bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparing Adolescent Reactions to National Tobacco Countermarketing Advertisements Using Web TV
Authors: Niederdeppe Jeff , Hersey James C. , Farrelly Matthew C. , Haviland M. Lyndon , Healton Cheryl G.
Published: January 2006

This study examined youth reactions to four tobacco countermarketing messages from the national truth® and “Think. Don't Smoke” tobacco countermarketing campaigns through Web TV using a forced exposure approach. More than 900 respondents completed a baseline survey that established their smoking intentions and behaviors; viewed a series of randomly ordered tobacco countermarketing advertisements; and, after each ad, answered six items gauging individual ad reactions. Respondents across smoking risk groups had more favorable reactions to two ads produced for Legacy's truth® campaign (“Body Bags” and “Daily Dose”) compared with all other messages tested. Philip Morris' “My Reasons” received favorable evaluations among teens at lowest risk for future smoking, but consistent with our predictions derived from the theory of psychological reactance (Brehm, 1966), older teens at elevated risk of future smoking responded much less favorably. Teens without prior exposure to another truth® ad using the counter-industry message (“Shredder”) rated this ad less favorably. Results underscore the importance of both prior exposure and message features and suggest the presence of other factors associated with ad effectiveness, including message clarity and stylistic presentation.
Psychographic Profiling of Fruit and Vegetable Consumption: The Role of Health Orientation
Authors: Dutta-Bergman Mohan J.
Published: January 2006

Based on the empirical evidence that documents the link between fruit and vegetable consumption and a plethora of health outcomes, multiple campaign initiatives have been launched in the past decade seeking to drive the consumption of fruits and vegetables in the U.S. population. A review of the existing literature suggests that most campaign initiatives have taken an episodic approach to the task of increasing fruit and vegetable consumption. This article offers an alternative framework by highlighting the importance of a psychographic approach that emphasizes the treatment of the whole individual. In this case, health orientation is defined and located as the underlying variable that drives a multitude of health-related behaviors including fruit and vegetable consumption. The study results support the notion that an underlying sense of health orientation drives health behaviors such as fruit and vegetable consumption. Specific recommendations are made for campaign initiatives that take a comprehensive and long-term approach to health behavior change.
Myc regulates keratinocyte adhesion and differentiation via complex formation with Miz1
Authors: Gebhardt Anneli , Frye Michaela , Herold Steffi , Benitah Salvador Aznar , Braun Kristin , Samans Birgit , Watt Fiona M. , Elsässer Hans-Peter , Eilers Martin
Published: January 2006

Myc plays a key role in homeostasis of the skin. We show that Miz1, which mediates Myc repression of gene expression, is expressed in the epidermal basal layer. A large percentage of genes regulated by the Myc–Miz1 complex in keratinocytes encode proteins involved in cell adhesion, and some, including the α6 and β1 integrins, are directly bound by Myc and Miz1 in vivo. Using a Myc mutant deficient in Miz1 binding (MycV394D), we show that Miz1 is required for the effects of Myc on keratinocyte responsiveness to TGF-β. Myc, but not MycV394D, decreases keratinocyte adhesion and spreading. In reconstituted epidermis, Myc induces differentiation and loss of cell polarization in a Miz1-dependent manner. In vivo, overexpression of β1 integrins restores basal layer polarity and prevents Myc-induced premature differentiation. Our data show that regulation of cell adhesion is a major function of the Myc–Miz1 complex and suggest that it may contribute to Myc-induced exit from the epidermal stem cell compartment.
Endothelial FAK is essential for vascular network stability, cell survival, and lamellipodial formation
Authors: Braren Rickmer , Hu Huiqing , Kim Yung Hae , Beggs Hilary E. , Reichardt Louis F. , Wang Rong
Published: January 2006

Morphogenesis of a vascular network requires dynamic vessel growth and regression. To investigate the cellular mechanism underlying this process, we deleted focal adhesion kinase (FAK), a key signaling mediator, in endothelial cells (ECs) using Tie2-Cre mice. Targeted FAK depletion occurred efficiently early in development, where mutants exhibited a distinctive and irregular vasculature, resulting in hemorrhage and lethality between embryonic day (e) 10.5 and 11.5. Capillaries and intercapillary spaces in yolk sacs were dilated before any other detectable abnormalities at e9.5, and explants demonstrate that the defects resulted from the loss of FAK and not from organ failure. Time-lapse microscopy monitoring EC behavior during vascular formation in explants revealed no apparent decrease in proliferation or migration but revealed increases in cell retraction and death leading to reduced vessel growth and increased vessel regression. Consistent with this phenotype, ECs derived from mutant embryos exhibited aberrant lamellipodial extensions, altered actin cytoskeleton, and nonpolarized cell movement. This study reveals that FAK is crucial for vascular morphogenesis and the regulation of EC survival and morphology.
Bcl-2 differentially regulates Ca2+ signals according to the strength of T cell receptor activation
Authors: Zhong Fei , Davis Michael C. , McColl Karen S. , Distelhorst Clark W.
Published: January 2006

To investigate the effect of Bcl-2 on Ca2+ signaling in T cells, we continuously monitored Ca2+ concentration in Bcl-2–positive and –negative clones of the WEHI7.2 T cell line after T cell receptor (TCR) activation by anti-CD3 antibody. In Bcl-2–negative cells, high concentrations of anti-CD3 antibody induced a transient Ca2+ elevation, triggering apoptosis. In contrast, low concentrations of anti-CD3 antibody induced Ca2+ oscillations, activating the nuclear factor of activated T cells (NFAT), a prosurvival transcription factor. Bcl-2 blocked the transient Ca2+ elevation induced by high anti-CD3, thereby inhibiting apoptosis, but did not inhibit Ca2+ oscillations and NFAT activation induced by low anti-CD3. Reduction in the level of all three inositol 1,4,5-trisphosphate (InsP3) receptor subtypes by small interfering RNA inhibited the Ca2+ elevation induced by high but not low anti-CD3, suggesting that Ca2+ responses to high and low anti-CD3 may have different requirements for the InsP3 receptor. Therefore, Bcl-2 selectively inhibits proapoptotic Ca2+ elevation induced by strong TCR activation without hindering prosurvival Ca2+ signals induced by weak TCR activation.
Seeing is believing? A beginners' guide to practical pitfalls in image acquisition
Authors: North Alison J.
Published: January 2006

Imaging can be thought of as the most direct of experiments. You see something; you report what you see. If only things were truly this simple. Modern imaging technology has brought about a revolution in the kinds of questions we can approach, but this comes at the price of increasingly complex equipment. Moreover, in an attempt to market competing systems, the microscopes have often been inappropriately described as easy to use and suitable for near-beginners. Insufficient understanding of the experimental manipulations and equipment set-up leads to the introduction of errors during image acquisition. In this feature, I review some of the most common practical pitfalls faced by researchers during image acquisition, and how they can affect the interpretation of the experimental data.

This article is targeted neither to the microscopy gurus who push forward the frontiers of imaging technology nor to my imaging specialist colleagues who may wince at the overly simplistic comments and lack of detail. Instead, this is for beginners who gulp with alarm when they hear the word “confocal pinhole” or sigh as they watch their cells fade and die in front of their very eyes time and time again at the microscope. Take heart, beginners, if microscopes were actually so simple then many people (including myself) would suddenly be out of a job!
Distinct roles for Pax7 and Pax3 in adult regenerative myogenesis
Authors: Kuang Shihuan , Chargé Sophie B. , Seale Patrick , Huh Michael , Rudnicki Michael A.
Published: January 2006

We assessed viable Pax7−/− mice in 129Sv/J background and observed reduced growth and marked muscle wasting together with a complete absence of functional satellite cells. Acute injury resulted in an extreme deficit in muscle regeneration. However, a small number of regenerated myofibers were detected, suggesting the presence of residual myogenic cells in Pax7-deficient muscle. Rare Pax3+/MyoD+ myoblasts were recovered from Pax7−/− muscle homogenates and cultures of myofiber bundles but not from single myofibers free of interstitial tissues. Finally, we identified Pax3+ cells in the muscle interstitial environment and demonstrated that they coexpressed MyoD during regeneration. Sublaminar satellite cells in hind limb muscle did not express detectable levels of Pax3 protein or messenger RNA. Therefore, we conclude that interstitial Pax3+ cells represent a novel myogenic population that is distinct from the sublaminar satellite cell lineage and that Pax7 is essential for the formation of functional myogenic progenitors from sublaminar satellite cells.
Embryonic stem cells assume a primitive neural stem cell fate in the absence of extrinsic influences
Authors: Smukler Simon R. , Runciman Susan B. , Xu Shunbin , van der Kooy Derek
Published: January 2006

The mechanisms governing the emergence of the earliest mammalian neural cells during development remain incompletely characterized. A default mechanism has been suggested to underlie neural fate acquisition; however, an instructive process has also been proposed. We used mouse embryonic stem (ES) cells to explore the fundamental issue of how an uncommitted, pluripotent mammalian cell will self-organize in the absence of extrinsic signals and what cellular fate will result. To assess this default state, ES cells were placed in conditions that minimize external influences. Individual ES cells were found to rapidly transition directly into neural cells, a process shown to be independent of suggested instructive factors (e.g., fibroblast growth factors). Further, we provide evidence that the default neural identity is that of a primitive neural stem cell (NSC). The exiguous conditions used to reveal the default state were found to present primitive NSCs with a survival challenge (limiting their persistence and proliferation), which could be mitigated by survival factors or genetic interference with apoptosis.
Dynamics of the peroxisomal import cycle of PpPex20p: Ubiquitin-dependent localization and regulation
Authors: Léon Sébastien , Zhang Lan , McDonald W. Hayes , Yates John , Cregg James M. , Subramani Suresh
Published: January 2006

We characterize the peroxin PpPex20p from Pichia pastoris and show its requirement for translocation of PTS2 cargoes into peroxisomes. PpPex20p docks at the peroxisomal membrane and translocates into peroxisomes. Its peroxisomal localization requires the docking peroxin Pex14p but not the peroxins Pex2p, Pex10p, and Pex12p, whose absence causes peroxisomal accumulation of Pex20p. Similarities between Pex5p and Pex20p were noted in their protein interactions and dynamics during import, and both contain a conserved NH2-terminal domain. In the absence of the E2-like Pex4p or the AAA proteins Pex1p and Pex6p, Pex20p is degraded via polyubiquitylation of residue K19, and the K19R mutation causes accumulation of Pex20p in peroxisome remnants. Finally, either interference with K48-branched polyubiquitylation or removal of the conserved NH2-terminal domain causes accumulation of Pex20p in peroxisomes, mimicking a defect in its recycling to the cytosol. Our data are consistent with a model in which Pex20p enters peroxisomes and recycles back to the cytosol in an ubiquitin-dependent manner.
Xorbit/CLASP links dynamic microtubules to chromosomes in the Xenopus meiotic spindle
Authors: Hannak Eva , Heald Rebecca
Published: January 2006

A family of microtubule (MT)-binding proteins, Orbit/multiple asters/cytoplasmic linker protein–associated protein, has emerged as an important player during mitosis, but their functional mechanisms are poorly understood. In this study, we used meiotic egg extracts to gain insight into the role of the Xenopus laevis homologue Xorbit in spindle assembly and function. Xorbit immunodepletion or its inhibition by a dominant-negative fragment resulted in chromosome alignment defects and aberrant MT structures, including monopolar and small spindles. Xorbit-depleted extracts failed to nucleate MTs around chromatin-coated beads, indicating its essential requirement for spindle assembly in the absence of centrosomes and kinetochores. Xorbit's MT stabilizing effect was most apparent during anaphase, when spindle MTs depolymerized rapidly upon Xorbit inhibition. Biochemical interaction between a COOH-terminal Xorbit fragment and the kinetochore-associated kinesin centromeric protein E may contribute to Xorbit's role in chromosome congression. We propose that Xorbit tethers dynamic MT plus ends to kinetochores and chromatin, providing a stabilizing activity that is crucial for spindle assembly and chromosome segregation.
The yeast lgl family member Sro7p is an effector of the secretory Rab GTPase Sec4p
Authors: Grosshans Bianka L. , Andreeva Anna , Gangar Akanksha , Niessen Sherry , Yates John R. , Brennwald Patrick , Novick Peter
Published: January 2006

Rab guanosine triphosphatases regulate intracellular membrane traffic by binding specific effector proteins. The yeast Rab Sec4p plays multiple roles in the polarized transport of post-Golgi vesicles to, and their subsequent fusion with, the plasma membrane, suggesting the involvement of several effectors. Yet, only one Sec4p effector has been documented to date: the exocyst protein Sec15p. The exocyst is an octameric protein complex required for tethering secretory vesicles, which is a prerequisite for membrane fusion. In this study, we describe the identification of a second Sec4p effector, Sro7p, which is a member of the lethal giant larvae tumor suppressor family. Sec4-GTP binds to Sro7p in cell extracts as well as to purified Sro7p, and the two proteins can be coimmunoprecipitated. Furthermore, we demonstrate the formation of a ternary complex of Sec4-GTP, Sro7p, and the t-SNARE Sec9p. Genetic data support our conclusion that Sro7p functions downstream of Sec4p and further imply that Sro7p and the exocyst share partially overlapping functions, possibly in SNARE regulation.
Necrotic death as a cell fate
Authors: Zong Wei-Xing , Thompson Craig B.
Published: January 2006

Organismal homeostasis depends on an intricate balance between cell death and renewal. Early pathologists recognized that this balance could be disrupted by the extensive damage observed in internal organs during the course of certain diseases. This form of tissue damage was termed “necrosis”, derived from the Greek “nekros” for corpse. As it became clear that the essential building block of tissue was the cell, necrosis came to be used to describe pathologic cell death. Until recently, necrotic cell death was believed to result from injuries that caused an irreversible bioenergetic compromise. The cell dying by necrosis has been viewed as a victim of extrinsic events beyond its control. However, recent evidence suggests that a cell can initiate its own demise by necrosis in a manner that initiates both inflammatory and/or reparative responses in the host. By initiating these adaptive responses, programmed cell necrosis may serve to maintain tissue and organismal integrity.
Tumor suppression and normal aging in mice with constitutively high p53 activity
Authors: Mendrysa Susan M. , O'Leary Kathleen A. , McElwee Matthew K. , Michalowski Jennifer , Eisenman Robert N. , Powell Douglas A. , Perry Mary Ellen
Published: January 2006

The p53 inhibitor murine double-minute gene 2 (Mdm2) is a target for potential cancer therapies, however increased p53 function can be lethal. To directly address whether reduced Mdm2 function can inhibit tumorigenesis without causing detrimental side effects, we exploited a hypomorphic murine allele of mdm2 to compare the effects of decreased levels of Mdm2 and hence increased p53 activity on tumorigenesis and life span in mice. Here we report that mice with decreased levels of Mdm2 are resistant to tumor formation yet do not age prematurely, supporting the notion that Mdm2 is a promising target for cancer therapeutics.
Multifactorial contributions to an acute DNA damage response by BRCA1/BARD1-containing complexes
Authors: Greenberg Roger A. , Sobhian Bijan , Pathania Shailja , Cantor Sharon B. , Nakatani Yoshihiro , Livingston David M.
Published: January 2006

The BRCA1 gene product and its stoichiometric binding partner, BARD1, play a vital role in the cellular response to DNA damage. However, how they acquire specific biochemical functions after DNA damage is poorly understood. Following exposure to genotoxic stress, DNA damage-specific interactions were observed between BRCA1/BARD1 and the DNA damage-response proteins, TopBP1 and Mre11/Rad50/NBS1. Two distinct DNA damage-dependent super complexes emerged; their activation was dependent, in part, on the actions of specific checkpoint kinases, and each super complex contributed to a distinctive aspect of the DNA damage response. The results support a new, multifactorial model that describes how genotoxic stress enables BRCA1 to execute a diverse set of DNA damage-response functions.
A pathway in quiescent cells that controls p27Kip1 stability, subcellular localization, and tumor suppression
Authors: Besson Arnaud , Gurian-West Mark , Chen Xueyan , Kelly-Spratt Karen S. , Kemp Christopher J. , Roberts James M.
Published: January 2006

We have created two knock-in mouse models to study the mechanisms that regulate p27 in normal cells and cause misregulation of p27 in tumors: p27S10A, in which Ser10 is mutated to Ala; and p27CK–, in which point mutations abrogate the ability of p27 to bind cyclins and CDKs. These two mutant alleles identify steps in a pathway that controls the proteasomal degradation of p27 uniquely in quiescent cells: Dephosphorylation of p27 on Ser10 inhibits p27 nuclear export and promotes its assembly into cyclin–CDK complexes, which is, in turn, necessary for p27 turnover. We further show that Ras-dependent lung tumorigenesis is associated with increased phosphorylation on Ser10 and cytoplasmic mislocalization of p27. Indeed, we find that p27S10A is refractory to Ras-induced cytoplasmic translocation and that p27S10A mice are tumor resistant. Thus, phosphorylation of p27 on Ser10 is an important event in the regulation of the tumor suppressor function of p27.
Translational resistance of late alphavirus mRNA to eIF2α phosphorylation: a strategy to overcome the antiviral effect of protein kinase PKR
Authors: Ventoso Iván , Sanz Miguel Angel , Molina Susana , Berlanga Juan José , Carrasco Luis , Esteban Mariano
Published: January 2006

The double-stranded RNA-dependent protein kinase (PKR) is one of the four mammalian kinases that phosphorylates the translation initiation factor 2α in response to virus infection. This kinase is induced by interferon and activated by double-stranded RNA (dsRNA). Phosphorylation of eukaryotic initiation factor 2α (eIF2α) blocks translation initiation of both cellular and viral mRNA, inhibiting virus replication. To counteract this effect, most viruses express inhibitors that prevent PKR activation in infected cells. Here we report that PKR is highly activated following infection with alphaviruses Sindbis (SV) and Semliki Forest virus (SFV), leading to the almost complete phosphorylation of eIF2α. Notably, subgenomic SV 26S mRNA is translated efficiently in the presence of phosphorylated eIF2α. This modification of eIF2 does not restrict viral replication; SV 26S mRNA initiates translation with canonical methionine in the presence of high levels of phosphorylated eIF2α. Genetic and biochemical data showed a highly stable RNA hairpin loop located downstream of the AUG initiator codon that is necessary to provide translational resistance to eIF2α phosphorylation. This structure can stall the ribosomes on the correct site to initiate translation of SV 26S mRNA, thus bypassing the requirement for a functional eIF2. Our findings show the existence of an alternative way to locate the ribosomes on the initiation codon of mRNA that is exploited by a family of viruses to counteract the antiviral effect of PKR.
Chameau HAT and DRpd3 HDAC function as antagonistic cofactors of JNK/AP-1-dependent transcription during Drosophila metamorphosis
Authors: Miotto Benoit , Sagnier Thierry , Berenger Hélène , Bohmann Dirk , Pradel Jacques , Graba Yacine
Published: January 2006

Gene regulation by AP-1 transcription factors in response to Jun N-terminal kinase (JNK) signaling controls essential cellular processes during development and in pathological situations. Here, we report genetic and molecular evidence that the histone acetyltransferase (HAT) Chameau and the histone deacetylase DRpd3 act as antagonistic cofactors of DJun and DFos to modulate JNK-dependent transcription during thorax metamorphosis and JNK-induced apoptosis in Drosophila. We demonstrate in cultured cells that DFos phosphorylation mediated by JNK signaling plays a central role in coordinating the dynamics of Chameau and DRpd3 recruitment and function at AP-1-responsive promoters. Activating the pathway stimulates the HAT function of Chameau, promoting histone H4 acetylation and target gene transcription. Conversely, in response to JNK signaling inactivation, DRpd3 is recruited and suppresses histone acetylation and transcription. This study establishes a direct link among JNK signaling, DFos phosphorylation, chromatin modification, and AP-1-dependent transcription and its importance in a developing organism.
Rho is a presynaptic activator of neurotransmitter release at pre-existing synapses in C. elegans
Authors: McMullan Rachel , Hiley Emma , Morrison Paul , Nurrish Stephen J.
Published: January 2006

Rho GTPases have important roles in neuronal development, but their function in adult neurons is less well understood. We demonstrate that presynaptic changes in Rho activity at Caenorhabditis elegans neuromuscular junctions can radically change animal behavior via modulation of two separate pathways. In one, presynaptic Rho increases acetylcholine (ACh) release by stimulating the accumulation of diacylglycerol (DAG) and the DAG-binding protein UNC-13 at sites of neurotransmitter release; this pathway requires binding of Rho to the DAG kinase DGK-1. A second DGK-1-independent mechanism is revealed by the ability of a Rho inhibitor (C3 transferase) to decrease levels of release even in the absence of DGK-1; this pathway is independent of UNC-13 accumulation at release sites. We do not detect any Rho-induced changes in neuronal morphology or synapse number; thus, Rho facilitates synaptic transmission by a novel mechanism. Surprisingly, many commonly available human RhoA constructs contain an uncharacterized mutation that severely reduces binding of RhoA to DAG kinase. Thus, a role for RhoA in controlling DAG levels is likely to have been underestimated.
Actin homolog MreB and RNA polymerase interact and are both required for chromosome segregation in Escherichia coli
Authors: Kruse Thomas , Blagoev Blagoy , Løbner-Olesen Anders , Wachi Masaaki , Sasaki Kumi , Iwai Noritaka , Mann Matthias , Gerdes Kenn
Published: January 2006

The actin-like MreB cytoskeletal protein and RNA polymerase (RNAP) have both been suggested to provide the force for chromosome segregation. Here, we identify MreB and RNAP as in vivo interaction partners. The interaction was confirmed using in vitro purified components. We also present convincing evidence that MreB and RNAP are both required for chromosome segregation in Escherichia coli. MreB is required for origin and bulk DNA segregation, whereas RNAP is required for bulk DNA, terminus, and possibly also for origin segregation. Furthermore, flow cytometric analyses show that MreB depletion and inactivation of RNAP confer virtually identical and highly unusual chromosome segregation defects. Thus, our results raise the possibility that the MreB–RNAP interaction is functionally important for chromosome segregation.
Carbon partitioning to mobile and structural fractions in poplar wood under elevated CO2 (EUROFACE) and N fertilization
Authors: LUO ZHI‐BIN , CALFAPIETRA CARLO , LIBERLOO MARION , SCARASCIA‐MUGNOZZA GIUSEPPE , POLLE ANDREA
Published: January 2006

To determine whether globally increasing atmospheric carbon dioxide (CO2) concentrations can affect carbon partitioning between nonstructural and structural carbon pools in agroforestry plantations, Populus nigra was grown in ambient air (about 370 μmol mol−1 CO2) and in air with elevated CO2 concentrations (about 550 μmol mol−1 CO2) using free‐air CO2 enrichment (FACE) technology. FACE was maintained for 5 years. After three growing seasons, the plantation was coppiced and one half of each experimental plot was fertilized with nitrogen. Carbon concentrations and stocks were measured in secondary sprouts in seasons of active growth and dormancy during 2 years after coppicing. Although FACE, N fertilization and season had significant tissue‐specific effects on carbon partitioning to the fractions of structural carbon, soluble sugars and starch as well as to residual soluble carbon, the overall magnitude of these shifts was small. The major effect of FACE and N fertilization was on cell wall biomass production, resulting in about 30% increased above ground stocks of both mobile and immobile carbon pools compared with fertilized trees under ambient CO2. Relative C partitioning between mobile and immobile C pools was not significantly affected by FACE or N fertilization. These data demonstrate high metabolic flexibility of P. nigra to maintain C‐homeostasis under changing environmental conditions and illustrate that nonstructural carbon compounds can be utilized more rapidly for structural growth under elevated atmospheric [CO2] in fertilized agroforestry systems. Thus, structural biomass production on abandoned agricultural land may contribute to achieving the goals of the Kyoto protocol.
Ecohydrological impacts of woody‐plant encroachment: seasonal patterns of water and carbon dioxide exchange within a semiarid riparian environment
Authors: SCOTT RUSSELL L. , HUXMAN TRAVIS E. , WILLIAMS DAVID G. , GOODRICH DAVID C.
Published: January 2006

Across many dryland regions, historically grass‐dominated ecosystems have been encroached upon by woody‐plant species. In this paper, we compare ecosystem water and carbon dioxide (CO2) fluxes over a grassland, a grassland–shrubland mosaic, and a fully developed woodland to evaluate potential consequences of woody‐plant encroachment on important ecosystem processes. All three sites were located in the riparian corridor of a river in the southwest US. As such, plants in these ecosystems may have access to moisture at the capillary fringe of the near‐surface water table. Using fluxes measured by eddy covariance in 2003 we found that ecosystem evapotranspiration (ET) and net ecosystem exchange of carbon dioxide (NEE) increased with increasing woody‐plant dominance. Growing season ET totals were 407, 450, and 639 mm in the grassland, shrubland, and woodland, respectively, and in excess of precipitation by 227, 265, and 473 mm. This excess was derived from groundwater, especially during the extremely dry premonsoon period when this was the only source of moisture available to plants. Access to groundwater by the deep‐rooted woody plants apparently decouples ecosystem ET from gross ecosystem production (GEP) with respect to precipitation. Compared with grasses, the woody plants were better able to use the stable groundwater source and had an increased net CO2 gain during the dry periods. This enhanced plant activity resulted in substantial accumulation of leaf litter on the soil surface that, during rainy periods, may lead to high microbial respiration rates that offset these photosynthetic fluxes. March–December (primary growing season) totals of NEE were −63, −212, and −233 g C m−2 in the grassland, shrubland, and woodland, respectively. Thus, there was a greater disparity between ecosystem water use and the strength of the CO2 sink as woody plants increased across the encroachment gradient. Despite a higher density of woody plants and a greater plant productivity in the woodland than in the shrubland, the woodland produced a larger respiration response to rainfall that largely offset its higher photosynthetic potential. These data suggest that the capacity for woody plants to exploit water resources in riparian areas results in enhanced carbon sequestration at the expense of increased groundwater use under current climate conditions, but the potential does not scale specifically as a function of woody‐plant abundance. These results highlight the important roles of water sources and ecosystem structure on the control of water and carbon balances in dryland areas.
Comparison of the rebound tonometer (ICare®) to the applanation tonometer (Tonopen XL®) in normotensive dogs
Authors: Leiva M. , Naranjo C. , Peña M. T.
Published: January 2006

ObjectiveTo compare intraocular pressure (IOP) measurements obtained by recently introduced rebound tonometer (ICare®) and the well‐known applanation tonometer Tonopen XL®in normal canine eyes.

MethodsIn a prospective, randomized, single‐center study, IOP measurements by ICare®and Tonopen XL®tonometers were compared in 160 nonpathologic canine eyes (80 dogs). Complete slit‐lamp biomicroscopy and indirect ophthalmoscopy were performed on each dog. Rebound tonometry was performed first and immediately after topical anesthetic drops were instilled in both eyes. One minute after the application of the topical anesthetic, applanation tonometry was performed in both eyes. The intraocular pressures obtained by use of both techniques were compared by statistical analysis.

ResultsThe mean IOP readings were 9.158 mmHg (SD 3.471 mmHg) for the ICare®tonometer (x) and 11.053 mmHg (SD 3.451 mmHg) for the Tonopen XL®readings (y). The mean difference in intraocular pressures (−1.905 mmHg) was within clinically acceptable limits. The correlation coefficient (r2) of the relationship within both tonometers wasr2 = 0.7477. The corresponding linear regression between the tonometers readings wasy = 0.6662x + 4.942.

ConclusionsIntraocular pressures obtained with the ICare®rebound tonometer were concordant with the IOP readings obtained by applanation Tonopen XL®, but ICare®values were significantly (P < 0.0001) lower. Rebound tonometry could be an appropriate tonometry method for routine clinical use after its calibration for canine eyes.
Evolutionary and functional analysis of the tailless enhancer in Musca domestica and Drosophila melanogaster
Authors: Wratten Naomi S. , McGregor Alistair P. , Shaw Philip J. , Dover Gabriel A.
Published: January 2006

To further understand the evolutionary dynamics of the regulatory interactions underlying development, we expand on our previous analysis of hunchback and compare the structure and function of the tailless enhancer between Musca domestica and Drosophila melanogaster. Our analysis shows that although the expression patterns and functional protein domains of tll are conserved between Musca and Drosophila, the enhancer sequences are unalignable. Upon closer investigation, we find that these highly diverged enhancer sequences encode the same regulatory information necessary for Bicoid, Dorsal, and the terminal system to drive tll expression. The binding sites for these transcription factors differ in the sequence, number, spacing, and position between the Drosophila and Musca tll enhancers, and we were unable to establish homology between binding sites from each species. This implies that the Musca and Drosophila Bcd‐binding sites have evolved de novo in the 100 million years since these species diverged. However, in transgenic Drosophila embryos the Musca tll enhancer is able to drive the same expression pattern as endogenous Drosophila tll. Therefore, during the rapid evolution of enhancer sequences individual binding sites are continually lost and gained, but the transcriptional output is maintained by compensatory mutations in cis and in trans.
Modularity and sense organs in the blind cavefish,Astyanax mexicanus
Authors: Franz‐Odendaal Tamara A. , Hall Brian K.
Published: January 2006

SUMMARYMexican tetra (Astyanax mexicanus)exist as two morphs: a sighted (surface) form and a blind (cavefish) form. In the cavefish, some modules are lost, such as the eye and pigment modules, whereas others are expanded, such as the taste bud and cranial neuromast modules. We suggest that modularity can be viewed as being nested in a manner similar toBaupläneso that modules express unique sets of genes, cells, and processes. In terms of evolution, we conclude that natural selection can act on any of these hierarchical levels within modules or on all the sensory modules as a whole. We discuss interactions within and between modules with reference to the blind cavefish from both genetic and developmental perspectives. The cavefish represents an illuminating example of module interaction, uncoupling of modules, and module expansion.
Unbeatable Value Low‐Price Guarantee: Collusive Mechanism or Advertising Strategy?
Authors: Mañez Juan A.
Published: January 2006

This paper investigates the effects of a low‐price guarantee (price‐beating guarantee) on the patterns of price setting of three supermarkets using micro‐level price data. Following recent theoretical developments, the paper analyzes the ability of low‐price guarantees to sustain anticompetitive prices. My empirical analysis suggests instead that this low‐price guarantee may serve as an advertising device to signal low prices. The supermarket offering the low‐price guarantee, aware of its price advantage in a subset of products, uses it to signal low prices to induce consumers to switch supermarkets.
Semiparametric Estimation of Animal Abundance Using Capture–Recapture Data from Open Populations
Authors: Huggins Richard
Published: January 2006

Summary A semiparametric partially linear model for the size of an open population is proposed and inference is conducted using weighted martingale estimating equations. This extends a previous nonparametric approach to modeling capture–recapture data for open populations with frequent capture occasions. Analytic expressions for the large sample variances are derived and these are confirmed in a simulation study. The method is illustrated on monthly penguin banding data collected over 6 years.
TRPC3 properties of a native constitutively active Ca2+‐permeable cation channel in rabbit ear artery myocytes
Authors: Albert A. P. , Pucovský V. , Prestwich S. A. , Large W. A.
Published: January 2006

Previously we have described a constitutively active, Ca2+‐permeable, non‐selective cation channel in freshly dispersed rabbit ear artery myocytes which has similar properties to some of the canonical transient receptor potential (TRPC) channel proteins. In the present work we have compared the properties of constitutive channel activity with known properties of TRPC proteins by investigating the effect of selective anti‐TRPC antibodies and pharmacological agents on whole‐cell and single cation channel activity. Bath application of anti‐TRPC3 antibodies markedly reduced channel activity in inside‐out patches and also produced a pronounced reduction of both current amplitude and variance of constitutively active whole‐cell cation currents whereas anti‐TRPC1/4/5/6/7 antibodies had no effect on channel activity. In the presence of antigenic peptide, anti‐TRPC3 antibodies had no effect on whole‐cell or single cation channel activity. Bath application of flufenamic acid, Gd3+, La3+ and Ca2+ inhibited spontaneous channel activity in outside‐out patches with IC50 values of 6.8 μm, 25 nm, 1.5 μm and 0.124 mm, respectively, which are similar values to those against TRPC3 proteins. Immunocytochemical studies combined with confocal microscopy showed expression of TRPC3 proteins in ear artery myocytes, and these were predominately distributed at, or close to, the plasma membrane. These data provide strong evidence that native constitutively active cation channels in rabbit ear artery myocytes have similar properties to TRPC3 channel proteins and indicate that these proteins may have an important role in mediating this conductance.
Optimization of multilayer wear-resistant thin films using finite element analysis on stiff and compliant substrates
Authors: Lakkaraju R. K. , Bobaru F. , Rohde S. L.
Published: January 2006

Extensive research has been carried out by researchers on the growth and characterization of multilayer protective coatings, but the design of these coatings still remains largely empirical. In this regard, recent progress has been made in developing a design approach for optimizing a multilayer coating structure before deposition, which would help save time and material. In pursuit of an optimal design, finite element analysis using a plane strain Hertzian contact model was developed to investigate the stress/strain behavior within the layers of the system. The present study looks to find the optimal thicknesses of individual layers in a multilayer coating/substrate system that can reduce stresses and/or strains in the system. Multilayer Cr∕CrN thin films were modeled and optimized to have effective “load support” by the films on stiff A2 steel and compliant 2024-Al substrates. Optimization was carried out using both multiobjective and single-objective procedures for the models of eight-layer film on substrates. For the multilayer on A2 steel substrate, the first test case is a multiobjective optimization performed by minimizing the strain discontinuities at the coating/substrate interface and the stresses developed in the uppermost layer under combined normal and tangential load conditions. Another option is a single-objective optimization (minimizing the strain discontinuity) and constraining the stress to values below the yield stress. The same two test cases were employed on the 2024-Al model, but the stresses considered were those in the substrate in order to keep the model within the elastic regime. Efficiency of several optimization algorithms, such as genetic algorithms and gradient based routines are discussed and the preliminary results are compared to experimental pin-on-disk wear results of empirically designed coatings. Architectures were found with improvements in the elastic measures employed here.
Investigation of Ni reaction with sputtered amorphous SiGe thin film on SiO2 substrate
Authors: Qu Xin-Ping , Duan Peng , Wu Yan-Qing , Chen Tao , Wang Guang-Wei , Ru Guo-Ping , Li Bing-Zong
Published: January 2006

Ni reaction with amorphous SiGe (a-SiGe) thin film on SiO2 substrate through rapid thermal annealing (RTA) was investigated. The amorphous SiGe thin film was deposited by ion beam sputtering. X-ray diffraction (XRD), Auger electron spectroscopy (AES) depth profiling, and four point probe (FPP) were used to check the phase formation, atom distribution, and sheet resistance during the reaction. It was found that the Ni reaction with a-SiGe was different from the Ni reaction with poly-SiGe. Besides an orthorhombic NiSi phase, a tetragonal η-NiSi phase was formed during Ni reaction with an a-SiGe layer and remained stable after 800°C annealing. A NiSi2 phase was formed at temperature as low as 550°C along with the crystallization of SiGe.When annealed at a higher temperature, Ge outdiffused to the surface and Ni diffused to the interface of SiGe∕SiO2 where it formed a thin layer of Ni silicide. The cause of the reduced temperature for formation of NiSi2 from Ni reaction with amorphous SiGe is discussed.
Low-resistivity atomic-layer-deposited-TaN with atomic-layer-deposited-TaN/physical-vapor-deposited-Ta multilayer structure for multilevel Cu damascene interconnect
Authors: Furuya Akira , Ohtsuka Nobuyuki , Ohashi Naofumi , Kondo Seiichi , Ogawa Shinichi
Published: January 2006

One important issue for integrating atomic-layer-deposited (ALD) TaN barrier metal into Cu interconnects is a low thickness margin due to high electrical resistivity (∼50mΩcm) of ALD-TaN. In investigating this issue, the median via resistance (0.16μmdiametervias) was found to increase from 0.5 to 26Ω∕via as the ALD-TaN thickness was increased from 1 to 2nm. To reduce the resistivity of ALD-TaN, its atomic concentration on various substrates was investigated. The N/Ta ratio of ALD-TaN was found to be about 4/5 on a SiO2 substrate but about 1/2 on a Ta substrate. We also confirmed that the Ta-rich ALD-TaN film on the Ta substrate had low electrical resistivity (∼2mΩcm). We could thus successfully obtain low via resistance (5.4Ω∕via) with thick ALD-TaN (5nm) by using a PVD-Ta/ALD-TaN/PVD-Ta multilayer structure.
High-rate deposition of MgO by reactive ac pulsed magnetron sputtering in the transition mode
Authors: Kupfer H. , Kleinhempel R. , Richter F. , Peters C. , Krause U. , Kopte T. , Cheng Y.
Published: January 2006

A reactive ac pulsed dual magnetron sputtering process for MgO thin-film deposition was equipped with a closed-loop control of the oxygen flow rate (FO2) using the 285nm magnesium radiation as input. Owing to this control, most of the unstable part of the partial pressure versus flowrate curve became accessible. The process worked steadily and reproducible without arcing. A dynamic deposition rate of up to 35nmm∕min could be achieved, which was higher than in the oxide mode by about a factor of 18. Both process characteristics and film properties were investigated in this work in dependence on the oxygen flow, i.e., in dependence on the particular point within the transition region where the process is operated. The films had very low extinction coefficients (<5×10−5) and refractive indices close to the bulk value. They were nearly stoichiometric with a slight oxygen surplus (Mg∕O=48∕52) which was independent of the oxygen flow. X-ray diffraction revealed a prevailing (111) orientation. Provided that appropriate rf plasma etching was performed prior to deposition, no other than the (111) peak could be detected. The intensity of this peak increased with increasing FO2, indicating an even more pronounced (111) texture. The ion-induced secondary electron emission coefficient (iSEEC) was distinctly correlated with the markedness of the (111) preferential orientation. Both refractive index and (111) preferred orientation (which determines the iSEEC) were found to be improved in comparison with the MgO growth in the fully oxide mode. Consequently, working in the transition mode is superior to the oxide mode not only with respect to the growth rate, but also to most important film properties.
Spectroscopic study of gas and surface phase chemistries of CF4 plasmas in an inductively coupled modified gaseous electronics conference reactor
Authors: Zhou Baosuo , Joseph Eric A. , Overzet Lawrence J. , Goeckner Matthew J.
Published: January 2006

Gas and surface phase chemistries of CF4 plasma were studied in an inductively coupled modified gaseous electronics conference reference cell, using in situ Fourier transform infrared spectroscopy enhanced by a multipass White cell and in situ spectroscopic ellipsometry. The self-bias dc voltage, densities of gaseous species, fluorocarbon film thickness on Si substrate, as well as etch rates of SiO2 and Si were measured during plasma processing as functions of the pressure, CF4 gas flow rate, rf source power, platen bias power, and source-platen gap. The gaseous molecules and radicals monitored included CF4, CF3, CF2, SiF4, and COF2, among which CF4 and SiF4 were found to be the two dominant species, combining for about 80% of the total concentration. The density ratio of SiF4 and COF2 was about 2:1 with no bias on the substrate and increased up to ∼8:1 when Si substrate etching took place. Specifically, as the Si etch rate increased, the COF2 density dropped, likely due to suppressed etching of the quartz source window, while the density of SiF4 increased. Comparisons between the gas phase data and etch rate results of Si and SiO2 indicate that the gas phase chemistry is strongly influenced by surface reactions on the substrate, wall, and quartz source window. The thickness of fluorocarbon reaction layer on Si substrate is mainly determined by densities of fluorocarbon radicals and fluorine atoms in the bulk plasma as well as the self-bias voltage on the substrate, and a thicker film is usually associated with a lower etch rate.
The Law of Elasticity for Isotropic and Quasi-Isotropic Substances by Finite Deformations
Authors: Hencky H.
Published: January 2006

Hooke's law, which is the foundation of the mathematical theory of elasticity, is unfit to describe satisfactorily the phenomena in elastic bodies even if we limit the scope of our research to ideal elastic deformations. We call a deformation ideally elastic, if the deformations disappear completely and if the energy stored up in the body is given back without loss, when the load is removed.
Some Physical Concepts in Theories of Plastic Flow
Authors: Peek R. L. , McLean D. A.
Published: January 2006

The mathematical formulation of any theory for the deformation of matter consists essentially in the development of differential equations relating the resistance developed by deforming forces to the relative displacements of differential elements and the successive time derivatives of these displacements. Such general formulations have been carried out for the elastic theory and for the theory of viscous flow, which are based on simple linear relations between the stress components and the strain components and their first time derivatives, respectively. For more complicated theories such general formulations are somewhat academic, as the resulting equations can only be solved for cases of flow in which a high degree of symmetry obtains, so that the equations and the boundary conditions reduce to comparatively simple forms. It is therefore sufficient to formulate any theory in terms general enough to include the cases of interest for which solutions can be obtained.
Viscosity Measurements in Molten Glass
Authors: Lillie Howard R.
Published: January 2006

The relations existing between viscosity determinations and the various stages of glass manufacture are pointed out and explained with reference to a typical viscosity-temperature curve. The rotation viscometer employed in making such determinations is described. Curves are shown for four representative types of glasses: a lead, a lime, a lead borosilicate, and a hard borosilicate, and the use to which such comparison curves may be put is indicated.