bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of an electric field and nonlinear optical rectification of confined excitons in quantum dots
Authors: Xie Wenfang 
Published: August 2009

AbstractAn interacting electron‐hole pair in a parabolic quantum dot (QD), under growth‐direction applied electric field, is studied within the framework of the effective‐mass approximation. The binding energies of the ground and the three low‐excited states of the confined excitons are calculated as a function of the confined potential radius and as a function of the intensity of the applied electric field. We find that the effect of the applied electric field on the binding energy of the low‐lying states of the confined exciton depends strongly on the quantum number (N, m), but the binding energy of the ground state is practically not influenced by the presence of the applied electric field in the regime of very strong confinement. The nonlinear optical rectification between the ground (N = 0, m = 0) and low‐excited (N = 1, m = 0) states have been examined based on the computed energies and wave functions in details for the excitons. The results show that the optical rectification susceptibility obtained in the spherical QD can reach the magnitude of 10−2 m/V, which is 3–4 orders of magnitude higher than that in one‐dimensional QDs. It is found that the second‐order nonlinear optical properties of exciton states in a QD are strongly affected by the confinement strength and the electric field.
Achieving environmental sustainability and growth in Africa: the role of science, technology and innovation
Authors: Webersik Christian , Wilson Clarice 
Published: August 2009

AbstractAfrican economies are closely linked to natural resources and rely heavily on agriculture, largely rain fed. Agricultural development has long being considered of secondary importance in African economic development. As the current food crisis shows, it is important as this article argues to rethink not only agricultural policies, but also agricultural practices, and particularly the role science and innovation can play to address development and sustainability challenges. It is predicted that Africa will be particularly vulnerable to climate change and climate variability associated with biodiversity loss, food insecurity, water scarcity and an increase in drought frequency. This article examines pressing environmental challenges Africa is facing and discusses the role of science and technology solutions in meeting these challenges. An environmental performance country methodology is used to identify areas of best practice in achieving environmental policy targets, such as clean water or biodiversity conservation, as well as areas of action. Copyright © 2009 John Wiley & Sons, Ltd and ERP Environment.
Geographic information systems
Authors: Wieczorek William F. , Delmerico Alan M. 
Published: August 2009

AbstractThis article presents an overview of the development, capabilities, and utilization of geographic information systems (GISs). There are nearly an unlimited number of applications that are relevant to GIS because virtually all human interactions, natural and man‐made features, resources, and populations have a geographic component. Everything happens somewhere and the location often has a role that affects what occurs. This role is often called spatial dependence or spatial autocorrelation, which exists when a phenomenon is not randomly geographically distributed. GIS has a number of key capabilities that are required to conduct a spatial analysis to assess this spatial dependence. This article presents these capabilities (e.g., georeferencing, adjacency/distance measures, and overlays) and provides a case study to illustrate how GIS can be used for both research and planning. Although GIS has developed into a relatively mature application for basic functions, development is required to more seamlessly integrate spatial statistics and models. Copyright © 2009 John Wiley & Sons, Inc.This article is categorized under:

Software for Computational Statistics > Software/Statistical Software
Financial time series
Authors: Politis Dimitris N. 
Published: August 2009

AbstractThe evolution of financial markets is a complicated real‐world phenomenon that ranks at the top in terms of difficulty of modeling and/or prediction. One reason for this difficulty is the well‐documented nonlinearity that is inherent at work. The state‐of‐the‐art on the nonlinear modeling of financial returns is given by the popular auto‐regressive conditional heteroscedasticity (ARCH) models and their generalizations but they all have their short‐comings. Foregoing the goal of finding the ‘best’ model, it is possible to simplytransformthe problem into a more manageable setting such as the setting of linearity. The form and properties of such a transformation are given, and the issue of one‐step‐ahead prediction using the new approach is explicitly addressed. Copyright © 2009 John Wiley & Sons, Inc.This article is categorized under:Applications of Computational Statistics > Computational Finance
Volatility calibration using spline and high dimensional model representation models
Authors: Feil Balazs , Kucherenko Sergei , Shah Nilay 
Published: August 2009

AbstractThe local volatility function is approximated using two different models: a bicubic spline and High Dimensional Model Representation (HDMR) model. For a bicubic spline the local volatility values σi at a chosen discrete set of knots are determined by minimizing the least square error between market and model option prices. Model option prices are found using the one‐factor diffusion process for the underlying asset. For the HDMR model, the parameters to be optimized are the parameters of the HDMR model. Smoothness of the approximation functions is crucial to overcome the ill‐posedness of the volatility calibration problem. Two models are compared using two test cases. It is shown that the HDMR model can produce more accurate results than the cubic spline model, and it is also cheaper to run. It is demonstrated that the considered approach can accurately reproduce not only option prices but Greeks as well. Copyright © 2009 Wilmott Magazine Ltd
Prediction of Survival After Liver Transplantation for Chronic Severe Hepatitis B Based on Preoperative Prognostic Scores: A Single Center’s Experience in China
Authors: Xiao Liang , Fu Zhi‐Ren , Ding Guo‐Shan , Fu Hong , Ni Zhi‐Jia , Wang Zheng‐Xin , Shi Xiao‐Min , Guo Wen‐Yuan , Ma Jun 
Published: August 2009

AbstractBackgroundThe aim of this study was to estimate the utility of a preoperative model of end‐stage liver disease (MELD) score and Child‐Turcotte‐Pugh (CTP) score in predicting the prognosis after othotopic liver transplantation (OLT) for chronic severe hepatitis B (CSHB) and explore the prognostic factors.MethodsThe outcome of 137 patients who underwent OLT using donors after cardiac death (DCDs) for CSHB in our center was reviewed retrospectively. Survival analysis was performed using the Kaplan‐Meier method; the log‐rank test was used for univariate analysis; and the Cox proportional hazards regression model was used for prognostic factors screening.ResultsThe overall mortality rate was 33.6% (46/137); and 1‐month, 6‐month, 1‐year, and 5‐year patient survival rates were 75.8, 72.0, 71.0, and 60.1%, respectively. Most patients (33/46) died during the first month after OLT. The area under the curve values generated by the receiver operating characteristics curves were 0.82 [95% confidence interval (CI) 0.72–0.92] and 0.68 (95% CI 0.58–0.79), respectively (P < 0.01), for the MELD and CTP models in predicting 1‐month mortality after OLT. Patients with a preoperative MELD score <33.8 or a CTP score <12.5 had significantly better prognosis than those with higher scores (P < 0.05). Other mortality predictors include hepatic encephalopathy, preoperative infection, serum creatinine ≥1.5 mg/dl.ConclusionsThe MELD score was more efficient than the CTP score for evaluating the short‐term prognosis in patients with CSHB undergoing OLT using DCDs, which should be taken into consideration during graft allocation.
Fatty Acid, Phytosterol, and Polyamine Conjugate Profiles of Edible Oils Extracted from Corn Germ, Corn Fiber, and Corn Kernels
Authors: Moreau Robert A. , Lampi Anna‐Maija , Hicks Kevin B. 
Published: August 2009

AbstractThis study compared the profiles of fatty acids, phytosterols, and polyamine conjugates in conventional commercial corn oil extracted from corn germ and in two “new‐generation” corn oils: hexane‐extracted corn fiber oil and ethanol‐extracted corn kernel oil. The fatty acid compositions of all three corn oils were very similar and were unaffected by degumming, refining, bleaching, and deodorization. The levels of total phytosterols in crude corn fiber oil were about tenfold higher than those in commercial corn oil, and their levels in crude corn kernel oil were more than twofold higher than in conventional corn oil. When corn kernel oil was subjected to conventional degumming, refining, bleaching, and deodorization, about half of the phytosterols was removed, whereas when corn fiber oil was subjected to a gentle form of degumming, refining, bleaching, and deodorization, only about 10% of the phytosterols was removed. Finally, when the levels of polyamine conjugates (diferuloylputrescine and p‐coumaroyl feruloylputrescine) were examined in these corn oils, they were only detected in the ethanol‐extracted crude corn kernel oil, confirming earlier reports that they were not extracted by hexane, and providing new information that they could be removed from ethanol‐extracted corn kernel oil by conventional degumming, refining, bleaching, and deodorizing.
Catalytic Activity of Ruthenium Nanoparticles Supported on Carbon Nanotubes for Hydrogenation of Soybean Oil
Authors: Guo Shanshan , Liew Kong Yong , Li Jinlin 
Published: August 2009

AbstractRuthenium catalysts supported on multiwalled carbon nanotubes (MCNTs) with different loadings (1% wt, 3% wt, 5% wt) were prepared by reduction with H2 or NaBH4 for selective hydrogenation of soybean oil at 338 K and initial pressure of 1.066 MPa. These catalysts were characterized using transmission electron microscopy (TEM), X‐ray powder diffraction (XRD), N2 adsorption–desorption, and H2‐temperature programmed desorption (TPD) techniques. Ru particles were dispersed more homogeneously on the surface of the nanotubes after being reduced with H2 than with NaBH4. The catalysts with 3% and 5% Ru loadings had higher hydrogenation activity. The NaBH4‐reduced catalyst had higher cis‐isomer selectivity.
A Comparative Study of the Properties of Six Sudanese Cucurbit Seeds and Seed Oils
Authors: Mariod Abdalbasit Adam , Ahmed Yousif M. , Matthäus Bertrand , Khaleel Galaledin , Siddig Abdeen , Gabra Aied Mohamed , Abdelwahab Siddig Ibrahim 
Published: August 2009

AbstractThe proximate analysis of seeds and physicochemical properties of oils extracted from six Sudanese cucurbit seeds Cucumis mello var. agrestis, Cucumis melo var. flexuosus, Cucumis sativus, Citrullus lanatus var. colocynthoides, Cucumis prophetarum, and Luffa echinata were examined by established methods. For each variety, the proximate analysis showed ranges for moisture, protein, and carbohydrates as 3.70–6.87, 14.50–17.50, and 15.62–28.89% on a dry matter basis, respectively. The oils were extracted by Soxhlet using petroleum ether, with yields that ranged from 10.9 to 27.10% (wt/wt). The obtained extracted oils were subjected to phyiscochemical, fatty acid, and tocopherol analysis. The physicochemical characterization of the oil revealed that the refractive indices and relative densities of the oils fell within the narrow ranges of 1.334–1.442 and 0.874–0.920 g/cm3, respectively. Unsaponifiable matters ranged between 0.8 and 1.2 mg KOH/g, whilst peroxide values (PV) ranged from 2.3 to 4.1 meq/kg. The ranges of the values for free fatty acid (FFA %) were 1.2–4.0%. The predominant fatty acids were 16:0, 18:0, 18:1, and 18:2 with ranges of 8.9–14.2, 6.0–9.4, 14.6–32.1, and 43.6–65.5%, respectively. γ‐Tocopherol was the predominant tocopherol in all samples ranging from 0.8 to 43.2% of the total tocopherols, followed by δ‐tocopherol and α‐tocopherol.
The Significance of Multifidus Atrophy After Successful Radiofrequency Neurotomy for Low Back Pain
Authors: Dreyfuss Paul , Stout Alison , Aprill Charles , Pollei Steve , Johnson Blake , Bogduk Nikolai 
Published: August 2009

ObjectiveTo determine the presence of lumbar multifidus atrophy and pain after successful lumbar medial branch radiofrequency neurotomy for zygapophysial joint mediated pain.DesignA prospective observational analysis of 5 patients who had undergone successful unilateral radiofrequency neurotomy (RFN) of the lumbar medial branch divisions of the lumbar dorsal rami. At 17 to 26 months after RFN, 3 blinded radiologists evaluated the relative composition and size of the multifidus muscle at different segmental levels on lumbar magnetic resonance imaging (MRI). They were asked to determine the lesioned levels by evidence of multifidus atrophy. The accuracy of predicting the correct side and level lesioned was evaluated.SettingPrivate spine practice in Tyler, Texas.PatientsFive patients who had unilateral lumbar medial branch RFN for proven lumbar zygapophysial joint‐mediated pain were selected.InterventionsMRI of the lumbar spine at a mean of 21 months (range, 17‐26) after successful lumbar RFN.Outcome MeasuresMultifidus atrophy on a lumbar MRI, pain assessment and use of cointerventions.ResultsDiffuse lumbar multifidus atrophy was detectable with MRI. However, radiologists could not reliably predict the side and segments lesioned. Despite denervation of the multifidus, at 12 months after RFN all subjects had ongoing pain relief and did not require or request additional treatment.ConclusionsThis preliminary study provides evidence that successful medial branch RFN for lumbar zygapophysial‐mediated pain does cause initial denervation but no discernable segmental atrophy of the multifidus at long‐term follow‐up. Previous denervation and diffuse atrophy in these subjects was not associated with pain.
The Effect of Prehabilitation Exercise on Strength and Functioning After Total Knee Arthroplasty
Authors: Topp Robert , Swank Ann M. , Quesada Peter M. , Nyland John , Malkani Arthur 
Published: August 2009

ObjectiveThe purpose of this study was to examine the effect of a preoperative exercise intervention on knee pain, functional ability, and quadriceps strength among patients with knee osteoarthritis before and after total knee arthroplasty (TKA) surgery.DesignA repeated‐measures design was used to compare 2 groups over 4 data collection points.Setting and PatientsCommunity‐dwelling subjects with osteoarthritis of the knee who were scheduled for a unilateral TKA were recruited from a single orthopedic surgeon's office and were randomized into control (n = 28) or prehab groups (n = 26).InterventionsThe control patients maintained usual care before their TKA. The exercisers performed prehabilitation exercises, which included resistance training, flexibility, and step training, 3 times per week before their TKA.Outcome MeasuresKnee pain, functional ability, quadriceps strength, and strength asymmetry were assessed at baseline (T1), at 1 week before the patients' TKA (T2), and again at 1 (T3) and 3 (T4) months after TKA.ResultsThe exercisers improved their sit‐to‐stand performance at T2, whereas the control group did not change their performance of functional tasks and had increased pain at T2. At T3 the exercisers demonstrated improved sit‐to‐stand performance. The control patients at T3 exhibited decreases in pain, their 6‐minute walk, surgical leg strength and an increase in their nonsurgical leg strength and leg strength asymmetry. At T4 the exercisers improved in their performance of 3 of the 4 functional tasks, decreased all of their pain measures, and increased their surgical and nonsurgical quadriceps strength. At T4 the control group improved their performance on 2 of the 4 functional tasks, decreased all of their pain measures, increased their nonsurgical leg strength, and exhibited greater leg strength asymmetry.ConclusionThese findings appear to indicate the efficacy of prehabilitation among TKA patients and support the theory of prehabilitation.
Therapeutic Effect of Microcurrent Therapy in Infants With Congenital Muscular Torticollis
Authors: Kim Min Young , Kwon Dong Rak , Lee Hak Il 
Published: August 2009

ObjectiveThe aim of this study was to determine whether microcurrent therapy is therapeutically effective in infants with torticollis.DesignProspective, unblinded, controlled trial.SettingBundang CHA Hospital.SubjectsFifteen infants were included in this study who received torticollis treatment from April to July 2008. The control group (CG) included 8 infants (3 male, 5 female) with a mean age of 7.1 months. The experimental group (EG) included 7 infants (6 male, one female) with a mean age of 10 months.MethodsThe CG underwent stretching exercises for 30 minutes after ultrasound therapy and the EG underwent stretching exercises for 2 minutes after microcurrent therapy for 30 minutes. Each group received 3 treatments per week for 2 consecutive weeks.Main Outcome MeasuresMeasurements included head tilting angle at supine (TA) and neck rotation range of motion to the affected side (RR) at the first day and the 14th day of treatment. The incidence of crying during therapy also was recorded. The results were assessed by Mann‐Whitney U and the Fisher exact tests.ResultsIn the CG, 4 infants showed TA improvement, one infant showed RR improvement, and 8 infants cried during therapy. In the EG, 6 infants showed TA improvement, 5 infants showed RR improvement, and 3 infants cried during therapy. In the CG, mean TA was 16.3 ± 9.2° at the first day and 13.9 ± 8.2° at the 14th day of treatment. In the EG, mean TA was 15.7 ± 8.2° at the first day and 6.7 ± 4.3° at the 14th day of treatment. TA improvement was greater in the EG (P < .01) as compared with the CG. In the CG, mean RR was 65.0 ± 24.6° at the first day and 66.3 ± 25.7° at the 14th day of treatment. In the EG, mean RR was 70.0 ± 11.5° at the first day and 80.7 ± 6.7° at the 14th day of treatment. RR showed greater improvement in the EG (P < .05). The incidence of crying during therapy was significantly lower in the EG (P < .05).ConclusionMicrocurrent therapy in infants with torticollis appears more effective in improving TA and RR and shows better therapeutic compliance than traditional therapy.
Caregivers' Concerns about Judgment and Safety of Patients with Brain Injury: A Preliminary Investigation
Authors: Kreutzer Jeffrey S. , Livingston Lee A. , Everley Rachel S. , Gary Kelli W. , Arango‐Lasprilla Juan Carlos , Powell Victoria D. , Marwitz Jennifer H. 
Published: August 2009

ObjectiveTo identify caregivers' most common concerns about the judgment and safety of patients with brain injury in home and community environments. To quantify caregivers' stress levels and their level of comfort leaving patients at home unsupervised and examine the interrelationships between caregivers' safety and judgment ratings, stress levels, and levels of comfort leaving patients unattended.DesignRetrospective, cross‐sectional design.SettingOutpatient brain injury neuropsychology clinic at a university medical center.ParticipantsA convenience sample of 121 caregivers of traumatic brain injury survivors at least 1 month postinjury and 18 years of age or older.Main Outcome MeasurementsScores in 9 domains from the Judgment and Safety Screening Inventory; ratings of stress levels and levels of comfort leaving patients at home unattended derived from the General Health and History Questionnaire.ResultsCaregivers' most common judgment and safety‐related concerns were in the Travel and Financial domains, with many reflecting patients' memory deficits. Heightened caregiver stress levels were prevalent. Higher levels of concern about judgment and safety were associated with higher stress levels and concerns about leaving patients unattended.ConclusionsConsistent with research on patients with other types of neurological disorders, concerns about driving and financial management among caregivers are prevalent. Additional research is needed to identify the most cost‐effective methods of evaluating patients and enabling them to function at their highest level in the community.
Luminescence-dated aeolian deposits of late Quaternary age in the southern Tibetan Plateau and their implications for landscape history
Authors: Lai ZhongPing , Kaiser Knut , Brückner Helmut 
Published: August 2009

AbstractAeolian deposits are widely distributed in the interior of the Tibetan Plateau, and their chronology is poorly known. It is not yet clear whether they accumulated only after the last deglaciation, or over a longer time. We applied quartz OSL dating to aeolian samples from the Lhasa area with OSL ages ranging from 2.9 ± 0.2 to at least 118 ± 11 ka. The probability density frequency (PDF) distribution of 24 ages reveals age clusters at about 3, 8, 16–21, 33, and 79–83 ka, indicating enhanced sediment accumulation then. The results show that aeolian deposition occurred throughout most of the last 100 ka. This implies that: 1) an ice sheet covering the whole Tibetan Plateau during the last glacial maximum (LGM) could not have existed; and 2) erosion during the last deglaciation was not as strong as previously proposed, such that not all pre-Holocene loess was removed. The age distribution shown in the PDF indicates that aeolian accumulation is episodic. Sand-formation events revealed by age clusters at 3, 8, and 16–21 ka imply roughly synchronous environmental responses to corresponding global-scale arid events.
OPTIMAL LOWER BOUND ON THE SUPREMAL STRICT p-NEGATIVE TYPE OF A FINITE METRIC SPACE
Authors: WESTON ANTHONY 
Published: August 2009

AbstractDetermining meaningful lower bounds on the supremal strict p-negative type of classes of finite metric spaces is a difficult nonlinear problem. In this paper we use an elementary approach to obtain the following result: given a finite metric space (X,d) there is a constant ζ>0, dependent only on n=∣X∣ and the scaled diameter 𝔇=(diamX)/min{d(x,y)∣x⁄=y} of X (which we may assume is >1), such that (X,d) has p-negative type for all p∈[0,ζ] and strict p-negative type for all p∈[0,ζ). In fact, we obtain A consideration of basic examples shows that our value of ζ is optimal provided that 𝔇≤2. In other words, for each 𝔇∈(1,2] and natural number n≥3, there exists an n-point metric space of scaled diameter 𝔇 whose supremal strict p-negative type is exactly ζ. The results of this paper hold more generally for all finite semi-metric spaces since the triangle inequality is not used in any of the proofs. Moreover, ζ is always optimal in the case of finite semi-metric spaces.
Hydrogen peroxide aids assessment of pharyngeal closure after laryngectomy
Authors: Tysome J R , Jeannon J P , Simo R 
Published: August 2009

AbstractObjective:Pharyngocutaneous fistula is a serious complication following total laryngectomy. We report a simple technique which is useful in assessing the adequacy of pharyngeal closure following total laryngectomy.Method:Installation of 1.5 per cent hydrogen peroxide into the oral cavity, while observing for leakage at the pharyngeal repair.Results:We have found this technique to be useful in 22 patients undergoing total laryngectomy with pharyngeal resection and neck dissection.Conclusion:This method ensures that pharyngeal closure has been technically adequate.