bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conformational studies on Arabidopsis sulfurtransferase AtStr1 with spectroscopic methods
Authors: Bartels Andrea , Forlani Fabio , Pagani Silvia , Papenbrock Jutta 
Published: January 2007

AbstractSulfurtransferases/rhodaneses (Str) are enzymes widely distributed in archaea, prokaryota and eukaryota, and catalyze the transfer of sulfur from a donor molecule to a thiophilic acceptor substrate. In this reaction, Str cycles between the sulfur-free and the sulfur-substituted form. Two-domain Str consist of two globular domains of nearly identical size and conformation connected by a short linker sequence, which is elongated in plant two-domain Str proteins compared to Str in other organisms. The two-domainArabidopsis thalianaStr1 protein (At1g79230) was expressed inEscherichia colias a mature protein, as a variant without the elongated linker sequence, and as AtStr1C332S and AtStr1C339V. The persulfuration state of the purified recombinant proteins was investigated in the presence and absence of sulfur donors by fluorescence spectroscopy. The secondary structure was analyzed by circular dichroism (CD) in the far-UV range, while overall changes in tertiary structure were determined by CD in the near-UV range. Finally, protein stability was analyzed by tryptic digestion. The elongated linker sequence is essential for correct conformation and stability, and thereby affects the catalytic activity of AtStr1. Replacement of the catalytic cysteine residue C332 leads to higher rigidity of the molecule, whereas replacement of C339 does not lead to any conformational changes, providing evidence of the direct involvement of C339 in catalysis.
Single-Tooth Implant Restorations in the Esthetic Zone With PureForm Ceramic Crowns: 3 Case Reports
Authors: Schiroli Guido 
Published: January 2007

Abstract
The anterior maxillary jaw is frequently called the “esthetic zone” because of its high visibility and influence on facial appearance. Implant placement and single-tooth restoration in this region can present some esthetic challenges for the clinician. The underlying titanium abutment, for example, can diminish porcelain translucency and result in a darkened prosthesis. Subsequent changes in soft-tissue margins can also result in the visibility of titanium at the gingival crevice. In recent years, all-ceramic restorations have gained popularity in response to increasing patient demands for improved esthetics. This article describes the clinical use of a new, tooth-shaped, ceramic coping system in the restoration of single teeth in the esthetic zones of 3 patients. Four tapered screw implants were placed in the locations of the central incisors (n = 3) and bicuspid (n = 1). Conventional ceramic protocols were used to fabricate all-ceramic crowns that were cemented onto small core abutments attached to the implants. All prostheses restored the biomechanical needs of the patients and achieved excellent esthetic results.
Response toward novel stimuli in a group of tufted capuchins (Cebus libidinosus) in Brasília National Park, Brazil
Authors: Sabbatini Gloria , Stammati Margherita , Tavares Maria Clotilde H. , Visalberghi Elisabetta 
Published: January 2007

AbstractWe investigated responses toward novel foods and novel objects by wild capuchins that routinely exploit visitors' foods in Brasília National Park. Given the capuchins' daily exposure to human foods and objects, we expected them to be more explorative toward novel foods and objects compared to capuchins that are not habituated to visitors. However, since the safety and palatability of potential foods have to be learned, we also expected the capuchins to be cautious about eating novel foods, as has been reported for wild and captive capuchins. Stimuli were presented on a platform in four experimental conditions: familiar food (FF), novel food (NF), familiar food plus novel object (FF+O), and novel food plus novel object (NF+O). Latencies to approach and contact the platform, and to approach and to ingest food did not differ across conditions. Nevertheless, the capuchins were significantly more responsive (measured in terms of interest, manipulation, etc.) toward familiar foods than novel foods, and ate significantly more of the former. In other words, their explorative response toward novel foods led to little consumption. Our results do not support the “readiness to eat” hypothesis, according to which a lower readiness to eat and food neophobia are the consequences of the presence of a distracting novel object. The finding that capuchins explore novel stimuli but remain cautious about eating novel foods supports the view that neophilia and neophobia are motivationally independent responses. Am. J. Primatol. 69:1–14, 2007. © 2007 Wiley‐Liss, Inc.
Measurement of eye‐gaze in chimpanzees (Pan troglodytes)
Authors: Bethell Emily J. , Vick Sarah‐Jane , Bard Kim A. 
Published: January 2007

AbstractGaze cues are used as an index of social cognition in primates, yet the sensitivity to different forms of gaze, and consequently the cues required to test gaze‐following abilities remain understudied. Whereas the eye is attributed special signal value in humans, the camouflaged ocular morphology of non‐human primates has led to the consensus that head orientation may be a more salient cue. This study presents the first documentation of the surface eye movements of the chimpanzee, Pan troglodytes, in order to determine the behavioral forms of eye‐gaze and their saliency as signals, document their functional variation, and address the signal value of the eyes distinct from head orientation. Movements of the eye were identified as Scan (continuous movement), Glance (a single movement <1 sec), or Fixate (no movement). Scans, glances, and fixations were reliably detected by humans during live observation and from video (Cohen's kappa over 0.70) and, therefore, are likely also to be detected by conspecifics. Eye‐gaze comprised a nonunitary measure of visual attention, reflecting the attentional task demands of different activities. Specifically, chimpanzees spent significantly more time scanning while feeding and resting, than grooming, F(2,28) = 10.23, P<0.001, and spent significantly more time fixating while grooming, than feeding or resting, F(2,28) = 7.52, P<0.01. Further, eye‐gaze was often incongruent with head movement, varying significantly with the form of eye‐gaze: incongruence was found during 12–21% of fixations, during 42–49% of scans, and during 70–100% of glances, F(2,16) = 30.17, P<0.001. These findings provide the basis for discrimination of the adaptive significance of gaze‐processing abilities with emphasis on sensitivity to eye‐gaze distinct from head orientation. If we are to continue exploring gaze‐processing abilities in primates, then we need greater consideration of the precise nature of the signals themselves. Here we present evidence for special consideration of the eyes as a salient signal in P. troglodytes. Am. J. Primatol. 69:562–575, 2007. © 2007 Wiley‐Liss, Inc.
Are rotation curves in NGC 6946 and the Milky Way magnetically supported?
Authors: Battaner E. , Florido E. 
Published: January 2007

AbstractThe inner disk rotation of NGC 6946 and the Milky Way is dominated by gravity but magnetism is not negligible at radii where the rotation curve becomes flat, and indeed could become dominant at very large radii. Values of the order of 1 μG, or even less, produce a centripetal force when the absolute value of the slope of the curve [B φ , R ] (azimuthal field strength versus radius) is less than the slope of a B φ ‐profile proportional to R –1. The ∝ R –1‐profile is here called the critical profile. From the hypothesis of magnetically driven rotation curves, the following is to be expected: at large radii, a “subcritical” profile (slope flatter than R –1); at still larger radii a B φ ‐profile becoming asymptotically critical as the density becomes asymptotically vanishing. Recent observations of magnetic fields in NGC 6946 and the Milky Way are in very good agreement with these predictions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A planetary system with an escaping Mars
Authors: Süli Á. , Dvorak R. 
Published: January 2007

AbstractThe chaotic behaviour of the motion of the planets in our Solar System is well established. In this work to model a hypothetical extrasolar planetary system our Solar System was modified in such a way that we replaced the Earth by a more massive planet and let the other planets and all the orbital elements unchanged. The major result of former numerical experiments with a modified Solar System was the appearance of a chaotic window at κ E ∈ (4, 6), where the dynamical state of the system was highly chaotic and even the body with the smallest mass escaped in some cases. On the contrary for very large values of the mass of the Earth, even greater than that of Jupiter regular dynamical behaviour was observed. In this paper the investigations are extended to the complete Solar System and showed, that this chaotic window does still exist. Tests in different ‘Solar Systems’ clarified that including only Jupiter and Saturn with their actual masses together with a more ‘massive’ Earth (4 < κ E < 6) perturbs the orbit of Mars so that it can even be ejected from the system. Using the results of the Laplace‐Lagrange secular theory we found secular resonances acting between the motions of the nodes of Mars, Jupiter and Saturn. These secular resonances give rise to strong chaos, which is the cause of the appearance of the instability window. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phospholipid and triacylglycerol fatty acid content and pattern in the cardiac endothelium of rats depleted in long‐chain polyunsaturated ω3 fatty acids
Authors: Carpentier Yvon A. , Portois Laurence , Louchami Karim , Zhang Ying , Sener Abdullah , Malaisse Willy J. 
Published: January 2007

AbstractRats depleted in long‐chain polyunsaturated ω3 fatty acids (ω3‐depleted rats) display several features of the metabolic syndrome including hypertension and cardiac hypertrophy. This coincides with alteration of the cardiac muscle phospholipid and triacylglycerol fatty acid content and/or pattern. In the present study, the latter variables were measured in the cardiac endothelium of normal and ω3‐depleted rats. Samples derived from four rats each were obtained from 16 female normal fed rats and three groups of 36–40 female fed ω3‐depleted rats each aged 8–9, 15–16 and 22–23 weeks. At comparable mean age, the ratio between the square root of the total fatty acid content of phospholipids and cubic root of the total fatty acid content of triacylglycerols was lower in ω3‐depleted rats than in control animals. The total fatty acid content of triacylglycerols was inversely related to their relative content in C20:4ω6. Other differences between ω3‐depleted rats and control animals consisted in a lower content of long‐chain polyunsaturated ω3 fatty acids in both phospholipids and triacylglycerols, higher content of long‐chain polyunsaturated ω6 fatty acids in phospholipids, higher activity of Δ9‐desaturase (C16:0/C16:1ω7 and C18:0/C18:1ω9 ratios) and elongase [(C16:0 + C16:1ω7)/(C18:0 + C18:1ω9) and C20:4ω6/C22:4ω6 ratios], but impaired generation of C22:6ω3 from C22:5ω3 in the former rats. These findings support the view that cardiovascular perturbations previously documented in the ω3‐depleted rats may involve impaired heart endothelial function. Copyright © 2007 John Wiley & Sons, Ltd.
Structures of the High‐Temperature Solid Phases of the Odd‐Numbered Fatty Acids from Tridecanoic Acid to Tricosanoic Acid
Authors: Gbabode Gabin , Negrier Philippe , Mondieig Denise , Moreno Calvo Evelyn , Calvet Teresa , Cuevas‐Diarte Miquel Àngel 
Published: January 2007

AbstractCrystal structures of the high‐temperature phases of odd‐numbered fatty acids (CnH2n−1OOH) from tridecanoic acid (C13H25OOH) to tricosanoic acid (C23H45OOH) are presented in this article. They have been determined from high‐quality X‐ray powder‐diffraction patterns. Two types of high‐temperature phases are adopted: one monoclinic A2/a with Z=8 for the fatty acids with n=13 and n=15, denoted as C′′, and one monoclinic P21/a with Z=4 for the longer‐chain fatty acids, denoted as C′. It appears that the packing arrangement of the alkyl chains and of the carboxyl groups is similar in all of the structures. However, the arrangement at the methyl‐group interface differs between the C′ and C′′ forms. A survey of the intermolecular interactions involved in these polymorphs coupled with a study of the effects of temperature on the structures have led us to a better understanding of the arrangement of the molecules within the high‐temperature solid phases of odd‐numbered fatty acids.
Simultaneous analysis of steady‐state intracellular pH and cell morphology by automated laser scanning cytometry
Authors: Koo Mei K. , Oh Chia H. , Holme Andrea L. , Pervaiz Shazib 
Published: January 2007

AbstractBackground:Cytosolic pH (pHi) changes are critical in cellular response to diverse stimuli, including cell survival and death signaling. The potential drawback in flow‐based analysis is the inability to simultaneously visualize the cells during pHi measurements. Here, the suitability of laser scanning cytometer (LSC) in pHi measurement was investigated.Aim:Using the two extensively reported pH‐sensitive fluorescent probes, 2,7‐bis(2‐Carboxyethyl)‐5(6)‐carboxyfluorescein acetoxymethyl ester (BCECF‐AM) and 5‐(and‐6)‐carboxy SNARF‐1 acetoxymethyl ester, we evaluated the potential of automated LSC as a platform for simultaneous determination of pHi and cell morphology. The effect of a variety of buffer systems‐commonly employed for pHi measurements‐on cell morphology before pH clamping with the ionophore, nigericin, was also assessed.Methods:Measurement of cytosolic pH was performed using pH‐sensitive fluorescent probes BCECF‐AM and SNARF‐1. pH clamping was carried out using nigericin and samples were analyzed on the LSC or CyAn™ ADP Flow Cytometer.Results:The pHi clamping conditions were optimized as 140 mM potassium and 10 μM nigericin. The suitable buffers used for pH clamping: 140 mM KCl, 1 mM MgCl2, 2 mM CaCl2·2H2O, 5 mM glucose, 20 mM MES and 140mM KCl, 1 mM MgCl2, 2 mM CaCl2·2H2O, 5 mM glucose, and 20 mM Tris. Results obtained with the LSC strongly correlated with those obtained by flow cytometry.Conclusion:We report here that LSC is an excellent and highly reproducible platform for pHi determination, and provides the added advantage of simultaneous imaging of cells before, during, and after pH measurements. © 2007 International Society for Analytical Cytology.
A Sall4 mutant mouse model useful for studying the role of Sall4 in early embryonic development and organogenesis
Authors: Warren Madhuri , Wang Wei , Spiden Sarah , Chen‐Murchie Dongrong , Tannahill David , Steel Karen P. , Bradley Allan 
Published: January 2007

AbstractSALL4 is a homologue of the Drosophila homeotic gene spalt, a zinc finger transcription factor, required for inner cell mass proliferation in early embryonic development. It also interacts with other transcription factors to control the development of the anorectal region, kidney, heart, limbs, and brain. Truncating mutations in SALL4 cause Okihiro syndrome, manifest as Duane anomaly, radial ray defects and sensorineural and conductive deafness. We report the characterization of a novel murine Sall4 null allele created by bacterial recombineering in ES cells. Homozygous mutant mice exhibit early embryonic lethality. Heterozygous mutant mice recapitulate phenotypic features of Okihiro syndrome including deafness, lower anogenital tract abnormalities, renal hypoplasia, anencephaly, Hirschprung's disease, and skeletal defects. This phenotype shows important differences in cardiac and ear manifestations to previously characterized Sall4 mutant alleles and should prove useful for the investigation of the influence of modifier alleles and protein interactions on the transcriptional regulatory function of Sall4. genesis 45:51–58, 2007. © 2007 Wiley‐Liss, Inc.
A microstrip‐line phase shifter constructed by a tunable filter
Authors: Morikawa Daisuke , Deguchi Hiroyuki , Tsuji Mikio , Shigesawa Hiroshi 
Published: January 2007

AbstractA phase shifter configuration based on a bandpass filter that can change the phase continuously is discussed. In this configuration, the phase change due to resonance is used by making variable the center frequency of a filter with a broad passband. The configuration consisting of varactor diodes loaded on a microstrip line filter with short‐circuited stubs to decrease the insertion loss is studied in detail by analysis and experiment. The possibility of application to a phase shifter is verified. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 90(2): 25– 32, 2007; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/ecjb.20253
Long‐period earthquake ground displacements recorded on Guadeloupe (French Antilles)
Authors: Jousset P. , Douglas J. 
Published: January 2007

AbstractDisplacement time‐histories derived from accelerograms of three recent earthquakes in western North America (Hector Mine, Mw 7.1; Denali, Mw 7.9; and San Simeon, Mw 6.5) have been shown to feature large long‐period (∼10 s) ground‐motion cycles. Such long‐period displacements cause a localized peak within the displacement response spectrum that is currently not considered within any earthquake engineering design spectra. These displacement pulses have also been shown to be persistent and to feature on time‐histories from widely separated stations (∼20 km).Broadband and accelerometric data from the Les Saintes earthquake sequence of 2004–2006 (4.9⩽Mw⩽5.3) recorded on Guadeloupe (French Antilles) are shown in this article to feature similar long‐period motions. The broadband data are used to independently corroborate the displacement time‐histories derived through high‐pass filtering and double integration of accelerometric data. It is shown that high‐quality broadband data are suitable for this purpose. The long‐period motions observed cause a localized peak in displacement response spectra at periods between 5 and 10 s. It is suggested here that the cause of these large‐amplitude long‐period motions are specific source mechanisms, which may possibly involve the presence of fluids within the source.The form of the displacement response spectra from these time‐histories is significantly different from the spectral shape specified in recent seismic design codes since the peak in the spectra is at a much greater period than expected. This leads to an underestimation of spectral displacements for periods between about 5 and 10 s. Therefore, if these observed long‐period cycles are a common feature of earthquake ground motions the standard form of displacement design spectra may need to be reconsidered. Copyright © 2007 John Wiley & Sons, Ltd.
Addition and multiplication of sets
Authors: Kirby Laurence 
Published: January 2007

AbstractOrdinal addition and multiplication can be extended in a natural way to all sets. I survey the structure of the sets under these operations. In particular, the natural partial ordering associated with addition of sets is shown to be a tree. This allows us to prove that any set has a unique representation as a sum of additively irreducible sets, and that the non‐empty elements of any model of set theory can be partitioned into infinitely many submodels, each isomorphic to the original model. Also any model of set theory has an isomorphic extension in which the empty set of the original model is non‐empty. Among other results, the relations between the arithmetical operations and the transitive closure and the adductive hierarchy are elucidated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Coherent Description of Nonlinear Flow Behavior of Entangled Polymers as Related to Processing and Numerical Simulations
Authors: Wang Shi‐Qing 
Published: January 2007

AbstractThis Feature Article describes a plausible picture of entangled polymer shear flow behavior, resulting from a decade of efforts in our laboratory to unravel the origins of a host of intricate and interconnected rheological phenomena. The first report of spurt flow by Bagley (1958) raised several key questions: Does the spurt flow reflect a constitutive failure as suggested by Vindogradov et al. (1972), Doi‐Edwards (1979) and McLeish‐Ball (1986)? How is it related to sharkskin, “melt fracture” and/or wall slip? The subject remained unsettled and “paradoxical” [Denn (1990)] until the 1990's when a first quantitative description of polymer slip was provided by Brochard and de Gennes (1992). The experimental elucidation [Rheol. Acta 1998, 37, 415] of the interfacial origin of the spurt flow led to the conclusion that the stress maximum in the Doi‐Edwards theory (1979) was a theoretical artefact and to a decade of efforts to derive a constitutive description of polymer flow by incorporating Marrucci's idea of convective constraint release (1996). Ongoing studies (2003–present) of constitutive flow and interfacial slip behavior of entangled polymer solutions have revealed something surprising: the entangled polybutadiene solutions appear to respond differently to rate‐controlled vs. stress‐controlled shear. The results [Macromolecules 2004, 37, 9083] imply that there would not necessarily be a homogeneous shear field in a simple‐shear apparatus in the rate‐controlled mode. An effective particle tracking velocimetric (PTV) method was developed to allow determination of the velocity profile across the gap in various shear apparatuses including cone‐plate and linear sliding‐plate setups for startup shear, large amplitude oscillatory shear (LAOS) and step strain experiments. Our PTV observations show an initial linear velocity variation across the gap and a nonlinear velocity profile beyond the shear stress overshoot [Phys. Rev. Lett. 2006, 96, 016001], growth of shear banding in LAOS [Phys. Rev. Lett. 2006, 96, 196001] and elastic breakup of several entangled solutions after step strain [Phys. Rev. Lett. 2006, 97, 187801]. These results present great challenges to both the prevailing theoretical description of entangled polymer flow that is based on tube models and the conventional rheometric protocols used to experimentally determine constitutive flow behavior, and questions the validity to perform numerical simulations of polymer processing based on the available constitutive models.magnified image
Titan's ion chemistry: A laboratory perspective
Authors: McEwan Murray J. , Anicich Vincent G. 
Published: January 2007

AbstractSome of the most interesting objects in the solar system are those bodies that have significant atmospheres. The discovery that Titan, Saturn's largest satellite, has a substantial nitrogen‐based atmosphere makes it a prime extraterrestrial object of interest. The advent of the Cassini orbiter spacecraft program that is able to observe and sample Titan's ionosphere adds greatly to this interest. We report here a summary of some of the efforts that have been made in the laboratory to understand the processes responsible for chemical processing of the primary ions formed in Titan's ionosphere, into the ions observed by in situ sampling. The presence of significant hydrocarbons and the colder temperatures of Titan's ionosphere lead to a much greater complexity in the ion chemistry of Titan than is apparent in the ion chemistry of Earth. A review of all the ion–molecule chemistry investigated in laboratory studies relevant to Titan is included as a table. The complexity of some of the hydrocarbon ion structures formed in just three reactive ion–molecule sequences from the primary ions has required a new experimental methodology which is discussed. © 2007 Wiley Periodicals, Inc., Mass Spec Rev 26:281–319, 2007