bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous determination of four sesquiterpene alkaloids in Tripterygium wilfordii Hook. F. extracts by High‐performance liquid chromatography
Authors: OuYang Xiao‐kun , Jin Mi‐cong , He Chao‐hong
Published: April 2007

Wilfortrine, wilfordine, wilforgine and wilforine are four major bioactive sesquiterpene alkaloids in Tripterygium wilfordii Hook. F. The first analytical determination of the four major bioactive alkaloids is described. The four alkaloids are well‐resolved within 15 min using the developed HPLC method. The identity of the analytes was confirmed by an HPLC‐MS experiment, with all compounds being clearly assignable by atmospheric pressure chemical ionization (APCI) positive mode analysis. The method was validated for limit of qualification, linearity and inter‐day variation of precision and accuracy. Seven T. wilfordii samples (extracts and commercial product) were successfully analysed. Copyright © 2007 John Wiley & Sons, Ltd.
An analysis of excluded‐volume effects in a polystyrene‐cyclohexane system
Authors: Suzuki Hidematsu
Published: April 2007

An attempt was made to analyse Miyaki's data for the radius of gyration  and the intrinsic viscosity [η] of very high molecular weight samples of polystyrene in cyclohexane. The excluded‐volume variable z was estimated by adopting the temperature dependence of the excluded‐volume integral as predicted by Eichinger. It was found that the volume expansion as given by the ratio of  to 0 under the unperturned state was a function of z only, as required by two‐parameter theories. These data were in good agreement with the Domb‐Barrett and the Suzuki equations. On the other hand, the ratio of [η] to [η] 0 under the unperturbed state also gave a single composite curve when plotted against z. However, it was found that the observed hydrodynamic behaviour was not satisfactorily explained by two‐parameter theories of [η]. A brief comment was made on the validity of two‐parameter theories from the experimental point of view.
Emulsion polymerisation in continuous reactor systems
Authors: Poehlein Gary W.
Published: April 2007

Continuous reactor systems find important applications in the production of sythetic polymer latexes and increased production rates are providing additional incentives for the development of new continuous systems. The fundamental factors that should be considered in the development of continuous processes are reviewed in this paper. Particular emphasis is placed on exploring the differences between batch and continuous reactors and why these difference can lead to different latex product, even if the same recipe is employed. These factors make the task of designing continuous reactor systems based on batch research and development very difficult and risky. Thus it is recommended that small‐scale continuous reactors be employed early in a product/process development effort if that effort is likely to lead to a continuous commercial process.

The published literature on continuous emulsion polymerization reactors has been reasonably active in the past ten years. Our understanding of the chemistry and reactor modelling has been advanced but a number of areas for fruitful research remains. Some of these problems are reviewed and directions for new efforts are suggested.
Curing polyester resins with visible light
Authors: Alexander Ian J. , Scott Roger J.
Published: April 2007

Radiation curing of unsaturated polyester resin‐based compositions offers a number of significant advantages over the use of peroxides and similar free‐radical polymerisation initiators; the cure process can be closely controlled, is usually much faster, and the fabricator is not required to measure out, add, and blend‐in small quantities of catalyst. However most forms of radiation including ultra violet (UV) involve heavy initial expense and the need to provide shielding to protect personnel. Furthermore UV radiation will not usually penetrate deeply into thick glassfibre‐containing compositions owing to the absorption of UV light by both resin and glass.

Photoinitiator systems which need only visible light have now been developed however. Using these systems almost any available light source including fluorescent tubes, tungsten filament bulbs and of course natural sunlight and daylight will cause the resin to cure rapidly and completely. By controlling the intensity of the incident light continuous close control of the cure process is easily achieved.

The advantages of reduced energy requirements, fast cure,‘one pot’ chemistry and built‐in indicators of degree of cure have already led to a number of special applications for visible light curable polyester resins.
Crosslinking of a polyacrylate bearing a spiroorthoester pendant group with mixtures of diglycidyl ether of bisphenol A and phosphorus‐containing glycidyl derivatives
Authors: Canadell J. , Mantecón A. , Cádiz V.
Published: April 2007

The cationic crosslinking of a polyacrylate bearing a spiroorthoester pendant group with mixtures of diglycidyl ether of bisphenol A and three phosphorus‐containing glycidyl derivatives was carried out with ytterbium triflate as an initiator. The curing process was monitored with Fourier transform infrared spectroscopy. The thermomechanical and thermogravimetric properties were evaluated. The glass transition temperatures of the obtained materials were, in general, above 100 °C. The incorporation of phosphorus into the network increased the limiting oxygen index values, thus improving the flame retardancy of the materials. During crosslinking, all the crosslinked polymers showed slight shrinkage that was much lower than that observed in conventional epoxy resins. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1920–1930, 2007
Diagnosis and management of asthma in children
Authors: Kanabar Dipak
Published: April 2007

Our series Prescribing in children gives practical advice for the successful management of childhood problems in general practice. Here, the author discusses the difficulties associated with the diagnosis of asthma and highlights options for management. Copyright © 2007 Wiley Interface Ltd
Intrinsic conformational preferences of and an anomeric‐like effect in 1‐substituted silacyclohexanes
Authors: Weldon Abby Jones , Tschumper Gregory S.
Published: April 2007

A series of ab initio computations have been performed to estimate the CCSD(T) complete basis set limit of the axial/equatorial energy difference for the chair conformation of 1‐fluoro, 1‐chloro, 1‐methyl, 1‐hydroxy, and 1‐methoxysilacyclohexanes. The equatorial conformation is more stable than the axial by 0.21 kcal mol−1 for 1‐methylsilacyclohexane, while the axial position is more stable for 1‐fluoro, 1‐chloro, and 1‐methoxysilacyclohexane (by 0.09, 0.40, and 0.15 kcal mol−1, respectively). The axial and equatorial orientations of 1‐hydroxysilacyclohexane are nearly electronically isoenergetic (equatorial favored by 0.03 kcal mol−1). Zero point vibrational energy corrections have very little effect on the relative energies (less than 0.08 kcal mol−1). These results suggest the presence of an interesting stereoelectronic effect, similar to the anomeric effect, in these silacyclohexanes even without an additional heteroatom, like O, in the ring. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Considering a joint venture with the Russians? what you can expect
Authors: Burt Jeffrey A.
Published: April 2007

Despite recent economic reforms in the Soviet Union, significant problems remain for prospective Western venture participants, like restrictions on the use of hard currency and unanswered questions about venture dissolution. Study the obstacles–as well as the opportunities–before you leap.
So you want to exhibit at a trade show
Authors: Kane William
Published: April 2007

Trade shows offer an excellent opportunity to show off your product to buyers from outside the U.S. or to distributors who can help you sell your products in foreign markets. How can you make the most of this opportunity?
Resolving international contract disputes
Authors: Scheuing Eberhard E. , Hagstrand Allen P.
Published: April 2007

An ounce of prevention is truly worth a pound of cure when the cure for a dispute between buyer and seller in the international arena is litigation in a foreign courtroom. Resolution may be time consuming and expensive, appeal impossible, and the outcome unpredictable.
Eastern Europe: The new enterpreneurial frontier
Authors: Kiam Victor K.
Published: April 2007

American entrepreneurs must dive into the Eastern European market‐place now, not wait until the economies there stabilize. The recipe for success in Eastern Europe: an ongoing presence in the major markets that adds to the understanding of the economic cultures of these new democracies and some prudent assistance from Uncle Sam.
Installing successful factories in developing countries
Authors: Plenert Gerhard
Published: April 2007

A big mistake of MNCs in installing factories in developing countries is to set up production planning systems similar to those in their other factories. The best system is one that reflects the resources and goals of the particular facility.
Serum lipid and lipoprotein profile of patients with glycogen storage disease types I, III and IX
Authors: Geberhiwot T. , Alger S. , McKiernan P. , Packard C. , Caslake M. , Elias E. , Cramb R.
Published: April 2007

With current dietary therapy, life expectancy in glycogen storage disease (GSD) has improved considerably and more children reach adulthood. Notwithstanding intensive dietary therapy, moderate to severe hyperlipidaemia is still observed frequently. There is limited information about the type and extent of hyperlipidaemia. We studied the lipid profile in 20 patients, aged 8–54 years, of the three (types I, III and IX) most common forms of adult GSD. Hyperlipidaemia was shown to be type‐specific #Affecting predominantly patients with GSD type Ia, who showed marked combined hypercholesterolaemia and hypertriglyceridaemia. By contrast, a heterogeneous distribution of HDL was found in patients with GSD I and III. There was no significant difference in Apo Al and Apo B concentrations between groups. In addition, mass measurements of the fractions of VLDL1, VLDL2 and IDL were raised in all patients with GSD Ia by comparison with all other patients with GSD. Patients with GSD type Ia have lipid concentrations and individual mass measurements that are consistent with ranges found in patients who have a significant risk of atherosclerosis. Accumulated evidence, however, suggest GSD type Ia patients do not have an increased risk of atherosclerotic cardiovascular disease (CVD) but the reason remains unknown. Intervention to reduce their lipid levels could therefore be on the basis of seeking to prevent the risk of pancreatitis rather than that of CVD.
Atopic dermatitis: insights from linkage overlap and disease co-morbidity
Authors: Willis-Owen Saffron A.G. , Morar Nilesh , Willis-Owen Charles A.
Published: April 2007

Atopic dermatitis (AD) is a strongly heritable, chronic relapsing dermatosis that frequently co-occurs with other atopic phenotypes including asthma and allergic rhinitis (the so-called atopic triad disorders). However, despite high levels of co-morbidity, relatively low levels of genomic co-incidence have been observed between atopic triad disorders. Conversely, current mapping data have revealed a striking pattern of co-localisation between AD disease loci and those mapped using another chronic dermatological disease – psoriasis. In this review, we examine the evidence for co-localisation between AD and a range of atopic, infectious, inflammatory and autoimmune diseases, and consider the implications of these data for the AD disease concept and future research in the field.
Reactive nitrogen distribution and partitioning in the North American troposphere and lowermost stratosphere
Authors: Singh H. B. , Salas L. , Herlth D. , Kolyer R. , Czech E. , Avery M. , Crawford J. H. , Pierce R. B. , Sachse G. W. , Blake D. R. , Cohen R. C. , Bertram T. H. , Perring A. , Wooldridge P. J. , Dibb J. , Huey G. , Hudman R. C. , Turquety S. , Emmons L. K. , Flocke F. , Tang Y. , Carmichael G. R. , Horowitz L. W.
Published: April 2007

A comprehensive group of reactive nitrogen species (NO, NO2, HNO3, HO2NO2, PANs, alkyl nitrates, and aerosol‐NO3−) were measured over North America during July/August 2004 from the NASA DC‐8 platform (0.1–12 km). Nitrogen containing tracers of biomass combustion (HCN and CH3CN) were also measured along with a host of other gaseous (CO, VOC, OVOC, halocarbon) and aerosol tracers. Clean background air as well as air with influences from biogenic emissions, anthropogenic pollution, biomass combustion, convection, lightning, and the stratosphere was sampled over the continental United States, the Atlantic, and the Pacific. The North American upper troposphere (UT) was found to be greatly influenced by both lightning NOx and surface pollution lofted via convection and contained elevated concentrations of PAN, ozone, hydrocarbons, and NOx. Observational data suggest that lightning was a far greater contributor to NOx in the UT than previously believed. PAN provided a dominant reservoir of reactive nitrogen in the UT while nitric acid dominated in the lower troposphere (LT). Peroxynitric acid (HO2NO2) was present in sizable concentrations peaking at around 8 km. Aerosol nitrate appeared to be mostly contained in large soil based particles in the LT. Plumes from Alaskan fires contained large amounts of PAN and aerosol nitrate but little enhancement in ozone. A comparison of observed data with simulations from four 3‐D models shows significant differences between observations and models as well as among models. We investigate the partitioning and interplay of the reactive nitrogen species within characteristic air masses and further examine their role in ozone formation.
Water use regimes: Characterizing direct human interaction with hydrologic systems
Authors: Weiskel Peter K. , Vogel Richard M. , Steeves Peter A. , Zarriello Philip J. , DeSimone Leslie A. , Ries Kernell G.
Published: April 2007

The sustainability of human water use practices is a rapidly growing concern in the United States and around the world. To better characterize direct human interaction with hydrologic systems (stream basins and aquifers), we introduce the concept of the water use regime. Unlike scalar indicators of anthropogenic hydrologic stress in the literature, the water use regime is a two‐dimensional, vector indicator that can be depicted on simple x‐y plots of normalized human withdrawals (hout) versus normalized human return flows (hin). Four end‐member regimes, natural‐flow‐dominated (undeveloped), human‐flow‐dominated (churned), withdrawal‐dominated (depleted), and return‐flow‐dominated (surcharged), are defined in relation to limiting values of hout and hin. For illustration, the water use regimes of 19 diverse hydrologic systems are plotted and interpreted. Several of these systems, including the Yellow River Basin, China, and the California Central Valley Aquifer, are shown to approach particular end‐member regimes. Spatial and temporal regime variations, both seasonal and long‐term, are depicted. Practical issues of data availability and regime uncertainty are addressed in relation to the statistical properties of the ratio estimators hout and hin. The water use regime is shown to be a useful tool for comparative water resources assessment and for describing both historic and alternative future pathways of water resource development at a range of scales.
Fractal topography and subsurface water flows from fluvial bedforms to the continental shield
Authors: Wörman Anders , Packman Aaron I. , Marklund Lars , Harvey Judson W. , Stone Susa H.
Published: April 2007

Surface‐subsurface flow interactions are critical to a wide range of geochemical and ecological processes and to the fate of contaminants in freshwater environments. Fractal scaling relationships have been found in distributions of both land surface topography and solute efflux from watersheds, but the linkage between those observations has not been realized. We show that the fractal nature of the land surface in fluvial and glacial systems produces fractal distributions of recharge, discharge, and associated subsurface flow patterns. Interfacial flux tends to be dominated by small‐scale features while the flux through deeper subsurface flow paths tends to be controlled by larger‐scale features. This scaling behavior holds at all scales, from small fluvial bedforms (tens of centimeters) to the continental landscape (hundreds of kilometers). The fractal nature of surface‐subsurface water fluxes yields a single scale‐independent distribution of subsurface water residence times for both near‐surface fluvial systems and deeper hydrogeological flows.
Comment on “Nested stochastic simulation algorithm for chemical kinetic systems with disparate rates” [J. Chem. Phys. 123, 194107 (2005)]
Authors: Gillespie D. T. , Petzold L. R. , Cao Y.
Published: April 2007

The slow-scale stochastic simulation algorithm (ssSSA) proposed by Cao et al. [J. Chem. Phys. 122, 014116 (2005)] and the nested stochastic simulation algorithm (nSSA) proposed by E et al. [J. Chem. Phys. 123, 194107 (2005)] are closely related approximate simulation procedures aimed at speeding up the stochastic simulation of stiff chemical systems, i.e., systems that evolve through fast and slow dynamical modes with the fast mode being stable. This Comment aims to clarify some misconceptions that have arisen over the relationship between the ssSSA and the nSSA as regards both their theoretical foundations and their practical implementations.
Particle simulation of bursting Alfvén modes in JT-60U
Authors: Briguglio S. , Fogaccia G. , Vlad G. , Zonca F. , Shinohara K. , Ishikawa M. , Takechi M.
Published: April 2007

The results of particle-in-cell simulations of a negative neutral beam heated Alfvén-mode experiment in the Japan Atomic Energy Research Institute Tokamak-60 Upgrade (JT-60U) [H. Ninomiya et al., Fusion Sci. Technol. 42, 7 (2002); A. Kitsunezaki et al., Fusion Sci. Technol. 42, 179 (2002)] are presented. They seem to match quite well the dynamics of the abrupt large-amplitude event (ALE) experimentally observed in the reference JT-60U discharge. The time scale and frequency spread of the ALE are well reproduced too. The issue of the weaker Alfvén fluctuation phase following the ALEs, characterized by fast frequency sweeping modes, is also investigated and an interpretation of the full JT-60U bursting-mode phenomenology is presented. Finally, the simulation tool is exploited by ad hoc synthetic diagnostics on the fast ion distribution function to get a deeper insight into the ALE nonlinear dynamics. The underlying fast-growing energetic particle mode saturates as resonant energetic ions are scattered out of the resonance region and displaced outwards. The radially displaced ions resonate with outer Alfvén modes and enhance their local drive, consistently with the “avalanche” paradigm for mode nonlinear dynamics and energetic ion transports.
Formaldehyde photodissociation: Dependence on total angular momentum and rotational alignment of the CO product
Authors: Farnum John D. , Zhang Xiubin , Bowman Joel M.
Published: April 2007

Quasiclassical trajectory calculations are reported to investigate the effects of rotational excitation of formaldehyde on the branching ratios of the fragmentation products, H2+CO and H+HCO. The results of tens of thousands of trajectories show that increased rotational excitation causes suppression of the radical channel and enhancement of the molecular channel. Decomposing the molecular channel into “direct” and “roaming” channels shows that increased rotation switches from suppressing to enhancing the roaming products across our chosen energy range. However, decomposition into these pathways is difficult because the difference between them does not appear to have a distinct boundary. A vector correlation investigation of the CO rotation shows different characteristics in the roaming versus direct channels and this difference is a potentially useful signature of the roaming mechanism, as first speculated by Kable and Houston in their experimental study of photodissociation of acetaldehyde [P. L. Houston and S. H. Kable, Proc. Nat. Acad. Sci. 103, 16079 (2006)].
Structures and stabilities of small lead oxide clusters PbmOn (m=1–4,n=1–2m)
Authors: Liu Haitao , Wang Shanying , Zhou Gang , Wu Jian , Duan Wenhui
Published: April 2007

The structures and stabilities of small lead oxide clusters PbmOn with m=1–4, n=1–2m are systematically studied using density functional theory. It is found that the lowest-energy structures of all these clusters can be obtained by the sequential oxidation of small “core” lead clusters. For Pb-rich clusters (oxygen-to-lead ratio<1), oxygen atoms favor bridge sites for Pb2On and Pb3On and surface sites for Pb4On. The lead-monoxide-like clusters (PbO)i (i=1–4) have great stability because of their significant dissociation energies and highest occupied molecular orbital–lowest unoccupied molecular orbital gaps. This suggests that they could be adopted as the building blocks of cluster-assembled materials. For O-rich clusters (oxygen-to-lead ratio>1), the grouping of oxygen atoms usually appears. It is found that the structures with a grouping of more than two oxygen atoms are unstable.
Determining the internal quantum efficiency of highly efficient polymer solar cells through optical modeling
Authors: Slooff L. H. , Veenstra S. C. , Kroon J. M. , Moet D. J. D. , Sweelssen J. , Koetse M. M.
Published: April 2007

A power conversion efficiency of 4.2% (AM1.5, 1000W∕m2) is measured for an organic solar cell based on an active layer of an alternating copolymer, containing a fluorene and a benzothiadiazole unit with two neighboring thiophene rings, and a fullerene derivative. Using optical modeling, the absorption profile in the active layer of the solar cell is calculated and used to calculate the maximum short circuit current. The calculated currents are compared with measured currents from current-voltage measurements for various film thicknesses. From this the internal quantum efficiency is estimated to be 75% at the maximum for the best device.
Social concepts are represented in the superior anterior temporal cortex
Authors: Zahn Roland , Moll Jorge , Krueger Frank , Huey Edward D. , Garrido Griselda , Grafman Jordan
Published: April 2007

Social concepts such as “tactless” or “honorable” enable us to describe our own as well as others' social behaviors. The prevailing view is that this abstract social semantic knowledge is mainly subserved by the same medial prefrontal regions that are considered essential for mental state attribution and self-reflection. Nevertheless, neurodegeneration of the anterior temporal cortex typically leads to impairments of social behavior as well as general conceptual knowledge. By using functional MRI, we demonstrate that the anterior temporal lobe represents abstract social semantic knowledge in agreement with this patient evidence. The bilateral superior anterior temporal lobes (Brodmann's area 38) are selectively activated when participants judge the meaning relatedness of social concepts (e.g., honor–brave) as compared with concepts describing general animal functions (e.g., nutritious–useful). Remarkably, only activity in the superior anterior temporal cortex, but not the medial prefrontal cortex, correlates with the richness of detail with which social concepts describe social behavior. Furthermore, this anterior temporal lobe activation is independent of emotional valence, whereas medial prefrontal regions show enhanced activation for positive social concepts. Our results demonstrate that the superior anterior temporal cortex plays a key role in social cognition by providing abstract conceptual knowledge of social behaviors. We further speculate that these abstract conceptual representations can be associated with different contexts of social actions and emotions through integration with frontolimbic circuits to enable flexible evaluations of social behavior.
Behavioral changes induced byToxoplasmainfection of rodents are highly specific to aversion of cat odors
Authors: Vyas Ajai , Kim Seon-Kyeong , Giacomini Nicholas , Boothroyd John C. , Sapolsky Robert M.
Published: April 2007

The protozoan parasiteToxoplasma gondiiblocks the innate aversion of rats for cat urine, instead producing an attraction to the pheromone; this may increase the likelihood of a cat predating a rat. This is thought to reflect adaptive, behavioral manipulation byToxoplasmain that the parasite, although capable of infecting rats, reproduces sexually only in the gut of the cat. The “behavioral manipulation” hypothesis postulates that a parasite will specifically manipulate host behaviors essential for enhancing its own transmission. However, the neural circuits implicated in innate fear, anxiety, and learned fear all overlap considerably, raising the possibility thatToxoplasmamay disrupt all of these nonspecifically. We investigated these conflicting predictions. In mice and rats, latentToxoplasmainfection converted the aversion to feline odors into attraction. Such loss of fear is remarkably specific, because infection did not diminish learned fear, anxiety-like behavior, olfaction, or nonaversive learning. These effects are associated with a tendency for parasite cysts to be more abundant in amygdalar structures than those found in other regions of the brain. By closely examining other types of behavioral patterns that were predicted to be altered we show that the behavioral effect of chronicToxoplasmainfection is highly specific. Overall, this study provides a strong argument in support of the behavioral manipulation hypothesis. Proximate mechanisms of such behavioral manipulations remain unknown, although a subtle tropism on part of the parasite remains a potent possibility.
X-ray structure analysis of a metalloprotein with enhanced active-site resolution using
in situ
x-ray absorption near edge structure spectroscopy
Authors: Arcovito Alessandro , Benfatto Maurizio , Cianci Michele , Hasnain S. Samar , Nienhaus Karin , Nienhaus G. Ulrich , Savino Carmelinda , Strange Richard W. , Vallone Beatrice , Della Longa Stefano
Published: April 2007

X-ray absorption spectroscopy is exquisitely sensitive to the coordination geometry of an absorbing atom and therefore allows bond distances and angles of the surrounding atomic cluster to be measured with atomic resolution. By contrast, the accuracy and resolution of metalloprotein active sites obtainable from x-ray crystallography are often insufficient to analyze the electronic properties of the metals that are essential for their biological functions. Here, we demonstrate that the combination of both methods on the same metalloprotein single crystal yields a structural model of the protein with exceptional active-site resolution. To this end, we have collected an x-ray diffraction data set to 1.4-Å resolution and Fe K-edge polarized x-ray absorption near edge structure (XANES) spectra on the same cyanomet sperm whale myoglobin crystal. The XANES spectra were quantitatively analyzed by using a method based on the multiple scattering approach, which yielded Fe-heme structural parameters with ±(0.02–0.07)-Å accuracy on the atomic distances and ±7° on the Fe–CN angle. These XANES-derived parameters were subsequently used as restraints in the crystal structure refinement. By combining XANES and x-ray diffraction, we have obtained an cyanomet sperm whale myoglobin structural model with a higher precision of the bond lengths and angles at the active site than would have been possible with crystallographic analysis alone.
The role of lubricin in the mechanical behavior of synovial fluid
Authors: Jay G. D. , Torres J. R. , Warman M. L. , Laderer M. C. , Breuer K. S.
Published: April 2007

Synovial fluid is a semidilute hyaluronate (HA) polymer solution, the rheology of which depends on HA–protein interactions, and lubricin is a HA-binding protein found in synovial fluid and at cartilage surfaces, where it contributes to boundary lubrication under load. Individuals with genetic deficiency of lubricin develop precocious joint failure. The role of lubricin in synovial fluid rheology is not known. We used a multiple-particle-tracking microrheology technique to study the molecular interactions between lubricin and HA in synovial fluid. Particles (200 nm mean diameter) embedded in normal and lubricin-deficient synovial fluid samples were tracked separately by using multiple-particle-tracking microrheology. The time-dependent ensemble-averaged mean-squared displacements of all of the particles were measured over a range of physiologically relevant frequencies. The mean-squared displacement correlation with time lag had slopes with values of unity for simple HA solutions and for synovial fluid from an individual who genetically lacked lubricin, in contrast to slopes with values less than unity (α ≈ 0.6) for normal synovial fluid. These data correlated with bulk rheology studies of the same samples. We found that the subdiffusive and elastic behavior of synovial fluid, at physiological shear rates, was absent in fluid from a patient who lacks lubricin. We conclude that lubricin provides synovial fluid with an ability to dissipate strain energy induced by mammalian locomotion, which is a chondroprotective feature that is distinct from boundary lubrication.
CCR9 is a homing receptor for plasmacytoid dendritic cells to the small intestine
Authors: Wendland Meike , Czeloth Niklas , Mach Nicolas , Malissen Bernard , Kremmer Elisabeth , Pabst Oliver , Förster Reinhold
Published: April 2007

Small intestine plasmacytoid dendritic cells (pDC) are poorly characterized. Here, we demonstrate that intestinal pDC show the characteristic plasma cell-like morphology, and are recognized by antibodies against B220, Ly6c, 120G8, and PDCA-1, markers that are typically expressed by pDC. Furthermore, intestinal pDC carry high levels of CCR9 and are largely absent in the intestine, but not in lung, liver, or secondary lymphoid organs of CCR9-deficient animals. Competitive adoptive transfers reveal that CCR9-deficient pDC are impaired in homing to the small intestine after i.v. transfer. In a model of cholera toxin-induced gut inflammation, pDC are recruited to the intestine in WT but not CCR9-deficient animals. Furthermore, after oral application of a Toll-like receptor (TLR) 7/8 ligand, myeloid DC of the lamina propria are rapidly mobilized in WT but not in CCR9-deficient animals. Mobilization of myeloid DC can be completely rescued by adoptively transferred WT pDC to CCR9-deficient mice before oral challenge. Together, our data reveal an essential role for CCR9 in the homing of pDC to the intestine under homeostatic and inflammatory conditions and demonstrate an important role for intestinal pDC for the rapid mobilization of lamina propria DC.
Phosphoproteomic identification of targets of the
Arabidopsis
sucrose nonfermenting-like kinase SnRK2.8 reveals a connection to metabolic processes
Authors: Shin Ryoung , Alvarez Sophie , Burch Adrien Y. , Jez Joseph M. , Schachtman Daniel P.
Published: April 2007

SnRK2.8 is a member of the sucrose nonfermenting-related kinase family that is down-regulated when plants are deprived of nutrients and growth is reduced. When this kinase is over expressed in
Arabidopsis
, the plants grow larger. To understand how this kinase modulates growth, we identified some of the proteins that are phosphorylated by this kinase. A new phosphoproteomic method was used in which total protein from plants overexpressing the kinase was compared with total protein from plants in which the kinase was inactivated. Protein profiles were compared on two-dimensional gels following staining by a dye that recognizes phosphorylated amino acids. Candidate target proteins were confirmed with
in vitro
phosphorylation assays, using the kinase and target proteins that were purified from
Escherichia coli
. Seven target proteins were confirmed as being phosphorylated by SnRK2.8. Certain targets, such as 14-3-3 proteins, regulate as yet unidentified proteins, whereas other targets, such as glyoxalase I and ribose 5-phosphate isomerase, detoxify byproducts from glycolysis and catalyze one of the final steps in carbon fixation, respectively. Also, adenosine kinase and 60S ribosomal protein were confirmed as targets of SnRK2.8. Using mass spectrometry, we identified phosphorylated residues in the SnRK2.8, the 14-3-3κ, and the 14-3-3χ. These data show that the expression of
SnRK2.8
is correlated with plant growth, which may in part be due to the phosphorylation of enzymes involved in metabolic processes.
Regulation of late B cell differentiation by intrinsic IKKα-dependent signals
Authors: Mills David M. , Bonizzi Giuseppina , Karin Michael , Rickert Robert C.
Published: April 2007

NF-κB-inducing kinase (NIK)-mediated IKKα phosphorylation activates the alternative NF-κB pathway, which is characterized by nuclear translocation of p52:RelB heterodimers. This alternative pathway is initiated by a select few receptors, including LT-βR, BAFF-R, and CD40. Although NIK, IKKα, and p52 are all critical regulators of LT-βR signaling in stromal cells during humoral immune responses, lymphocytes require NIK, but not p52, for optimal Ig production. This disparity suggests that NIK possesses critical cell-type-specific functions that do not depend on NF-κB. Here we use mice bearing targeted mutations of the IKKα activation loop Ser176/180(IKKαAA) to address the B cell-intrinsic functions of NIK–IKKα signalingin vivo. We find that IKKαAAB cells mount normal primary antibody responses but do not enter germinal centers. This defect likely derives from ineffective early T–B cell collaboration and leads to impaired generation of humoral memory and relatively short-lived, low-affinity antibody production. Our findings contrast with those obtained by using p52−/−B cells, which mount normal Ig responses, and alymphoplasia (NIK mutant) B cells, which produce very little primary Ig. Thus, the NIK–IKKα–p52 axis is not as linear and exclusive as previous studies suggest, and IKKα possesses critical NF-κB-independent functions in B cells.
DNA-nanotube-induced alignment of membrane proteins for NMR structure determination
Authors: Douglas Shawn M. , Chou James J. , Shih William M.
Published: April 2007

Membrane proteins are encoded by 20–35% of genes but represent <1% of known protein structures to date. Thus, improved methods for membrane-protein structure determination are of critical importance. Residual dipolar couplings (RDCs), commonly measured for biological macromolecules weakly aligned by liquid-crystalline media, are important global angular restraints for NMR structure determination. For α-helical membrane proteins >15 kDa in size, Nuclear-Overhauser effect-derived distance restraints are difficult to obtain, and RDCs could serve as the main reliable source of NMR structural information. In many of these cases, RDCs would enable full structure determination that otherwise would be impossible. However, none of the existing liquid-crystalline media used to align water-soluble proteins are compatible with the detergents required to solubilize membrane proteins. We report the design and construction of a detergent-resistant liquid crystal of 0.8-μm-long DNA-nanotubes that can be used to induce weak alignment of membrane proteins. The nanotubes are heterodimers of 0.4-μm-long six-helix bundles each self-assembled from a 7.3-kb scaffold strand and >170 short oligonucleotide staple strands. We show that the DNA-nanotube liquid crystal enables the accurate measurement of backbone N
H
and C
α
H
α
RDCs for the detergent-reconstituted ζ-ζ transmembrane domain of the T cell receptor. The measured RDCs validate the high-resolution structure of this transmembrane dimer. We anticipate that this medium will extend the advantages of weak alignment to NMR structure determination of a broad range of detergent-solubilized membrane proteins.
The role of CaMKII as an F-actin-bundling protein crucial for maintenance of dendritic spine structure
Authors: Okamoto Ken-Ichi , Narayanan Radhakrishnan , Lee Sang H. , Murata Kazuyoshi , Hayashi Yasunori
Published: April 2007

Ca
2+
-calmodulin-dependent protein kinase II (CaMKII) is a serine/threonine protein kinase critically involved in synaptic plasticity in the brain. It is highly concentrated in the postsynaptic density fraction, exceeding the amount of any other signal transduction molecules. Because kinase signaling can be amplified by catalytic reaction, why CaMKII exists in such a large quantity has been a mystery. Here, we provide biochemical evidence that CaMKII is capable of bundling F-actin through a stoichiometric interaction. Consistent with this evidence, in hippocampal neurons, RNAi-mediated down-regulation of CaMKII leads to a reduction in the volume of dendritic spine head that is mediated by F-actin dynamics. An overexpression of CaMKII slowed down the actin turnover in the spine head. This activity was associated with β subunit of CaMKII in a manner requiring its actin-binding and association domains but not the kinase domain. This finding indicates that CaMKII serves as a central signaling molecule in both functional and structural changes during synaptic plasticity.
Myosin VI is required for sorting of AP-1B–dependent cargo to the basolateral domain in polarized MDCK cells
Authors: Au Josephine Sui-Yan , Puri Claudia , Ihrke Gudrun , Kendrick-Jones John , Buss Folma
Published: April 2007

In polarized epithelial cells, newly synthesized membrane proteins are delivered on specific pathways to either the apical or basolateral domains, depending on the sorting motifs present in these proteins. Because myosin VI has been shown to facilitate secretory traffic in nonpolarized cells, we investigated its role in biosynthetic trafficking pathways in polarized MDCK cells. We observed that a specific splice isoform of myosin VI with no insert in the tail domain is required for the polarized transport of tyrosine motif containing basolateral membrane proteins. Sorting of other basolateral or apical cargo, however, does not involve myosin VI. Site-directed mutagenesis indicates that a functional complex consisting of myosin VI, optineurin, and probably the GTPase Rab8 plays a role in the basolateral delivery of membrane proteins, whose sorting is mediated by the clathrin adaptor protein complex (AP) AP-1B. Our results suggest that myosin VI is a crucial component in the AP-1B–dependent biosynthetic sorting pathway to the basolateral surface in polarized epithelial cells.
A distal effect of microsomal triglyceride transfer protein deficiency on the lysosomal recycling of CD1d
Authors: Sagiv Yuval , Bai Li , Wei Datsen G. , Agami Reuven , Savage Paul B. , Teyton Luc , Bendelac Albert
Published: April 2007

Microsomal triglyceride transfer protein (MTP) is an endoplasmic reticulum (ER)–resident lipid transfer protein involved in the biosynthesis and lipid loading of apolipoprotein B. MTP was recently suggested to directly regulate the biosynthesis of the MHC I–like, lipid antigen presenting molecule CD1d, based on coprecipitation experiments and lipid loading assays. However, we found that the major impact of MTP deficiency occurred distal to the ER and Golgi compartments. Thus, although the rates of CD1d biosynthesis, glycosylation maturation, and internalization from the cell surface were preserved, the late but essential stage of recycling from lysosome to plasma membrane was profoundly impaired. Likewise, functional experiments indicated defects of CD1d-mediated lipid presentation in the lysosome but not in the secretory pathway. These intriguing findings suggest a novel, unexpected role of MTP at a late stage of CD1d trafficking in the lysosomal compartment.
Importance of group X–secreted phospholipase A2 in allergen-induced airway inflammation and remodeling in a mouse asthma model
Authors: Henderson William R. , Chi Emil Y. , Bollinger James G. , Tien Ying-tzang , Ye Xin , Castelli Luca , Rubtsov Yuri P. , Singer Alan G. , Chiang Gertrude K.S. , Nevalainen Timo , Rudensky Alexander Y. , Gelb Michael H.
Published: April 2007

Arachidonic acid metabolites, the eicosanoids, are key mediators of allergen-induced airway inflammation and remodeling in asthma. The availability of free arachidonate in cells for subsequent eicosanoid biosynthesis is controlled by phospholipase A2s (PLA2s), most notably cytosolic PLA2-α. 10 secreted PLA2s (sPLA2s) have also been identified, but their function in eicosanoid generation is poorly understood. We investigated the role of group X sPLA2 (sPLA2-X), the sPLA2 with the highest in vitro cellular phospholipolysis activity, in acute and chronic mouse asthma models in vivo. The lungs of sPLA2-X−/− mice, compared with those of sPLA2-X+/+ littermates, had significant reduction in ovalbumin-induced infiltration by CD4+ and CD8+ T cells and eosinophils, goblet cell metaplasia, smooth muscle cell layer thickening, subepithelial fibrosis, and levels of T helper type 2 cell cytokines and eicosanoids. These data direct attention to sPLA2-X as a novel therapeutic target for asthma.
In Defense of Comparative Statics: Specifying Empirical Tests of Models of Strategic Interaction
Authors: Carrubba Clifford J. , Yuen Amy , Zorn Christopher
Published: April 2007

Beginning in 1999, Curtis Signorino challenged the use of traditional logits and probits analysis for testing discrete-choice, strategic models. Signorino argues that the complex parametric relationships generated by even the simplest strategic models can lead to wildly inaccurate inferences if one applies these traditional approaches. In their stead, Signorino proposes generating stochastic formal models, from which one can directly derive a maximum likelihood estimator. We propose a simpler, alternative methodology for theoretically and empirically accounting for strategic behavior. In particular, we propose carefully and correctly deriving one's comparative statics from one's formal model, whether it is stochastic or deterministic does not particularly matter, and using standard logit or probit estimation techniques to test the predictions. We demonstrate that this approach performs almost identically to Signorino's more complex suggestion.
Discovery of tMAC: a Drosophila testis-specific meiotic arrest complex paralogous to Myb–Muv B
Authors: Beall Eileen L. , Lewis Peter W. , Bell Maren , Rocha Michael , Jones D. Leanne , Botchan Michael R.
Published: April 2007

The Drosophila Myb–Muv B (MMB)/dREAM complex regulates gene expression and DNA replication site-specifically, but its activities in vivo have not been thoroughly explored. In ovarian amplification-stage follicle cell nuclei, the largest subunit, Mip130, is a negative regulator of replication, whereas another subunit, Myb, is a positive regulator. Here, we identified a mutation in mip40 and generated a mutation in mip120, two additional MMB subunits. Both mutants were viable, but mip120 mutants had many complex phenotypes including shortened longevity and severe eye defects. mip40 mutant females had severely reduced fertility, whereas mip120 mutant females were sterile, substantiating ovarian regulatory role(s) for MMB. Myb accumulation and binding to polytene chromosomes was dependent on the core factors of the MMB complex. In contrast to the documented mip130 mutant phenotypes, both mip40 and mip120 mutant males were sterile. We purified Mip40-containing complexes from testis nuclear extracts and identified tMAC, a new testis-specific meiotic arrest complex that contained Mip40, Caf1/p55, the Mip130 family member, Always early (Aly), and a Mip120 family member, Tombola (Tomb). Together, these data demonstrate that MMB serves diverse roles in different developmental pathways, and members of MMB can be found in alternative, noninteracting complexes in different cell types.
The Ambiguity of Paradise Lost and Contemporary Critical Theory
Authors: Hyman Lawrence W.
Published: April 2007

When we hear someone say that Satan is the true hero of Paradise Lost or that God's ways are manifestly unjust, most of us are disturbed. We are disturbed not because such an interpretation violates our traditional feelings about God and Satan, but because it violates our sense of literary propriety. We might easily accept Satan as the hero of a novel or poem, regardless of our own feelings. What we cannot accept, or at least what most of us have been educated not to accept, is that a great writer, who is obviously in full command of his powers, could have set out to justify God's ways to men and succeed in doing the opposite. If Paradise Lost is really a great literary work, how can it fail so completely in carrying out the intention of its author? Or, if it is indeed a work which fails in doing what it has set out to do, if the narrator tells us that we should see and feel God's justice and mercy and the average reader admires Satan and feels that Adam and Eve are justified in their disobedience, how can we say that it is a great poem?
The Milton Window, The Americans, And Matthew Arnold
Authors: Parker Lois W.
Published: April 2007

“The New World honors him,“ states the verse on the stained glass panels that embellish the entrance archway at St. Margaret's Church in London. The brilliantly wrought window was given by an American, journalist George William Childs, then Editor‐in‐Chief of the Philadelphia Public Ledger,1 commemorating the Englishman who had spoken out for liberty in his own country at the same time the American colonists were just beginning their long approach to the eventual Declaration. Herein lies not only our claim to kinship with Milton, but as well a pew reserved “in perpetuity” (p. 186) for Americans at St. Margaret's. At the ceremony for unveiling the gift, however, Matthew Arnold emphasized Milton's poetic excellence, not his libertarianism.
The Magnetic Field and the Central Core of the Earth
Authors: Knopoff Leon , MacDonald Gordon J. F.
Published: April 2007

The suggestion that the inner core of the Earth is liquid and is the seat of a strong magnetic field is examined. Contrary to expectations of a magneto-hydrodynamic rigidity for the inner core, it is shown that a liquid inner core with a strong magnetic field should not transmit shear waves. The absence of the phase PKJKP in seismic records is favourable to the hypothesis of a strong magnetic field in a liquid inner core. If the jump in P wave velocity at the inner core boundary is due to a magnetic field, the strength of the field must be of the order of 5 × 106 G whether the field geometry is toroidal or random. A strong toroidal field leads to an apparent ellipticity of the inner core. No such ellipticity is observed, so that if the field in the inner core is toroidal, it must be less than 5 × 105 G. A random field does not lead to an ellipticity effect and no limit can be set on the magnitude of a random field.

The energy required for a magneto-hydrodynamic rigidity in the inner core is excessive. The magnetic energy is equally divided between the inner and outer cores. The hypothesis of a strong magnetic field in the inner core cannot explain the observed short period variations of the surface field.
Palaeogeographic Reconstruction from Palaeomagnetism
Authors: Irving E.
Published: April 2007

A method for constructing maps of the positions of the continents in the past, using palaeomagnetic results, is described. It is illustrated by using results from Europe, Australia, India, Africa and South America to provide possible reconstructions of the past positions of these continents.
Geophysics in South Africa
Authors: Hales A. L.
Published: April 2007

The scope of this review is more restricted than is suggested by the title for it deals only with those branches of fundamental geophysics which are concerned with the solid Earth.