bluuebunny/crossref_metadata_2025 huggingface dataset:
Closure of skin incisions in rabbits by laser soldering: I: Wound healing pattern
Authors: Simhon David , Brosh Tamar , Halpern Marisa , Ravid Avi , Vasilyev Tamar , Kariv Naam , Katzir Abraham , Nevo Zvi
Published: July 2004

Background and Objectives

Temperature‐controlled tissue laser soldering is an innovative sutureless technique awaiting only solid experimental data to become the gold‐standard surgical procedure for incision closure. The goals of the current study were: (1) to define the optimal laser soldering conditions, (2) to explore the immediate skin reparative healing events after sealing the wound, and (3) to determine the long‐term trajectory of skin wound healing.

Study Design/Materials and Methods

Skin incisions were generated over rabbit dorsa and were closed using different wound‐closure interventions, in three groups: (a) closure, using a temperature‐controlled infrared fiberoptic CO2 laser system, employing 47% bovine serum albumin as a solder; (b) wound closure by cyanoacrylate glues; and (c) wound closure by sutures. The reparative outcomes were evaluated macroscopically and microscopically, employing semi‐quantitative grading indices.

Results

Laser soldering of incisions at T = 65°C emerged as the optimal method achieving immediate wound sealing. This in turn induced accelerated reparative events characterized by a reduced inflammatory reaction, followed by minimal scarring and leading to a fine quality healing.

Conclusions

Temperature‐controlled laser soldering offers an accelerated wound reparative process with numerous advantages over the conventional methods. Further investigations may reveal additional benefits in the spectrum of advantages that this innovative surgical technology has to offer. This can introduce new scientific insight that will pave the way for clinical use. Lasers Surg. Med. 35:1–11, 2004. © 2004 Wiley‐Liss, Inc.
Thermosetting Blends of Polybenzoxazine and Poly(ε‐caprolactone): Phase Behavior and Intermolecular Specific Interactions
Authors: Zheng Sixun , Lü Han , Guo Qipeng
Published: July 2004

Summary: Polybenzoxazine (PBA‐a)/poly(ε‐caprolactone) (PCL) blends were prepared by an in situ curing reaction of benzoxazine (BA‐a) in the presence of PCL. Before curing, the benzoxazine (BA‐a)/PCL blends are miscible, which was evidenced by the behaviors of single and composition‐dependant glass transition temperature and equilibrium melting point depression. However, the phase separation induced by polymerization was observed after curing at elevated temperature. It was expected that after curing, the PBA‐a/PCL blends would be miscible since the phenolic hydroxyls in the PBA‐a molecular backbone have the potential to form intermolecular hydrogen‐bonding interactions with the carbonyls of PCL and thus would fulfil the miscibility of the blends. The resulting morphology of the blends prompted an investigation of the status of association between PBA‐a and PCL under the curing conditions. Although Fourier‐transform infrared spectroscopy (FT‐IR) showed that there were intermolecular hydrogen‐bonding interactions between PBA‐a and PCL at room temperature, especially for the PCL‐rich blends, the results of variable temperature FT‐IR spectroscopy by the model compound indicate that the phenolic hydroxyl groups could not form efficient intermolecular hydrogen‐bonding interactions at elevated temperatures, i.e., the phenolic hydroxyl groups existed mainly in the non‐associated form in the system during curing. The results are valuable to understand the effect of curing temperature on the resulting morphology of the thermosetting blends.

SEM micrograph of the dichloromethane‐etched fracture surface of a 90:10 PBA‐a/PCL blend showing a heterogeneous morphology.

magnified image

SEM micrograph of the dichloromethane‐etched fracture surface of a 90:10 PBA‐a/PCL blend showing a heterogeneous morphology.
Continuous dependence on modelling for a complex Ginzburg–Landau equation with complex coefficients
Authors: Yang Yongfu , Gao Hongjun
Published: July 2004

Continuous dependence on a modelling parameter is established for solutions of a problem for a complex Ginzburg–Landau equation. A homogenizing boundary condition is also used to discuss the continuous dependence results. We derive a priori estimates that indicate that solutions depend continuously on a parameter in the governing differential equation. Copyright © 2004 John Wiley & Sons, Ltd.
A regularity result for stationary electrorheological fluids in two dimensions
Authors: Bildhauer Michael , Fuchs Martin
Published: July 2004

We proveC1,α‐regularity for the strong solution to a non‐linear system of partial differential equations modeling electrorheological fluids in the stationary case which has been constructed by Ettwein and Ettwein‐Růžička [Elektrorheologische Flüssigkeiten: Existenz starker Lösungen in zweidimensionalen Gebieten. Diplomarbeit, Universität Freiburg, 2002;Geometric Analysis and Nonlinear Partial Differential Equations, Hildebrandt S, Karcher H (eds). Springer: Berlin–Heidelberg–New York, 2003; 591–602]. Copyright © 2004 John Wiley & Sons, Ltd.
Service delivery in francophone West Africa: the challenge of balancing deconcentration and decentralisation
Authors: Pinto Rogerio F.
Published: July 2004

The article reviews the experiences with decentralisation of one West African country, Guinea, with the intent of drawing lessons and exploring approaches to assist countries in the sub‐region in rendering decentralisation—an effective means for service delivery improvements. Section II describes the West Africa context in terms of the dynamics of deconcentration–decentralisation and lays out a conceptual framework to guide the analytical assessment of countries in the sub‐region, attempting to decentralise. This framework is used in the Guinea case, described in Section III. Section IV concludes by synthesising the profile of Guinea, and positions its dominant style in relation to the proposed ideal types of decentralisation approaches. This part of the article discusses the implications of its findings for decentralisation policy and implementation, and offers some remarks on the road ahead for decentralisation in West Africa. Copyright © 2004 John Wiley & Sons, Ltd.
Use of menopausal hormones in the United States, 1992 through June, 2003
Authors: Wysowski Diane K. , Governale Laura A.
Published: July 2004

Purpose

The Women's Health Initiative (WHI) study that documented an unfavorable benefit to risk ratio of Prempro and subsequently an increased risk of stroke with menopausal estrogen prompted us to investigate the use during 1992 through June 2003 of menopausal hormones in the United States.

Methods

Two pharmaceutical research databases from IMS Health, the National Prescription Audit Plus™ and the National Disease and Therapeutic Index™, were accessed and analyzed.

Results

The number of dispensed outpatient prescriptions for oral menopausal estrogens and oral combination estrogen–progestins increased 2.5‐fold (153%) from 34.5 million dispensed in 1992 to a high of 87.3 million in 2000. For July 2002 through June 2003, the year following the publication of the results of the WHI trial, prescriptions for these products declined to 59.6 million, a 32% decrease from their peak in 2000. Prescriptions for transdermal estrogen and transdermal combination estrogen–progestin products increased from 5.2 million dispensed in 1992 to their peak of 8.3 million in 2000, and declined 10% to 7.5 million during July 2002 through June 2003. By contrast, prescriptions for oral menopausal progestins rose to 17.5 million in 1995 and then steadily declined. In the year after the WHI, prescriptions for oral progestins decreased 49% to 8.9 million from their peak in 1995. The earlier decline in oral progestin prescriptions was primarily due to the marketing in 1995 of the popular oral combination estrogen–progestin drugs.

Conclusions

Prescriptions dispensed for menopausal hormones increased substantially between 1992 and peaked in 2000. By June 2003, prescriptions for oral menopausal estrogens and oral combination estrogen–progestins had declined by about one‐third from their peak year. Published in 2004 by John Wiley & Sons, Ltd.
Visual observation of CO2 foaming of polypropylene‐clay nanocomposites
Authors: Taki Kentaro , Yanagimoto Tatsunori , Funami Eita , Okamoto Masami , Ohshima Masahiro
Published: July 2004

Using a newly developed high‐pressure autoclave, which has two sapphire windows on the walls, we visually observed the batch physical foaming of polymer‐clay nanocomposites to understand the effect of nano‐sized clay on the initial stage of foaming. With CO2 as a physical foaming agent, polypropylene‐montmorillonite clay nanocomposites were foamed at 150°C. A high‐speed digital camera with a microscope could observe the bubble nucleation and bubble growth behavior of the early stage of foaming in situ. The series of micrographs was analyzed in order to investigate the effect of clay content on bubble nucleation and growth. The experiments, together with CO2‐solubility and diffusivity data, show that the clay enhances bubble nucleation as a nucleation agent and retards the growth of bubbles at the early stage of foaming. Polym. Eng. Sci. 44:1004–1011, 2004. © 2004 Society of Plastics Engineers.
Melt compounding of different grades of polystyrene with organoclay. Part 1: Compounding and characterization
Authors: Tanoue Shuichi , Utracki Leszek A. , Garcia‐Rejon Andrés , Tatibouët Jacques , Cole Kenneth C. , Kamal Musa R.
Published: July 2004

Nanocomposites of polystyrene (PS) with up to 20 wt% organoclay were prepared by melt compounding in a co‐rotating, intermeshing twin‐screw extruder. Three grades of PS with different molecular weights were used. In this paper we discuss preparation and characterization of the mixtures. Residence time and its distribution were measured by ultrasonics (US). They were found to be independent of the PS grade, but the US attenuation and sound velocity varied with the organoclay loading. According to the XRD diffraction data, the organoclay was dispersed into two types of platelet stacks evidenced by the diffraction peaks at about 2θ = 2.1 and 5.5°, i.e., with the interlayer spacings of d001 = 4.20 and 1.6 nm, respectively. Since neat organoclay has d001 = 1.93 nm, the first peak indicates intercalation by PS and the other a collapse of the interlamellar gallery during compounding. The XRD spectra depended on the organoclay content, but not on PS grade. According to TEM analysis, the degree of intercalation of organoclay in the polymer matrix is highest for the low‐molecular‐weight polystyrene. TEM results also confirm the collapse of interlamellar spacing in parts of the samples. FT‐IR spectroscopy showed that there was some thermal degradation of the onium compound present in the nanoclay. Polym. Eng. Sci. 44:1046–1060, 2004. © 2004 Society of Plastics Engineers.
Melt compounding of different grades of polystyrene with organoclay. Part 2: Rheological properties
Authors: Tanoue Shuichi , Utracki Leszek A. , Garcia‐Rejon Andrés , Sammut Pierre , Ton‐That Minh‐Tan , Pesneau Isabelle , Kamal Musa R. , Lyngaae‐Jørgensen Jørgen
Published: July 2004

Polystyrene‐based nanocomposites (PNC) were prepared using three grades of polystyrene (different molecular weights). The resin was melt‐compounded with 0 to 10 wt% of commercial organoclay in a co‐rotating twin‐screw extruder. Owing to thermo‐oxidative degradation the degree of dispersion was poor. The rheological properties of PNC were determined under dynamic and steady state shear as well as under extensional flow conditions. At the higher clay content, dynamic strain sweep demonstrated that the storage and loss moduli decrease continuously with an increase of strain. To characterize this nonlinear viscoelastic behavior, the Fourier‐transform rheology was applied. The low strain frequency sweep showed that the storage and loss moduli increase with organoclay content. The extracted zero‐shear viscosity data were used to calculate the intrinsic viscosity and then the aspect ratio of dispersions. In spite of nonlinear viscoelastic behavior, the time‐temperature superposition was observed in the full range of concentration. The horizontal and vertical shift factors were found to be almost independent of organoclay content and molecular weight of PS. For comparison, PNC was also prepared by the solution method. A high degree of dispersion was obtained, reflected in the aspect ratio: p = 269, to be compared with p = 16 calculated for the melt‐compounded PNC. Polym. Eng. Sci. 44:1061–1076, 2004. © 2004 Society of Plastics Engineers.
Relative energies, stereoelectronic interactions and conformational interconversions in silathiacyclohexanes
Authors: Freeman Fillmore , Cha Chansa , Fang Christine , Huang Angela C. , Hwang Jee H. , Louie Patricia L. , Shainyan Bagrat A.
Published: July 2004

Stereoelectronic hyperconjugative interactions and the relative energies of conformers and transition states of 2‐, 3‐, and 4‐silathiacyclohexane were calculated at the B3LYP/6–311+G(d,p) level of theory. The chair conformer of 2‐silathiacyclohexane is 15.4 and 15.9 kcal mol−1 (1 kcal = 4.184 kJ), respectively, lower in energy than the chair conformers of 3‐ and 4‐silathiacyclohexane. Intrinsic reaction path calculations were used to connect the transition states between the respective chair and twist conformers and different chair–chair conformational interconversion paths were located for 3‐ and 4‐silathiacyclohexane. The energy of the transition state that connects the chair and 2,5‐twist conformers of 3‐silathiacyclohexane is 5.58 kcal mol−1 higher in energy than the chair. The transition state that connects the chair and 2,5‐twist conformers of 4‐silathiacyclohexane is 4.82 kcal mol−1 higher in energy than the chair. The energy differences (ΔE, kcal mol−1) between the chair conformer of 2‐silathiacyclohexane and the respective 1,4‐twist (ΔE = 4.16), 2,5‐twist (ΔE = 3.20) and 3,6‐twist (ΔE = 3.87) conformers were calculated. Small relative energy differences were calculated between the chair conformer and the respective 1,4‐twist (ΔE = 3.95), 2,5‐twist (ΔE = 4.07) and 3,6‐twist (ΔE = 3.46) conformers of 3‐silathiacyclohexane. The calculated energy differences (ΔE) between the chair conformer and the 1,4‐twist and 2,5‐twist conformers of 4‐silathiacyclohexane were 3.50 and 4.04 kcal mol−1, respectively. The geometric parameters and stereoelectronic hyperconjugative interactions in the silathiacyclohexanes are compared and discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Block copolymers of styrene andn‐alkyl methacrylates with long alkyl groups. Micellization behavior in selective solvents
Authors: Pitsikalis Marinos , Siakali‐Kioulafa Ekaterini , Hadjichristidis Nikos
Published: July 2004

The micellization properties of well‐defined block copolymers of styrene and decyl methacrylate (SDMA) were studied in two different solvents, methyl acetate (MAc) selective for the polystyrene (PS) block and dodecane, selective for the poly(decyl methacrylate) (PDMA) block. The results were compared with those obtained, in the same solvents, from block copolymers of styrene and stearyl methacrylate (SSMA). In MAc, SDMA copolymers with a decyl methacrylate (DMA) content of 15% or less formed unimolecular micelles, whereas those with a content of 18.5% or higher formed multimolecular micelles. The degrees of association were lower than the corresponding SSMA samples. In dodecane, SDMA form large, monodisperse, spherical, and thermally stable micelles with degrees of association higher than the corresponding SSMA samples. The different behaviors can be attributed to the steric hindrance effect and the ability of the long alkyl groups of the polymethacrylate, MA blocks to crystallize. When the MA blocks are in the soluble corona of the micelles, the steric hindrance effect prevails, thus leading to higher degrees of association for the less bulky alkyl group. In the case where the MA block is in the insoluble core of the micelles, the higher the tendency for crystallization the higher the degree of association. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4177–4188, 2004
Segmental cystic malformation of the lung with chondrolipomatous component
Authors: Cohen Marta , Diez Graciela , Segal Edgardo , Drut Ricardo
Published: July 2004

A peculiar cystic and chondrolipomatous malformation affecting the right upper lobe of the lung as presented in a 10‐year‐old girl with a history of recurrent pneumonia and pneumothorax is reported. The lesion combined bronchial‐type cavities with intervening stroma containing adipose tissue, with cartilage nodules of different sizes. The findings do not fit with any already‐known malformations of the lung. Pediatr Pulmonol. © 2004 Wiley‐Liss, Inc.
Aggressive and non‐violent videogames: short‐term psychological and cardiovascular effects on habitual players
Authors: Baldaro Bruno , Tuozzi Giovanni , Codispoti Maurizio , Montebarocci Ornella , Barbagli Francesco , Trombini Elena , Rossi Nicolino
Published: July 2004

The purpose of this study is to evaluate the short‐term effects on several physiological (arterial pressure and heart rate) and psychological (anxiety and aggressiveness) indexes of playing violent and non‐violent videogames in young adults. The study was carried out on a sample of 22 male participants. Subjects invited to participate in the study were recruited from a videogame leisure club. Before and during playing either a violent or non‐violent computer game, blood pressure and heart rate were measured. Before and after the game session, the subjects completed the State‐Anxiety Inventory‐Y (STAI‐Y) and the Buss–Durkee Hostility Inventory. The results of the study showed a range of short‐term effects of playing violent and non‐violent videogames on arterial pressure and on the state anxiety of subjects, but not on hostility measurements. More specifically, the group that played the violent videogames showed a significant increase in the state anxiety score at the end of the game, as compared to the pre‐game self‐evaluation, and an increase in the systolic blood pressure while the subjects were playing as compared to pre‐ and post‐game values. A decrease in diastolic blood pressure after playing any game was also found. Copyright © 2004 John Wiley & Sons, Ltd.
R&D, organization structure, and the development of corporate technological knowledge
Authors: Argyres Nicholas S. , Silverman Brian S.
Published: July 2004

We explore the link between a firm's organization of research—specifically, its choice to operate a centralized or decentralized R&D structure—and the type of innovation it produces. We propose that by reducing the internal transaction costs associated with R&D coordination across units, centralized R&D will generate innovations that have a larger and broader impact on subsequent technological evolution than will decentralized research. We also propose that, by facilitating more distant (‘capabilities‐broadening’) search, centralized R&D will generate innovations that draw on a wider range of technologies. Our empirical results provide support for our predictions concerning impact, and mixed results for our predictions concerning breadth of search. We also find that control over research budgets complements direct authority relations in contributing to innovative impact. We propose several extensions of this research. Copyright © 2004 John Wiley & Sons, Ltd.
The scope and governance of international R&D alliances
Authors: Oxley Joanne E. , Sampson Rachelle C.
Published: July 2004

Participants in research and development alliances face a difficult challenge: how to maintain sufficiently open knowledge exchange to achieve alliance objectives while controlling knowledge flows to avoid unintended leakage of valuable technology. Prior research suggests that choosing an appropriate organizational form or governance structure is an important mechanism in achieving a balance between these potentially competing concerns. This does not exhaust the set of possible mechanisms available to alliance partners, however. In this paper we explore an alternative response to hazards of R&D cooperation: reduction of the ‘scope’ of the alliance. We argue that when partner firms are direct competitors in end product or strategic resource markets even ‘protective’ governance structures such as equity joint ventures may provide insufficient protection to induce extensive knowledge sharing among alliance participants. Rather than abandoning potential gains from cooperation altogether in these circumstances, partners choose to limit the scope of alliance activities to those that can be successfully completed with limited (and carefully regulated) knowledge sharing. Our arguments are supported by empirical analysis of a sample of international R&D alliances involving electronics and telecommunications equipment companies. Copyright © 2004 John Wiley & Sons, Ltd.
How do multinational companies leverage technological competencies? Moving from single to interdependent explanations
Authors: Hansen Morten T. , Løvås Bjørn
Published: July 2004

This paper explores the relationships among four fundamental determinants of intrafirm competence transfers that have hitherto been analyzed only separately: formal organization structure, informal relations, geographical distance, and relatedness of competencies across subsidiaries. Using a data set consisting of 4840 dyads between new product development teams and subsidiaries that were potential targets for competence transfers in a high‐technology multinational company, we find that these determinants interact in surprising ways to explain different patterns of transfers. Results revealed that teams preferred to approach people they knew rather than people who knew related technologies well. They also showed that teams steered away from spatially distant subsidiaries that had related competencies and that the negative effect of large spatial distances could be overcome through established informal relations. These findings indicate that studying one of the determinants separately can yield biased results, as their net effect may change when the moderating effects of the other determinants are considered. Research on synergies, integration, technology transfers, and geographical and cultural differentiation in multinational enterprises therefore needs to be broadened by analyzing multiple determinants of competence transfers. Copyright © 2004 John Wiley & Sons, Ltd.
Technological and product‐market experience and the success of new product introductions in the pharmaceutical industry
Authors: Nerkar Atul , Roberts Peter W.
Published: July 2004

The growth and development of a firm depend on its ability to introduce new products over time. To do this successfully, it requires technological knowledge, the ability to combine knowledge elements into valuable new products, and the complementary assets that facilitate the manufacturing, sales, and distribution of those products. We argue that these all develop as a function of a firm's experience in its technological and product‐market domains. Moreover, given the prospect of complementarities among technological and product‐market experience, the value of any one type of experience may be enhanced by the presence of another. Therefore, new products will be more successful when a firm possesses the appropriate stocks of technological and product‐market experience. We test this idea by analyzing whether pharmaceutical firms' experience in their technological and product‐market domains confer early advantages to their new product offerings, and lead to higher initial sales levels. Copyright © 2004 John Wiley & Sons, Ltd.
Are we all global now? Local vs. foreign sources of corporate competence: the case of the Japanese pharmaceutical industry
Authors: Thomas L. G.
Published: July 2004

This study links the highly distinctive national contexts of the pharmaceutical industry to the evolution of innovative capabilities for Japanese drug firms from 1975 to 1995. During these two decades, the Japanese domestic environment for pharmaceuticals changed radically, encouraging a ‘bubble’ of trivial innovations. Experience by Japanese firms in their domestic market predominantly determined their innovative capabilities, pushing these firms towards trivial innovation. Corporate experience in the socially ‘proximate’ markets of Southern Europe served as a strategic complement for significant innovation by Japanese drug firms, and thus as a partial counterweight to the home market. Unfortunately, corporate diversification was a strategic substitute for significant innovation, and many Japanese drug firms are significantly diversified. The resulting degradation of innovative capability for Japanese drug firms has locked most of them into an increasingly unattractive home market. Copyright © 2004 John Wiley & Sons, Ltd.
Institutions and events of the eleventh century mirrored in Geniza letters (Part I)
Authors: GIL MOSHE
Published: July 2004

This article is based on letters from the Geniza. The writers were merchants who dealt in imports and exports between Egypt and other countries of the Mediterranean basin. These merchants were part of the Jewish elite and maintained close ties with the Muslim authorities. They enjoyed considerable status with these authorities, who co-operated with the merchants, especially in the transport of goods; some of the high officials were, in fact, ship-owners. The administration of the time took a great interest in imports and exports, and would at times confiscate goods required by the army. The article reviews a series of citations from letters thus examining the relationship between the merchants and the authorities. The second part deals with the evidence of the droughts found in the merchants' letters; it is interesting to compare the details on droughts with the information in the Arabic sources. The third part discusses the information contained in the Geniza documents on the conquest of Jerusalem (638). This is followed by a discussion of two figures who are also known from Arabic sources: Manasseh b. Abraham Ibn al-Qazza¯z, and Barjawa¯n. The letters also reflect the restrictive measures against Jews and Christians in the days of Caliph al-Ha¯kim.
Institutions and events of the eleventh century mirrored in Geniza letters (part II)
Authors: GIL MOSHE
Published: July 2004

This article deals with a further series of events reflected in the Geniza letters, as listed below. In 1016, Jerusalem was afflicted by a severe earthquake; the letters help to determine the exact date of the event. Between 970 and 1030, Palestine was beset by battles; I have referred to this period as the ‘Sixty Years War’. In the Geniza letters, we find information on these events, beginning in 1021 and continuing to the Fatimid victory at Uqhuwa¯na in 1029. The letters provide information on the heavy taxes imposed on the Jewish population in Jerusalem. Because the liveliest trade took place between Egypt and the Maghrib, a great many letters were sent from the Maghrib, containing information on the incessant struggles there, especially between 1010 and 1027. The letters supply information on the struggle in Spain between the ‘slaves’ and the Berbers. We find an extremely detailed description of the events related to the earthquake of 1033, which is also described by the Persian traveller Na¯sir Khusraw. Also contained in the letters is information on the mutinies in the Maghrib under al-Mu‘izz; the separation of Ifri¯qiya¯ from Fatimid supremacy (1048/49); events during the rule of the vizier al-Ya¯zu¯ri¯; and the destruction of the city of Qayrawa¯n (1059). The article ends with a discussion of the great rebellion which took place in Safa¯qus in 1062/63.
The head of the Jews (ra'is al-yahud) in Fatimid Egypt: a re-evaluation
Authors: BAREKET ELINOAR
Published: July 2004

The debate concerning the Head of the Jews (ra'is al-yahud) in the Fatimid kingdom, which has interested researchers since the late nineteenth century, has yet to reach a final conclusion. Today's researchers usually argue that this position was established in Egypt at the end of the eleventh century with the final fall of the Palestinian Yeshiva; prior to this the Head of the Jews was the gaon of Palestine, appointed by the Fatimid Imam. More recently a new argument has emerged, re-embracing the approach of J. Mann, who argued that the position of the Head of the Jews was established at the beginning of Fatimid rule (late tenth century), and the person to hold the position was a Jewish courtier from the field of finance or medicine, appointed by the Imam to be the supreme leader for all Jews in the Fatimid kingdom: Rabbanites, Karaites and Samaritans. This old–new notion is yet to be clearly proven. Such views are mainly supported by circumstantial analysis of logical arguments that arise from the Geniza documents, without real written proof, but the Geniza is known for surprises and it is possible that we will soon find unequivocal proof to show that the Head of the Jews in the Fatimid kingdom was indeed a Jewish courtier appointed by the Imam, since the beginning of the Fatimid rule over Egypt, Palestine and Syria at the end of the tenth century.
Abraham Tal: A Dictionary of Samaritan Aramaic—a review article
Authors: FLORENTIN MOSHE
Published: July 2004

This article presents a detailed review of A Dictionary of Samaritan Aramaic (Leiden: Brill, 2000). Samaritan Aramaic (SA) is a Palestinian Aramaic dialect similar to Jewish Aramaic and Christian Aramaic, the two other dialects in use during the first millennium CE in Palestine. Based on the best critical editions of Samaritan texts (for each of them the author initially prepared a comprehensive concordance), it presents the entire vocabulary of SA literature as it is known at present; namely the Samaritan Targum, liturgical poems, midrashic literature and SA material attested in Samaritan texts written in Late Samaritan Hebrew. The article deals with lexicographical issues, such as the method of introducing entries and the scope of the dictionary (e.g. its being a sort of mini-encyclopedia). It focuses mainly on matters relating to SA, such as differences between ancient and late layers of the dialect, lexical loans (from Hebrew, Arabic, Greek and Latin) and influences of Jewish texts (e.g. Onkelos). The scope of the dictionary, its method and, above all, the way its author deals with the vast lexical problems of SA, make it one of the most important contributions to the research into this dialect. It is therefore unsurprising that DSA has already gained an important place on the bookshelves of scholars of other dialects of Aramaic, Hebrew and biblical studies.
Impacts of suspended sediment on the ecosystem in Lake Michigan: A comparison between the 1998 and 1999 plume events
Authors: Chen Changsheng , Wang Lixia , Ji Rubao , Budd Judith Wells , Schwab David J. , Beletsky Dmitry , Fahnenstiel Gary L. , Vanderploeg Henry , Eadie Brian , Cotner James
Published: July 2004

The impact of a reflective, recurrent coastal resuspension plume on the lower trophic food web system in Lake Michigan was examined using a 3‐D coupled physical and biological model. Numerical experiments were conducted for the March 1998 and 1999 plume events. The comparison between modeling results of these 2 years shows that the spatial distributions of the biological fields (i.e., phosphorus, phytoplankton, detritus, etc.) were closely coupled to the physical environment associated with wind‐induced three‐dimensional circulation and mixing. The influence of suspended sediment plumes on the lake ecosystem was reflected in heterotrophic (secondary) production rather than in the autotrophic (primary) production. Nutrients were maintained through nutrient release from suspended sediments within the plume, while it was supplied by current advection and diffusion in the interior. The cross‐shore flux of nutrients was driven by episodic wind events with a period of about 5–7 days. The flux was offshore during northerly winds and onshore during southerly winds. Comparisons between energy fluxes among biological variables suggest that the microbial loop (detritus‐heterotrophic bacteria and microzooplankton) played an important role in the ecosystem dynamics during plume events. Bacteria were good competitors with phytoplankton for inorganic phosphorus and were also a key supporter for growth of microzooplankton inside and outside the plume. As a result, the lower food web system could be divided into two decoupled loops: (1) detritus‐bacteria‐microzooplankton‐large zooplankton and (2) nutrient‐phytoplankton‐detritus.
A modeling study of benthic detritus flux's impacts on heterotrophic processes in Lake Michigan
Authors: Chen Changsheng , Wang Lixia , Qi Jianhua , Liu Hedong , Budd Judith Wells , Schwab David J. , Beletsky Dmitry , Vanderploeg Henry , Eadie Brian , Johengen Thomas , Cotner James , Lavrentyev Peter J.
Published: July 2004

Effects of sediment resuspension‐induced benthic detrital flux on the heterotrophic part of the microbial food web in Lake Michigan were examined using a three‐dimensional (3‐D) coupled biological and physical model. The model was driven by the realistic meteorological forcing observed in March 1999. Wind‐induced surface wave dynamics were incorporated into the physical model to generate the bottom flux. The model‐generated benthic detrital flux was assumed to be proportional to the difference between model‐calculated and critical stresses at the bottom. The model results indicate that detrital flux at the bottom was a key factor causing a significant increase of phosphorus and detritus concentrations in the nearshore region of the springtime plume. Inside the plume the sediment‐resuspended bottom detritus flux could directly enhance heterotrophic production, while outside the plume, detrital flux from river discharge might have a direct contribution to the high abundance of bacteria and microzooplankton in the nearshore region. Model‐data comparison on cross‐shore transects near Chicago, Gary, St. Joseph, and Racine suggests that other physical and biological processes may play a comparative role as the bottom detritus flux in terms of the spatial distribution of bacteria and microzoplankton. A more complete microbial food web model needs to be developed to simulate the heterotrophic process in southern Lake Michigan.
Analysis of wideband forward looking synthetic aperture radar for sensing land mines
Authors: Kovvali Narayan , Carin Lawrence
Published: July 2004

Signal processing algorithms are considered for the analysis of wideband, forward looking synthetic aperture radar data and for sensing metal and plastic land mines, with principal application to unpaved roads. Simple prescreening algorithms are considered for reduction of the search space required for a subsequent classifier. The classifier employs features based on viewing the target at multiple ranges, with classification implemented via a support vector machine and a relevance vector machine (RVM). Concerning classifier training, we consider cases for which training is performed on both mine and nonmine (clutter) data. In addition, motivated by the fact that the clutter statistics may vary significantly between the training and testing data, we also consider RVM implementation when we only train on mine data.
Testing the linearity of the response to combined greenhouse gas and sulfate aerosol forcing
Authors: Gillett N. P. , Wehner M. F. , Tett S. F. B. , Weaver A. J.
Published: July 2004

Detection and attribution studies of the temperature response to anthropogenic greenhouse gases and tropospheric sulfate aerosol have relied on the assumption that the responses to each of these forcings add linearly. Using surface temperature from three ensembles of integrations of the second Hadley Centre coupled model (HadCM2) forced with observed changes in greenhouse gases alone, the direct effect of sulfate aerosol alone, and combined changes in greenhouse gases and sulfate aerosol, we test this assumption. We examine the residual, defined as the response to the combined forcings, minus the sum of the responses to the individual forcings, and compare its distribution with that of control variability. Considering both global mean changes and changes at each grid point, we find no evidence that the responses to greenhouse gases and sulfate aerosol combine nonlinearly in HadCM2.
EPR Studies of Spin Correlation in Some Ion Radical Salts
Authors: Chesnut D. B. , Phillips W. D.
Published: July 2004

Electron spin resonance studies have been carried out on a number of ion-radical salts based on the strong π-acceptor tetracyanoquinodimethane (TCNQ). These studies have established that spin correlation exists between the magnetic electrons in these salts, giving rise to a ground singlet state and a thermally accessible triplet state. Typical singlet-triplet separations (J) derived from observed temperature dependences of EPR signal intensities are 0.034 ev for the [(C2H5)3NH]+(TCNQ)2− salt, 0.062 ev for the (φ3PCH3)+(TCNQ)2− and (φ3AsCH3)+(TCNQ)2− salts, and 0.41 ev for the (morpholinium)+(TCNQ)− salt.

The triplet states of the (φ3PCH3)+(TCNQ)2− and (φ3AsCH)+(TCNQ)2− salts are further manifested by an anisotropic splitting of the resonance into a doublet (zero-field splitting) and the appearance of half-field Δm=±2 transitions. Detailed analysis reveals that both salts may be represented by the spin Hamiltonian H=βH·g·S+DSz2+E(Sx2−Sy2),with | D/hc |=0.0062 cm−1, | E/hc |=0.00098 cm−1, and gx, gy, and gz equal to 2.0040, 2.0031, and 2.0027, respectively. Temperature-dependent exchange interactions observed for the (φ3PCH3)+(TCNQ)2− and (φ3AsCH3)+(TCNQ)2− salts cause the doublet zero-field components to broaden, move together, and collapse into a single, progressively sharper line as the temperature is increased. The exchange frequency follows an exponential temperature dependence and is governed by the concentration of triplet entities in the solid (J=0.062 ev).

The importance of paramagnetic impurities in studies of the magnetic properties of organic solids is emphasized. Examples are given which illustrate how a percent or so of doublet-state impurity species can dominate resonances near g=2.002 in molecular solids obeying singlet-triplet statistics.
Irreversible Thermodynamics of Systems Containing Radiation. Application to Photochemical Reactions
Authors: Mortimer Robert G. , Mazo Robert M.
Published: July 2004

The general theory of the irreversible thermodynamics of chemically reacting systems interacting with radiation is developed. From this, a limit to the efficiency of photochemical processes is derived, and this is compared with approximate experimental efficiencies of published researches. The computed efficiencies are appreciably lower than the theoretical limit; reasons for this are discussed.
Cohesive Energies of Europium, Gadolinium, Holmium, and Erbium
Authors: Trulson O. Conrad , Hudson Donald E. , Spedding Frank H.
Published: July 2004

A mass spectrometric method has been employed to study the solid-gas phase change in four rare-earth metals. The enthalpies of sublimation in kcal/M reducted to 298°K are: Eu, 43.11±0.25; Gd, 81.22±0.32; Ho, 75.04±0.44; and Er, 75.39±0.34. The corresponding cohesive energies in kcal/M as determined from presently available thermodynamic data are: Eu, 43.4; Gd, 81.9; Ho, 75.5; and Er, 75.7.

A summary of the cohesion in the rare-earth series is included. A qualitative explanation of the unexpected variations is given in terms of the energetics of the metallic and gaseous states.
Nature of the Metal-Ligand Bond in Some Complex Cyanides from a Study of Raman Intensities
Authors: Chantry George W. , Plane Robert A.
Published: July 2004

A study of the Raman spectra of solutions of Zn (CN)4=, Cd (CN)4=, Hg (CN)4=, Co (CN)6−3, Cu (CN)4−3, Ag (CN)4−3, and Fe (CN)6−4 shows that these complex ions fall into two distinct sets. For the first set, consisting of the first four species, the A1CN frequencies are 2143, 2145, 2148, and 2152 cm−1 and the ᾱCN′ lie intermediate between those determined for free CN− and CH3CN. For the latter three species, the corresponding frequencies are 2094, 2097, and 2094 cm−1. Furthermore, members of the latter set have abnormally large Raman intensities, i.e., large ᾱCN′, and an additional ultraviolet absorption band at 2600 A. For the first group, the assumption of partial sigma bonding of metal to C, consistent with the principle of essential electroneutrality, explains both the observed force constants and the values of ᾱCN′. The low intensity found for the ν2 mode is explained in terms of the effect on this quantity of the large amount of s character in the carbon sigma orbital. The second group cannot be simply treated and appears to present an example of the breakdown of bond localized polarizabilities.
Charge Distribution and Electric Field Gradients in Ionic Crystals
Authors: Belford Geneva G. , Bernheim Robert A. , Gutowsky H. S.
Published: July 2004

A method is presented by means of which one can investigate the validity of the point-charge model often used for the calculation of electric field gradients in ionic crystals. The asymmetry parameter of the electric field gradient at a nucleus and the Eulerian angles describing the orientation of the field gradient's principal axes with respect to the crystallographic axes are linear functions of the point charges assigned to each set of atoms in the lattice. If the unit cell is of low symmetry and if there are more than one set of nuclei for which quadrupole interaction data can be observed, the number of observables and equations may equal or exceed the number of unknown charges, thereby enabling the charge distribution to be determined and its internal consistency checked. Such is the case for spodumene, for which the charge distribution thus calculated is neither internally consistent nor very reasonable. An analysis is made of the sensitivity of the apparent charge distribution to experimental errors in the quadrupole interactions, and the errors are found to be much too small to account for the anomalies. However, further investigations, including a refinement of the crystallographic parameters of spodumene, are necessary before the anomalies could be attributed to deficiencies in the point-charge model. With allowance for the uncertainties in the charge distribution, the analysis lends some support to a value of ≈0.04 b for Q7, the nuclear quadrupole moment of Li7. Further charge distribution anomalies result from a similar, but less detailed treatment of another silicate, beryl, which gives a very approximate value of Q9≈0.1 b for Be9.
Rotational Isomerism in 2,3 Dihalopropenes
Authors: Whipple Earl B.
Published: July 2004

Previously reported variations in different solvents of the long-range (1,3) NMR coupling constants in 2,3 dihalopropenes have suggested the existence of rotational isomers in rapid equilibrium. This view is supported by infrared spectra. By assuming an angular dependence of the form J=J0 cos2φ between the observed coupling constants and the dihedral angle of the methylene C–H bonds as suggested in calculations by Karplus, the identities of the isomers are deduced, the equilibrium constants calculated, and the energy differences expressed as a function of solvent dielectric constant using an Onsager cavity model. The results for 2,3 dichloropropene are compared with published dipole moment measurements in solution and in the vapor at elevated temperatures.
Effect of an Attractive Potential on the Classical Theory of Vibrational Energy Exchange
Authors: Turner R. E. , Rapp Donald
Published: July 2004

The usual theory of vibrational energy transfer between molecules uses a purely repulsive exponential potential with an energy zero at the bottom of the van der Waals attractive potential well. One therefore uses a velocity distribution modified by a factor exp (ε/kT) to take the attractive forces into account. This method is an artifice to avoid dealing with the detailed dynamics of motion in the attractive potential well. In the present paper, the complete dynamical problem for a ``Morse''-type potential, consisting of an atrractive term in addition to the exponential repulsion, has been solved. A more rigorous correction for the attractive forces is therefore proposed.
Vibrational Spectra of Inorganic Molecules. II. Infrared Reflection Spectra of Liquid Lithium, Sodium, Potassium, and Silver Nitrates
Authors: Wilmshurst J. K. , Senderoff S.
Published: July 2004

The optical constants of liquid lithium, sodium, potassium, and silver nitrates have been obtained by a one-angle-reflection method using the analysis of Robinson and Price. The derived absorption spectra are consistent with the Raman spectra observed by Bues and suggest that in all melts, the point group symmetry of the cations about the nitrate ion does not contain D3h as a subgroup. Further, in both lithium and silver nitrate the highest symmetry subgroup common to the nitrate ion and the surrounding cations is at most C2v and in these melts the nitrate ion is not rotating freely about its threefold axis. In all the melts there is a low-frequency band which must be ascribed to a cation-anion vibration of a lattice-like type. The intensity of the a2″ band has been discussed and the bond dipole moment derived has been interpreted in terms of the polarizing field of the cations.
Nuclear Quadrupole Resonance in TiCl4, ThCl4, NbCl5, and TaCl5
Authors: Reddoch Allan H.
Published: July 2004

The chlorine resonance in titanium tetrachloride has been re-examined, confirming the existence of four resonances. A chlorine-35 resonance at about 6 Mc has been discovered in thorium tetrachloride. The frequency suggests highly ionic bonding, which contradicts earlier conclusions from x-ray studies. Some double-bond character may be present in the Th–Cl bond.

Niobium and chlorine resonances have been discovered in niobium pentachloride. The niobium resonances are described by a single set of parameters, the coupling constant eqQ being approximately 78 Mc, and the asymmetry parameter, η=0.32. Because of the large asymmetry parameter, it was possible to observe two ΔM=2 and one ΔM=3 transitions. Only a single Cl35 resonance was found at about 13 Mc, although two more chlorine resonances would be expected on the basis of crystal structure. The frequency of the chlorine resonance suggests appreciable covalency in the niobium-chlorine bond in niobium pentachloride.

A single resonance has been found in tantalum pentachloride at about 13 Mc. It is believed to be a chlorine-35 resonance. A fairly simple method is outlined for determining the asymmetry parameter of the electric-field gradient from the observed transition frequencies without directly solving the secular equations.
Motions of Molecules in Condensed Systems. X. The Infrared Spectrum and Structure of a Single Crystal of Cyclopropane
Authors: Brecher Charles , Krikorian Esther , Blanc Joseph , Halford Ralph S.
Published: July 2004

The absorption of polarized infrared radiation by thin sections of single crystals of cyclopropane, grown in a specially designed apparatus, has been recorded in the frequency range between 700 and 5000 cm−1, and compared with spectra, similarly recorded, of liquid and vapor. The assignment of molecular modes is completed: The ν5 fundamental, not previously measured, is located in the crystal at 1078 cm−1, while ν4 and ν13 appear at 1133 and 1194 cm−1, respectively, confirming previously uncertain assignments. The frequencies of the primary lattice modes of the molecule in the crystal are inferred from combinations. Site group and factor group splittings are seen to be of the same magnitude (≈10 cm−1). The cyclopropane crystal is found to be orthorhombic (C2v or D2h), with the molecules located at sites of Cs symmetry. An arrangement of the molecules, described by space group Pnm (C2v7), which gives the most efficient packing, is proposed as the actual crystal structure.