bluuebunny/crossref_metadata_2025 huggingface dataset:
Halothane Inhibits an Intermediate Conductance Ca2+-activated K+Channel by Acting at the Extracellular Side of the Ionic Pore
Authors: Hashiguchi-Ikeda Mitsuko , Namba Tsunehisa , Ishii Takahiro M. , Hisano Taizo , Fukuda Kazuhiko
Published: November 2003

Background

Actions of volatile anesthetics on ligand-gated ion channels, such as gamma-aminobutyric acid type A receptors, have been studied extensively. However, actions on other types of channels, such as K+ channels, are poorly understood. The authors previously showed that a Ca2+-activated K+ channel, IK, is sensitive to halothane, whereas SK1, another Ca2+-activated K+ channel, is insensitive. To explore how halothane acts on Ca2+-activated K+ channels, chimeras between IK and SK1 were constructed, and halothane sensitivity was analyzed.

Methods

IK, SK1, and chimera channels were expressed in Xenopus laevis oocytes. Currents of expressed channels were measured in the presence of 10 microm Ca2+ by excised patch clamp analysis. Time constants of inhibition by halothane were compared between inside-out and outside-out patch configurations.

Results

Currents from chimera channels possessing the pore domain derived from IK were inhibited by halothane, whereas those possessing the SK1 pore domain were insensitive. Time constants of inhibition by halothane were significantly smaller in the outside-out patches than in the inside-out patches of both wild-type IK and a chimera with pore domain of IK.

Conclusions

It is suggested that halothane interacts with the extracellular part of the ionic pore of IK. Whether this type of interaction is involved in the mechanism of anesthetic actions on ligand-gated ion channels warrants further investigation.
Relative Analgesic Potencies of Levobupivacaine and Ropivacaine for Epidural Analgesia in Labor
Authors: Polley Linda S. , Columb Malachy O. , Naughton Norah N. , Wagner Deborah S. , van de Ven Cosmas J. M. , Goralski Kathryn H.
Published: November 2003

Background

The minimum local analgesic concentration has been defined as the median effective local analgesic concentration (EC50) in a 20-ml volume for epidural analgesia in the first stage of labor. The aim of this study was to assess the relative analgesic potencies of epidural levobupivacaine and ropivacaine by determination of their respective minimum local analgesic concentrations.

Methods

Parturients at 7 cm of cervical dilation or less who requested epidural analgesia were allocated to one of two groups in this double-blind, randomized, prospective study. After lumbar epidural catheter placement, 20 ml of the test solution was given: levobupivacaine (n = 35) or ropivacaine (n = 35). The concentration of local anesthetic was determined by the response of the previous patient in that group to a higher or lower concentration using up-down sequential allocation. Analgesic efficacy was assessed using 100-mm visual analog pain scale scores, with 10 mm or less within 30 min defined as effective. An effective result directed a 0.01% wt/vol decrement for the next patient. An ineffective result directed a 0.01% wt/vol increment.

Results

Of 105 women enrolled, 35 were excluded, leaving 70 for analysis. The minimum local analgesic concentration of levobupivacaine was 0.087% wt/vol (95% CI, 0.081-0.094%), and the minimum local analgesic concentration of ropivacaine was 0.089% wt/vol (95% CI, 0.075-0.103%). Levobupivacaine and ropivacaine were of similar potency with a ropivacaine:levobupivacaine potency ratio of 0.98 (95% CI, 0.80-1.20). No difference in motor effects was observed.

Conclusions

This study demonstrated that levobupivacaine and ropivacaine are of similar potency for epidural analgesia in the first stage of labor.
Influence of Age and Sex on the Position of the Conus Medullaris and Tuffier's Line in Adults
Authors: Kim Jin-Tae , Bahk Jae-Hyon , Sung Joohon
Published: November 2003

Background

The purpose of this study was to analyze the position of the conus medullaris and Tuffier's line in the same patient population, to correlate this position with age and sex, and to determine an objective guide for the selection of a safe intervertebral space during spinal block.

Methods

Magnetic resonance imaging studies of the lumbar spine were reviewed in 690 consecutive patients. The study population consisted of patients older than 20 yr who had been referred for imaging to assess possible causes of low back pain. The position of the conus medullaris was defined as the most distal point of the cord that could be visualized on the sagittal sequence. A line perpendicular to the long axis of the cord was extended to the adjacent vertebra. In the lumbar plain films, the Tuffier's line was defined by drawing a horizontal line across the highest points of the iliac crests. Each vertebral body and intervertebral space was divided into four segments: upper, middle, and lower thirds of a vertebral body, and the intervertebral space. Each segment of a vertebral body or intervertebral space that the lines crossed was identified and recorded. The positions, stratified by decade of age, were compared using analysis of variance. The Tukey test was used for post hoc comparisons. Comparisons between sex were performed with the unpaired t test.

Results

The conus medullaris and Tuffier's line (median [range]) were positioned at L1-lower (T12-upper-L3-upper) and L4L5 (L3L4-L5S1), respectively. The distance between the conus medullaris and Tuffier's line (mean +/- SD [range]) was 12.6 +/- 1.9 [7-18] segments, which corresponded to the height of approximately three vertebral bodies and intervertebral spaces. In no case did Tuffier's line overlap with the conus medullaris. The distance in segments between the conus medullaris and Tuffier's line was shorter with increased age (P < 0.001). The position of the conus medullaris and Tuffier's line was lower in female patients than in male patients (P < 0.001) and higher in patients with sacralization than in those with lumbarization or without transitional vertebra (P < 0.001). The in-between distances were not significantly different regardless of sex or presence of transitional vertebra.

Conclusions

During spinal block, there seems to be a safety margin of 2-4 vertebral bodies and intervertebral spaces between the conus medullaris and Tuffier's line, which is consistent regardless of sex or presence of transitional vertebra. However, because the conus medullaris and Tuffier's line become closer with age and the clinical use of Tuffier's line requires palpation through subcutaneous fat, caution must be exercised regarding selection of the intervertebral space, especially in the aged and obese population.
Plastic Change of N-type Ca Channel Expression after Preconditioning Is Responsible for Prostaglandin E2-induced Long-lasting Allodynia
Authors: Yokoyama Kazuaki , Kurihara Takashi , Makita Koshi , Tanabe Tsutomu
Published: November 2003

Background

Although considerable evidence indicates neuronal Ca channels play significant roles in pain perception, their possible importance in hypersensitization after acute inflammation has not been investigated.

Methods

Using carrageenan for inducing hypersensitization, the authors investigated the analgesic effects of intrathecally administered N- and P/Q-type channel blockers, omega-conotoxin GVIA and omega-agatoxin IVA, respectively, and also examined the level of N-type channel expression.

Results

Acute inflammation, produced by carrageenan injection in a rat hind paw, caused mechanical hypersensitivity that resolved within several days. Injection of prostaglandin E2 into the same hind paw after resolution caused a markedly prolonged mechanical allodynia lasting more than 4 h. Similar but less potent prolonged allodynia was also induced in the contralateral hind paws. Intrathecal administration of omega-conotoxin GVIA (0.03-0.3 microg) produced dose-dependent inhibition of the allodynia in both control and carrageenan-preconditioned rats. However, the potency of omega-conotoxin GVIA was significantly lower in carrageenan-preconditioned paws than in those in the contralateral and saline-preconditioned paws. In contrast, omega-agatoxin IVA (0.01-0.1 microg) did not reduce the allodynia. Significant up-regulation of N-type channel expression was observed in both dorsal root ganglia and the spinal cord ipsilateral to the carrageenan-preconditioned hind paw.

Conclusions

The results suggest an aggravating role of the N-type channel in pain sensation and a selective plastic change of this channel expression that could underlie the mechanism of hypersensitization after acute inflammation.
Tumescent Local Anesthesia for the Surgical Treatment of Burns and Postburn Sequelae in Pediatric Patients
Authors: Bussolin Leonardo , Busoni Paolo , Giorgi Letizia , Crescioli Massimo , Messeri Andrea
Published: November 2003

Background

Tumescent local anesthesia is a technique for regional anesthesia of the skin and the subcutaneous tissue, using infiltration of large volumes of local anesthetic. The advantages of this technique are (1) simplicity, (2) prolonged postoperative analgesia, (3) low incidence of bleeding, and (4) anesthetization of a large area of the body. There are no reports on the use of tumescent local anesthesia in pediatric patients.

Methods

In 30 consecutive pediatric burn patients with American Society of Anesthesiologists physical status class I or II who were 1-120 months old (34 +/- 31.6 months), after induction of anesthesia with nitrous oxide-oxygen-sevoflurane, infiltration with 0.05% (14 ml/kg) or 0.1% (7 ml/kg) lidocaine solution was performed. Anesthesia was maintained with patients spontaneously breathing with 1.5% sevoflurane in nitrous oxide-oxygen (50%). The maximum dose of lidocaine used was 7 mg/kg. Postoperative pain was assessed by using the Children's Hospital of Eastern Ontario Pain Scale (for patients aged up to 5 yr) and by using a visual analog scale (for patients older than 5 yr). A comparison with a historic control group not treated with the tumescent local anesthesia technique was performed.

Results

No patients were excluded from the study, and no significant variations in the monitored intraoperative parameters were observed. Five patients had an increase in heart rate and respiratory rate at the beginning of surgery, and of these, two needed a temporary increase in sevoflurane concentration. After the initial incision, no response to painful stimulus was observed. No complications occurred. Six patients required postoperative acetaminophen administration, and 24 patients did not require analgesic treatment.

Conclusions

Tumescent local anesthesia with maximum dose of 7 mg/kg lidocaine seems to be safe and the sole possible effective locoregional anesthesia technique for the surgical treatment of noncontiguous pediatric burns.
Dural Tissue Trauma and Cerebrospinal Fluid Leak after Epidural Needle Puncture
Authors: Angle Pamela J. , Kronberg Jean E. , Thompson Dorothy E. , Ackerley Cameron , Szalai John Paul , Duffin James , Faure Peter
Published: November 2003

Background

The effects of epidural needle design, angle, and bevel orientation on cerebrospinal fluid leak after puncture have not been reported. The impact of these factors on leak rate was examined using a dural sac model. Dural trauma was examined using scanning electron microscopy.

Methods

Human cadaveric dura, mounted on a cylindrical model, was punctured with epidural needles using a micromanipulator. Tissue was punctured at 15 cm H2O (left lateral decubitus) system pressure, and leak was measured at 25 cm H2O (semisitting) pressure. Leak rates and trauma were compared for the following: (1) six different epidural needles at 90 degrees, bevel parallel to the dural long axis; (2) 18-gauge Tuohy and 18-gauge Special Sprotte epidural needles, 30 degrees versus 90 degrees; (3) 18-gauge Tuohy, bevel perpendicular versus parallel to the dural long axis.

Results

With the 90 degrees puncture, bevel parallel, the greatest leak occurred with a 17-gauge Hustead (516 +/- 319 ml/15 min), and the smallest leak occurred with a 20-gauge Tuohy (100 +/- 112 ml/15 min; P = 0.0018). A 20-gauge Tuohy puncture led to statistically significant reductions in leak (P value range, 0.0001-0.0024) compared with all needles except the Special Sprotte. With the 30 degrees versus 90 degrees angle, 30 degrees punctures with an 18-gauge Tuohy produced nonstatistically significant leak reductions compared with the 18-gauge Tuohy at 90 degrees. The puncture angle made no difference for the Special Sprotte. Nonsignificant reductions were found for the Special Sprotte compared with the Tuohy. With the 18-gauge Tuohy bevel orientation, perpendicular orientation produced nonstatistically significant reductions in leak compared with parallel orientation.

Conclusions

Cerebrospinal fluid leak after puncture was influenced most by epidural needle gauge. Leak rate was significantly less for the 20-gauge Tuohy needle.
A Randomized Sequential Allocation Study to Determine the Minimum Effective Analgesic Concentration of Levobupivacaine and Ropivacaine in Patients Receiving Epidural Analgesia for Labor
Authors: Benhamou Dan , Ghosh Caroline , Mercier Frédéric J.
Published: November 2003

Background

This study was designed to determine and compare the minimum local analgesic concentrations of levobupivacaine and ropivacaine when used in epidural obstetric analgesia.

Methods

In a double-blind study, healthy women requiring epidural analgesia for labor pain were randomized to receive either ropivacaine or levobupivacaine. Drugs were administered as a 20-ml epidural bolus. The concentration of each started at 0.11% and increased or decreased at intervals of 0.01%, depending on the response of the previous patient, using the technique of up-down sequential allocation. Minimum local analgesic concentrations were calculated using the formula of Dixon and Massey. Efficacy was assessed using visual analog pain scores and motor and sensory block assessments, and safety was assessed by recording maternal and fetal/neonate vital signs and adverse events.

Results

Forty-seven patients received levobupivacaine, and 47 received ropivacaine. Minimum local analgesic concentrations for levobupivacaine (0.077%; 95% CI, 0.058-0.096%) were lower than those for ropivacaine (0.092%; 95% CI, 0.082-0.102%). The 0.015% difference was not statistically significant. There was no notable difference between treatment groups in the proportion of patients reporting drug-related adverse events.

Conclusions

Levobupivacaine was 19% more potent than ropivacaine and provided similar safety results.
Cervical and High Thoracic Ligamentum Flavum Frequently Fails to Fuse in the Midline
Authors: Lirk Philipp , Kolbitsch Christian , Putz Guenther , Colvin Joshua , Colvin Hans Peter , Lorenz Ingo , Keller Christian , Kirchmair Lukas , Rieder Josef , Moriggl Bernhard
Published: November 2003

Background

Cervical and high thoracic epidural anesthesia and analgesia have gained increasing importance in the treatment of painful conditions and as components of anesthetics for cardiac and breast surgery. In contrast to the hanging-drop technique, the loss-of-resistance technique is thought to rely on the penetration of the ligamentum flavum. However, the exact morphology of the ligamentum flavum at different vertebral levels remains controversial. Therefore, the aim of this study was to investigate the incidence and morphology of cervical and high thoracic ligamentum flavum mid-line gaps in embalmed cadavers.

Methods

Vertebral column specimens were obtained from 52 human cadavers. On each dissected level, ligamentum flavum mid-line gaps were recorded and evaluated with respect to shape and size.

Results

The following variations were encountered: complete fusion in the mid-line, mid-line fusion with a gap in the caudal part, mid-line gap, and mid-line gap with widened caudal end. The incidence of mid-line gaps at the following levels was: C3-C4: 66%, C4-C5: 58%, C5-C6: 74%, C6-C7: 64%, C7-T1: 51%, Th1-Th2: 21%, Th2-Th3: 11%, Th3-Th4: 4%, Th4-Th5: 2%, and Th5-Th6: 2%. The mean width of mid-line gaps was 1.0 +/- 0.3 mm.

Conclusions

In conclusion, the present study shows that gaps in the ligamenta flava are frequent at cervical and high thoracic levels but become rare at the T3/T4 level and below, such that one cannot always rely on the ligamentum flavum as a perceptible barrier to epidural needle placement at these levels.
Spin-echo small-angle neutron scattering in neutron reflectometry
Authors: Rekveldt M. Theo
Published: November 2003

A new method to perform neutron reflectometry measurements is discussed. The method is based on Larmor precession of polarized neutrons in the spin-echo mode. Two different modes of application are discussed, giving successively information about the structure perpendicular to and parallel to the sample plane. After describing the method, simulated results of the perpendicular mode are compared with those obtained by conventional neutron reflectometry methods. In this comparison, first the results obtained by the SESANS method are translated to those obtained by conventional methods. After that, more specific applications of the new method are considered. In the comparison, attention is focused on measuring statistics and resolution as readily comparable quantities.
The resolution function in neutron spin-echo spectroscopy with three-axis spectrometers
Authors: Habicht Klaus , Keller Thomas , Golub Robert
Published: November 2003

A resolution function for inelastic neutron spin-echo spectroscopy on a three-axis spectrometer is derived. Inelastic dispersive excitations where the tilted field technique applies are being considered. Using a Gaussian approximation of the transmission function of the three-axis spectrometer and a second-order expansion of the total Larmor phase, the instrumental resolution function of an idealized spin-echo instrument is obtained. Furthermore, the resolution function is extended to include the effects of sample properties, such as mosaicity, spread in lattice spacings and the curvature of the four-dimensional dispersion surface in a line-width measurement.
A method of precise misorientation determination
Authors: Morawiec A.
Published: November 2003

A method that improves the accuracy of misorientations determined from Kikuchi patterns is described. It is based on the fact that some parameters of a misorientation calculated from two orientations are more accurate than other parameters. A procedure which eliminates inaccurate elements is devised. It requires at least two foil inclinations. The quality of the approach relies on the possibility to set large sample-to-detector distances and the availability of good spatial resolution of transmission electron microscopy. Achievable accuracy is one order of magnitude better than the accuracy of the standard procedure.
Energetic materials: variable-temperature crystal structures of two biguanidinium dinitramides
Authors: Bolotina Nadezhda B. , Hardie Michaele J. , Pinkerton A. Alan
Published: November 2003

The crystal structures of the energetic materials biguanidinium mono-dinitramide C2H8N{}_{5}^{\,+}.N3O{}_{4}^{\,-}, (BIGH)(DN), and biguanidinium bis-dinitramide C2H9N{}_{5}^{\,2+}.2N3O{}_{4}^{\,-}, (BIGH2)(DN)2, have been determined at several temperatures in the range 85–298 K using single-crystal X-ray diffraction techniques. The thermal expansion second-rank tensors have been determined to describe the thermal behavior of the crystals studied. Strongly anisotropic thermal expansion is most important in the direction perpendicular to the least-squares planes of the dinitramide ions in both cases, suggesting that the atomic thermal motion is significantly anharmonic in these crystals. Anharmonicity of thermal motion is also evident from the non-linear temperature dependence of the atomic displacement parameters. Rigid-body analysis of thermal motion both of dinitramide anions and of biguanidinium cations was performed using the libration and translation second-rank tensors. For both compounds, the libration thermal motion is strongly anisotropic with the dominating libration axes oriented in a similar manner in both anions and cations. Although the translation motion of the ions is not strongly anisotropic, the axes of largest thermal displacements are close to the directions of greatest thermal expansion of the crystals.
Piezoelectric coefficients ofL-arginine hydrochloride monohydrate obtained by X-ray multiple diffraction using synchrotron radiation
Authors: Almeida J. M. A. , Miranda M. A. R. , Remédios C. M. R. , Melo F. E. A. , Freire P. T. C. , Sasaki J. M. , Cardoso L. P. , dos Santos A. O. , Kycia S.
Published: November 2003

In this paper, a very useful development to improve the application of a method based on the multiple-diffraction technique to determine the piezoelectric coefficients of crystals is described. The idea is to choose any specific crystallographic direction (plane) through the secondary peaks in the Renninger scan instead of those directions related to the electric field by the piezoelectric tensor. For a set of multiple-diffraction planes, it is possible to obtain an equation system based on the ordinary peak position for eachHsecondary plane that appears in the Renninger scan. This useful development was successfully applied to the amino acid L-arginine hydrochloride monohydrate in order to provide thed21,d22,d23andd25piezoelectric coefficients by applying the electric field along the [010] crystallographic direction.
Direct inversion of interfacial reflectivity data using the Patterson function
Authors: Bataillou Benoît , Moriceau Hubert , Rieutord François
Published: November 2003

It is shown here that the interfacial profile between two bonded wafers can be directly determined using X-ray reflectivity without resorting to standard model-fitting of the data. The phase problem inherent to any structure determination by scattering technique is solved in this case using a known silicon/silicon oxide interface, which acts as a phase reference for the reflected signals.
The SAS structure functions of a `dead leaves' tessellation cell
Authors: Gille Wilfried
Published: November 2003

This paper deals with the real-space small-angle scattering (SAS) structure functions and with the isotropic scattering intensity of the isolated single cells of the tessellation of a `dead leaves' model (DLM). The DLM is produced by spherical primary grains of constant diameterd. The cells possess a random shape like the pieces of a puzzle. The maximum diameter of the different pieces isd.
Structural analysis of weakly ordered membrane stacks
Authors: Pabst Georg , Koschuch Richard , Pozo-Navas Beatriz , Rappolt Michael , Lohner Karl , Laggner Peter
Published: November 2003

The applicability of full-q-range models to fit low-resolution X-ray diffraction data from multibilayers exhibiting only weak quasi-Bragg peak scattering has been analysed. The models consider different structure factors, accounting for different types of lattice disorder caused by stacking faults or bending fluctuations. Numerical tests of the models, considering instrumental influence of a line-focus collimation system, demonstrated that Bragg peak line shapes given by different lattice disorders cannot be discerned. However, line-shape parameters can be determined for a particular sample, if the type of disorder is knowna priori. This has been verified by comparing the experimental results for the fluctuation parameter of palmitoyl-oleoyl phosphatidylcholine (POPC) as a function of temperature with high-resolution data on the same lipid. Tests further show that the calculation of structural parameters, such as the membrane thickness or the extent of the interbilayer water region, is not obscured by the smearing imposed by the instrument. The model was further applied successfully to experimental data of lipid mixtures composed of sphingomyelin (SM)/POPC/cholesterol and dipalmitoyl phosphatidylethanolamine (DPPE)/dipalmitoyl phosphatidylglycerol (DPPG). The structural parameters determined give valuable insight into the physical state of the membrane system, which is not accessible when quasi-Bragg reflections only are considered.
Rapid-acquisition pair distribution function (RA-PDF) analysis
Authors: Chupas Peter J. , Qiu Xiangyun , Hanson Jonathan C. , Lee Peter L. , Grey Clare P. , Billinge Simon J. L.
Published: November 2003

An image-plate (IP) detector coupled with high-energy synchrotron radiation was used for atomic pair distribution function (PDF) analysis, with high probed momentum transferQmax≤ 28.5 Å−1, from crystalline materials. Materials with different structural complexities were measured to test the validity of the quantitative data analysis. Experimental results are presented for crystalline Ni, crystalline α-AlF3, and the layered Aurivillius type oxides α-Bi4V2O11and γ-Bi4V1.7Ti0.3O10.85. Overall, the diffraction patterns show good counting statistics, with measuring time from one to tens of seconds. The PDFs obtained are of high quality. Structures may be refined from these PDFs, and the structural models are consistent with the published literature. Data sets from similar samples are highly reproducible.
A standard local coordinate system for multipole refinements of the estrogen core structure
Authors: Kirschbaum Kristin , Poomani Kumaradhas , Parrish Damon A. , Pinkerton A. Alan , Zhurova Elizabeth
Published: November 2003

A comparative charge density study on a series of estrogen derivatives has been initiated. The study utilizes the Hansen–Coppens atom-centred multipole model to describe the valence electron density distribution. Direct comparison of the population parameters for each estrogen after the respective multipole refinements requires standardization of the atom-centred local coordinate systems. Such a standard coordinate system for the common estrogen core is reported, taking advantage of the shape of those multipoles which have the spatial characteristics ofsp2andsp3hybrid orbitals. Additionally, populating these principal multipoles at the beginning stage of the refinements improves the stability of these large highly correlated calculations.
Investigation of nanocrystalline CdS–glutathione particles by radial distribution function
Authors: Korsounski V. I. , Neder R. B. , Hradil K. , Barglik-Chory Ch. , Müller G. , Neuefeind J.
Published: November 2003

Using high-energy synchrotron radiation, powder diffraction experiments were carried out on CdS nanocrystals stabilized with glutathione. The radial distribution function was calculated from the data and analysed. The nanoparticle core, of diameter estimated as 15–20 Å, consists of Cd and S atoms in the proportion 1:1. Inside the core, both Cd and S atoms coordinate each other approximately tetrahedrally. The surface S atoms are connected to just two or three Cd atoms of the core and belong to the glutathione molecules of the particle shell. These S atoms are also a part of the core structure and contribute about one half of the total number of S atoms per particle. First-neighbour Cd—S distances are 2.523 Å with a narrow distance distribution. No difference is observed between the lengths of Cd—S bonds involving the sulfur of the glutathione molecules and the sulfur atoms which are solely bound to Cd. The bond angle Cd—S—Cd at the surface bridging S atoms of glutathione isca99.5°,i.e.significantly smaller than an average one of 109.5° characteristic of the Cd and S atom packing inside the core. Beyond the range of the near interatomic distances, the influence of the surface and the defects cause a significant distinction of the particle core structure from those of zincblende and wurtzite, characteristic of bulk CdS.
Microfabricated mounts for high-throughput macromolecular cryocrystallography
Authors: Thorne R. E. , Stum Z. , Kmetko J. , O'Neill K. , Gillilan R.
Published: November 2003

A new approach is described for mounting microcrystals of biological macromolecules for cryocrystallography. The sample mounts are prepared by patterning thin polyimide films by standard microfabrication techniques. The patterned structures contain a small hole for the crystal connected to a larger holeviaa drainage channel, allowing removal of excess liquid and easier manipulation in viscous solutions. These polyimide structures are wrapped around small metal rods. The resulting curvature increases their rigidity and allows a convenient scoop-like action in retrieving crystals. The polyimide contributes minimally to X-ray background and absorption, and can be treated to obtain desired hydrophobicity or hydrophilicity. The new mounts are fully compatible with existing automated sample-handling hardware for cryocrystallography. Their potential advantages include completely reproducible sample hole sizes to below 10 µm; accurate and reproducible sample positioning and good sample-to-mount contrast, simplifying alignment; more convenient manipulation of small crystals; easier removal of excess liquid and reduced background scatter; reduced thermal mass and more rapid flash-cooling; and easy design customization and mass production. They are especially well suited to data collection from the smaller crystals produced in high-throughput crystallization trials, and are suitable for automated crystal retrieval. They should be more generally useful for X-ray data collection from small organic and inorganic crystals of all types.
Evaluation ofSnBfor the location of anomalous scattering atoms in SAD/MAD phasing
Authors: Wang Jun , Ealick Steven E.
Published: November 2003

Sixteen existing single-wavelength/multi-wavelength anomalous diffraction (SAD/MAD) data sets with a broad range of crystallographic properties have been used to investigate the various parameters inSnBwith the goal of finding the optimum values for locating the positions of anomalous scatterers. The results of the analysis indicate some changes in default parameters that may be useful for non-routine and difficult cases.
UMWEG: a program for the calculation and graphical representation of multiple-diffraction patterns
Authors: Rossmanith Elisabeth
Published: November 2003

UMWEG, an update of the programUMWEG-98[E. Rossmanith,J. Appl. Cryst.(1999).32, 355–361], makes possible the calculation and graphical representation of multiple-diffraction patterns (Renninger scans, multiple-diffraction peak location plots) and can be applied to X-rays as well as to neutrons. The program is written in Lahey Fortran 95. The program runs without further commercial subroutine libraries. It is distributed for Windows 2000viahttp://www.rrz.uni-hamburg.de/mpi/rossmanith. Executable (binary) files are available free of charge for academic use only.
Nano-volume plates with excellent optical properties for fast, inexpensive crystallization screening of membrane proteins
Authors: Cherezov Vadim , Caffrey Martin
Published: November 2003

A simple convenient and low-cost glass-based plate for high-throughput screening of membrane protein crystallization is described. The plates are robust and reduce dramatically the amount of protein and precipitant solution used per crystallization trial, while offering excellent optical properties for the detection of micro-crystals and crystals of colorless proteins. The plates were developed primarily for crystallization of membrane proteins in lipidic mesophases. They can also be used in batch crystallization of soluble and membrane proteins.
Ultra-low-temperature X-ray data collection with a newly developed 0.1 mm Kapton-film cylinder for a closed-cycle helium cryostat
Authors: Meserschmidt Marc , Meyer Mathias , Luger Peter
Published: November 2003

A 0.1 mm Kapton-film vacuum chamber was constructed to be mounted on the cold head of a closed-cycle helium cryostat. The use of Kapton instead of beryllium results in a low and practically non-structured background, which is thus tolerable on the area-detection frames of modern CCD detectors. The Kapton chamber is only fixed at the upper and lower holders of the cryostat and its counterweight, and is stabilized by spanning with fine pitch threads, holding constant the necessary vacuum of 10−6 mbar for at least several days. Low costs and non-toxicity are further advantages of this material; moreover, the sample remains visible even after cooling. Data collections on strychnine single crystals at 15 K showed improvedI/σ ratios of high-order reflections compared with 100 K data, most favourably when synchrotron primary radiation was used.
Structural transitions of hard-sphere colloids studied by spin-echo small-angle neutron scattering
Authors: Krouglov Timofei , Bouwman Wim G. , Plomp Jeroen , Rekveldt M. Theo , Vroege Gert Jan , Petukhov Andrei V. , Thies-Weesie Dominique M. E.
Published: November 2003

The structure of hard-sphere colloidal suspensions is measured at different concentrations using the recently developed spin-echo small-angle neutron scattering (SESANS) technique. It is shown that SESANS measures real-space correlations ranging from the size of a single particle for a dilute suspension to several particle diameters for a concentrated suspension, glass and crystalline state.
The `seed-skewness' integration method generalized for three-dimensional Bragg peaks
Authors: Peters J.
Published: November 2003

The integration of the three-dimensional profile of each node of the reciprocal lattice without ana priorimodelling of the shape of the reflections is a prerequisite in order to improve the capability of area detectors in diffraction studies. Bolotovskyet al.[J. Appl. Cryst.(1995),28, 86–95] published a new method of area-detector peak integration based on a statistical analysis of pixel intensities and suggested its generalization for processing of high-resolution three-dimensional electronic detector data. This has been done in the present work, respecting the special requirements of data collected from neutron diffraction. The results are compared with other integration methods. It is shown that the seed-skewness method is successful in giving very reliable results and simultaneously optimizes the standard deviations. The integration procedures are applied to real data, which are refined and compared with benchmark results.
Diffuse neutron scattering in benzil, C14D10O2, using the time-of-flight Laue technique
Authors: Welberry T. R. , Goossens D. J. , David W. I. F. , Gutmann M. J. , Bull M. J. , Heerdegen A. P.
Published: November 2003

Diffuse neutron scattering data have been recorded for the molecular crystald-benzil, C14D10O2, using the time-of-flight Laue technique on the SXD and PRISMA instruments at ISIS. Using SXD it was possible to access a large fraction of the total three-dimensional reciprocal space out to aQvalue of 15 Å−1, using only four individual exposures and by making use of the \bar{3}m Laue symmetry of the crystal. By segregating the scattered data according to the incident neutron energy used, patterns were obtained from those neutrons in the range of ∼20 meV to 150 meV, which showed little sign of inelastic effects and so could be compared with previously analysed X-ray data. For neutron energies of <20 meV, interesting inelastic effects were observed, which have been used to obtain an estimate for the energy of phonons associated with a vibrational mode in which an intramolecular mode couples to a low-energy shearing motion of the hydrogen-bonded network linking neighbouring molecules. The estimated value of 8.95 cm−1(1.11 meV) for this mode is less than the lowest energy mode reported from spectroscopic measurements for hydrogenous benzil (∼16 cm−1). A model previously derived from analysis of X-ray data observed over a limited range ofQhas been used to calculate neutron patterns over the fullQrange. Comparison with the present neutron data has shown that while the model gives a good description of the form of the diffuse patterns, the magnitudes of the atomic displacements are underestimated by a factor of ∼2.25.
Challenging behaviour: the perceptions of teachers of children and young people with severe learning disabilities
Authors: Male Dawn
Published: November 2003

This paper reports the findings of a study which aimed to elicit teachers’ perceptions of pupils’ challenging behaviour. Teachers were asked to indicate: which aspects of challenging behaviour concerned them; their responses to it; which strategies they found effective; what they believed to be the causes of it; how stressed they felt; and how effective they felt when dealing with it. They were also asked to identify sources of information, advice and help and to rate different types of challenging behaviour in terms of severity of challenge. Results indicate that teachers are concerned about challenging behaviour and find it stressful. Whilst considering themselves to be effective in dealing with it, a proportion report feeling frustrated by it, angry, upset and/or at a loss. The most frequently cited challenging behaviour was aggression, although self‐injury was found to be the most challenging. Whilst recognising the communicative basis of many forms of challenging behaviour teachers nevertheless tended to select strategies which were concerned with diffusion rather than prevention. The most likely source of information, advice and help was other teachers. Some differences in responses were noted according to experience and whether or not additional qualifications were held.
Head-to-head Z Dimerization of Terminal Alkynes Catalyzed by Thiolate-bridged Diruthenium Complexes
Authors: Qü Jing-Ping , Masui Dai , Ishii Youichi , Hidai Masanobu
Published: November 2003

The thiolate-bridged diruthenium complexes [Cp*RuCl(μ-SR)2RuCp*Cl] (R = Me, Et, nPr) were found to be effective and highly selective catalysts for the head-to-head Z dimerization of various terminal alkynes including straight-chain aliphatic alkynes and those with functional groups.
A Novel Discrete d-f Heterobinuclear Complex Designed from Tetrahedrally Distorted [Cu(salabza)](H2salabza: N,N′-Bis(salicylidene)-2-aminobenzylamine) and [Gd(hfac)3]
Authors: Sasaki Miwa , Horiuchi Hiroaki , Kumagai Motoko , Sakamoto Masatomi , Sakiyama Hiroshi , Nishida Yuzo , Sadaoka Yoshihiko , Ohba Masaaki , Okawa Hisashi
Published: November 2003

Binuclear Cu(II)-Gd(III) complex, [Cu(salabza)Gd(hfac)3], was synthesized by the combination of a tetrahedrally distorted Cu(II) complex, [Cu(salabza)] with [Gd(hfac)3]·2H2O, where H2salabza and Hhfac denote N,N′-bis(salicylidene)-2-aminobenzylamine and 1,1,1,5,5,5-hexafluoroacetylacetone, respectively. Structural analysis revealed that the complex has the long intermolecular metal-metal distances enough to be regarded as a discrete one.
Supramolecular Inclusion Complexes of Fullerenes Using Cyclotriveratrylene Derivatives with Aromatic Pendants
Authors: Matsubara Hiroshi , Hasegawa Akio , Shiwaku Kaoru , Asano Kaori , Uno Mitsunari , Takahashi Shigetoshi , Yamamoto Koji
Published: November 2003

CTV derivatives with aromatic pendants were synthesized and their inclusion abilities for C60 and C70 were examined by UV spectroscopy. CTV derivative with three N-methylpyrrole pendants showed the highest association constant for C60 (48000 dm3mol−1 in benzene). The structure of inclusion complex for C60 with CTV derivative which has six benzoyl pendants has been determined by single-crystal X-ray diffraction.
Stereoselective Electron-Transfer Reaction between Metmyoglobin and Chiral Viologen-Radical Cation through Pre-Complexation
Authors: Tsukahara Keiichi , Goda Mariko
Published: November 2003

Metmyoglobin was reduced by chiral viologen-radical cations containing ((1-phenyl- or ((1-cyclohexylethyl)carbamoyl)-methyl group through pre-complexation followed by intracomplex electron transfer; (S,S)-isomers of chiral viologens showed slightly higher association constants as well as larger intracomplex electron-transfer rates.
Palladium-Catalyzed Arylation of 2,6-Di-tert-butylphenol with Aryl Bromides to Produce 1,1′-Biphenyl-4-ol Derivatives
Authors: Kawamura Yoshiki , Satoh Tetsuya , Miura Masahiro , Nomura Masakatsu
Published: November 2003

A sterically hindered phenol, 2,6-di-tert-butylphenol, efficiently reacts with various bromobenzenes in the presence of a palladium catalyst and a base to selectively afford the corresponding 1,1′-biphenyl-4-ol derivatives.
Vertical Standing of Amphiphilic Helical Peptides at the Hexane-Water Interface
Authors: Kishihara Kiyonobu , Kinoshita Takatoshi , Mori Toshiaki , Okahata Yoshio
Published: November 2003

Amphiphilic poly(L-leucine) (n=20) helixes having a trimethylammonium head group at the terminal end were stood vertical with a tilt at the hexane-water interface, although they usually laid down to the air-water interface. Structures of the transferred monolayer on a substrate were confirmed by FT-IR spectra and atomic force microscopy(AFM).
The Influence and Value of Analogical Thinking during New Product Ideation
Authors: Dahl Darren W. , Moreau Page
Published: November 2003

Although both the academic and the trade literature have widely acknowledged the need to foster the development of more-innovative products, little empirical research has examined the cognitive processes underlying the creation of these novel product concepts. In this research, three empirical studies examine how analogical thinking influences the idea-generation stage of the new product development process. The first study uses the verbal protocols of real-world industrial designers to trace the role of analogy in the context of a new product development task, and the second and third studies use an experimental approach to assess the effectiveness of different ideation strategies and conditions. Findings from these studies indicate that the originality of the resulting product design is influenced by the extent of analogical transfer, the type of analogies used, and the presence of external primes. In addition, these studies reveal a positive relationship between the originality of the product concept and consumers' willingness to pay for it, an important measure in the concept-testing phase of product development.
A Multiple Ideal Point Model: Capturing Multiple Preference Effects from within an Ideal Point Framework
Authors: Lee Jack K.H. , Sudhir K. , Steckel Joel H.
Published: November 2003

Previous research has suggested that households and individuals may possess multiple preferences for a given product category. These multiple preferences may be the result of multiple individuals in a household, different uses and usage occasions, and/or variety seeking. As such, single ideal point models that assume a single invariant ideal point may be operating from a false and misleading assumption. We propose a multiple ideal point model to capture these multiple preference effects. The basic premise of the model is that consumers may possess a set of ideal points, each of which represents a distinct preference. At any given purchase occasion, one of these points is “activated” with some probability, and choices are made with respect to its characteristics. In this article, the authors assess the multiple ideal point model and an associated estimation procedure with respect to the model's ability to recover a true choice structure. The authors then empirically test the model on Information Resources Inc. panel data from the powdered soft drink category. The authors discuss the results and introduce directions for further research.
Hierarchical Bayes versus Finite Mixture Conjoint Analysis Models: A Comparison of Fit, Prediction, and Partworth Recovery
Authors: Andrews Rick L. , Ansari Asim , Currim Imran S.
Published: November 2003

A study conducted by Vriens, Wedel, and Wilms (1996) and published in Journal of Marketing Research found that finite mixture (FM) conjoint models had the best overall performance of nine conjoint segmentation methods in terms of fit, prediction, and parameter recovery. Since that study, hierarchical Bayes (HB) conjoint analysis methods have been proposed to estimate individual-level partworths and have received much attention in the marketing research literature. However, no study has compared the relative effectiveness of FM and HB conjoint analysis models in terms of fit, prediction, and parameter recovery. To conduct such a comparison, the authors employ the simulation methodology proposed by Vriens, Wedel, and Wilms with some modification. The authors estimate traditional individual-level conjoint models as well. The authors show that FM and HB models are equally effective in recovering individual-level parameters and predicting ratings of holdout profiles. Two surprising findings are that (1) HB performs well even when partworths come from a mixture of distributions and (2) FM produces good parameter estimates, even at the individual level. The authors show that both models are quite robust to violations of underlying assumptions and that traditional individual-level models overfit the data.
A Simulated Annealing Heuristic for a Bicriterion Partitioning Problem in Market Segmentation
Authors: Brusco Michael J. , Cradit J. Dennis , Stahl Stephanie
Published: November 2003

K-means clustering procedures are frequently used to identify homogeneous market segments on the basis of a set of descriptor variables. In practice, however, market research analysts often desire both homogeneous market segments and good explanation of an exogenous response variable. Unfortunately, the relationship between these two objective criteria can be antagonistic, and it is often difficult to find clustering solutions that yield adequate levels for both criteria. The authors present a simulated annealing heuristic for solving bicriterion partitioning problems related to these objectives. A large computational study and an empirical demonstration reveal the effectiveness of the methodology. The authors also discuss limitations and extensions of the method.
Characteristics of Mental Health Specialists Who Shifted Their Practice Entirely to Telemedicine
Authors: Hailu Ruth , Huskamp Haiden A. , Busch Alisa B. , Uscher-Pines Lori , Raja Pushpa , Mehrotra Ateev
Published: January 2024

This cohort study investigates the number and characteristics of US mental health specialists who had shifted to a fully virtual practice as of 2022.