance spectroscopy based damage precursors have been correlated to the optically measured transient strain based feature vectors. High speed cameras have been used to capture the transient strain histories during shock-impact. Statistical pattern recognition techniques have been used to identify damage initiation and progression and determine the statistical significance in variance between healthy and damaged assemblies. Models for healthy and damaged packages have been developed based on package characteristics. Data presented show that high-frequency characteristics and system-transfer characteristics based on resistance spectroscopy measurements can be used for condition-monitoring, damage initiation, and progression in electronic systems. A positive prognostic distance has been demonstrated for each of the interconnect technologies tested.
Automated chest wall line detection for whole‐breast segmentation in sagittal breast MR images
Authors: Wu Shandong , Weinstein Susan P. , Conant Emily F. , Schnall Mitchell D. , Kontos Despina
Published: March 2013

Purpose:

Breast magnetic resonance imaging (MRI) plays an important role in the clinical management of breast cancer. Computerized analysis is increasingly used to quantify breast MRI features in applications such as computer‐aided lesion detection and fibroglandular tissue estimation for breast cancer risk assessment. Automated segmentation of the whole‐breast as an organ from the other parts imaged is an important step in aiding lesion localization and fibroglandular tissue quantification. For this task, identifying the chest wall line (CWL) is most challenging due to image contrast variations, intensity discontinuity, and bias field.

Methods:

In this work, the authors develop and validate a fully automated image processing algorithm for accurate delineation of the CWL in sagittal breast MRI. The CWL detection is based on an integrated scheme of edge extraction and CWL candidate evaluation. The edge extraction consists of applying edge‐enhancing filters and an edge linking algorithm. Increased accuracy is achieved by the synergistic use of multiple image inputs for edge extraction, where multiple CWL candidates are evaluated by the dynamic time warping algorithm coupled with the construction of a CWL reference. Their method is quantitatively validated by a dataset of 60 3D bilateral sagittal breast MRI scans (in total 3360 2D MR slices) that span the full American College of Radiology Breast Imaging Reporting and Data System (BI‐RADS) breast density range. Agreement with manual segmentation obtained by an experienced breast imaging radiologist is assessed by both volumetric and boundary‐based metrics, including four quantitative measures.

Results:

In terms of breast volume agreement with manual segmentation, the overlay percentage expressed by the Dice's similarity coefficient is 95.0% and the difference percentage is 10.1%. More specifically, for the segmentation accuracy of the CWL boundary, the CWL overlay percentage is 92.7% and averaged deviation distance is 2.3 mm. Their method requires ∼4.5 min for segmenting each 3D breast MRI scan (56 slices) in comparison to ∼35 min required for manual segmentation. Further analysis indicates that the segmentation performance of their method is relatively stable across the different BI‐RADS density categories and breast volume, and also robust with respect to a varying range of the major parameters of the algorithm.

Conclusions:

Their fully automated method achieves high segmentation accuracy in a time‐efficient manner. It could support large scale quantitative breast MRI analysis and holds the potential to become integrated into the clinical workflow for breast cancer clinical applications in the future.
Actin-Propelled Invasive Membrane Protrusions Promote Fusogenic Protein Engagement During Cell-Cell Fusion
Authors: Shilagardi Khurts , Li Shuo , Luo Fengbao , Marikar Faiz , Duan Rui , Jin Peng , Kim Ji Hoon , Murnen Katherine , Chen Elizabeth H.
Published: March 2013

To Fuse or Not to Fuse?

Cell-cell fusion is poorly understood, although we know that in the nematode,
Caenorhabditis elegans
, it involves cell-surface fusogens and in the fly,
Drosophila
, the actin cytoskeleton plays a role.

Shilagardi
et al.

(p.
359
) reconstituted a high-efficiency, inducible cell-fusion culture system, in which they found that the
C. elegans
fusogen, Eff-1, induced a low level of cell-cell fusion that was enhanced by coexpression with a cell adhesion molecule, Sticks and stones (Sns), required for myoblast fusion in
Drosophila.
Sns-enhanced cell-cell fusion was mediated by dynamic actin polymerization that generated invasive membrane protrusions at sites of fusion.
Complete Genome Sequence of the Sugar Beet Endophyte Pseudomonas poae RE*1-1-14, a Disease-Suppressive Bacterium
Authors: Müller Henry , Zachow Christin , Alavi Mohammadali , Tilcher Ralf , Krempl Peter Mauritius , Thallinger Gerhard Günther , Berg Gabriele
Published: March 2013

The endophytic bacterium
Pseudomonas poae
RE*1-1-14 shows broad antagonistic activity and is applied to seeds as a biocontrol agent to suppress late root rot in the sugar beet. The completely sequenced 5.5-Mb genome reveals genes that putatively contribute to this antagonistic activity and the intimate plant-microbe interaction.
Genome Sequence of the Butanol Hyperproducer Clostridium saccharoperbutylacetonicum N1-4
Authors: del Cerro Carlos , Felpeto-Santero Carmen , Rojas Antonia , Tortajada Marta , Ramón Daniel , García José L.
Published: March 2013

Clostridium saccharoperbutylacetonicum
is one of the most important acetone-butanol-ethanol (ABE)-generating industrial microorganisms and one of the few bacteria containing choline in its cell wall. Here, we report the draft genome sequence of
C. saccharoperbutylacetonicum
strain N1-4 (6.6 Mbp; G+C content, 29.4%) and the findings obtained from the annotation of the genome.
Genome Sequence of Avirulent Riemerella anatipestifer Strain RA-SG
Authors: Yuan Jianfeng , Li Linlin , Sun Minhua , Dong Jiawen , Hu Qilin
Published: March 2013

Riemerella anatipestifer
is a pathogenic bacterium that has spread all over the world and is associated with epizootic infections in waterfowl and other avian species.
R. anatipestifer
RA-SG is an avirulent strain, isolated from an infected duck in Guangdong province, China. The genome sequence of this species is presented herein.
The varying role of the GP in the pathway between colonoscopy and surgery for colorectal cancer: a retrospective cohort study
Authors: Goldsbury David , Harris Mark , Pascoe Shane , Barton Michael , Olver Ian , Spigelman Allan , Beilby Justin , Veitch Craig , Weller David , O'Connell Dianne L
Published: March 2013

Objectives

To describe general practitioner (GP) involvement in the treatment referral pathway for colorectal cancer (CRC) patients.

Design

A retrospective cohort analysis of linked data.

Setting

A population-based sample of CRC patients diagnosed from August 2004 to December 2007 in New South Wales, Australia, using the 45 and Up Study, cancer registry diagnosis records, inpatient hospital records and Medicare claims records.

Participants

407 CRC patients who had a colonoscopy followed by surgery.

Primary outcome measures

Patterns of GP consultations between colonoscopy and surgery (ie, between diagnosis and treatment). We investigated whether consulting a GP presurgery was associated with time to surgery, postsurgical GP consultations or rectal cancer cases having surgery in a centre with radiotherapy facilities.

Results

Of the 407 patients, 43% (n=175) had at least one GP consultation between colonoscopy and surgery. The median time from colonoscopy to surgery was 27 days for those with an intervening GP consultation and 15 days for those without the consultation. 55% (n=223) had a GP consultation up to 30 days postsurgery; it was more common in cases of patients who consulted a GP presurgery than for those who did not (65% and 47%, respectively, adjusted OR 2.71, 95% CI 1.50 to 4.89, p=0.001). Of the 142 rectal cancer cases, 23% (n=33) had their surgery in a centre with radiotherapy facilities, with no difference between those who did and did not consult a GP presurgery (21% and 25% respectively, adjusted OR 0.84, 95% CI 0.27 to 2.63, p=0.76).

Conclusions

Consulting a GP between colonoscopy and surgery was associated with a longer interval between diagnosis and treatment, and with further GP consultations postsurgery, but for rectal cancer cases it was not associated with treatment in a centre with radiotherapy facilities. GPs might require a more defined and systematic approach to CRC management.
Moral differences in deep continuous palliative sedation and euthanasia
Authors: Juth Niklas , Lindblad Anna , Lynöe Niels , Sjöstrand Manne , Helgesson Gert
Published: March 2013

In palliative care there is much debate about which end of life treatment strategies are legitimate and which are not. Some writers argue that there is an important moral dividing-line between palliative sedation and euthanasia, making the first acceptable and the latter not. We have questioned this. In a recent article, Lars Johan Materstvedt has argued that we are wrong on two accounts: first, that we fail to account properly for the moral difference between continuous deep palliative sedation at the end of life and euthanasia, and, second, that we fail to account properly for the difference between permanent loss of consciousness and death. Regarding the first objection, we argue that Materstvedt misses the point: we agree that there is a difference in terms of intentions between continuous deep palliative sedation and euthanasia, but we question whether this conceptual difference makes up for a moral difference. Materstvedt fails to show that it does. Regarding the second objection, we argue that if nothing else is at stake than the value of the patient's life, permanent unconsciousness and death are morally indifferent.
Comparison of CPR outcome predictors between rhythmic abdominal compression and continuous chest compression CPR techniques
Authors: Kammeyer Ryan M , Pargett Michael S , Rundell Ann E
Published: March 2013

Objective

Bystander cardiopulmonary resuscitation (CPR) provides treatment for out-of-hospital cardiac arrest since perfusion of vital organs is critical to resuscitation. Alternatives to standard CPR are evaluated for effectiveness based upon outcome predictive metrics and survival studies. This study focuses on evaluating the performance of rhythmic-only abdominal compression CPR (OAC-CPR) relative to chest compression (CC-CPR) using a complementary suite of mechanistically based CPR outcome predictors. Combined, these predictors provide insight on the transduction of compression-induced pressures into flow perfusing vital organs.

Methods

Intrasubject comparisons between the CPR techniques were made during multiple 2-min intervals of induced fibrillation in 17 porcine subjects. Arterial pO2, cardiac output, carotid blood flow, coronary perfusion pressure (CPP), minute alveolar ventilation (MAV), end-tidal CO2, and time from defibrillation to the return of spontaneous circulation (ROSC) were recorded. Organ damage was assessed by necropsy.

Results

Compared with CC-CPR, OAC-CPR had higher pressure and ventilation metrics with increased relative CPP (+16 mm Hg), MAV (+75/ml/min/kg) and a lower reduction in arterial pO2(−22% baseline), but suffered from lower carotid flows (−9.3 ml/min). No significant difference was found comparing cardiac outputs. Furthermore, resuscitation was qualitatively more difficult after OAC-CPR, with a longer time to ROSC (+70 s). No abdominal damage was observed over short periods of OAC-CPR.

Conclusions

Although OAC-CPR appeared superior to CC-CPR by pressure and ventilation metrics, lower carotid flow and longer delay until ROSC raise concerns about overall performance. These paradoxical observations suggest that the evaluation of efficacious alternative CPR techniques may require more direct measurements of vital organ perfusion.
Roux-en-Y gastric bypass for morbid obesity: what are the preoperative predictors of weight loss?
Authors: Adams Simon T , Salhab Mohammed , Hussain Zeiad I , Miller Glenn V , Leveson Stephen H
Published: March 2013

Obesity has become an increasingly important health problem over the past 30 years. Presently around a quarter of the UK adult population are obese and this figure is set to increase further in the coming decades. The health consequences of obesity on multiple body systems have been well established as has the financial cost of the condition to both the individuals affected as well as to society as a whole. Bariatric surgery has been shown to be the only long term effective solution in terms of sustained weight loss and comorbidity resolution. The commonest bariatric procedure in the UK is the Roux-en-y gastric bypass which consistently results in the loss of 70%-80% of excess bodyweight. Results however are variable and in order to optimise resource allocation and avoid exposing patients unlikely to benefit from surgery to its inherent risks, much research has been done to try to identify those patients most likely to obtain a good result. The only factor which has been subjected to meta-analysis is that of preoperative weight loss which shows a positive association with postoperative weight loss following bypass surgery. Although the remaining data are not based on level 1 evidence those other preoperatively identifiable factors which are associated with an improved outcome include Caucasian or Hispanic ethnicity, higher educational status, non-shift-work working patterns, female gender and divorced or single marital status. Similarly increased levels of preoperative physical activity and an absence of binge eating behaviour are consistent with a favourable result whereas increased age, smoking and other socioeconomic factors have not been shown to have a significant impact. Conversely diabetes mellitus seems to have a slight negative correlation with postoperative weight loss; however, a history of sexual abuse or psychiatric illness has not been shown to have a lasting influence.
Branched-chain amino acids alleviate nonalcoholic steatohepatitis in rats
Authors: Li Tianrun , Geng Leiluo , Chen Xin , Miskowiec Miranda , Li Xuan , Dong Bing
Published: March 2013

Nonalcoholic steatohepatitis (NASH) is a prevalent disease in countries around the world. The branched-chain amino acids (BCAAs) leucine, isoleucine, and valine cannot be synthesized by the body and have been shown to promote muscle buildup; thus, it is logical to suggest that BCAAs can reduce fat deposition in the body. We used gonadectomized rats fed a high-fat diet to investigate the effects of BCAAs on lipid metabolism over an 8-week experimental period. Body composition, tissue histology, plasma lipid indices, and hormone levels were examined. We demonstrated that the body weights of rats were not significantly decreased but the mesenteric fat was significantly decreased (p < 0.05) in BCAA-treated rats. In addition, BCAAs decreased plasma lipid levels and fat deposition in the liver. At week 4, when the untreated rats displayed macrovesicular steatosis, BCAA-treated rats had only macrovesicular droplets in their hepatocytes. At week 8, when the untreated rat livers displayed profound inflammation and cirrhosis, BCAA-treated rat livers remained in the macrovesicular stage of steatosis. BCAAs induced higher blood glucose and plasma insulin levels (p < 0.05). BCAAs also improved liver blood flow by increasing mean arterial blood pressure and decreasing portal pressure, which helped delay the change in blood flow pattern to that of cirrhosis. BCAAs also induced the skeletal muscle to express higher levels of branched-chain α-keto acid dehydrogenase E1α, which indicates an enhanced metabolic capacity of BCAAs in muscle tissue. This study clearly demonstrates the effects of BCAAs on the amelioration of fat deposition in rats fed a high-fat diet.
Annual and seasonal dynamics of ectomycorrhizal fungi colonizing white pine (Pinus strobus) seedlings following catastrophic windthrow in northern Georgia, USA
Authors: Cowden Charles C. , Peterson Chris J.
Published: March 2013

The effect of wind disturbance on ectomycorrhizal fungal (EMF) communities in forests remains largely uninvestigated. We monitored EMF colonizing Pinus strobus L. seedlings in an oak–pine forest in northern Georgia, USA, after catastrophic wind disturbance. Over three years, we sampled naturally regenerating P. strobus seedlings across three growing seasons in the windthrow area and an adjacent undisturbed forest, identifying 53 unique EMF taxa using molecular techniques. The diversity of EMF colonizing seedlings in the undisturbed forest was consistently greater than in the windthrow area. Although the EMF compositional similarity between EMF in the gap and in the undisturbed forest was low throughout the study, many EMF taxa colonized seedlings in both the gap and the undisturbed forest. Seasonal differences in EMF composition and diversity were pronounced in the undisturbed forest, with diversity increasing from spring to fall. In contrast, EMF composition and diversity were relatively constant throughout seasons in the windthrow gap. We hypothesize that the extent of host community mortality and the extent of EMF host community regeneration following disturbance drive both EMF species composition and community dynamics. However, this hypothesis warrants further study.
Fourier transform far-infrared spectroscopy of HN2+ on the AILES beamline of synchrotron SOLEIL
Authors: Gruet S. , Morvan A. , Pirali O. , Chamaillé T. , Bouisset E. , Vervloet M.
Published: March 2013

We report the pure rotation spectrum of HN2+ as measured by Fourier transform (FT) absorption spectroscopy in the 20–40 cm−1 spectral range. The cations are produced in a liquid nitrogen cooled hollow cathode discharge cell developed on the AILES beamline of synchrotron SOLEIL. The setup was optimized by recording rotation–vibration spectra of H3+ (with the ν2 band centered at about 2521 cm−1), HN2+ (with the ν1 band centered at about 3234 cm−1), and HCO+ (with the ν1 band centered at about 3089 cm−1). Many rotation–vibration lines have been assigned for each ion and five pure rotational transitions have been detected for HN2+. These results demonstrate the feasibility of recording far-infrared spectra of cationic species using FT broad band spectroscopy associated with the bright synchrotron radiation continuum as an alternative to laser-based frequency tunable techniques.
How squid swim and fly
Authors: O’Dor R.K.
Published: March 2013

Squid have been studied extensively since 1982 to quantitatively measure their cost of locomotion and compare it with costs for fishes that are their primary competitors in the ocean. Early work focused on oxygen consumption in swim tunnels and led to the use of jet pressure tags to relate captive studies to behaviour in nature. Dosidicus gigas (d’Orbigny, 1835) (jumbo flying squid or Humboldt squid), which has expanded its range more than 10-fold, is used to illustrate how “live fast, die young” squid can out compete fishes in changing times by both swimming and flying. Recent work has provided quantitative data on the costs of flying and this report provides some comparisons. Costs of flight in nature require new technology, which has fortunately arrived just in time. Accelerometry tags can now provide similar and perhaps better data on travel rate in nature, both in water and in air. These work on both squid and fish, so more and better comparisons are becoming possible.
Aspalathus linearis(Rooibos tea) as potential phytoremediation agent: a review on tolerance mechanisms for aluminum uptake
Authors: Kanu Sheku A. , Okonkwo Jonathan O. , Dakora Felix D.
Published: March 2013

Aspalathus linearis (Burm. F.) R. Dahlg., commonly referred to as Rooibos tea, grows naturally in nutrient-poor, sandy, acidic soils (pH 3–5.3) with high aluminum concentration ranging from 110 to 275 μg Al g−1in the Cederberg’s mountainous areas in South Africa. Earlier studies found significant differences in Al concentration in organs of A. linearis, with roots having higher amounts (1262–4078 μg Al g−1), suggesting that the plant is capable of accumulating excess Al in acidic soils. Identification of the mineralogical constituents of organs of A. linearis using X-ray diffraction (XRD) analysis revealed the presence of an Al–Si complex (aluminosilicate or hydroxyaluminosilicate (HAS) species) in the shoot and root, possibly to internally ameliorate Al toxicity. In addition, A. linearis has specialized cluster roots that exude Al-chelating organic acid ligands such as citric, malic, and malonic acids. Organic acids can bind strongly to Al in the plant and rhizosphere to reverse its phytotoxic effects to the plants. Field and glasshouse studies revealed significant differences in pH between rhizosphere and nonrhizosphere soils of A. linearis and also showed that roots of the plant release OH−and HCO3−anions to raise rhizosphere pH possibly to immobilize Al through complexation. Furthermore, A. linearis is easily infected by arbuscular mycorrhizae (AM) fungi, but mycorrhizal associations are known to inhibit transport of metallic cations into plant roots. These features of A. linearis are perceived as good indicators for bioremediation; and the plant could, therefore, be a suitable candidate for phytoremediation technologies such as phytoaccumulation, phytostabilization, and phytodegradation. The environmental and economic implications of the potential of A. linearis to bioremediate Al-contaminated soils are briefly discussed. Furthermore, this review briefly highlights future studies investigating the utilization of the shoot of A. linearis as adsorbent for the removal of trace and (or) heavy metal from aqueous solutions.
NONLINEAR MASSIVE GRAVITY AND COSMOLOGY
Authors: MUKOHYAMA SHINJI
Published: March 2013

We review cosmological solutions and their stability in nonlinear massive gravity. After constructing homogeneous and isotropic solutions, we show that they suffer from ghost instability. We then find new attractor solutions, in which the physical metric is of Friedmann–Robertson–Walker (FRW) type but anisotropy in the fiducial metric leads to statistical anisotropy of perturbations.
ON QUANTUM GRAVITY, ASYMPTOTIC SAFETY AND PARAMAGNETIC DOMINANCE
Authors: NINK ANDREAS , REUTER MARTIN
Published: March 2013

We discuss the conceptual ideas underlying the Asymptotic Safety approach to the nonperturbative renormalization of gravity. By now numerous functional renormalization group (RG) studies predict the existence of a suitable nontrivial ultraviolet (UV) fixed point. We use an analogy to elementary magnetic systems to uncover the physical mechanism behind the emergence of this fixed point. It is seen to result from the dominance of certain paramagnetic-type interactions over diamagnetic ones. Furthermore, the spacetimes of quantum Einstein gravity (QEG) behave like a polarizable medium with a "paramagnetic" response to external perturbations. Similarities with the vacuum state of Yang–Mills theory are pointed out.
ARTHROSCOPIC ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION WITH LARS ARTIFICIAL LIGAMENT: AN 8–15-YEAR FOLLOW-UP
Authors: WANG CHO-LIN , HSIAO CHIH-KUN , KU MING-CHOU , CHANG CHIH-HAN
Published: March 2013

The aim of this study was to evaluate the clinical results of anterior cruciate ligament (ACL) reconstruction with an artificial ligament of the Ligament Augmentation and Reconstruction System (LARS) via an 8–15-year follow-up. Between January 1996 and January 2003, 38 patients received arthroscopic anterior cruciate reconstruction with the LARS artificial ligament at the Show Chwan Memorial Hospital, Changhua, Taiwan. Among them, 28 cases were included in this study. Excluding two failure cases, 26 cases were involved in the statistical analysis of various clinical assessments. The mean follow-up period after reconstruction was 11.4 ± 1.9 years. Assessment of clinical results included physical examination, magnetic resonance imaging, radiography, KT-1000 arthrometer test for knee stability, range of motion measurement, Lysholm score, and Tegner scale activity evaluations. The outcomes showed that among these 28 follow-up patients, there were two failure cases. The survival rate of LARS ligament reconstruction in this long-term follow-up was 92.9%. Among the 26 clinical assessed cases, the stability of the knee joint was improved as the anterior translation displacement measured by arthrometer reduced from 7.0 ± 3.1 mm (range: 4–17 mm) pre-operatively to 1.7 ± 1.7 mm (range: 0–6 mm) post-operatively. The Lysholm score improved from 39.7 ± 11.5 pre-operatively to 85.9 ± 19.6 post-operatively. Tegner activity scale improved from 3.2 ± 1.5 pre-operatively to 5.4 ± 2.4 post-operatively. All three improvements have statistic significance as the p-values were less than 0.05. In conclusion, ruptured ACL reconstruction with LARS artificial ligament has a survival rate of 92.9% and complication rate of 28.6% in this 8–15-year follow-up.
Embroidered confessions
Authors: Benedetti Julynn Miller , Koepfinger Katie , Turkmen Burcum , Simpson Laura , Spikman Bob , SuijkerBuijk Sandra , Minten Rico , Kemerink Jorien
Published: March 2013

Demo Hour highlights new prototypes and projects that exemplify innovation and novel forms of interaction.

Leah Maestri, Editor
Should Instructional Designers care about the Tin Can API?
Authors: Kelly David , Thorn Kevin
Published: March 2013

The Tin Can API is an extremely hot topic in the elearning industry. But what exactly is it, and what does it mean to today's instructional designer? In this article, David Kelly and Kevin Thorn explain what the Tin Can API is, and explore just how much it may impact the world of today's instructional designer.
An overview of codes tailor-made for better repairability in networked distributed storage systems
Authors: Datta Anwitaman , Oggier Frédérique
Published: March 2013

The increasing amount of digital data generated by today's society asks for better storage solutions. This survey looks at a new generation of coding techniques designed specifically for the maintenance needs of networked distributed storage systems (NDSS), trying to reach the best compromise among storage space efficiency, fault-tolerance, and maintenance overheads. Four families of codes, namely, pyramid, hierarchical, regenerating and locally repairable codes such as self-repairing codes, along with a heuristic of cross-object coding to improve repairability in NDSS are presented at a high level. The code descriptions are accompanied with simple nexamples emphasizing the main ideas behind each of these code families. We discuss their pros and cons before concluding with a brief and preliminary comparison. This survey deliberately excludes technical details and does not contain an exhaustive list of code constructions. Instead, it provides an overview of the major novel code families in a manner easily accessible to a broad audience, by presenting the big picture of advances in coding techniques for maintenance of NDSS.
Statistical Physics of T-Cell Development and Pathogen Specificity
Authors: Košmrlj Andrej , Kardar Mehran , Chakraborty Arup K.
Published: March 2013

In addition to an innate immune system that battles pathogens in a nonspecific fashion, higher organisms, such as humans, possess an adaptive immune system to combat diverse (and evolving) microbial pathogens. Remarkably, the adaptive immune system mounts pathogen-specific responses, which can be recalled upon reinfection with the same pathogen. It is difficult to see how the adaptive immune system can be preprogrammed to respond specifically to a vast and unknown set of pathogens. Although major advances have been made in understanding pertinent molecular and cellular phenomena, the precise principles that govern many aspects of an immune response are largely unknown. We discuss complementary approaches from statistical mechanics and cell biology that can shed light on how key components of the adaptive immune system, T cells, develop to enable pathogen-specific responses against many diverse pathogens. The mechanistic understanding that emerges has implications for how host genetics may influence the development of T cells with differing responses to the human immunodeficiency virus (HIV) infection.
Assessing the Use of Archaeal Lipids as Marine Environmental Proxies
Authors: Pearson Ann , Ingalls Anitra E.
Published: March 2013

Archaea are abundant in marine and terrestrial aquatic environments, sediments, and soils. They inhabit at least an 85°C temperature range from the polar ocean to hydrothermal springs. Many Archaea produce membrane lipids called glycerol dialkyl glycerol tetraethers (GDGTs). Experiments on pure and enrichment cultures as well as an empirical correlation for marine sediments (the TEX86 index) together show positive relationships between temperature and the number of cyclopentane or cyclohexane rings in GDGTs. The resulting TEX86 paleotemperature proxy has been applied across a wide range of geologic history and depositional settings. The exact relationship between TEX86 and temperature, however, remains poorly understood. Environmental systems and cultures have different temperature dependencies, and the ecological niche(s) of aquatic Archaea are still a subject of active investigation. Here we review some of the remaining questions about GDGT paleotemperature proxies. Better answers to these challenging problems will help refine future paleoceanographic applications.
The Politics of Energy
Authors: Hughes Llewelyn , Lipscy Phillip Y.
Published: March 2013

The politics of energy is reemerging as a major area of inquiry for political science after two decades of relative quiet. We survey the theoretical and empirical literature on the politics of energy, as well as recent developments that have revived interest in the topic—renewed oil price volatility, the rise of China, and concern over global climate change. We also outline several avenues for future research, arguing that there are ample opportunities for scholars of political economy to apply insights developed in other fields to the study of energy.