bluuebunny/crossref_metadata_2025 huggingface dataset:
Node partition formula for directed graph reliability
Authors: Buzacott J. A.
Published: May 2007

Cut set inclusion and exclusion is a well known reliability evaluation procedure. However, many of the cut set intersection terms cancel so it can be laborious to use. In directed graphs it is shown that the number of noncancelling terms cannot exceed the number of possible ordered partitions of the set of nodes. The resulting node partition formula will still contain cancelling terms when applied to incomplete graphs. An algorithm is developed to determine the set of noncancelling terms and its application illustrated on some special classes of graphs: acyclic graphs and graphs admitting a modular decomposition.
Postman tour on a graph with precedence relation on arcs
Authors: Dror Moshe , Stern Helman , Trudeau Pierre
Published: May 2007

Since the introduction of the Chinese Postman Problem (CPP), many variations on the same theme have been developed. In this paper we examine still another variation. The arcs of the graph are partitioned and a precedence relation defined, specifying the order in which the elements of the partition have to be traversed. We first examine the conditions for a feasible solution to the problem. Next, we specify the graph properties of the precedence partition that insure a polynomial complexity solution of O(N5), where N is the number of nodes in the original graph. When the precedence relation on sets of arcs is general, we prove that the problem of finding the minimum length of feasible postman tour is NP‐complete.
A linear time algorithm to check for the existence of a rectangular dual of a planar triangulated graph
Authors: Bhasker Jayaram , Sahni Sartaj
Published: May 2007

We develop a linear time algorithm to determine if a given planar triangulated graph has a rectangular dual.
On a function for the vulnerability of a directed flow network
Authors: Sengoku Masakazu , Shinoda Shoji , Yatsuboshi Reigo
Published: May 2007

The concept of vulnerability of a network, by which we mean the susceptibility of the network to attack, is very useful for the design of networks such as computer networks and communication networks. In this paper, a directed flow network, in which a nonnegative real number called edge capacity or capacity is associated with each edge is considered. If an edge in a network is destroyed, the value of maximum flow between two vertices in the network is decreased in general. If the decrease of the value of maximum flow by the destruction is large, the degree of influence of the edge on the vulnerability of the network is considered to be large. Two indices measuring the degree of influence of an edge on the vulnerability in the above sense are proposed and their properties are studied in this paper. Furthermore, the two indices are generalized to functions measuring the degree of influence of an edge on the vulnerability in a network.
A network flow algorithm to find an elementary I/O matching
Authors: Yamada Takeo
Published: May 2007

Linnemann (Decoupling of structured systems. Syst. Contr. Lett. 1 (1981) 79‐86) proved that a linear square (m‐input, m‐output) dynamic system is structurally decouplable via a linear feedback if and only if there exists an elementary i/o matching in the graph representation of that system. This note supplements the above result by presenting an efficient network flow algorithm to find such a matching.
On graphs with signed inverses
Authors: Buckley Fred , Doty Lynne L. , Harary Frank
Published: May 2007

A graph G is called invertible if its adjacency matrix A has an inverse which is the adjacency matrix of some graph H. All such graphs were shown by Harary and Minc to have the form nK2. We now introduce signed invertible (or briefly s‐invertible) graphs G as those whose inverse H is a signed graph. We identify two infinite classes of s‐invertible graphs: the paths P2n of even order, and the corona of any graph with K1. We then characterize s‐invertible trees.
Differential expression of AQP1 in microdomain‐enriched membranes of renal cell carcinoma
Authors: Ticozzi‐Valerio Davide , Raimondo Francesca , Pitto Marina , Rocco Francesco , Bosari Silvano , Perego Roberto , Sarto Cecilia , Di Fonzo Andrea , Bosso Niccolò , Mocarelli Paolo , Galli‐Kienle Marzia , Magni Fulvio
Published: May 2007

Human aquaporin‐1 (AQP1) is the most studied member of the aquaporin family, acting as molecular water channel. It is also considered a differentiation marker for proximal renal tubular cells, from which clear cells renal cell carcinoma (RCC) originates, playing an important role in urine formation. We therefore studied AQP1 expression at the proteomic level in RCC and normal tissues, mainly focusing on microdomain‐enriched membranes in which AQP1 is highly concentrated. Subcellular fractions were prepared through differential centrifugation, and microdomain‐enriched fractions were purified from a plasma membrane‐enriched fraction by 1% Triton X‐100 treatment followed by ultracentrifugation in sucrose gradient. After SDS‐PAGE and Western blot analyses with antibodies against AQP1, lower expression levels of AQP1 isoforms were observed in each subcellular fraction of RCC compared to fractions from normal kidney tissues. The presence of AQP1 in the immunoreactive bands was verified by MALDI‐TOF‐MS and LC‐ESI‐MS/MS analysis. Glycosylation of AQP1 was also investigated using N‐glycosidase F, confirming the presence of a N‐glycosylated isoform of AQP1 in the 35–45‐kDa region. These results highlight an under‐expression of AQP1 protein and its glycosylated isoforms in homogenate and subcellular fraction obtained from RCC tissue compared to adjacent normal cortex.
Anomalous U(1)'s, Chern‐Simons couplings and the Standard Model
Authors: Anastasopoulos P.
Published: May 2007

This proceeding is based on hep‐th/0605225 and it shows that the most general anomaly related effective action contains Stückelberg, axionic and Chern‐Simons‐like couplings. Such couplings are generically non‐trivial in orientifold string vacua. A similar analysis in quantum field theories provides similar couplings. These Chern‐Simons couplings generate new signals which might be visible at LHC.
Attractor black holes and quantum distribution functions
Authors: Montañez S. , Gómez C.
Published: May 2007

Using the attractor mechanism and the wavefunction interpretation of the topological string partition function on a Calabi Yau threefold M we study the relation between the Bekenstein‐Hawking‐Wald entropy of BPS Calabi‐Yau black holes and quantum distribution functions defined on H3(M). We discuss the OSV conjecture in this context. This talk is based on [1].
Dilatation operator or Hamiltonian?
Authors: Sochichiu C.
Published: May 2007

We analyze the situation when the Hamiltonian in field theory at finite temperature can be replaced by the dilatation operator.
Gravitational theories coupled to matter as invariant theories under Kac‐Moody algebras
Authors: Tabti N.
Published: May 2007

Many recent researches indicate that several gravitational D‐dimensional theories suitably coupled to some matter fields (including in particular pure gravity in D dimensions, the low energy effective actions of the bosonic string and the bosonic sector of M‐theory) would be characterized by infinite dimensional Kac‐Moody algebras 𝒢++ and 𝒢+++. The possible existence of these extended symmetries motivates a development of a new description of gravitational theories based on these symmetries. The importance of Kac‐Moody algebras and the link between the 𝒢+++‐invariant theories and the uncompactified space‐time covariant theories are discussed.
Tensor supermultiplets and toric quaternion‐Kähler geometry
Authors: de Wit B. , Saueressig F.
Published: May 2007

We review the relation between 4n‐dimensional quaternion‐Kähler metrics with n + 1 abelian isometries and superconformal theories of n + 1 tensor supermultiplets. As an application we construct the class of eight‐dimensional quaternion‐Kähler metrics with three abelian isometries in terms of a single function obeying a set of linear second‐order partial differential equations.
Scherk‐Schwarz reductions and their quantum moduli space
Authors: Angelantonj C.
Published: May 2007

The one‐loop vacuum energy is computed for a class of perturbative string vacua where supersymmetry is spontaneously broken by a stringy Scherk‐Schwarz deformation. The spectrum of light excitations is tachyon‐free and the generated quantum potential exhibits an anti de Sitter minimum where the geometric moduli are naturally stabilised.
M‐theory compactifications on hyperbolic spaces
Authors: Orlando D.
Published: May 2007

Negatively‐curved, maximally symmetric hyperbolic spaces enjoy a number of remarkable properties that can be traced back to Riemannian geometry, group theory and algebraic geometry. In this note we recall some such properties and find Hn as M‐theory solutions. Based on a talk given at the RTN Workshop 2006, Napoli.
Matrix factorizations and D‐branes on K3
Authors: Brunner I.
Published: May 2007

We review the description of D‐branes in Landau Ginzburg models using Matrix Factorizations. A number of simple examples are discussed, the main example being Matrix factorizations for the K3 given by the quartic hypersurface in P3. We discuss deformations of matrix factorizations and their obstructions in simple cases. Based on Brunner et al., J. High Energy Phys. 0606, 015 (2006) [arXiv:hep‐th/0603196].
*‐Lie derivative, *‐covariant derivative and *‐gravity
Authors: Aschieri P.
Published: May 2007

The Lie algebra of infinitesimal diffeomorphisms on noncommutative space allows to develop differential and Riemannian noncommutative geometry. Noncommutative Einstein's gravity equations are formulated.
GaN alternating current light‐emitting device
Authors: Yen Hsi‐Hsuan , Yeh Wen‐Yung , Kuo Hao‐Chung
Published: May 2007

We report a new design of the light‐emitting device which can be operated under alternating current source directly. The new type alternating current driven light‐emitting device (AC LED) can increase the radition area in each bias direction to improve the device efficiency by the Wheatstone Bridge (WB) circuit design. WB‐AC LEDs with different designs were fabricated and the electrical and optical characteristics were measured. It is found that the efficiency of the WB‐AC LED is influenced by the varied area ratio of the rectified microchip to the central one because of the different current density and forward bias of each microchip. Additionally, the relationship between the area ratio of microchips and the wall plug efficiency of the WB‐AC LED has also been discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
N‐face high electron mobility transistors with a GaN‐spacer
Authors: Wong M. H. , Rajan S. , Chu R. M. , Palacios T. , Suh C. S. , McCarthy L. S. , Keller S. , Speck J. S. , Mishra U. K.
Published: May 2007

N‐face AlGaN (cap)/GaN (channel)/AlGaN (barrier)/GaN (buffer) high electron mobility transistors (HEMTs) provide a simple solution for strong confinement of the two‐dimensional electron gas (2DEG) from the back since carriers are induced on top of the AlGaN barrier. To reduce the adverse effects of random alloy scattering from the AlGaN barrier, an N‐face GaN‐spacer HEMT was designed with an epi‐structure consisting of an AlGaN (cap)/GaN (channel)/AlN/GaN (spacer)/AlGaN (barrier)/GaN (buffer). The 2DEG is confined at the GaN (channel)/AlN interface, while the GaN‐spacer layer separates the 2DEG from the AlGaN barrier. The large polarization‐induced electric field of the AlN and its large conduction band discontinuity with GaN provide strong confinement for good pinch‐off and low output conductance under high electric fields. Up to 20% improvement in electron mobility was measured in these devices. The devices showed a current gain cut‐off frequency (ft) of 24 GHz and power gain cut‐off frequency (fmax) of 44 GHz for a nominal gate length of 0.7 μm. An output power density of 4.5 W/mm was measured at 4 GHz, with 34% power added efficiency and a gain of 10.3 dB at a drain bias of 40 V. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Chemical susceptibility of fullerenes in view of Hartree–Fock approach
Authors: Sheka Elena F.
Published: May 2007

Constituting a part of fullerenes odd electrons which are removed from the covalent bonding (Int J Quantum Chem, 2004, 100, 375), effectively unpaired electrons are posed by the singlet instability of the unrestricted Hartree–Fock SCF solution. The feature occurs to be of a particular importance leading to a quantitative description of atomically matched chemical susceptibility of the odd‐electron molecular species via the relevant electron density on atoms. A correct determination of the total number of effectively unpaired electrons ND and its partial density NDA is well provided by the UHF solution. The calculation procedure and the obtained results reliability are justified for a set of diatomic molecules and ethylene. Practically full identity of the distribution of both NDA values and independently calculated free valence over atoms of X60 (X = C, Si) and C70 molecules makes it possible to consider the NDA maps as chemical portraits of the fullerenes. The NDA value is offered to be a quantitative pointer of the atom chemical activity thus highlighting targets, which are the most favorable for addition reactions of any type. Basic grounds for a NDA‐based computational synthesis of the fullerene derivatives are illustrated for initial steps of C60 fluorination. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
High‐performance liquid chromatography‐diode array detection/electrospray ionization mass spectrometry for the simultaneous analysis of cis‐, trans‐ and dihydro‐2‐glucosyloxycinnamic acid derivatives from Dendrobium medicinal plants
Authors: Yang Li , Nakamura Norio , Hattori Masao , Wang Zhengtao , Bligh S. W. Annie , Xu Luoshan
Published: May 2007

Sensitive, selective and reliable high‐performance liquid chromatography (HPLC)‐diode array detection (DAD)/electrospray ionization multi‐stage mass spectrometry (ESI‐MSn) methods have been developed for the characterization of nine 2‐glucosyloxycinnamic acid derivatives and quantitative analysis of three of the major 2‐glucosyloxycinnamic acids, cis‐melilotoside, trans‐melilotoside and dihydromelilotoside, present in Dendrobium medicinal plants. The identities of the latter three major 2‐glucosyloxycinnamic acids were confirmed by comparing their retention times, UV and mass spectra with those of the reference standards. The characteristic ESI‐MSn fragmentation patterns of the remaining six 2‐glucosyloxycinnamic acid derivatives, which are similar to the three major compounds, have allowed the putative elucidation of their structures. The concentrations of the cis‐, trans‐ and dihydromelilotosides were simultaneously determined by HPLC/ESI‐MS2 using the multiple reaction monitoring (MRM) mode in extracts of Dendrobium species. The method was validated with respect to the overall intra‐ and inter‐day variation (RSD less than 8%) and the limits of quantification for the cis‐, trans‐ and dihydromelilotosides were 0.09, 0.09 and 0.01 µg/mL, respectively. Copyright © 2007 John Wiley & Sons, Ltd.
Lethal and sublethal responses of an aquatic insect Culex quinquefasciatus (Diptera: Culicidae) challenged with individual and joint exposure to dissolved sodium selenate and methylmercury chloride
Authors: Jensen Peter D. , Sorensen Mary A. , Walton William E. , Trumble John T.
Published: May 2007

Pollutants rarely occur alone in the natural environment, and few studies have focused on the potential interactions between metals or metalloids. In this study an aquatic insect, the southern house mosquito (Culex quinquefasciatus: Diptera), was used to test the individual and joint effects of dissolved sodium selenate (Se) and methyl mercury chloride (MeHg). We conducted ovipositional preference tests and 14‐day chronic toxicity studies to determine lethal and sublethal responses of C. quinquefasciatus to a range of Se and MeHg concentrations and mixtures. No evidence was found for female ovipositional preference in field trials using artificial ponds. Larvae were more sensitive to MeHg than Se, with LC50 values of 30 μg/L (CI = 28–31 μg/L) and 11 mg/L (CI = 10–12 mg/L) respectively. In addition, larval survival was significantly reduced at concentrations as low as 25 μg/L of MeHg and 8 mg/L of Se. A synergistic interaction was observed in the toxicity of the Se‐MeHg mixtures to C. quinquefasciatus larvae. Larval mosquito survival was significantly reduced at 7.5 μg/L MeHg + 2.75 mg/L Se and an LC50 value of 9 μg/L MeHg + 3.4 mg/L Se was determined for a fixed ratio mixture. The rate of growth of the larvae was analyzed using a Growth Index that provided a sensitive measure of the developmental effects of toxicant exposure. Sodium selenate at concentrations as low as 2 mg/L caused a significant decrease in growth between larvae in treatment versus control solutions after only 4 days. Similarly, MeHg at concentrations as low as 25 μg/L and a Se‐MeHg mixture of 3 μg/L MeHg plus 1.1 mg/L Se caused significant growth reductions after only 2 and 3 days, respectively. These are the first reported survival and developmental data for an aquatic insect exposed to MeHg and Se‐MeHg mixtures. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 287–294, 2007.
Effect of di(n‐butyl) phthalate on testicular oxidative damage and antioxidant enzymes in hyperthyroid rats
Authors: Lee Ena , Ahn Mee Young , Kim Hee Jin , Kim In Young , Han Soon Young , Kang Tae Seok , Hong Jin Hwan , Park Kui Lea , Lee Byung Mu , Kim Hyung Sik
Published: May 2007

This study compared the effects of di(n‐butyl) phthalate (DBP) on the oxidative damage and antioxidant enzymes activity in testes of hyperthyroid rats. Hyperthyroidism was induced in pubertal male rats by intraperitoneal injection of triiodothyronine (T3, 10 μg/kg body weight) for 30 days. An oral dose of DBP (750 mg/kg) was administered simultaneously to normal or hyperthyroid (T3) rats over a 30‐day period. No changes in body weight were observed in the hyperthyroid groups (T3, T3 + DBP) compared with controls. There were significantly higher serum T3 levels observed in the hyperthyroid rats than in the control, but the serum thyroid stimulating hormone levels were markedly lower in the hyperthyroid rats. DBP significantly decreased the weight of the testes in the normal (DBP) and hyperthyroid (T3 + DBP) groups. The serum testosterone concentrations were significantly lower in only DBP group. DBP significantly increased the 8‐hydroxy‐2‐deoxyguanosine (8‐OHdG) level in the testes, whereas the DBP‐induced 8‐OHdG levels were slightly higher in T3 + DBP group. Superoxide dismutase and glutathione peroxidase activities were significantly higher in the testes of the DBP or T3 + DBP groups. Catalase (CAT) activity was significantly higher in the DBP treatment group, but the T3 + DBP group showed slightly lower DBP‐induced CAT activity. The testicular expression of thyroid hormone receptor α‐1 (TRα‐1) was significantly higher in the DBP groups, and androgen receptor (AR) expression was not detected in the DBP treatment group. In addition, DBP significantly increased the peroxisome proliferator‐activated receptor‐r (PPAR‐r) levels in the testis. These results suggest that hyperthyroidism can cause a change in the expression level of PPAR‐r in testes, and may increase the levels of oxidative damage induced by the metabolic activation of DBP. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 245–255, 2007.
Bioaccumulation and ROS generation in liver of freshwater fish, goldfish Carassius auratus under HC Orange No. 1 exposure
Authors: Sun Yuanyuan , Yin Ying , Zhang Jingfei , Yu Hongxia , Wang Xiaorong
Published: May 2007

HC Orange No. 1 (CAS No. 54381‐08‐7, 2‐nitro‐4′‐hydroxydiphenylamine) is used as a color additive in hair dyes. In this study, laboratory experiment was carried out to determine HC Orange No. 1 bioaccumulation and oxidative stress in the liver of freshwater fish, goldfish Carassius auratus. Fish were exposed to different concentrations (0.05, 0.1, 0.2, 0.5, and 1.0 mg/L) of HC Orange No. 1 for 10 days, with one group assigned as control. The accumulation of HC Orange No. 1 in liver increased with the exposure concentration (R2 = 0.94). A secondary spin trapping technique was used followed by electron paramagnetic resonance (EPR) analysis to study the reactive oxygen species (ROS) production. On the basis of the hyperfine splitting constants and shape of the EPR spectrum, the ROS generated in fish liver after exposure was identified as hydroxyl radical (•OH). There is a good correlation between the exposure concentrations and •OH generation (R2 = 0.92). The •OH signal intensity of the EPR spectrum showed a significant increase (P < 0.05) when the HC Orange No. 1 concentration was 1.0 mg/L, compared with that of the control. A good positive relationship (R2 = 0.95) was found between the •OH formation and accumulation level of HC Orange No. 1 in liver. The changes of the activities of catalase (CAT), superoxide dismutase (SOD), glutathione S‐transferase (GST), and contents of reduced glutathione (GSH) were also detected. These observations indicated a possible mechanism of oxidative stress induced by HC Orange No. 1 on fish. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 256–263, 2007.
Engineering volatile thiol release in Saccharomyces cerevisiae for improved wine aroma
Authors: Swiegers Jan H. , Capone Dimitra L. , Pardon Kevin H. , Elsey Gordon M. , Sefton Mark A. , Francis I. Leigh , Pretorius Isak S.
Published: May 2007

Volatile thiols, such as 4‐mercapto‐4‐methylpentan‐2‐one (4MMP), 3‐mercaptohexan‐1‐ol (3MH) and 3‐mercaptohexyl acetate (3MHA), are among the most potent aroma compounds found in wine and can have a significant effect on wine quality and consumer preferences. At optimal concentrations in wine, these compounds impart flavours of passionfruit, grapefruit, gooseberry, blackcurrant, lychee, guava and box hedge. The enzymatic release of aromatic thiols from grape‐derived, non‐volatile cysteinylated precursors (Cys‐4MMP and Cys‐3MH) and the further modification thereof (conversion of 3MH into 3MHA) during fermentation, enhance the varietal characters of wines such as Sauvignon Blanc. Wine yeast strains have limited and varying capacities to produce aroma‐enhancing thiols from their non‐volatile counterparts in grape juice. Even under optimal fermentation conditions, the most efficient thiol‐releasing Saccharomyces cerevisiae wine strain known realizes less than 5% of the thiol‐related flavour potential of grape juice. The objective of this study was to develop a wine yeast able to unleash the untapped thiol aromas in grape juice during winemaking. To achieve this goal, the Escherichia coli tnaA gene, encoding a tryptophanase with strong cysteine‐β‐lyase activity, was cloned and overexpressed in a commercial wine yeast strain under the control of the regulatory sequences of the yeast phosphoglycerate kinase I gene (PGK1). This modified strain expressing carbon–sulphur lyase activity released up to 25 times more 4MMP and 3MH in model ferments than the control host strain. Wines produced with the engineered strain displayed an intense passionfruit aroma. This yeast offers the potential to enhance the varietal aromas of wines to predetermined market specifications. Copyright © 2007 John Wiley & Sons, Ltd.
A methodology to model spatially distributed uncertainties in thin‐walled structures
Authors: Machina G. , Zehn M.W.
Published: May 2007

In modern engineering structures, light weight and thin walled composite parts play an important role. The thin walled composite and other structural elements show uncertainties in material properties and in geometry (e.g., wall thickness) among other due to the manufacturing process. These uncertainties are generally spatially distributed in nature, which cannot be reduced by any refined discretization. To obtain information about the distribution of system responses, the uncertainties have to be included in the modelling and calculation. The implementation of these parameters into finite element (FE) models requires a statistical approach. From our research and experience, the variogram method is the tool to model different types of spatially distributed uncertainties. However, the application of the variogram approach is quite common procedure in various fields but it is still widely unknown in mechanical engineering. This paper presents some theoretical background for the application of variogram method to thin walled composite and other structures, as basis for the implementation of the simulated parameters into FE models.
Evaluating Mitochondrial Membrane Potential in Cells
Authors: Solaini Giancarlo , Sgarbi Gianluca , Lenaz Giorgio , Baracca Alessandra
Published: May 2007

Permeant cationic fluorescent probes are widely employed to monitor mitochondrial transmembrane potential and its changes. The application of such potential-dependent probes in conjunction with both fluorescence microscopy and fluorescence spectroscopy allows the monitoring of mitochondrial membrane potential in individual living cells as well as in large population of cells. These approaches to the analysis of membrane potential is of extremely high value to obtain insights into both the basic energy metabolism and its dysfunction in pathologic cells. However, the use of fluorescent molecules to probe biological phenomena must follow the awareness of some principles of fluorescence emission, quenching, and quantum yield since it is a very sensitive tool, but because of this extremely high sensitivity it is also strongly affected by the environment. In addition, the instruments used to monitor fluorescence and its changes in biological systems have also to be employed with cautions due to technical limits that may affect the signals. We have therefore undertaken to review the most currently used analytical methods, providing a summary of practical tips that should precede data acquisition and subsequent analysis. Furthermore, we discuss the application and feasibility of various techniques and discuss their respective strength and weakness.
Late Holocene environmental reconstruction using cave sediments from Belize
Authors: Polk Jason S. , van Beynen Philip E. , Reeder Philip P.
Published: May 2007

Cave sediments collected from Reflection Cave on the Vaca Plateau, Belize show variations in the δ13C values of their fulvic acids (FAs), which indicate periods of vegetation change caused by climatic and Maya influences during the late Holocene. The δ13C values range from − 27.11‰ to − 21.52‰, a shift of ∼ 5.59‰, which suggests fluctuating contributions of C3 and C4 plants throughout the last 2.5 ka, with C4 plant input reflecting periods of Maya agriculture. Maya activity in the study area occurred at different intensities from ∼ 2600 cal yr BP until ∼ 1500 cal yr BP, after which agricultural practices waned as the Maya depopulated the area. These changes in plant assemblages were in response to changes in available water resources, with increased aridity leading to the eventual abandonment of agricultural areas. The Ix Chel archaeological site, located in the study area, is a highland site that would have been among the first agricultural settlements to be affected during periods of aridity. During these periods, minimal water resources would have been available in this highly karstified, well-drained area, and supplemental groundwater extraction would have been difficult due to the extreme depth of the water table.
Urine flavonoids and plasma carotenoids in the validation of fruit, vegetable and tea intake during pregnancy in the Norwegian Mother and Child Cohort Study (MoBa)
Authors: Brantsæter Anne Lise , Haugen Margaretha , Rasmussen Salka E , Alexander Jan , Samuelsen Sven Ove , Meltzer Helle Margrete
Published: May 2007

Objective

To validate a new food-frequency questionnaire (FFQ) for measuring the intake of fruit, vegetables and tea reported by women participating in the Norwegian Mother and Child Cohort Study (MoBa).

Design

Intake of fruits, vegetables and tea estimated by the FFQ was compared with urinary flavonoid excretion, plasma carotenoid concentration and intake measured by a 4-day weighed food diary (FD). The triangular method was applied to calculate FFQ validity coefficients using two independent biomarkers.

Setting and subjects

One hundred and nineteen women participating in MoBa.

Results

The FFQ estimate of fruit intake was significantly correlated with urine phloretin (r = 0.33), citrus fruit/juice with urine hesperetin (r = 0.44), cooked vegetables with plasma α-carotene (r = 0.37), and tea with urine kaempferol (r = 0.41) (P < 0.01 for all). On average, 60% of the participants fell into the same or adjacent quintiles when classified by FFQ and biomarkers. Significant correlations between the FFQ and FD were found for fruit (r = 0.39), vegetables (r = 0.34), juices (r = 0.50) and tea (r = 0.53). The FFQ validity coefficient was 0.65 for citrus fruit/juice and 0.59 for cooked vegetables as calculated by the triangular method.

Conclusions

The validation study shows that the MoBa FFQ can be used to estimate fruit, juice, vegetable and tea intake in pregnant Norwegian women, and to rank individuals within the distribution.
A case of empire envy? German Jesuits meet an Asian mystic in Spanish America
Authors: Strasser Ulrike
Published: May 2007

This essay deals with the hagiographic afterlife of Catarina de San Juan, the seventeenth-century slave from Asia who became a renowned mystic in colonial Mexico, in writings by German Jesuits, notably Joseph Stöcklein’s popular Welt-Bott. Why and how was Catarina de San Juan’s story told for a German-speaking audience in Central Europe? The specific German appropriations of her vita suggest that missionary writings could serve as a transmission belt for ‘colonial fantasies’, linking the early modern period when the Holy Roman Empire did not have colonies to the modern period when the German Nation acquired colonial holdings in the Pacific.
Africa and the globalization process: western Africa, 1450–1850
Authors: Inikori Joseph E.
Published: May 2007

The article examines the debate on globalization as a historical process and provides a context for the assessment of western Africa’s long-run contribution to the process, the main subject of the article. It argues that the process began in the Atlantic basin in the sixteenth century; in the nineteenth, it gave rise to an integrated Atlantic economy, the nucleus of the modern global economy. The process involved the transformation of the predominantly subsistence economies of the Atlantic basin in 1450 to market-based economies before their integration by the Atlantic market could occur. Large-scale specialization of the plantation and mining economies of the Americas was central to the transformation process. Because of abundant land, large-scale plantation agriculture in the Americas was made possible by coerced African labour. In the end, the unique characteristics of the export slave trade that supplied coerced African labour to the Americas retarded the development of the market economy in western Africa and kept the region’s economies out of the integrated commodity production processes of the Atlantic economy until that trade ended in the mid-nineteenth century. The analysis of the commercializing process in the Atlantic basin and its causal link to England’s Industrial Revolution, with its new technologies, and to the establishment of the integrated nineteenth-century Atlantic economy presents a powerful argument that places Africa at the centre stage of the globalization process
India in the early modern world economy: modes of production, reproduction and exchange
Authors: Washbrook David
Published: May 2007

India played a leading role in the growth of the early modern world economy. Yet its historiography has been dominated by forebodings of the colonial conquest and decline, which were to overtake it at the end of the eighteenth century. This essay seeks to explore the strengths rather than weaknesses of the Indian economy between the sixteenth and eighteenth centuries when the goods which it produced were in heavy demand in Asia, Africa, Europe and the Americas. However, it also points to ways in which specific features of India’s commercial development created vulnerabilities to conquest from overseas, which would be exploited later on.
Toward elucidating the microstructure of warm rainfall: A survey
Authors: Testik F. Y. , Barros Ana P.
Published: May 2007

Quantitative measurement, estimation, and prediction of precipitation remains one of the grand challenges in the hydrological and atmospheric sciences with far‐reaching implications across the natural sciences. Although the roots of current research activity in this topic go back to the beginning of the twentieth century, advances in radar technology and in numerical modeling have provided the impetus for prolific research in the area of cloud and precipitation physics over the last 50 years. As radar rainfall measurements progressively became the staple of hydrometeorological observing systems, cloud and precipitation microphysics emerged as increasingly preeminent areas of research. Here we present a synthesis of the state of the science with respect to the physical dynamics of hydrometeors and, specifically, the transient processes that affect the temporal evolution of rainfall microstructure and that are directly relevant to the quantitative interpretation of radar rainfall measurements and explicit numerical simulations. The focus of our survey is on raindrop morphodynamics (equilibrium raindrop shape and raindrop oscillations), drop‐drop interactions (bounce, coalescence, and breakup), and the dynamical evolution of raindrop size distributions in precipitating clouds.
A potential pollen proxy for ENSO derived from the Sajama ice core
Authors: Liu Kam‐Biu , Reese Carl A. , Thompson Lonnie G.
Published: May 2007

An annually resolved pollen record spanning a 39‐year period (1958–1996) from the Sajama Ice Cap, located on the western Bolivian Altiplano, reveals significant interannual variations in both pollen concentration and composition. The pollen assemblages within the annual layers are dominated by typical Altiplano taxa, especially Poaceae and Asteraceae. On an annual basis the pollen concentrations are strongly negatively correlated (Pearson's r = −0.716) with the Southern Oscillation Index (SOI). Studies from Sajama and other tropical ice caps have shown that during El Niño years, the weather on the Altiplano is decidedly warmer and drier, which enhances ablation on tropical ice caps through increased sublimation. This process results in the concentration of pollen within an annual layer, and thus provides a mechanism to reconstruct past El Niño events, so long as annual resolution is obtainable within the ice core.
Global Pc5 pulsations observed at unusually low L during the great magnetic storm of 24 March 1991
Authors: Lee E. A. , Mann I. R. , Loto’aniu T. M. , Dent Z. C.
Published: May 2007

Using CANOPUS, GREENLAND, IMAGE, SAMNET, and 210 MM ground‐based magnetometer array data, we examine the global characteristics of ULF waves during the onset day of the great magnetic storm of 24 March 1991. We focus on the main phase in the period of decreasing Dst and investigate the characteristics of discrete frequency Pc5 pulsations. Pc5 pulsations with multiple discrete spectral peaks including a 2.8 mHz pulsation were seen at 0815–0915 UT, and a monochromatic 1.9 mHz wave appeared at 1010–1110 UT. Also, a very monochromatic and large‐amplitude 1.7 mHz wave was observed at 1200–1340 UT across a wide range of dayside local times and at unusually low latitudes. We have analyzed the amplitude and phase relationships of waves at these frequencies. The 2.8 mHz, 1.9 mHz, and 1.7 mHz spectral peaks have maximum amplitudes at L = 3.6, L = 4, and L = 4.3, respectively, and exhibit the characteristic features of field line resonances (FLRs). The discrete mHz frequencies are consistent with some of the discrete peaks seen by Samson et al. (1992) and support the hypothesis of the existence of MHD cavity or waveguide modes in the magnetosphere. However, our results show evidence for the penetration of ULF wave power in the Pc5 band to much lower L‐values than normal, suggesting a significant reduction of the local Alfvén eigenfrequency continuum as compared to nonstorm times. This may have considerable significance for the interaction between ULF waves and MeV electrons in the outer radiation belt during storms.
Crustal deformation across the Sierra Nevada, northern Walker Lane, Basin and Range transition, western United States measured with GPS, 2000–2004
Authors: Hammond William C. , Thatcher Wayne
Published: May 2007

Global Positioning System (GPS) data collected in campaigns in 2000 and 2004 were processed and interpreted with other GPS data in the western Basin and Range province to provide new constraints on the rate, style, and pattern of deformation of the central and northern Walker Lane (WL), which lies near the western boundary of the Basin and Range. Across the central WL, near 38°N latitude, the velocities with respect to North America increase westward by ∼10 mm/yr inducing dextral shear. Farther north between 40° and 41°N latitude, a western zone of ∼7 mm/yr relative motion undergoes dextral shear, and an eastern zone of ≤3 mm/yr relative motion undergoes extension and shear. These data show that the northern WL is essentially a dextral shear zone experiencing minor net dilatation (ɛΔ = 2.6 ± 0.8 nstrain/yr). Near most Holocene normal faults, dilatation inferred from the velocity field is not greater than the uncertainties. However, near the central Nevada seismic belt we detect significant dilatation expressed as extension in a direction approximately normal to the range fronts (ɛΔ = 23.0 ± 3.9 nstrain/yr), some of which is attributable to transient postseismic deformation following large historic earthquakes. A block model constrained by velocities corrected for transient effects shows that the sum of dextral slip rates across the Honey Lake, Warm Springs, east Pyramid fault system, and Mohawk Valley faults is ∼7 mm/yr. The WL is a zone whose width and dilatation rate increase northwestward, consistent with counterclockwise rotation of the Sierra Nevada microplate and transfer of deformation into the Pacific Northwest.
Permeability‐porosity relationships in seafloor vent deposits: Dependence on pore evolution processes
Authors: Zhu Wenlu , Tivey Margaret K. , Gittings Hilary , Craddock Paul R.
Published: May 2007

Systematic laboratory measurements of permeability and porosity were conducted on three large vent structures from the Mothra Hydrothermal vent field on the Endeavor segment of the Juan de Fuca Ridge. Geometric means of permeability values obtained from a probe permeameter are 5.9 × 10−15 m2 for Phang, a tall sulfide‐dominated spire that was not actively venting when sampled; 1.4 × 10−14 m2 for Roane, a lower‐temperature spire with dense macrofaunal communities growing on its sides that was venting diffuse fluid of <300°C; and 1.6 × 10−14 m2 for Finn, an active black smoker with a well‐defined inner conduit that was venting 302°C fluids prior to recovery. Twenty‐three cylindrical cores were then taken from these vent structures. Permeability and porosity of the drill cores were determined on the basis of Darcy's law and Boyle's law, respectively. Permeability values range from ∼10−15 to 10−13 m2 for core samples from Phang, from ∼10−15 to 10−12 m2 for cores from Roane, and from ∼10−15 to 3 × 10−13 m2 for cores from Finn, in good agreement with the probe permeability measurements. Permeability and porosity relationships are best described by two different power law relationships with exponents of ∼9 (group I) and ∼3 (group II). Microstructural analyses reveal that the difference in the two permeability‐porosity relationships reflects different mineral precipitation processes as pore space evolves within different parts of the vent structures, either with angular sulfide grains depositing as aggregates that block fluid paths very efficiently (group I), or by late stage amorphous silica that coats existing grains and reduces fluid paths more gradually (group II). The results suggest that quantification of permeability and porosity relationships leads to a better understanding of pore evolution processes. Correctly identifying permeability and porosity relationships is an important first step toward accurately estimating fluid distribution, flow rate, and environmental conditions within seafloor vent deposits, which has important consequences for chimney growth and biological communities that reside within and on vent structures.
Observed horizontal temperature advection by tropical instability waves
Authors: Jochum Markus , Cronin Meghan F. , Kessler William S. , Shea Dennis
Published: May 2007

Velocity data from moored current meters is combined with satellite sea surface temperature (SST) to compute oceanic mixed layer temperature advection by tropical instability waves (TIWs). For the years 2002 to 2005 it is found that this process heats the equatorial mixed layer at an annual mean rate of +0.8°C/month at 0°N, 140°W; and +2.8°C/month at 0°N, 110°W. At 0°N, 110°W, approximately 25% of the heating is contributed by zonal temperature advection, a process that has often been assumed to be negligible. From a nine month segment of data (May 2004–February 2005), the zonal temperature advection at 2°N, 140°W has been estimated to be approximately 0.7°C/month, much larger than the equatorial value for the same time period. Thus, the data supports a recent hypothesis that tropical instability waves contribute a significant mean zonal temperature advection with off‐equatorial maxima to the equatorial mixed‐layer heat budget. Comparisons with numerical model results suggest that current ocean general circulation models can realistically simulate important aspects of tropical eddy‐mixed layer interactions.
Climate change consequences on the biome distribution in tropical South America
Authors: Salazar Luis F. , Nobre Carlos A. , Oyama Marcos D.
Published: May 2007

We studied the consequences of projected climate change on biome distribution in South America in the 21st century by forcing a potential vegetation model with climate scenarios from 15 climate models for two emission scenarios (A2 and B1). This analysis was carried out for the savanna and tropical forest biomes, which are the predominant biomes in tropical South America. In both scenarios, the results indicate reduction of tropical forest cover areas which would be replaced by savannas. This reduction of tropical forests increases with the time through the end of the 21st century, mostly over southeastern Amazonia. Considering the biome changes from current potential vegetation in the case when at least 75% of the calculations agree on the projected biome change (consensus), the decrease of the tropical forest area in South America is 3% for the period 2020–2029, 9% for 2050–2059 and 18% for 2090–2099 for the A2 emission scenario.
Characterization and optoelectronic properties of p-type N-doped CuAlO2 films
Authors: Yu Ruei-Sung , Liang Shih-Chang , Lu Chih-Jung , Tasi Du-Cheng , Shieu Fuh-Sheng
Published: May 2007

This letter reports a technique for increasing the carrier concentration and the conductivity of the p-type CuAlO2 through doping the material with nitrogen. The x-ray photoelectron spectroscopy and the optical band gap analyses suggested that the nitrogen atoms occupying the interstitial sites of the delafossite structure provided the p-type CuAlO2 with an impurity energy level in the energy gap. It was also found that the N-doped CuAlO2 film had its optimum conduction properties when the dopant level reached 1.1at.%. Here, the carrier concentration was raised from 4.81×1016 in the undoped film to 2.13×1017cm−3 in the doped film, and the corresponding film’s conductivity was increased from 3.8×10−2to5.4×10−2(Ωcm)−1, as compared with the undoped CuAlO2 film.
A variable temperature Fe3+ electron paramagnetic resonance study of Sn1−xFexO2 (0.00⩽x⩽0.05)
Authors: Misra S. K. , Andronenko S. I. , Reddy K. M. , Hays J. , Thurber A. , Punnoose A.
Published: May 2007

X -band (∼9.5GHz) electron paramagnetic resonance (EPR) studies of Fe3+ ions in Sn1−xFexO2 powders with 0.00⩽x⩽0.05 at various temperatures (5–300K) are reported. These samples are interesting to investigate as Fe doping (⩽5%) produces ferromagnetism in SnO2 [A. Punnooose et al., Phys. Rev. B 72, 054402 (2005)], making it a promising ferromagnetic semiconductor at room temperature. The EPR spectrum at 5K can be simulated reasonably well as the overlap of spectra due to seven magnetically inequivalent Fe3+ ions: four low-spin (S=1∕2) and three high-spin (S=5∕2) ions, characterized by different spin-Hamiltonian parameters, overlapped by three broad ferromagnetic resonance spectra. The three high-spin ions, situated substitutionally in the interior of nanodomains, are characterized by smaller zero-field splitting (ZFS) parameters D and E, so that all their energy levels are populated at 5K. On the other hand, the four low-spin ions are situated interstitially at the surfaces of nanodomains. They are characterized by much larger ZFS, so that only their lowest Kramers doublets are occupied at 5K. Based on this simulation, it is concluded that the observed spectra at different temperatures can be reproduced by changing appropriately the relative overlaps of the various paramagnetic and ferromagnetic characters, which remain present over the temperature range studied.
Magnetic properties and magnetocaloric effect around phase boundary in La(FexAl1−x)13 compounds
Authors: Hu F. X. , Shen B. G. , Sun J. R. , Wang G. J. , Gao J.
Published: May 2007

Magnetic properties and magnetocaloric effect (MCE) around phase boundary were investigated in La(FexAl1−x)13 compounds. We tuned the Fe content from 0.86 to 0.89 and observed a gradual change from ferromagnetic (F) to weak antiferromagnetic (AF) state. A completely F ground state at x=0.86 is followed by the emergence of AF coupling at x=0.87 and 0.88, in which two spaced transitions appear, one at TO from F to AF and the other at TN from AF to paramagnetic state. Continuously increasing Fe to x=0.89 results in a completely AF ground state. The magnetic properties of sample x=0.89 is especially interesting under an increasing external field. The state under a field of around 3.2T shows two successive transitions, predicting that two peaks may appear in the temperature dependent magnetic entropy change ΔS. Maxwell relation was employed to calculate ΔS. With the emergence and enhancement of AF coupling, the ΔS profile evolves from a single-peak shape at x=0.86 to a nearly constant-peak shape at x=0.87 and 0.88, and then to two-peak shape at x=0.89. The influence of Fe content on magnetic properties, metamagnetic transition behavior, and MCE is discussed.
Influence of Mn substitution on microstructure and magnetic properties of Cu1−xMnxO nanoparticles
Authors: Rao G. Narsinga , Yao Y. D. , Chen J. W.
Published: May 2007

Mn-doped CuO nanoparticles were synthesized using a coprecipitation method. Powder x-ray analysis reveals that all the samples crystallize into a monoclinic-type structure. Significant changes occur in both the microstructure and particle size with calcination temperature TA. The average particle size d increases from 11to85nm as the TA increases from 250to850°C. For particles of size d⩽22nm, energy dispersive spectroscopy indicates the existence of a crystalline Cu1−xMnxO core surrounded by an amorphous CuO shell. M(T) curves reveal a spin-glass behavior for the 11 and 22nm particles and a ferromagnetic behavior for particles of size d⩾35nm. The observed ferromagnetic behavior is attributed to the coexistence of Mn2+ and Mn3+ ions.