bluuebunny/crossref_metadata_2025_split huggingface dataset:
POLYNOMIAL-TIME COMPLEXITY FOR INSTANCES OF THE ENDOMORPHISM PROBLEM IN FREE GROUPS
Authors: CIOBANU LAURA 
Published: March 2007

We say the endomorphism problem is solvable for an element W in a free group F if it can be decided effectively whether, given U in F, there is an endomorphism ϕ of F sending W to U. This work analyzes an approach due to Edmunds and improved by Sims. Here we prove that the approach provides an efficient algorithm for solving the endomorphism problem when W is a two-generator word. We show that when W is a two-generator word this algorithm solves the problem in time polynomial in the length of U. This result gives a polynomial-time algorithm for solving, in free groups, two-variable equations in which all the variables occur on one side of the equality and all the constants on the other side.
Grading Scale for Prediction of Outcome in Primary Intracerebral Hemorrhages
Authors: Ruiz-Sandoval José L. , Chiquete Erwin , Romero-Vargas Samuel , Padilla-Martínez Juan J. , González-Cornejo Salvador 
Published: March 2007

Background and Purpose—This study aimed to independently derive an intracerebral hemorrhage grading scale (ICH-GS) for prediction of 3 outcome measures.Methods—We evaluated 378 patients with primary ICH at hospital arrival and during the next 30 days. Independent predictors were identified by multivariate models of in-hospital and 30-day mortality. Points were allotted to each predictor based on its prognostic performance. ICH-GS was also evaluated to predict good 30-day functional status and ICH-GS was compared with the ICH score as the reference scoring system.Results—Independent predictors were age, Glasgow Coma Scale, ICH location, ICH volume, and intraventricular extension, all components of the ICH score. Nevertheless, different cutoffs and scoring improved substantially the prognostic power of the predictors. Compared with the ICH score, ICH-GS explained more variance in the 3 outcome measures, had higher sensitivity in predicting in-hospital and 30-day mortality, and performed equally well in predicting good functional outcome at 30 days follow up.Conclusions—The derived ICH-GS is a simple yet robust scale in predicting in-hospital and 30-day mortality, as well as good 30-day functional status, with equivalent performance.
Determination of the Horizontal Pressure Gradient Force Using Global Positioning System on board an Instrumented Aircraft
Authors: Parish Thomas R. , Burkhart Matthew D. , Rodi Alfred R. 
Published: March 2007

Abstract
The horizontal pressure gradient force is the single most important dynamical term in the equation of motion that governs the forcing of the atmosphere. It is well known that the slope of an isobaric surface is a measure of the horizontal pressure gradient force. Measurement of this force over mesoscale distances using an airborne platform has been attempted for over two decades in order to understand the dynamics of various wind systems. The most common technique has been to use a radar altimeter to measure the absolute height of an isobaric surface above sea level. Typical values of the horizontal pressure gradient force in the atmosphere are quite small, amounting to an isobaric surface slope of 0.0001 for a 10 m s−1 geostrophic wind at middle latitudes. Detecting the horizontal pressure gradient over irregular terrain using an instrumented aircraft has proven to be especially difficult since correction for the underlying terrain features must be made. Use of the global positioning system (GPS) is proposed here as a means to infer the horizontal pressure gradient force without the need for altimetry and terrain registration over irregular surface topography. Differential kinematic processing of data from dual-frequency, carrier phase tracking receivers on research aircraft with similar static base station receivers enables the heights of an isobaric surface to be determined with an accuracy estimated to be a few decimeters. Comparison of results obtained by conventional altimetry-based methods over the ocean and Lake Michigan with GPS reveals the potential of the GPS method at determining the horizontal pressure gradient force, even over complex terrain.
Managing Stock Option Expense: The Manipulation of Option‐Pricing Model Assumptions*
Authors: Johnston Derek 
Published: March 2007

AbstractThis paper examines whether firms that voluntarily recognize stock option expense in their financial statements manage that expense downward more than firms that do not recognize the expense by adjusting option‐pricing model assumptions. To examine this issue, I collect option‐pricing model assumptions from fiscal year 2002 for both a sample of firms that voluntarily recognize stock option expense (“recognizing firms”) and a sample of control firms that do not (“disclosing firms”). The empirical results suggest that recognizing firms manage the recognized stock‐based compensation expense reported in their financial statements downward more than do firms that only disclose the expense. Additional analyses reveal that recognizing firms assume a lower level of volatility than disclosing firms in the option‐pricing model calculations; however, I find no evidence that recognizing firms manage the dividend yield and risk‐free interest rate assumptions more than disclosing firms. The Financial Accounting Standards Board (FASB) recently issued Statement of Financial Accounting Standards No. 123(R), which requires the expensing of the fair value of stock options, so these results may be of interest to capital‐market participants and the FASB as they assess the reliability of stock option expense as determined by option‐pricing models.
Employee Stock Option Fair‐Value Estimates: Do Managerial Discretion and Incentives Explain Accuracy?*
Authors: Hodder Leslie , Mayew William J. , McAnally Mary Lea , Weaver Connie D. 
Published: March 2007

AbstractWe examine the determinants of managers' use of discretion over employee stock option (ESO) valuation‐model inputs that determine ESO fair values. We also explore the consequences of such discretion. Firms exercise considerable discretion over all model inputs, and this discretion results in material differences in ESO fair‐value estimates. Contrary to conventional wisdom, we find that a large proportion of firms exercise value‐increasing discretion. Importantly, we find that using discretion improves predictive accuracy for about half of our sample firms. Moreover, we find that both opportunistic and informational managerial incentives together explain the accuracy of firms' ESO fair‐value estimates. Partitioning on the direction of discretion improves our understanding of managerial incentives. Our analysis confirms that financial statement readers can use mandated contextual disclosures to construct powerful ex ante predictions of ex post accuracy.
The Circumstances and Legal Consequences of Non‐GAAP Reporting: Evidence from Restatements*
Authors: PALMROSE ZOE‐VONNA , SCHOLZ SUSAN 
Published: March 2007

AbstractOur study examines the circumstances of non‐GAAP financial reporting by 492 U.S. companies that announced restatements from 1995 to 1999. We focus on income statements to analyze the occurrence and resolution of litigation over restatements and explore the role of accounting items in bringing and resolving this litigation. We provide evidence on the pervasiveness of accounting misstatements, describe their nature, and show how, if at all, they affect litigation. We assess the nature of restatements by determining whether regular, recurring earnings from primary operations (core) or other components of earnings (noncore) are misstated, and we assess their pervasiveness by estimating the number of primary accounts misstated. In our sample, companies with core restatements have higher frequencies of intentional misstatements (fraud) and subsequent bankruptcy or delisting. Likewise, these companies have, on average, more material misstatements, more negative security price reactions to restatement announcements, and more negative security price changes over the six months preceding and following restatement announcements. However, controlling for these and other factors, we find a significant association between accounting items and litigation, whether occurrences or resolutions. Specifically, core restatements — driven primarily by misstatements of revenue, a component of core earnings — and more pervasive restatements each play a role, while misstatements of noncore earnings alone do not.
High-Throughput Identification of Genes Promoting Neuron Formation and Lineage Choice in Mouse Embryonic Stem Cells
Authors: Falk Anna , Karlsson Tobias E. , Kurdija Sanja , Frisén Jonas , Zupicich Joel 
Published: March 2007

Abstract
The potential of embryonic stem cells to differentiate to all cell types makes them an attractive model for development and a potential source of cells for transplantation therapies. Candidate approaches have identified individual genes and proteins that promote the differentiation of embryonic stem cells to desired fates. Here, we describe a rapid large-scale screening strategy for the identification of genes that influence the pluripotency and differentiation of embryonic stem cells to specific fates, and we use this approach to identify genes that induce neuron formation. The power of the strategy is validated by the fact that, of the 15 genes that resulted in the largest increase in neuron number, 8 have previously been implicated in neuronal differentiation or survival, whereas 7 represent novel genes or known genes not previously implicated in neuronal development. This is a simple, fast, and generally applicable strategy for the identification of genes promoting the formation of any specific cell type from embryonic stem cells.
Disclosure of potential conflicts of interest is found at the end of this article.
Celestite in the Weathering Crust on Limestone Exposed to an Urban Atmosphere in Cracow (Poland)
Authors: Wilczyńska-Michalik Wanda , Michalik Marek 
Published: March 2007

Celestite in the Weathering Crust on Limestone Exposed to an Urban Atmosphere in Cracow (Poland)Celestite containing very low amounts of barium occurs in weathering reaction zones developed on the Pińczów limestone exposed to the polluted atmosphere of Cracow. The mineral occurs both in limestone pore spaces filled with gypsum and in black gypsum crust. The Pińczów limestone contains ca 500 ppm strontium which was released during the reaction with atmospheric pollutants. The nucleation and growth of celestite, requiring significant concentration of components in evaporating solutions, is associated with gypsum crystallization.
Dissimilarity analysis based batch process monitoring using moving windows
Authors: Zhao Chunhui , Wang Fuli , Jia Mingxing 
Published: March 2007

AbstractIn recent years, a novel MSPC method known as DISSIM, which is based on the dissimilarity of process time series data, has been developed focusing on continuous and stable processes. However, its further application is hindered because of its unsuitability to batch processes which lie at the heart of many industries. In the present work, combined with variable moving windows, an important extension of the novel DISSIM method, termed EDISSIM, is made for its practical application to batch processes monitoring as well as the theoretical analysis basis for the determination of control limit. Moreover, contribution plots of dissimilarity index are used to identify the variables that contribute significantly to the out‐of‐control state. The applications of the proposed EDISSIM method are illustrated with respect to simulated data collected from both a simple 2 × 2 numerical process and a fed‐batch penicillin fermentation industrial batch process. The results clearly show that it functions very well to successfully detect and diagnose fault in batch processes, which implies the significant investigation potential of the proposed method. © 2007 American Institute of Chemical Engineers AIChE J, 2007
The σ‐CAM Mechanism: σ Complexes as the Basis of σ‐Bond Metathesis at Late‐Transition‐Metal Centers
Authors: Perutz Robin N. , Sabo‐Etienne Sylviane 
Published: March 2007

AbstractComplexes in which a σ‐HE bond (E=H, B, Si, C) acts as a two‐electron donor to the metal center are called σ complexes. Clues that it is possible to interconvert σ ligands without a change in oxidation state derive from CH activation reactions effecting isotope exchange and from dynamic rearrangements of σ complexes (see Frontispiece). Through these pathways, metathesis of ME bonds can occur at late transition metals. We call this process σ‐complex‐assisted metathesis, or σ‐CAM, which is distinct from the familiar σ‐bond metathesis (typical for d0 metals and requiring no intermediate) and from oxidative‐reductive elimination mechanisms (inherently requiring intermediates with changed oxidation states and sometimes involving σ complexes). There are examples of σ‐CAM mechanisms in catalysis, especially for alkane borylation and isotope exchange of alkanes. It may also occur in silylation and alkene hydrogenation.
Einfluss der Eigenspannung auf die Rissbildung bei dicken Bauteilen im jungen Betonalter
Authors: Viet Tue Nguyen , Bödefeld Jörg , Dietz Jörg 
Published: March 2007

AbstractEntsprechend den geltenden nationalen und internationalen Massivbaunormen darf die in Stahlbetonbauteilen von Bewehrung aufzunehmende Kraft bei überwiegender Zwangbeanspruchung mit zunehmenden Bauteildicken bis auf 50% reduziert werden. Als Begründung werden Eigenspannungen genannt. Die Ergebnisse einer umfangreichen FE‐Untersuchung zu den Eigenspannungen während der Betonerhärtung haben bestätigt, dass der Einfluss der Eigenspannung auf die Risslast mit der Bauteildicke zunimmt. Deren Zusammenhang ist jedoch sehr komplex, so dass die heutige Annahme zur Zwangkraft für die Begrenzung der Rissbreite infolge Zwangbeanspruchung nur als eine pragmatische Vorgehensweise bewertet werden kann. Für einen mechanisch fundierten Bemessungsvorschlag sind weitere Untersuchungen erforderlich.
Weiße Wanne in Additiv‐Bauweise
Authors: Fastabend Michael , Doering Norbert , Nagel Felix 
Published: March 2007

AbstractAusgehend von den Hinweisen zur regelkonformen Ausbildung von Weißen Wannen wird an einem konkreten Beispiel gezeigt, dass auch die Verletzung der Konstruktionsregeln zu erfolgreichen Bauwerken führen kann. Aus den geometrischen und grundbaulichen Randbedingungen ergab sich die Notwendigkeit, eine Weiße Wanne mit einer Additivaußenwand sowie einer Bodenplatte mit mannigfachen Festhaltungen auszuführen. Die Additivaußenwand wurde vermittels einer Stahlspundwand sowie einer Betoninnenschale konstruiert. Die Verklammerungen der Gesamtkonstruktion mit dem umgebenden Boden ergaben sich aus der profilierten Außenkante der Spundwand sowie aus den Pfahlgründungen für die Bodenplatte. Besonderheiten bei den Bemessungkonzepten waren insbesondere bei der Additivaußenwand festzustellen. Nicht über das übliche Maß hinausgehende Rissbildungen in Wand und Bodenplatte zeigten die erfolgreiche Umsetzung der speziellen Bauweise einer Weißen Wanne auf.
Fmoc‐2‐mercaptobenzothiazole, for the introduction of the Fmoc moiety free of side‐reactions
Authors: Isidro‐Llobet Albert , Just‐Baringo Xavier , Ewenson Ariel , Álvarez Mercedes , Albericio Fernando 
Published: March 2007

AbstractA double side‐reaction, consisting in the formation of Fmoc‐β‐Ala‐OH and Fmoc‐β‐Ala‐AA‐OH, during the preparation of Fmoc protected amino acids (Fmoc‐AA‐OH) with Fmoc‐OSu is discussed. Furthermore, the new Fmoc‐2‐MBT reagent is proposed for avoiding these side‐reactions as well as the formation of the Fmoc‐dipeptides (Fmoc‐AA‐AA‐OH) and even tripeptides, which is another important side‐reaction when chloroformates such as Fmoc‐Cl is used for the protection of the α‐amino function of the amino acids. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 733–737, 2007.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Randomized clinical trial of perioperative systemic warming in major elective abdominal surgery
Authors: Wong P F , Kumar S , Bohra A , Whetter D , Leaper D J 
Published: March 2007

Abstract

Background
Hypothermia is common in the operating theatre and may increase susceptibility to postoperative complications. Intraoperative systemic warming has been shown to improve outcomes of surgery. This study aimed to examine the effects of additional perioperative systemic warming on postoperative morbidity.

Methods
All patients admitted for elective major abdominal surgery and fulfilling the inclusion criteria were randomized into control or warming groups. Both groups were warmed during surgery, but patients in the warming group were additionally warmed 2 h before and after surgery using a conductive carbon polymer mattress.

Results
The trial recruited 103 patients (56 in the control group, 47 in the warming group). Both groups were well matched for age, sex and clinical state. Patients in the warming group had lower blood loss (median 200 (range 5–1000) ml versus median 400 (range 50–2300) ml in the control group; P = 0·011) and complication rates (15 (32 per cent) of 47 versus 30 (54 per cent) of 56 in the control group; P = 0·027). There were three deaths; two in the control group (P = 0·566).

Conclusion
Extending systemic warming to the perioperative period had additional beneficial effects, with minimal additional cost and patient discomfort.
Meta-analysis and systematic review of the relationship between volume and outcome in abdominal aortic aneurysm surgery
Authors: Holt P J E , Poloniecki J D , Gerrard D , Loftus I M , Thompson M M 
Published: March 2007

Abstract

Background
This study investigated the volume–outcome relationship for abdominal aortic aneurysm (AAA) surgery and quantified critical volume thresholds.

Methods
PubMed, EMBASE and the Cochrane library were searched for articles on the operation volume–outcome relationship in elective and ruptured AAA surgery. UK Hospital Episode Statistics data were also considered. Elective and ruptured AAA repairs were dealt with separately. The data were meta-analysed, and the odds ratios (95 per cent confidence interval) for mortality at higher- and lower-volume hospitals were compared. Volume thresholds were identified from each paper.

Results
The analysis included 421 299 elective and 45 796 ruptured AAA operations. Significant relationships between mortality and annual volume were noted for both groups. Overall, the weighted odds ratio was 0·66 (0·65 to 0·67) for elective repair at a threshold of 43 AAAs per annum and 0·78 (0·73 to 0·82) for ruptured aneurysm repair at a threshold of 15 AAAs per annum, both in favour of high-volume institutions.

Conclusion
Higher annual operation volumes are associated with significantly lower mortality in both elective and ruptured AAA repair. This suggests that AAA surgery should be performed only at higher-volume centres.
Semiconductor Behavior of a Metal‐Organic Framework (MOF)
Authors: Alvaro Mercedes , Carbonell Esther , Ferrer Belén , Llabrés i Xamena Francesc X. , Garcia Hermenegildo 
Published: March 2007

AbstractUpon light excitation MOF‐5 behaves as a semiconductor and undergoes charge separation (electrons and holes) decaying in the microsecond time scale. The actual conduction band energy value was estimated to be 0.2 V versus NHE with a band gap of 3.4 eV. Photoinduced electron transfer processes to viologen generates the corresponding viologen radical cation, while holes of MOF‐5 oxidizes N,N,N′,N′‐tetramethyl‐p‐phenylenediamine. One application investigated for MOF‐5 as a semiconductor has been the shape‐selective photocatalyzed degradation of phenol in aqueous solutions.
From Molecule to Bulk Material: Optical Properties of Hydrogen‐Bonded Dimers [C12H12N4O2AgPF6]2 and [C28H28N6O3AgPF6]2 Depend on the Arrangement of the Oxime Moieties
Authors: Cheng Wen‐Dan , Wu Dong‐Sheng , Shen Juan , Huang Shu‐Ping , Xie Zhi , Zhang Hao , Gong Ya‐Jing 
Published: March 2007

AbstractThe dependence of the optical properties of [C12H12N4O2AgPF6]2 (dimer‐1) and [C28H28N6O3AgPF6]2 (dimer‐2) on the arrangement of the oxime moieties in the molecule and in bulk crystals was investigated by means of time‐dependent density functional theory. Dimer‐1 with simple pyridine oxime ligands and a wavy arrangement has a smaller dipole moment and larger transition energy between the two states, and thus smaller third‐order polarizabilities and two‐photon absorption cross sections. Dimer‐2 with extended pyridine oxime ligands and a ladder arrangement has a larger dipole moment and smaller transition energy between the two states, and thus larger third‐order polarizabilities and two‐photon absorption cross sections. The lowest energy absorption band is red‐shifted for dimer‐2 as compared with dimer‐1, due to more pronounced π–π delocalization interactions and weaker hydrogen bonding in dimer‐2. The electronic absorption spectra, frequency‐dependent third‐order polarizabilities, and two‐photon absorption cross sections involve significant contributions from charge transfers from π/π* orbitals of the pyridine oxime ligands but no contribution from PF6− ions or H2O molecules in the wavelength range studied for the monomers and dimers of the C12H12N4O2AgPF6 and C28H28N6O3AgPF6 molecules. The third‐order susceptibilities and two‐photon absorption coefficients of bulk solids were estimated on the basis of the optical properties of the corresponding dimers, and the bulk material constructed from dimer‐2 has the larger optical parameters of the two.
Dienyne Ring‐Closing Metathesis Approach for the Construction of Taxosteroids
Authors: Aldegunde María J. , García‐Fandiño Rebeca , Castedo Luis , Granja Juan R. 
Published: March 2007

AbstractA cascade dienyne ring‐closing metathesis approach has been applied to the synthesis of the tetracyclic carbon framework of a new class of hybrid compounds—the taxosteroids—possessing carbon frameworks incorporating moieties characteristic of both taxanes (such as AB rings) and steroids (i.e., CD system and side chain). This tandem cyclization is highly stereoselective, allowing the one‐step formation of the bicyclo[5.3.1]undecene system characteristic of taxol. In this work we describe the scope and limitations of such cyclizations.