bluuebunny/crossref_metadata_2025 huggingface dataset:
Increase in physical activity and cardiometabolic risk profile change during lifestyle intervention in primary healthcare: 1-year follow-up study among individuals at high risk for type 2 diabetes
Authors: Kujala Urho M , Jokelainen Jari , Oksa Heikki , Saaristo Timo , Rautio Nina , Moilanen Leena , Korpi-Hyövälti Eeva , Saltevo Juha , Vanhala Mauno , Niskanen Leo , Peltonen Markku , Tuomilehto Jaakko , Uusitupa Matti , Keinänen-Kiukaannemi Sirkka
Published: December 2011

Objectives

To investigate the association between increase in physical activity and changes in cardiometabolic risk factors during a lifestyle intervention programme in routine clinical settings.

Design

Prospective follow-up.

Setting

400 primary healthcare centres and occupational healthcare outpatient clinics in Finland.

Participants

Individuals at high risk for type 2 diabetes identified in the implementation project of the national diabetes prevention programme (FIN-D2D) and participating in baseline and 1-year follow-up visits. Final study group comprised the 1871 non-diabetic participants who responded at follow-up visit to a question on stability versus increase of physical activity.

Interventions

Lifestyle intervention.

Primary outcome measures

Cardiometabolic risk factors (body composition, blood pressure and those measured from fasting venous blood samples) measured at baseline and follow-up visits.

Results

Of the participants, 310 (16.6% of all responders) reported at follow-up having clearly increased their physical activity during the past year, while 1380 (73.8%) had been unable to increase their physical activity. Those who increased their activity decreased their weight by 3.6 kg (95% CI 2.9 to 4.3, age and sex adjusted, p<0.001) and waist circumference by 3.6 cm (95% CI 2.9 to 4.3, p<0.001) more than those who did not increase their activity. Similarly, those who increased their physical activity had greater reductions in total cholesterol (group difference in reduction 0.17 mmol/l, 95% CI 0.06 to 0.28, p=0.002), low-density lipoprotein cholesterol (0.16 mmol/l, 95% CI 0.06 to 0.26, p=0.001), low-density lipoprotein/high-density lipoprotein ratio (0.17, 95% CI 0.08 to 0.25, p<0.001) as well as fasting glucose (0.09 mmol/l, 95% CI 0.03 to 0.15, p=0.004) and 2 h glucose levels (0.36 mmol/l, 95% CI 0.17 to 0.55, p=0.023) than those who did not increase their physical activity.

Conclusion

Increasing physical activity seems to be an important feature of cardiometabolic risk reduction among individuals at high risk for type 2 diabetes participating in preventive interventions in routine clinical settings.
Suicide by burning in the South Asian origin population in England and Wales a secondary analysis of a national data set
Authors: Tuck Andrew , Bhui Kamaldeep , Nanchahal Kiran , McKenzie Kwame
Published: December 2011

Objectives

A descriptive analysis of suicide by burning in England and Wales in the general population and in people of South Asian origin.

Design

A cross-sectional secondary analysis of a national data set.

Setting

A population study of all those who died by suicide in England and Wales between 1993 and 2003 inclusive.

Participants

All cases of suicide and undetermined intent identified by the Office for National Statistics for England and Wales. A computer algorithm was used to identify people of the South Asian origin from their names. There were 55 140 suicides in the UK between 1993 and 2003. The ratio of male to female suicides was 3:1. There were 1455 South Asian suicides identified by South Asian Name and Group Recognition Algorithm.

Primary and secondary outcome measures

Death by suicide and undetermined intent, as determined by Coroner's Inquest. ICD9 codes E958.1 and E988.1 and ICD10 codes X76 and Y26.

Results

1.77% of suicides in the general population and 8.45% of suicides in the South Asian origin population were by burning. The suicide rate by burning was 0.8/100 000 person-years for England and Wales and 2.9/100 000 person-years for the South Asian origin population. The odds of suicide by burning were increased in the South Asian group as a whole (OR 3.06, 95% CI 2.30 to 4.08). Those born in Asia and Africa were at higher risk than those born in the UK (OR 2.69, 95% CI 2.01 to 3.60 and OR 2.10, 95% CI 1.46 to 3.01, respectively). The increased risk was for those aged 25–64 years.

Conclusion

Suicide by burning remains a significant issue in the South Asian origin working-age population in England and Wales. A prevention strategy could target working-age people of South Asian origin born abroad as they are at the highest risk. More in depth research on the reasons for using this method may help to identify possible prevention strategies.
Age-related cerebral white matter disease (leukoaraiosis): a review
Authors: Grueter Basil E , Schulz Ursula G
Published: December 2011

With the availability of improved brain imaging techniques, the high prevalence and clinical importance of cerebral small vessel disease have been increasingly recognised in recent years. As age is one of the most important risk factors for this condition, its prevalence is set to rise further as populations age. This may lead to an increase in the clinical consequences of white matter disease, namely cognitive decline, decreased mobility and increased stroke risk. Given the impact this will have on individuals and on healthcare systems, knowledge of the risk factors for small vessel disease, its prevention and its treatment is becoming more important. Although a lot of data are now available on the epidemiology, risk factors, clinical consequences and prognosis of leukoaraiosis, some of this information is conflicting. In this review, we summarise the current literature on cerebral small vessel disease, with an emphasis on its clinical aspects.
Centrifuge modelling of soil slopes containing model plant roots
Authors: Sonnenberg R. , Bransby M.F. , Bengough A.G. , Hallett P.D. , Davies M.C.R.
Published: December 2011

A series of centrifuge model tests were conducted to investigate the contribution of root reinforcement to slope stability. A compacted sandy clay slope, inclined at 45°, was reinforced with model roots. The model roots were varied in material, architecture, and numbers. They had stiffness values corresponding to upper and lower values found for plant roots. The architecture included taproots and branched roots. Slope collapse was triggered by raising the water table while soil displacements, pore-water pressures, and root strains were measured. The mode of failure was changed by the presence of roots from a progressive block failure to translational failure. The tests revealed how axial strains and bending strains were mobilized in the roots and how the roots influenced the slope failure mechanism. Different limit equilibrium slope stability calculations were performed at slope failure conditions to quantify the amount of reinforcement provided by different root types. These measured root reinforcement contributions were compared with those predicted according to common root reinforcement models. A reinforcement calculation method allowing for root pull-out was found to give the best agreement.
New method to determine proper strain rate for constant rate-of-strain consolidation tests
Authors: Ozer A. Tolga , Lawton Evert C. , Bartlett Steven F.
Published: December 2011

The development of a new semiempirical method to predict the proper strain rate for constant rate-of-strain (CRS) consolidation tests is described herein. The validity of the proposed method is analyzed using experimental results from CRS and incremental loading tests on four types of soil: Lake Bonneville clay, Massena clay, kaolinite, and montmorillonite. It is found that the maximum allowable strain rate depends on the initial void ratio of the soil and thus is related to the compressibility of the soil. The effect of the strain rate on the distribution of the pore pressure within the sample is investigated by comparing values of effective vertical stress calculated using a linear equation published by Wissa et al. in 1971 with values of effective stress at the base of the specimen determined from measured values of pore pressure. Overall, the proposed method predicts the maximum allowable strain rate very well for three of the four soils and moderately well for the other soil.
50-NM SELF-ALIGNED HIGH ELECTRON-MOBILITY TRANSISTORS ON GaAs SUBSTRATES WITH EXTREMELY HIGH EXTRINSIC TRANSCONDUCTANCE AND HIGH GAIN
Authors: XU DONG , YANG XIAOPING , SEEKELL P. , PLEASANT L. MT. , ISAAK R. , KONG W.M.T. , CUEVA G. , CHU K. , MOHNKERN L. , SCHLESINGER L. , STEDMAN R. , KARIMY H. , CARNEVALE R. , VERA A. , GOLJA B. , DUH K.H.G. , SMITH P.M. , CHAO P.C.
Published: December 2011

We report the design, fabrication and characterization of metamorphic high electron-mobility transistors (MHEMTs) with self-aligned ohmic electrodes. In this work, asymmetrically recessed 50-nm Γ-gates have been successfully used as the shadow mask for ohmic metal deposition. Extremely high extrinsic transconductance over a wide drain bias from 0.1 to 1.25 V can be made possible by fabricating devices with small gate-source spacing, small source-drain spacing, and the non-alloyed ohmic. Measured maximum extrinsic transconductance of 3 S/mm is a new record for all HEMT devices on GaAs and equals the best results from InP -based HEMTs. The same devices also show a voltage gain of 22, maximum stable gain of 10.8 dB at 110 GHz, and breakdown voltage of 4.3 V, which all are the highest among any self-aligned HEMTs based on InGaAs channel. The outstanding performance is the result of the seamless integration of the asymmetric gate recess and Γ-gate-based self-aligned ohmic process.
AMPLIFIER GAIN PER STAGE UP TO 0.5 THz USING 35 NM InP HEMT TRANSISTORS
Authors: SARKOZY S. , MEI X. , YOSHIDA W. , LIU P.-H. , LANGE M. , LEE J. , ZHOU Z. , DEAL W.R. , RADISIC V. , LEONG K. , LAI R.
Published: December 2011

Pivotal in the design of circuits is the ability to efficiently translate available transistor gain to high gain per stage. Remarkably, for 35-nm InP HEMT transistors, the efficiency of this translation remains high even up to ~0.5 THz. The ever shrinking wavelength correlated with higher frequencies necessitates a scaling of not only the device layout, but also of the passive elements and wafer thickness. Furthermore, to avoid distributed effects, the length of transistor gate fingers must be reduced.
NOVEL HIGH TEMPERATURE ANNEALED SCHOTTKY METAL FOR GaN DEVICES
Authors: DIDUCK QUENTIN , WALSH IAN , BABIĆ DUBRAVKO , EASTMAN LESTER F.
Published: December 2011

We have found that Scandium metal is near ohmic as deposited on GaN , but when it is annealed at high temperatures a large barrier height Schottky forms. In this study we used Sc - Au contacts to form Schottky barrier diodes on AlGaN / GaN HEMT material. We have found that the morphology remains unchanged even after an 800 degrees centigrade anneal. This investigation has revealed that the reverse leakage current of this metal system is an order of magnitude lower than a conventional Ni - Au contact and supports a reverse breakdown that is 1/3rd larger. The similarity of the anneal temperatures to ohmic contacts enable gates and contacts to be annealed at the same time thus simplifying processing. The lack of morphology change supports the use of Sc - Au for E -beam alignment marks as well. Diode contacts on AlGaN / GaN with Schottky-ohmic separation of 10 microns demonstrated reverse breakdown in excess of 100V when the contacts were annealed at 800C. These results suggest this metallization may have applications as a new HEMT gate metal, and Schottky diodes.
PERFORMANCE OF A 600-V, 30-A, BI-DIRECTIONAL SILICON CARBIDE SOLID-STATE CIRCUIT BREAKER
Authors: URCIUOLI D. P. , VELIADIS VICTOR
Published: December 2011

Bi-directional solid-state circuit breakers (BDSSCBs) can provide performance benefits over mechanical fault protection devices. A common-source configuration of normally ON, junction field effect transistors (JFETs) is favorable for BDSSCB implementations. SiC 0.1-cm2 1200-V JFETs designed for normally-ON operation at a zero-volt gate bias, and having low leakage currents, were used in the fabrication of a 30-A BDSSCB switch module. Operation of the module under continuous current and during turn-OFF transitions was evaluated to verify the parallel scalability of the common-source configuration. A bi-directional snubber connected across the switch module mitigated inductive voltage overshoot during BDSSCB turn-OFF transitions. At turn-OFF, under maximum power tests in both directions, the load current was reduced from 30 A to 0 A in approximately 10 μs, with a supply voltage of 600 V, and a BDSSCB peak voltage of 680 V. These results demonstrate the functionality and current scalability of this BDSSCB topology.
PULSE EVALUATION AND RELIABILITY ANALYSIS OF 4H-SiC SGTO MODULES
Authors: OGUNNIYI ADERINTO , O'BRIEN HEATHER
Published: December 2011

Army applications require power components that are utilized in pulsed power systems to be reliable and durable, compact, have high power and energy density, and lastly, to be easily integrated into combat vehicles. The U.S. Army Research Laboratory (ARL) is currently investigating silicon carbide Super-gate turn-off thyristors ( SiC SGTOs) to meet the future pulsed power system requirements for the Army. ARL's methodology is to evaluate the device performance in pulsed power circuits that emulate the electrical stresses that the power devices would encounter in a pulsed power system. Each module being evaluated utilized four 0.6 cm2 SiC SGTOs. The packaging design for the module utilizes ThinPak technology. The module has reliably been pulsed over 2000 times at peak currents greater than 8 kA with a pulse width of 170 μs. The module has also been pulsed greater than 3.6 kA at a pulse width of 1 ms, corresponding to an action rate of 7000 A2s and a current density of 2.5 kA/cm2 over the cathode mesa area. This work evaluates SiC SGTO modules under various pulsed conditions. This paper includes details on device structure, module package design, and module pulsed switching and reliability.
SECOND BREAKDOWN AND SAFE OPERATING AREA OF E-MODE POWER pHEMTs
Authors: PALA VIPINDAS , CHOW T. PAUL
Published: December 2011

The safe operating area of E -pHEMTs have been explored using device simulations. It is proposed that the second breakdown is triggered by the debiasing of the channel potential due to the gate reverse current at high drain voltages. A mathematical description of this behavior and experimental results are presented.
A UNIVERSAL SOI-BASED HIGH TEMPERATURE GATE DRIVER INTEGRATED CIRCUIT FOR SiC POWER SWITCHES WITH ON-CHIP SHORT CIRCUIT PROTECTION
Authors: ZUO LIANG , GREENWELL ROBERT , ISLAM SYED K. , HUQUE M. A. , BLALOCK BENJAMIN J. , TOLBERT LEON M.
Published: December 2011

In recent years, increasing demand for hybrid electric vehicles (HEVs) has generated the need for reliable and low-cost high-temperature electronics which can operate at the high temperatures under the hood of these vehicles. A high-voltage and high temperature gate-driver integrated circuit for SiC FET switches with short circuit protection has been designed and implemented in a 0.8-micron silicon-on-insulator (SOI) high-voltage process. The prototype chip has been successfully tested up to 200°C ambient temperature without any heat sink or cooling mechanism. This gate-driver chip can drive SiC power FETs of the DC-DC converters in a HEV, and future chip modifications will allow it to drive the SiC power FETs of the traction drive inverter. The converter modules along with the gate-driver chip will be placed very close to the engine where the temperature can reach up to 175ΰC. Successful operation of the chip at this temperature with or without minimal heat sink and without liquid cooling will help achieve greater power-to-volume as well as power-to-weight ratios for the power electronics module.
III-NITRIDE/SiC SEPARATE ABSORPTION AND MULTIPLICATION AVALANCHE PHOTODIODES: THE IMPORTANCE OF CONTROLLING POLARIZATION-INDUCED INTERFACE CHARGE
Authors: SAMPATH ANAND V. , ENCK R. W. , SHEN H. , WRABACK M. , ZHOU Q. , MCINTOSH D. , CAMPBELL J.
Published: December 2011

A III-Nitride/ SiC separate absorption and multiplication avalanche photodiode (SAM-APD) offers a novel approach for fabricating high gain photodetectors with tunable absorption over a wide spectrum from the visible to deep ulltraviolet. However, unlike conventional heterojunction SAM APDs, the formation of polarization-induced charge at the hetero-interface arising from spontaneous and piezoelectric polarization can dramatically affect the performance of this detector. In this paper we report on the role of this interface charge on the performance of GaN / SiC SAM APDs. Simulations of the electric field profile within this device structure while biased near avalanche breakdown indicate that the density of positive interface charge may be sufficient to confine the electric field within the SiC multiplication region with negligible punch-through into the GaN absorption region, a distribution that is likely undesirable for efficient collection of photo-generated holes due to the presence of defects at the hetero-interface. Simulations further show that the incorporation of a p -type doped interface charge control layer at the hetero-interface can modify the total density of charge at the interface and allow for the tailoring of the electric field profile within this device. Experimental results are provided that correlate well with the simulation results.
BIO-SENSING SENSITIVITY OF A NANOPARTICLE BASED ULTRAVIOLET PHOTODETECTOR
Authors: SHING CHRISTOPHER , QIN LIQIAO , SAWYER SHALYA
Published: December 2011

Bio-sensing sensitivity of a spectrally selective nanoparticle based ultraviolet (UV) photodetector is characterized in comparison to a silicon photodiode and a photomultiplier tube (PMT). The nanoparticle based photodetector is comprised of poly-vinyl alcohol (PVA) coated zinc-oxide ( ZnO ) nanoparticles deposited on an aluminum-gallium-nitride ( AlGaN ) epitaxially grown substrate. The sensitivity was determined by measuring the fluorescence intensity of the native fluorophore, tryptophan, in Escherichia coli (E-coli, ATCC-25922) cells. Tryptophan intrinsically fluoresces with a peak at 340 nm under 280 nm UV light illumination. It is shown that this detector can sense the concentration of E-coli to 2.5 × 108 cfu/mL while the silicon photodiode cannot detect the intrinsic fluorescence at all. Nevertheless, the PMT outperformed the ZnO nanoparticle- AlGaN substrate based photodetector with the ability to sense E-coli concentrations to 3.91 × 106 cfu/mL. However, because PMT based systems are commonly limited by high dark current, susceptible to environmental changes, sensitive to ambient light, are not spectrally selective and have high power consumption, biological detection systems comprised of these ZnO nanoparticle- AlGaN substrate based photodetectors can be more effective for near real time characterization of potential bacterial contamination.
PERFORMANCE ENHANCEMENT OF InGaN-BASED LASER DIODES USING A STEP-GRADED AlxGa1-xN ELECTRON BLOCKING LAYER
Authors: ZHANG Y. , LIU J.-P. , KAO T.-T. , KIM S. , LEE Y.-C. , LOCHNER Z. , RYOU J.-H. , YODER P. D. , DUPUIS R. D. , SHEN S.-C.
Published: December 2011

A step-graded Al x Ga 1- x N electron blocking layer (EBL) is introduced to the InGaN -based edge-emitting blue-violet laser diode (LD) structure to suppress the undesired built-in interface polarization charges. When compared to a conventional abrupt Al 0.18 Ga 0.82 N EBL design, the step-graded Al x Ga 1- x N EBL design may help reduce the electron accumulation at the edge of the active region and hence improve the quantum efficiency in LD operation. The effects of the step-graded Al x Ga 1- x N EBL on the fabricated device performance are also investigated. LDs with the step-graded Al x Ga 1- x N EBL demonstrated significantly reduced threshold current density and increased slope efficiency under the continuous-wave operation.
ENGINEERING THE BARRIER OF QUANTUM DOTS-IN-A-WELL (DWELL) INFRARED PHOTODETECTORS FOR HIGH TEMPERATURE OPERATION
Authors: BARVE A. V. , SHARMA Y. D. , MONTOYA J. , SHAO J. , VANDERVELDE T. , ROTTER T. , KRISHNA S.
Published: December 2011

Reduction in the dark current and improvement in signal to noise ratio in the quantum dots in a well infrared photodetectors using resonant tunneling barriers have been demonstrated. Ultra-low dark current levels and high detectivity of 3×1010 cm.Hz1/2/W at 77K for f/2 optics has been obtained for longwave infrared detection. In another experiment, the ability to control the excited state in the DWELL has been demonstrated by systematically varying the quantum well thickness. These detectors demonstrate high operating temperature with high detectivity values, even for high operating temperatures.
SEMICONDUCTING CARBON NANOTUBE PHOTOVOLTAIC PHOTODETECTORS
Authors: BINDL DOMINICK J. , ARNOLD MICHAEL S.
Published: December 2011

A photovoltaic photodetector harnessing near infrared band gap absorption by thin films of post-synthetically sorted semiconducting single walled carbon nanotubes ( s -SWCNTs) is described. Peak specific detectivity of 6×1011 Jones at -0.1 V bias at 1210 nm is achieved using a heterojunction device architecture: indium tin oxide/ ca. 5 nm s -SWCNT / 120 nm C60 / 10 nm 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) / Ag. The photodiodes are characterized by a series resistance of 2.9 Ω cm2 and a rectification ratio of 104 at ±1V. These results are expected to guide the exploration of new classes of solution-processable, mechanically flexible, integrable, thin film photovoltaic photodetectors with tunable sensitivity in the visible and infrared spectra based on semiconducting carbon nanotubes.
COMPARISON OF MONOLITHIC PASSIVELY MODE-LOCKED LASERS USING In(Ga)As QUANTUM DOT OR QUANTUM WELL MATERIALS GROWN ON GaAs SUBSTRATES
Authors: CROWLEY M. T. , PATEL N. , MURRELL D. , XIN Y.-C. , STINTZ A. , LESTER L. F.
Published: December 2011

In this paper, a technology comparison between monolithic passively mode-locked lasers (MLLs) fabricated from 1.24 μm InAs dots-in-a-Well (DWELL) and 1.25 μm InGaAs single quantum well (SQW) structures grown using elemental source molecular beam epitaxy (MBE) is presented. 5 GHz optical pulses with sub-picosecond RMS jitter, high pulse peak power (1W) and narrow pulse width (< 10 ps) are typical of these monolithic two-section InAs DWELL passive MLLs. An InGaAs single quantum well MLL with the 42% indium is shown to exhibit a superior high-temperature performance. Compared with the typical operating range of the InAs DWELL devices (<60°C), the operation is in excess of 100 °C and is particularly attractive for clocking applications in next generation microprocessors. Based on an 8-band k . p analysis the reduction in the band edge density of states for such a quantum well is discussed.
ABNORMAL MOTION DETECTION IN REAL TIME USING VIDEO SURVEILLANCE AND BODY SENSORS
Authors: BARANWAL MAYANK , KHAN M. TAHIR , DE SILVA CLARENCE W.
Published: December 2011

This paper presents a method for detecting abnormal motion in real time using a computer vision system. The method is based on the modeling of human body image, which takes into account both orientation and velocity of prominent body parts. A comparative study is made of this method with other existing algorithms based on optical flow and the use of accelerometer body sensors. From the real time experiments conducted in the present work, the developed method is found to be efficient in characterizing human motion and classifying it into basic types such as falling, sitting, and walking. The method uses a Radial Basis Function Network (RBFN) to compute the severity coefficient associated with the type of motion, based on experience. The paper evaluates the various methods and incorporates the advantages of other methods in order to develop a more reliable system for abnormal motion detection.
SIMULTANEOUS COOPERATIVE LOCALIZATION FOR AUVs USING RANGE-ONLY SENSORS
Authors: RASHIDI ALI JABAR , MOHAMMADLOO SAEED
Published: December 2011

The absence of GPS underwater makes navigation for autonomous underwater vehicles (AUVs) a challenge. Moreover, the use of static beacons in the form of a long baseline (LBL) array limits the operation area to a few square kilometers and requires substantial deployment effort before operations. In this paper, an algorithm for cooperative localization of AUVs is proposed. We describe a form of cooperative Simultaneous Localization and Mapping (SLAM). Each of the robots in the group is equipped with an Inertial Measurement Unit (IMU) and some of them have a range-only sonar sensor that can determine the relative distance to the others. Two estimators, in the form of a Kalman filter, process the available position information from all the members of the team and produce a pose estimate for every one of them. Simulation results are presented for a typical localization example of three AUVs formation in a large environment and indirect trajectory. The results show that our proposed method offers good localization accuracy, although a small number of low-cost sensors are needed for each vehicle, which validates that it is an economical and practical localization approach.
AN EFFICIENT EIGEN VALUES BASED TECHNIQUE FOR ONLINE IRIS IMAGE COMPRESSION AND IDENTIFICATION
Authors: MISHRA KAMTA NATH , AGRAWAL ANUPAM , SRIVASTAVA PRAKASH C. , TRIPATHI VIVEK , GUPTA VISHAL
Published: December 2011

This paper introduces an efficient Eigen values based technique for online iris image compression and identification of a human including the case of identical twins. The iris image is extracted after removing the pupil, eye brow, skin and other noise disturbances from an actual image. The extracted iris image is divided into different blocks of size of 16 × 16. Now, Eigen values are calculated for each block and these Eigen values are stored in the smart card memory for further identification.

Therefore, when checking if two iris images are identical or not, all we need is to compare the stored Eigen values with online calculated Eigen values. If two iris images have the same Eigen values, this means that both iris images belong to the same person. In our research, we have concluded that iris images of different persons have different Eigen values, including the case of identical twins. We conducted experiments on CASIA and Multimedia University iris image databases and we found that our Eigen Values Based Iris Image Identification Technique is giving 99.99% accuracy for the same image of identical twins and individuals. The implementation leads us to believe that our method is giving the best matching result in the case of identical twins and individuals. It is an efficient, secure and economically feasible approach for online personal identification.
COMPARISON OF DIMENSIONALITY REDUCTION TECHNIQUES USING A BACKPROPAGATION NEURAL NETWORK BASED CLASSIFIER
Authors: SIVASANKAR E. , SRIDHAR H. , BALAKRISHNAN V. , ASHWIN K. , RAJESH R. S.
Published: December 2011

Data mining methods are used to mine voluminous data to find useful information from data. The data that is to be mined may have a large number of dimensions, so the mining process will take a lot of time. In general, the computation time is an exponential function of the number of dimensions. It is in this context that we use dimensionality reduction techniques to speed up the decision-making process. Dimensionality reduction techniques can be categorized as Feature Selection and Feature Extraction Techniques. In this paper we compare the two categories of dimensionality reduction techniques. Feature selection has been implemented using the Information Gain and Goodman–Kruskal measure. Principal Component Analysis has been used for Feature Extraction. In order to compare the accuracy of the methods, we have also implemented a classifier using back-propagation neural network. In general, it is found that feature extraction methods are more accurate than feature selection methods in the framework of credit risk analysis.
Characterizing schema mappings via data examples
Authors: Alexe Bogdan , Cate Balder TEN , Kolaitis Phokion G. , Tan Wang-Chiew
Published: December 2011

Schema mappings are high-level specifications that describe the relationship between two database schemas; they are considered to be the essential building blocks in data exchange and data integration, and have been the object of extensive research investigations. Since in real-life applications schema mappings can be quite complex, it is important to develop methods and tools for understanding, explaining, and refining schema mappings. A promising approach to this effect is to use “good” data examples that illustrate the schema mapping at hand.

We develop a foundation for the systematic investigation of data examples and obtain a number of results on both the capabilities and the limitations of data examples in explaining and understanding schema mappings. We focus on schema mappings specified by source-to-target tuple generating dependencies (s-t tgds) and investigate the following problem: which classes of s-t tgds can be “uniquely characterized” by a finite set of data examples? Our investigation begins by considering finite sets of positive and negative examples, which are arguably the most natural choice of data examples. However, we show that they are not powerful enough to yield interesting unique characterizations. We then consider finite sets of universal examples, where a universal example is a pair consisting of a source instance and a universal solution for that source instance. We first show that unique characterizations via universal examples is, in a precise sense, equivalent to the existence of Armstrong bases (a relaxation of the classical notion of Armstrong databases). After this, we show that every schema mapping specified by LAV s-t tgds is uniquely characterized by a finite set of universal examples with respect to the class of LAV s-t tgds. Moreover, this positive result extends to the much broader classes of
n
-modular schema mappings,
n
a positive integer. Finally, we study the unique characterizability of GAV schema mappings. It turns out that some GAV schema mappings are uniquely characterizable by a finite set of universal examples with respect to the class of GAV s-t tgds, while others are not. By unveiling a tight connection with homomorphism dualities, we establish an effective, sound, and complete criterion for determining whether or not a GAV schema mapping is uniquely characterizable by a finite set of universal examples with respect to the class of GAV s-t tgds.
Bag equivalence of tree patterns
Authors: Cohen Sara , Weiss Yaacov Y.
Published: December 2011

When a query is evaluated under bag semantics, each answer is returned as many times as it has derivations. Bag semantics has long been recognized as important, especially when aggregation functions will be applied to query results. This article is the first to focus on bag semantics for tree pattern queries. In particular, the problem of bag equivalence of a large class of tree pattern queries (which can be used to model XPath) is explored. The queries can contain unions, branching, label wildcards, the vertical child and descendant axes, the horizontal following and following-sibling axes, as well as positional (i.e., first and last) axes. Equivalence characterizations are provided, and their complexity is analyzed. As the descendant axis involves a recursive relationship, this article is also the first to address bag equivalence over recursive queries, in any setting.
Capturing continuous data and answering aggregate queries in probabilistic XML
Authors: Abiteboul Serge , Chan T.-H. HUBERT , Kharlamov Evgeny , Nutt Werner , Senellart Pierre
Published: December 2011

Sources of data uncertainty and imprecision are numerous. A way to handle this uncertainty is to associate probabilistic annotations to data. Many such probabilistic database models have been proposed, both in the relational and in the semi-structured setting. The latter is particularly well adapted to the management of uncertain data coming from a variety of automatic processes. An important problem, in the context of probabilistic XML databases, is that of answering aggregate queries (count, sum, avg, etc.), which has received limited attention so far. In a model unifying the various (discrete) semi-structured probabilistic models studied up to now, we present algorithms to compute the distribution of the aggregation values (exploiting some regularity properties of the aggregate functions) and probabilistic moments (especially expectation and variance) of this distribution. We also prove the intractability of some of these problems and investigate approximation techniques. We finally extend the discrete model to a continuous one, in order to take into account continuous data values, such as measurements from sensor networks, and extend our algorithms and complexity results to the continuous case.
Collaborative personalized top-k processing
Authors: Bai Xiao , Guerraoui Rachid , Kermarrec Anne-Marie , Leroy Vincent
Published: December 2011

This article presents P4Q, a fully decentralized gossip-based protocol to personalize query processing in social tagging systems. P4Q dynamically associates each user with social acquaintances sharing similar tagging behaviors. Queries are gossiped among such acquaintances, computed on-the-fly in a collaborative, yet partitioned manner, and results are iteratively refined and returned to the querier. Analytical and experimental evaluations convey the scalability of P4Q for top-
k
query processing, as well its inherent ability to cope with users updating profiles and departing.
The data cyclotron query processing scheme
Authors: Goncalves Romulo , Kersten Martin
Published: December 2011

A grand challenge of distributed query processing is to devise a self-organizing architecture which exploits all hardware resources optimally to manage the database hot set, minimize query response time, and maximize throughput without single point global coordination. The Data Cyclotron architecture [Goncalves and Kersten 2010] addresses this challenge using turbulent data movement through a storage ring built from distributed main memory and capitalizing on the functionality offered by modern remote-DMA network facilities. Queries assigned to individual nodes interact with the storage ring by picking up data fragments, which are continuously flowing around, that is, the hot set.

The storage ring is steered by the
Level Of Interest
(
LOI
) attached to each data fragment, which represents the cumulative query interest as it passes around the ring multiple times. A fragment with
LOI
below a given threshold, inversely proportional to the ring load, is pulled out to free up resources. This threshold is dynamically adjusted in a fully distributed manner based on ring characteristics and locally observed query behavior. It optimizes resource utilization by keeping the average data access latency low. The approach is illustrated using an extensive and validated simulation study. The results underpin the fragment hot set management robustness in turbulent workload scenarios.

A fully functional prototype of the proposed architecture has been implemented using modest extensions to MonetDB and runs within a multirack cluster equipped with Infiniband. Extensive experimentation using both microbenchmarks and high-volume workloads based on TPC-H demonstrates its feasibility.

The Data Cyclotron architecture and experiments open a new vista for modern distributed database architectures with a plethora of new research challenges.
Feasibility of Stepwise Design of Multitolerant Programs
Authors: Ebnenasir Ali , Kulkarni Sandeep S.
Published: December 2011

The complexity of designing programs that simultaneously tolerate multiple classes of faults, called
multitolerant
programs, is in part due to the conflicting nature of the fault tolerance requirements that must be met by a multitolerant program when different types of faults occur. To facilitate the design of multitolerant programs, we present sound and (deterministically) complete algorithms for stepwise design of two families of multitolerant programs in a high atomicity program model, where a process can read and write all program variables in an atomic step. We illustrate that if one needs to design failsafe (respectively, nonmasking) fault tolerance for one class of faults and masking fault tolerance for another class of faults, then a multitolerant program can be designed in separate polynomial-time (in the state space of the fault-intolerant program) steps regardless of the order of addition. This result has a significant methodological implication in that designers need not be concerned about unknown fault tolerance requirements that may arise due to unanticipated types of faults. Further, we illustrate that if one needs to design failsafe fault tolerance for one class of faults and nonmasking fault tolerance for a different class of faults, then the resulting problem is NP-complete in program state space. This is a counterintuitive result in that designing failsafe and nonmasking fault tolerance for the same class of faults can be done in polynomial time. We also present sufficient conditions for polynomial-time design of
failsafe-nonmasking
multitolerance. Finally, we demonstrate the stepwise design of multitolerance for a stable disk storage system, a token ring network protocol and a repetitive agreement protocol that tolerates Byzantine and transient faults. Our automatic approach decreases the design time from days to a few hours for the token ring program that is our largest example with 200 million reachable states and 8 processes.
Lattice-Based Sampling for Path Property Monitoring
Authors: Diep Madeline M. , Dwyer Matthew B. , Elbaum Sebastian
Published: December 2011

Runtime monitoring can provide important insights about a program’s behavior and, for simple properties, it can be done efficiently. Monitoring properties describing sequences of program states and events, however, can result in significant runtime overhead. This is particularly critical when monitoring programs deployed at user sites that have low tolerance for overhead. In this paper we present a novel approach to reducing the cost of runtime monitoring of path properties. A set of original properties are composed to form a single integrated property that is then systematically decomposed into a set of properties that encode necessary conditions for property violations. The resulting set of properties forms a lattice whose structure is exploited to select a sample of properties that can lower monitoring cost, while preserving violation detection power relative to the original properties. The lattice is then complemented with a weighting scheme that assigns each property a different priority that can be adjusted continuously to better drive the property sampling process. Our evaluation using the Hibernate API reveals that our approach produces a rich, structured set of properties that enables control of monitoring overhead, while detecting more violations more quickly than alternative techniques.
The Choice Calculus
Authors: Erwig Martin , Walkingshaw Eric
Published: December 2011

Many areas of computer science are concerned with some form of variation in software---from managing changes to software over time to supporting families of related artifacts. We present the choice calculus, a fundamental representation for software variation that can serve as a common language of discourse for variation research, filling a role similar to the lambda calculus in programming language research. We also develop an associated theory of software variation, including sound transformations of variation artifacts, the definition of strategic normal forms, and a design theory for variation structures, which will support the development of better algorithms and tools.
Beyond biology
Authors: Schulman Rebecca
Published: December 2011

As biology demonstrates, evolutionary algorithms are an extraordinarily powerful way to design complex nanoscale systems. While we can harness the biological apparatus for replicating and selecting DNA sequences to evolve enzymes and to some extent, organisms, we would like to build replication machinery that would allow us to evolve designs for a much wider variety of materials and systems. Here we describe work that uses techniques from the new field of structural DNA nanotechnology to modularly design nanoscale components that together can be assembled into a system for self-replicating a new form of chemical information or genome, and thus for evolving a new type of chemical sequence.
A geostatistical framework for categorical spatial data modeling
Authors: Cao Guofeng , Kyriakidis Phaedon , Goodchild Michael
Published: December 2011

This paper presents a general geostatistical framework for modeling categorical spatial data, an all important information source in many scientific fields. In the proposed framework, the multi-point class occurrence probability for (target) locations with unknown class labels given observed class labels at sample (source) locations is decomposed into a weighted combination of two-point spatial interactions in two different approaches, while accounting for complex spatial interdependencies. In the first approach, two-point spatial interactions are quantified directly by transiograms, a recently proposed set of spatial continuity measures in categorical fields. The sought-after multi-point class occurrence probability is then approximated based on a general paradigm (Tau model) for integrating knowledge from interdependent diverse information sources while accounting for information redundancy between them. In the second approach, geostatistical modeling of categorical spatial data is set in the framework of generalized linear mixed models (GLMMs), where latent spatially correlated Gaussian variables are assumed for the observable non-Gaussian responses to account for spatial correlation. Instead of using Markov Chain Monte Carlo sampling to infer the assumed latent variables, an ad-hoc method is proposed to approximate the analytically intractable posterior probability of the latent variables. The advantages of the new proposed framework are analyzed and highlighted through real and synthetic cases studies involving the generation of spatial patterns via sequential indicator simulation and interpolation of categorical spatial data.
Very high resolution digital elevation models (VHR DEMs) and multiscale landscape genomics analysis applied to an alpine plant species
Authors: Kevin Leempoel , Sylvie Stucki , Christian Parisod , Stéphane Joost
Published: December 2011

In landscape genomics, choosing the appropriate environmental parameter is primordial. While most studies are looking at large scale associations between genetic markers and environmental variables, adaptation of plants can also happen on a fine scale. However, the predictive ability of large scale predictors is weak when considering microclimates and landscape heterogeneity in mountainous areas. In that context, DEM's derivatives have been proven useful but remain confidential. This research focuses on the alpine herb Biscutella laevigata subsp. laevigata L., an autotetraploid perennial plant, which occurs in small patches in a heterogeneous landscape. The objectives are firstly, to explore correlations between environmental variables, exclusively derived from two DEMs of different spatial resolutions, respectively 25 and 2 meters, and genetic markers. Secondly, to analyze the effect of different spatial resolutions on significant correlations. The most important result obtained is the large congruency between results from a population genomics and a spatial coincidence approach. In addition, three variables show interesting results that is altitude, duration of insolation and morphometric protection index, which is rarely used. And finally, better significances were found most of the times with the 25m DEM, which raises questions about the most appropriate scale of computation of geomorphological and environmental processes.
Analytical framework for polygon-based land use change
Authors: Mizutani Chiaki , Murayama Yuji
Published: December 2011

Polygon representation is important for characterizing land use and the relationships among the land use polygon. This study aims to establish an analytical framework for polygon-based land use change to understand the land use change process considering types of land use and the shape. Polygon event and polygon state help to grasp the continuity spatially and temporally. Polygon event represents the combination of both changes in type of land use and the shape through the change process. Polygon state reflects homogeneity during the change process. Compactness, which recognizes geometrical characteristics of a polygon, was used to enhance understanding of the change process. A case study in Tsukuba City, Japan was tested to demonstrate the feasibility of the presented approach. The proposed framework supports the clarification of land use change pattern and is effective in explaining the spatio-temporal land use change process.
Measuring terrain distances through extracted channel networks
Authors: Stuetzle Christopher , Franklin W. Randolph , Cutler Barbara , Kamalzare Mehrad , Chen Zhongxian , Zimmie Thomas
Published: December 2011

This paper initiates a forensic analysis of the causes of levee failures by analyzing and extracting information from a sequence of elevation data. This is a crucial step in bettering the design and construction of levees and dams. (Fully diagnosing failures usually requires knowledge beyond the geometry of the levee, such as weather conditions and material properties). We use results from computer simulations of levee overtopping for training data. The simulations use smoothed particle hydrodynamics coupled with a well-known erodibility model. Using the sequential nature of our data, we extract important channel networks that form as the soil is scoured away. We present a series of metrics to measure the distance between channel networks to assist in determining the critical threshold value used to extract important channels from the flow network. Methods for determining this "ideal" threshold have gone mainly unexplored, and so we present a comparison of various threshold values and how closely they identify matching channel networks on sequential terrains. These threshold values allow us to identify important properties of the terrain that form its "fingerprint," a way of characterizing the geometry of the terrain. Our method for fingerprinting terrain is an important step toward the diagnosis of levee failure from digital elevation data.
Hypopigmented Mycosis Fungoides in Type V Skin: A Report of 5 Cases
Authors: Ranawaka Ranthilaka R. , Abeygunasekara Priyanka H. , de Silva M. V. Chandu
Published: December 2011

Five patients with type V skin were studied to describe the clinical manifestations, pathological features, and treatment response in hypopigmented mycosis fungoides (HMF). The mean age of patients was 22.4 years at diagnosis, with a mean of 36 months of diagnostic delay. Two were children aged 11 and 13 years. Skin patches were limited to sunlight-covered body areas. In tropical climate, exposure to natural sunlight possibly cured the lesions on sun-exposed areas at early stage of onset. HMF may frequently be misinterpreted as eczema, vitiligo, or progressive macular hypomelanosis clinically and histopathologically as seen in our case series.