bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long‐term monitoring of French polarimetric radar data quality and evaluation of several polarimetric quantitative precipitation estimators in ideal conditions for operational implementation at C‐band
Authors: Figueras i Ventura Jordi , Boumahmoud Abdel‐Amin , Fradon Béatrice , Dupuy Pascale , Tabary Pierre 
Published: April 2012

AbstractThis article presents the evaluation of several polarimetric quantitative precipitation estimation (Pol‐QPE) algorithm candidates for operational implementation in the Météo‐France polarimetric weather radars (nine C‐band and one S‐band out of a total of 24 radars in 2011). Since the performance of the algorithms depends on both the quality of the polarimetric variables and the applied polarimetric processing, the article first describes the current polarimetric processing chain and then provides a comprehensive analysis of the quality of the polarimetric variables.Three types of QPE algorithms have been studied at C‐band in ideal conditions (short ranges, no partial beam blocking, no vertical profile of reflectivity effects):(i) algorithms based on simple Z‐R relationships with and without attenuation correction using the differential phase Φdp,(ii) an algorithm based on reflectivity (Zh) and differential reflectivity (Zdr), and(iii) algorithms based on specific differential phase (Kdp).Evaluation against rain‐gauges, performed hourly, confirms the superiority of polarimetric algorithms as repeatedly reported in the literature. It also shows that the benefits brought by algorithms based on power variables, Zh and Zdr, are critically dependent upon the capability to correctly calibrate them. Long‐term monitoring shows that, with the current radar systems and operational calibration procedures, a stability of ±0.4 dB is achieved on Zdr. In that context, QPE algorithms based on Kdp, which are considered to be immune to partial beam blocking, calibration, attenuation, etc., are preferred for operational use until improvements are made to the calibration of Zdr. To this end, a hybrid algorithm based on attenuation‐corrected Zh for low rain rates and Kdp for higher rain rates has been designed and tested Copyright © 2012 Royal Meteorological Society
Interpreting an evaluation of the ECMWF global model with CloudSat observations: ambiguities due to radar reflectivity forward operator uncertainties
Authors: Di Michele Sabatino , Ahlgrimm Maike , Forbes Richard , Kulie Mark , Bennartz Ralf , Janisková Marta , Bauer Peter 
Published: April 2012

AbstractThis article explores the uncertainties associated with evaluating a global atmospheric model with radar reflectivity observations. A forward operator for radar reflectivity (ZmVar) is described and used for the comparison of the ECMWF global numerical weather prediction model short‐range forecasts with radar data from CloudSat. A sensitivity study is performed to determine which differences can be attributed to either specific radar forward operator assumptions or to deficiencies in the global model. The results show that model‐derived reflectivities are particularly sensitive to the definition of subgrid precipitation fraction, as precipitation dominates the radar reflectivity signal, but also to the choice of particle size distribution and scattering properties of the different hydrometeor categories. However, there are a number of consistent differences in the reflectivity comparison that are significantly larger than can be explained by the sensitivity tests. This suggests that these discrepancies are due to deficiencies in the model cloud and precipitation frequency of occurrence and hydrometeor water contents. These include too frequent occurrence at high altitudes, too low occurrence in the Southern Hemisphere storm track and an overestimate of rain in warm‐phase low cloud. The study shows the value of CloudSat for evaluating the model in terms of radar reflectivity and highlights the importance of taking into account forward operator uncertainties for both model evaluation and data assimilation applications. Copyright © 2012 Royal Meteorological Society
Does one‐photon photocyclization of trans‐diarylethylenes involve adiabatic trans‐to‐cis photoisomerization? potential energy surface calculations for 1‐styrylnaphthalene
Authors: Budyka Mikhayl F. 
Published: April 2012

AbstractPotential energy surface (PES) for 1‐styrylnaphthalene was calculated by PM3 method for the S0 state and PM3‐CI(2x2) method with configuration interaction for the S1 state. Scanning PES along both isomerization and cyclization reaction coordinates enabled to reveal the minimum energy path (MEP) with low barriers on the S1 PES from E‐isomer to dihydrocyclophotoproduct (DHP). This is consistent with formation of the photocyclization product in one‐photon process during irradiation of E‐isomer. Additionally, the MEP was found to bypass the coordinate region of Z‐isomer, i.e. one‐photon E‐isomer‐to‐DHP photocyclization does not demand participation of the excited Z‐isomer. Therefore, adiabatic trans‐to‐cis isomerization is likely not an intermediate stage on the E‐isomer photocyclization pathway, and experimentally observed one‐photon formation of the DHP from the E‐isomer is likely not an evidence for adiabatic trans‐to‐cis photoisomerization, as it is usually assumed. According to the results obtained, two photochemical reactions of E‐isomer, photoisomerization to Z‐isomer and photocyclization to DHP, are not consecutive but parallel reactions with branching at perpendicular conformer on the S1 PES. © 2012 Wiley Periodicals, Inc.
Conformational analysis, tautomeric preference, intramolecular hydrogen bonding, and solvent effect on dinitrosamine: A quantum chemical study
Authors: Jahani Peyman Mohammadzadeh , Nowroozi Alireza 
Published: April 2012

AbstractHF, B3LYP, and MP2 methods with the standard basis set, 6‐311++G(d,p), were used to study various aspects of dinitrosamine. These results were compared with the outcomes of G2 and CBS‐QB3 methods. First, the conformational analysis and characterization of equilibrium conformations, especially global minima, were performed. On the basis of relative energies, we found that the dinitroso tautomers are more stable than the nitroso‐hydroxy (NH) ones. This preference is well‐interpreted in terms of tautomerization process and nitrosamine resonance. Furthermore, the nature of OH···O intramolecular hydrogen bond (IMHB), in chelated forms of NH (NH‐11 and NH‐13) was comprehensively studied to evaluate the effect of hetero atoms (N) on the characteristic of IMHB systems. According to the results of isodesmic reaction method, the hydrogen bond energy of NH‐11 is greater than the malonaldehyde (MA) and NH‐13, whereas the electron density analysis and energy‐geometry correlation methods clearly predict that the hydrogen bond of NH‐11 is weaker than the MA. Additionally, the geometrical, atoms in molecules (AIM) and natural bond orbital's (NBO) parameters also emphasize on the MA as a chelated form with the strongest hydrogen bond. Finally, the solvent effects on the relative stability of selected dinitrosamine conformers are evaluated by different continuum (polarizable‐continuum model, isodensity polarizable continuum model, and self‐consistent isodensity polarizable continuum model), discrete and mixed solvent models. Theoretical results readily show that the potential energy surface of dinitrosamine, especially global minima, is strongly affected by the solvent. © 2012 Wiley Periodicals, Inc.
Computational simulations of hydrolysis of phosphazene oligomer utilizing atom‐centered density matrix propagation
Authors: Kroger Jessica L. , Fried Joel R. , Skelton Adam A. 
Published: April 2012

AbstractDensity functional theory (DFT) calculations, including the ab initio molecular dynamics method, atom‐centered density matrix propagation (ADMP), were used to investigate the hydrolysis reaction of a dichlorophosphazene trimer. The model trimer, intermediate structures and the product of the first step of hydrolysis, were optimized using DFT with the B3LYP density functional, followed by a 600 fs ADMP simulation. Natural bond order analysis (NBO) was used to determine atomic charges and occupancy of the bond orbitals and the lone pair orbitals of the molecule at various points along the simulation pathway. The simulation successfully shows dissociation of the trimer backbone into two distinct product molecules, shown through both increasing separation of the product units and through the more thorough NBO analysis of the bond orbitals. © 2012 Wiley Periodicals, Inc.
Differentiation of underivatized monosaccharides by atmospheric pressure chemical ionization quadrupole time‐of‐flight mass spectrometry
Authors: Zhu Zhenqian , Song Liguo , Bartmess John E. 
Published: April 2012

RATIONALEDifferentiation of underivatized monosaccharides is essential in the structural elucidation of oligosaccharides which are closely involved in many life processes. So far, such differentiation has been usually achieved by electrospray ionization mass spectrometry (ESI‐MS). As an alternative to ESI‐MS, atmospheric pressure chemical ionization mass spectrometry (APCI‐MS) should provide complementary results.METHODSA quadrupole time‐of‐flight (QTOF) mass spectrometer with accurate mass measurement ability was used with an APCI heated nebulizer ion source because we believe that a recently published article using a single quadrupole mass spectrometer assigned incorrect identities for APCI ions from hexoses. Using APCI‐QTOF, the MS2andpseudo‐MS3mass spectra of 11 underivatized monosaccharides were obtained under various collision voltages. The mass spectra were carefully interpreted after accurate mass measurement.RESULTSDifferentiation of three hexoses was achieved by different MS2spectra of their [M + NH4]+and [M − H]–ions. The MS2spectra of the [M + NH4]+ions were also used to distinguish methylα‐D‐glucose and methylβ‐D‐glucose, while thepseudo‐MS3spectra of the [M + H]+ions were utilized to differentiate the three hexosamine andN‐acetylhexosamine stereoisomers. Unique [M + O2]–ions were observed and their distinctive fragmentation patterns were utilized to differentiate the three hexosamine stereoisomers.CONCLUSIONSAlthough ESI coupled with single or triple quadrupole and ion trap mass spectrometers has been widely utilized in the differentiation of monosaccharides, this report demonstrated that APCI‐QTOF‐MS had its own advantages in achieving the same goal. Copyright © 2012 John Wiley & Sons, Ltd.
Non‐lithographic SERS Substrates: Tailoring Surface Chemistry for Au Nanoparticle Cluster Assembly
Authors: Adams Sarah M. , Campione Salvatore , Caldwell Joshua D. , Bezares Francisco J. , Culbertson James C. , Capolino Filippo , Ragan Regina 
Published: April 2012

AbstractNear‐field plasmonic coupling and local field enhancement in metal nanoarchitectures, such as arrangements of nanoparticle clusters, have application in many technologies from medical diagnostics, solar cells, to sensors. Although nanoparticle‐based cluster assemblies have exhibited signal enhancements in surface‐enhanced Raman scattering (SERS) sensors, it is challenging to achieve high reproducibility in SERS response using low‐cost fabrication methods. Here an innovative method is developed for fabricating self‐organized clusters of metal nanoparticles on diblock copolymer thin films as SERS‐active structures. Monodisperse, colloidal gold nanoparticles are attached via a crosslinking reaction on self‐organized chemically functionalized poly(methyl methacrylate) domains on polystyrene‐block‐poly(methyl methacrylate) templates. Thereby nanoparticle clusters with sub‐10‐nanometer interparticle spacing are achieved. Varying the molar concentration of functional chemical groups and crosslinking agent during the assembly process is found to affect the agglomeration of Au nanoparticles into clusters. Samples with a high surface coverage of nanoparticle cluster assemblies yield relative enhancement factors on the order of 109 while simultaneously producing uniform signal enhancements in point‐to‐point measurements across each sample. High enhancement factors are associated with the narrow gap between nanoparticles assembled in clusters in full‐wave electromagnetic simulations. Reusability for small‐molecule detection is also demonstrated. Thus it is shown that the combination of high signal enhancement and reproducibility is achievable using a completely non‐lithographic fabrication process, thereby producing SERS substrates having high performance at low cost.
Deformation Behavior and Damage Evaluation in a New Titanium Diboride (TiB2) Steel‐Based Composite
Authors: Hadjem‐Hamouche Zehoua , Chevalier Jean‐Pierre , Cui Yiting , Bonnet Frédéric 
Published: April 2012

AbstractDeformation behavior and damage evaluation of a new composite steel has been investigated by means of in situ three‐point bend tests in the scanning electron microscope. The titanium diboride (TiB2)‐reinforced steel composite is produced by in situ precipitation of the TiB2 particles during eutectic solidification. This production process developed by ArcelorMittal leads to a steel composite with a significant increase in specific stiffness (>20%), and good strength/ductility compromise. The microstructures obtained consist of primary TiB2 crystals surrounded by a eutectic mixture of ferrite and TiB2 particles. The primary mode of damage is particle fracture and inhomogeneous plastic deformation in the matrix. In contrast with other production process, particle fracture was more common than interfacial debonding indicating that interfacial strength is not the limiting factor in damage accumulation and fracture in this composite. Crack growth occurred by particle fracture ahead of the crack tip, producing large microvoids, which then link up to the growing crack by ductile failure of the remaining matrix ligaments. The results suggest also that the cracks tended to avoid direct particle interactions.
Deformation Mechanisms and Martensitic Phase Transformation in TRIP‐Steel/Zirconia Honeycombs
Authors: Ehinger David , Krüger Lutz , Martin Ulrich , Weigelt Christian , Aneziris Christos G. 
Published: April 2012

AbstractThe mechanical and structural response of powder metallurgical square‐celled honeycomb structures to quasi‐static and dynamic impact loads are described. By constructing the cellular lattice with a novel metal matrix composite material based on a metastable high‐alloyed austenitic TRIP‐steel particle‐reinforced by magnesia partially stabilized zirconia (Mg‐PSZ), high specific yield and ultimate collapse strengths as well as a high ductility and an enhanced specific energy absorption were gained. In order to prove the temperature sensitivity of the honeycomb structures, a selected low‐reinforced composite condition was investigated in a pre‐series of quasi‐static compression tests at temperatures in the range between −190 and 150°C. The present study shows that the deformation mechanisms of the TRIP‐matrix composite honeycomb structures can be classified with respect to strain rate and deformation temperature, including the failure characteristics and the strain‐induced α′‐martensite transformation in the austenitic steel matrices ensuring the TRIP effect. The evolution of the α′‐martensite phase content in the central crush zone of the TRIP steel and TRIP‐Matrix Composite honeycombs is demonstrated based on the results of magnetic balance measurements.
Fast‐Track Surgery Improves Postoperative Clinical Recovery and Immunity After Elective Surgery for Colorectal Carcinoma: Randomized Controlled Clinical Trial
Authors: Yang Dongjie , He Weiling , Zhang Sheng , Chen Huayun , Zhang Changhua , He Yulong 
Published: April 2012

AbstractBackgroundFew clinical studies or randomized clinical trial results have reported the impact of fast‐track surgery on human immunity. This study aimed to investigate the clinical and immune impact of fast‐track surgery in colorectal cancer patients undergoing elective open surgery.MethodsA controlled randomized clinical trial was conducted from November 2008 to January 2009 with a 1‐month postdischarge follow‐up. A total of 70 patients with colorectal carcinoma requiring colorectal resection were randomized into two groups: a fast‐track group (35 cases) and a conventional care group (35 cases). All included patients underwent elective open colorectal resection with combined tracheal intubation and general anesthesia. Clinical parameters and markers of immune function were evaluated in both groups postoperatively.ResultsIn all, 62 patients completed the study: 32 in the fast‐track group and 30 in the conventional care group. Our findings revealed a significantly shorter postoperative hospital stay and faster return of gastrointestinal function in patients undergoing fast‐track rehabilitation. In addition, we found a quicker response of white blood cells in the fast‐track group than in the conventional care group. We also found that blood levels of globulin, immunoglobulin G, and complement 4 on postoperative day 3 were higher in the fast‐track group than in the conventional care group.ConclusionsFast‐track surgery accelerates clinical recovery and improves postoperative immunity after elective open surgery for colorectal carcinoma.
Subjectivism — a reply in defence of classical actuarial methods
Authors: Ryder J. M. 
Published: April 2012

The work of science is to substitute facts for appearances and demonstrations for impressions.1.1 .This paper is an attempt to describe the extent of ‘Subjectivist’ infiltration into theories of actuarial concern, and to present counter arguments defending the objective ‘classical’ actuarial position. The principal entry point for subjectivist ideas has been the ‘latter day rediscovery of the basically statistical nature of actuarial work’ (F. A. Menzler) which has introduced us to Bayesian Statistical Theory and the concept of Insurance Theory as a Theory of Risk. Classical actuarial theory, however, regards this use of Bayesian theory as fallacious, and the Theory of Risk as of relatively minor interest.
Some aspects of the London reinsurance market in world-wide short-term business
Authors: Craighead D. H. 
Published: April 2012

This paper is partly descriptive, partly analytical, and covers the following aspects:a description of the market in general;a brief description of the organization of Lloyd's;currencies and exchange rates;calculation of reserves;taxation;underwriting; andaccumulation of risk.§§ 1 and 2 and the earlier paragraphs of § 3 convey information regarding the market that will be well known to actuaries practising in this field and may be passed over without loss. They are added in an attempt to convey a picture of the type of operation that results within an office concentrating on reinsurance business, as against looking at reinsurance in its peripheral effect on a direct writing office.
Matching and portfolio selection: Part 1
Authors: Wise A. J. 
Published: April 2012

1.1 My paper entitled ‘The Matching of Assets to Liabilities’ described a new study of the subject of matching. The paper outlined the mathematical framework, showed some calculations, and suggested various applications in the field of actuarial valuation.1.2 Subsequently A. D. Wilkie published a note entitled ‘Portfolio Selection in the Presence of Fixed Liabilities: a Comment on “The Matching of Assets to Liabilities”’. Wilkie's note appears to represent a new extension of portfolio selection theory which enables him to encompass the conventional portfolio theory and to show where my approach to matching fits into the picture.1.3 This paper is in the nature of a reply to that of Wilkie. My objective at the stage of the first draft was to re-examine the matching portfolio, as defined in relation to specified liabilities, in view of the wide range of alternative portfolios which Wilkie has described. The scope of this work progressed well beyond my original plans when I found a most interesting mathematical relationship between the ‘matching portfolios’ described in my earlier paper and the ‘efficient portfolios’ described in Wilkie's.
Objectives and methods of funding defined benefit pension schemes
Authors: McLeish D. J. D. , Stewart C. M. 
Published: April 2012

The Objective of Funding1.1. As every actuarial student is taught:‘Pay-as-you-go is acceptable for a State pension scheme because the State is, for practical purposes, assured of a continuing existence.’However:‘The position is quite different in the case of an occupational scheme, since an employer's business may cease to exist.’1.2. It seems to us to follow, therefore, that the prime purpose of funding an occupational pension scheme must be to secure the accrued benefits, whatever they might be, in the event of the employer being unable or unwilling to continue to pay at some time in the future. To that end, the contributions would have to be sufficient both to pay the benefits as they fell due for as long as the scheme continued, and also to establish and maintain a fund which would be sufficient to secure the accrued benefits in the event of contributions ceasing and the scheme being discontinued, whenever that might occur.
Bias in q and m rate estimates
Authors: Roberts L. A. 
Published: April 2012

Bias in estimates of the initial decremental rate q and the central decremental rate m is considered for several survival functions. It is first shown that the central rate estimate is unbiased when the survival function is an exponential curve; is similarly unbiased when the survival function assumes the Balducci shape. The evidence presented here also indicates that the proportional bias (the bias divided by the true value) is approximately twice as great for as for when the survival function is a straight line.Life tables in common use in the United Kingdom are, however, concave at ages arising most frequently in actuarial calculations, while none of the above curves is concave. In order to investigate the bias properties of general survival functions a quadratic is chosen, with a parameter indicating the extent of curvature. For this particular class of survival functions, one can show that bias is approximately minimized when exposure to risk is symmetric about the middle of the rate year.
Address by the President. Developing a proactive role
Authors: Scurfield Hugh Hedley 
Published: April 2012

ABSTRACTThe Presidential Address visits some of the current issues affecting the actuarial profession and expresses some personal views of the President. Subjects covered include with-profits policies, life assurance withdrawals and disclosure, Europe, education (concerning both actuarial examinations and continuing professional education), general insurance and pensions. The Address demonstrates the need for proactivity in a world which is continually changing, which is the theme of the 2-year presidency.
Strategy for the 1990s. Document prepared by The Planning Joint Committee of the Institute of Actuaries and the Faculty of Actuaries (Chairman, Mr C. D. Daykin) and Approved by Both Councils
Authors: Daykin C. D. 
Published: April 2012

ABSTRACTThe Institute of Actuaries and the Faculty of Actuaries have embarked on a joint planning exercise with a view to developing a more proactive profession, by focusing the attention and energy of members and ensuring effective use of scarce financial and human resources. ‘Strategy for the 1990s’ sets the overall framework of key objectives, which were agreed by a historic joint meeting of the Councils of the Institute and the Faculty on 4 March 1991.
Chain ladder and maximum likelihood
Authors: Verrall R. J. 
Published: April 2012

ABSTRACTThis paper derives second moments of estimates of the parameters in the chain ladder model. Thus, the so-called link ratios, and proportions of ultimate claims for each development year are considered. This enables confidence statements about the chain ladder parameters to be made with statistical rigour. The methods are illustrated using 6 sets of real data taken from the DTI returns.