cssi/SciSciGPT-SciSciNet huggingface dataset:
The Hidden Complexities of 'Entrepreneurial Opportunity'

We look at the historical context within which the entrepreneurial opportunity construct arose before exploring the challenges specific to the discovery-opportunity view. We then examine the deeper, underlying challenges that any approach (i.e., discovery-opportunity or subjective-creation views) that relies upon the opportunity construct must confront. The challenges involve diverse considerations--theoretical, philosophical, logical, and linguistic. In the end such challenges point to the overarching conclusion that the opportunity construct is extraordinarily complex and any researcher who intends to rely upon ‘opportunity’ as a construct in their theoretical framework must face the fact that this construct is far more ambiguous than typically presumed.
Super-resolution Imaging of Amyloid Structures over Extended Times by Using Transient Binding of Single Thioflavin T Molecules.

Oligomeric amyloid structures are crucial therapeutic targets in Alzheimer's and other amyloid diseases. However, these oligomers are too small to be resolved by standard light microscopy. We have developed a simple and versatile tool to image amyloid structures by using thioflavin T without the need for covalent labeling or immunostaining. The dynamic binding of single dye molecules generates photon bursts that are used for fluorophore localization on a nanometer scale. Thus, photobleaching cannot degrade image quality, allowing for extended observation times. Super‐resolution transient amyloid binding microscopy promises to directly image native amyloid by using standard probes and record amyloid dynamics over minutes to days. We imaged amyloid fibrils from multiple polypeptides, oligomeric, and fibrillar structures formed during different stages of amyloid‐β aggregation, as well as the structural remodeling of amyloid‐β fibrils by the compound epi‐gallocatechin gallate.
Cryopreservation of Plant Germplasm: Introduction and Some Observations

It has been amply stated that preservation of germplasm is important not only for plant improvement and utilization for food, fiber, medicinal and forest crops, but also for conservation of rare and endangered species (Knutson and Stoner 1989; Falk and Holsinger 1991; Reaka-Kudla et al. 1997). As documented in contributed chapters in this volume and in comprehensive compendia, reasons for species or landrace loss are diverse but usually related to pressures from increasing human populations and the attendant habitat loss, land use changes and desire for productive crops. Whatever the root causes, the final effect is certainly the loss of genotypes. In efforts to stave off further loss, preservation systems have been devised to retain as much genetic diversity for the species as possible. Broadly classed, both in situ and ex situ preservation systems have been proposed and have been implemented in varying degrees for different species. In situ preservation allows for evolutionary forces to continue and can be argued to be important, for example, for disease-resistance development. However, in situ preservation still requires management and is not suitable for more domesticated lines. Preservation ex situ (within genebanks) is, therefore, used as a system around the world for many species, both commercially important and endangered.
Introduction: Consideration of Epidemiologic Factors

The most alarming trend in the past half-century has been the sharp increase in sudden deaths from ischemic heart disease (IHD), particularly in middle-aged men, and the increasing number of younger men who suddenly develop myocardial infarctions, cardiac arrhythmias, or arrests. That men in the prime of life are thus afflicted is the dramatic and tragic tip of the iceberg. Underlying these catastrophes is the widespread increase in incidence of atherosclerosis in young age groups, and in myocardial hyperexcitability and cardiomyopathy without notable coronary atherosclerosis. It is proposed that magnesium deficiency or loss may be a common etiologic factor in the increased incidence of sudden infant deaths, infantile myocardial infarction and arteriosclerosis, and the disease that becomes manifest later in life. It is also suggested that magnesium deficiency might also cause or predispose to some skeletal and renal diseases, all of which can coexist.
Foveal cone ERGs in fellow eyes of patients with unilateral neovascular age-related macular degeneration.

PURPOSE To determine whether fellow eyes with normal visual acuity of patients with unilateral neovascular age-related macular degeneration (AMD) have retinal malfunction. METHODS Foveal cone electroretinograms (ERGs) were recorded from fellow eyes with visual acuities of 20/25 or better of 73 patients with unilateral neovascular AMD and from 28 normal volunteers of comparable age. Responses were elicited with a 4 degrees stimulus flickering at 42 Hz presented by a stimulator-ophthalmoscope. RESULTS The study eyes of the patients were found to have foveal cone ERGs that, on average, were normal in amplitude but delayed in implicit (peak) time after adjustment of the data for age, sex, iris pigmentation, and refractive error by multiple linear regression. Based on all subjects, amplitude declined with increasing age and was smaller in eyes with darker irides; implicit time increased with increasing age. CONCLUSIONS These findings suggest that fellow eyes with normal visual acuity of patients with unilateral neovascular AMD tend to have foveal cones that are normal in number but that function abnormally. In addition, foveal cone ERG amplitude should be adjusted for both age and iris pigmentation and implicit time should be adjusted for age when assessing retinal function of elderly patients.
Laser assisted cold spray of Fe–Ni–Zr oxide dispersion strengthened steel

Abstract This letter demonstrates the use of laser assisted cold spray for consolidation of oxide dispersion strengthened steel. Cold spray with and without the use of an in situ laser for heating of the substrate was used to deposit coatings of a Fe–Ni–Zr based oxide dispersion strengthened steel powder. Nanoscale zirconium oxide dispersants were found to be present in deposits produced with and without use of the heating laser. Higher substrate temperatures increased deposition efficiency, but also produced samples with lower hardness, larger grain size, and coarser oxide dispersants.
BES1 hinders ABSCISIC ACID INSENSITIVE5 and promotes seed germination in Arabidopsis

Proper regulation of seed germination is essential for the successful propagation of a plant. The transcription factor ABSCISIC ACID INSENSITIVE5 (ABI5) of the abscisic acid (ABA) signaling pathway plays a central role in the inhibition of seed germination. ABI5 is precisely regulated by the core ABA signaling components and multiple other factors. However, the complex regulatory network of ABI5 remains largely unknown. In this study, we determined the biochemical interaction between ABI5 and the BRINSENSITIVE1 (BRI1)-EMS-SUPPRESSOR1 (BES1) transcription factor of the brassinosteroid (BR) signaling pathway, as well as the function of BES1 regulating ABI5 during seed germination in Arabidopsis. BES1 directly interacts with ABI5 both in vitro and in vivo. The bZIP domain of ABI5, which is responsible for DNA binding, is critical for ABI5 binding to BES1. The interaction of BES1 with ABI5 significantly suppressed the binding of ABI5 to the promoter regions of downstream genes, which resulted in their reduced expression and consequently facilitated seed germination. This study shed new light on the coordination of multiple signaling pathways during seed germination. In particular, BES1 directly binds to ABI5, which interferes with its transcriptional activity and suppresses ABA signaling output.
Laser and White-Light Speckle Techniques: A Tutorial Review

This instructional review begins with descriptions of simple experiments that illustrate the phenomenon of coherent-light speckle and its properties that cause it to be useful for measurement of displacements and strains, namely the sensitivity of speckle brightness to object motion and the relationship between speckle size and imaging aperture. The concepts of laser speckle interferometry, speckle shearography, speckle photography, and white-light speckle photography are presented, and basic apparatus setups for implementation are illustrated. Exceptional data density and flexible displacement sensitivities cause these techniques to be favored for whole-field non-contacting measurements of displacement, strain, and vibrations, as well as for nondestructive inspection. The concept of using phase shifting to increase the precision of speckle interferometry far beyond that offered by analyzing fringe patterns is presented along with details of one method of execution. A simple MATLAB® code for phase-shifting interferometry is included. Illustrative and suggestive applications are drawn from studies in geomechanics, biomechanics, fluid mechanics, NDI, strain analysis, residual stresses, and vibration characterization.
Resonance Marketing in the Age of the Truly Informed Consumer: Creating Profits Through Differentiation and Delight

Resonance marketing has transformed what we buy and the delight we take in our purchases. Resonance marketing has also transformed what companies sell and increased the margins they earn on their sales. Resonance marketing is the move away from the original goal of the industrial revolution, which was mass production of uniform, interchangeable products, to achieve the highest volume at the lowest cost. This resulted in a small number of high-volume market fat spots , with identical beers and identical white breads and a small number of candies and blue jeans competing for consumer attention through advertising. When nearly identical products compete, in the presence of complete information, competition drives margins down. Consumers wanted more choice, while companies wanted higher margins. Online community content—reviews from experts and from other shoppers—provides far better information than traditional advertising. With perfect information, consumers can accurately evaluate everything in the market and buy whatever delights them the most. When consumers can find and buy exactly what they want, then corporations change their strategy and start producing to occupy a wide range of high-margin, niche-focused market sweet spots , selling unique offerings where margins are not depressed by head-to-head competition with nearly identical offerings.
International Law and Domestic Legitimacy: Remarks prepared for Lincoln’s Constitutionalism in Time of War: Lessons for the Current War on Terror?

It is serendipitous that the bicentennial of Abraham Lincoln’s birth coincides with the seating of a new American president facing tremendous economic and national security difficulties. The success of the Lincoln Presidency in concluding and assuring the survival of the United States from the divisions of the Civil War reminds us of the enormous hardships the American people can bear and the power of a perseverant president. The focus of this symposium on Lincoln’s Constitutionalism in a Time of War and this particular panel of discussants on Suspending Rights to Sustain Public Safety is apt. Lincoln’s policies during the Civil War are perhaps most noteworthy for their elevation of necessity over formalism. His political pragmatism asserted that no President can allow the foundation of the nation to crumble due to reflexive pursuit of rigid formalism.1 In other words, the President’s responsibility to faithfully execute the laws of the nation could not countenance a world in which, when referencing habeas corpus protections, “all the laws, but one, to go unexecuted, and the government itself go to pieces, lest that one be violated.”2 Under Lincoln’s doctrine, no law would morally be held as preeminent when the fabric of the nation is at risk of being pulled asunder. In comparison to many of the rather drastic measures taken during the Civil War, the policies of the Bush Administration appear tame and unobjectionable. I presume that Professors John Yoo and
Management of the Adult Patient With Congenitally Corrected Transposition: Challenges and Uncertainties

Congenitally corrected transposition (ccTGA) is a rare form of congenital heart disease characterized by atrioventricular and ventriculoarterial discordance. Patients with ccTGA usually have associated congenital cardiovascular conditions; less than 1% have no associated lesions. Generally, ccTGA is identified during infancy or childhood with features of heart failure or cyanosis when there are associated lesions such as ventricular septal defect and/or pulmonic stenosis. Presentation later in life generally occurs when there are either mild or no associated lesions. Presentation during adulthood may be prompted by symptoms or signs of cardiovascular disease or due to abnormal findings on cardiac testing. Management of patients with ccTGA depends on presentation, symptoms, and associated defects. In this review, we will focus on the management of adult patients with ccTGA.
Partial-depth paved shoulder effect on part-time shoulder use pavement bearing capacity

In areas of high population density, widening all classifications of roadways for growing traffic volumes becomes increasingly complex and expensive to complete. For major highways in Europe and the United States (US), use of the shoulder as a part-time lane is becoming progressively common and may be a solution to growing traffic on lower roadway classifications. This approach is known as hard shoulder running internationally and part-time shoulder use (PTSU) in the US. For interstates or other major highways, the shoulder design is a full-depth paved shoulder, the same pavement cross-section as the mainline lanes, and is structurally sound. For arterials and collectors, the shoulder design commonly has a different pavement cross-section from the mainline lanes, a partial-depth paved shoulder design. This study focused on evaluating the design strength of typical partial-depth paved shoulder designs in the US for PTSU using the American Association of State Highway and Transportation Officials (AASHTO) Guidelines for Design of Pavement Structures 1993 design. The study sites were also redesigned according to the AASHTO design methodology to handle the PTSU design traffic volumes. This study found that two of the nine states evaluated could withstand PTSU with minor to no reconstruction.
A Structural Estimation Approach to Agent Attrition

Worker attrition is a costly and operationally disruptive challenge throughout the world. Although large bodies of research have documented drivers of attrition and its operational consequences, managers still lack an integrated approach to understanding attrition and making decisions to address it on a forward-going basis. To fill this need, we build a structural model that captures both the firm's decision to terminate a workers' employment (involuntary attrition) and uses an optimal stopping problem process to model a workers' decision to leave the firm (voluntary attrition). We then estimate the parameters of the model and conduct counterfactual analyses on the population of 1,135 agents serving one client over four years for an Indian business process management (BPM) company. Our model reveals a number of interesting findings as we see that agents' voluntary attrition decisions are relatively insensitive to salary. We also find that supervisors have a strong impact on whether employees stay as they reshape the way that agents make their decisions. If all employees were managed by the best supervisor in our data then voluntary attrition would reduce by over 40%. Altogether our paper contributes to the burgeoning literature on people operations, as well as to managerial practice.
Kinetics of Strain-Induced Domain Formation at Surfaces

By applying an external and variable strain to a Si(100) sample, it is possible to alter the relative populations of the 2×1 and 1×2 domains in a controlled and reversible way. This means one alters the configuration of monatomic steps which are the domain boundaries. This is conveniently observed by bending a thin bar of Si and observing either the superlattice LEED reflections or STM images. This effect is driven by the relaxation of the energy associated with long-range strain fields in the bulk which are due to the anisotropy of the intrinsic surface stress tensor of the two reconstructed domains. It is similar to the reduction of magnetic field energy by the configuration of magnetic domains. Here, we first briefly review the experimental observations for both nominally flat and vicinal surfaces and show that they are consistent with the theory of Alerhand et al. While the kinetics to produce or remove the unequal domain populations depend on the temperature, the steady state depends only on the strain and the vicinality but not on the temperature. The kinetics closely follow a simple relaxation \(\Delta \textup{I}(\textup{t})=\Delta \textup{I}(\infty )(1-e^{-t/\tau})\). 1/r is thermally activated with an activation energy of 2.2 ± 0.2 eV. One striking feature is that the time constants for establishing the asymmetric population upon applying the external strain are the same as those for removing the asymmetry after relieving the strain. Changing the populations requires moving steps and mass transport. It involves the same microscopic processes that are important in other phenomena like coarsening, step bunching, etc., and therefore understanding the kinetics in the present experiments may contribute to the understanding of a broader range of problems involving step motion.
Chinese Tourism to the United States: The Role of Perceived Cultural Similarity

China is the largest outbound tourism market in the world, and the United States is the most popular non-Asian destination. Research reveals an influence of country-level cultural differences on to...
EFFECT OF OVERCONSOLIDATION AND ANISOTROPY OF KAOLIN CLAY USING TRUE TRIAXIAL TESTING

ABSTRACT A series of strain controlled undrained true triaxial tests on cubical specimens have been performed using a fully automated flexible boundary experimental setup, with real-time feedback control system to evaluate the three-dimensional mechanical behavior of kaolin clay. This paper concentrates on the comparative response of the soil elements under monotonic shear loading observed at various overconsolidation levels. A possible shape of the initial yield surface is explored based on the limit of purely elastic deformations. The discussion includes the influence of the relative magnitudes of principal stresses on the clay behavior observed at different overconsolidation ratio values. Failure conditions are shown to be governed by the onset of localizations developed within the specimens, and because of which the specimens show sudden failure response before reaching a perfectly plastic deformation conditions. A reference surface constraining the ultimate plastic yielding of clay is found to be different from the observed failure surface. Based on the experimental observations, a 3-D failure criterion is developed that grows in size as a function of pre-consolidation stress.
The Wrong Line between Freedom and Restraint: The Unreality, Obscurity, and Incivility of the Fourth Amendment Consensual Encounter Doctrine

This article is a critical examination of the theory and factual assumptions behind the Supreme Court's notion of consensual encounters, unregulated by the Fourth Amendment, between police officers and citizens. It applies social science research to the Court's view of the "reasonable person," the concept on which the Court grounds the consensual encounter doctrine. The article focuses particularly on the incivility and confrontation that are required of the public in order to differentiate a consensual encounter from an actual seizure, using two accounts of individuals who chose to rebuff encounters with the police. Concluding that the line between freedom and restraint is wrongly located, too fuzzily drawn, and inimical to trust between individuals and the police, the article makes several suggestions for reform. These include greater judicial reliance on empirical data about how individuals perceive police approaches; a presumption that an investigative encounter amounts to a seizure, requiring Fourth Amendment oversight; or, at the least, a requirement that police state their business at the outset of any encounter with a member of the public.
Defining Data Migration Across Multidisciplinary Ambulatory Clinics Using Participatory Design.

Objective This study aimed to develop an institutional approach for defining data migration based on participatory design principles. Methods We outline a collaborative approach to define data migration as part of an electronic health record (EHR) transition at an urban hospital with 20 ambulatory clinics, based on participatory design. We developed an institution-specific list of data for migration based on physician end-user feedback. In this paper, we review the project planning phases, multidisciplinary governance, and methods used. Results Detailed data migration feedback was obtained from 90% of participants. Depending on the specialty, requests for historical laboratory values ranged from 2 to as many as 145 unique laboratory types. Lookback periods requested by physicians varied and were ultimately assigned to provide the most clinical data. This clinical information was then combined to synthesize an overall proposed data migration request on behalf of the institution. Conclusion Institutions undergoing an EHR transition should actively involve physician end-users and key stakeholders. Physician feedback is vital for developing a clinically relevant EHR environment but is often difficult to obtain. Challenges include physician time constraints and overall knowledge about health information technology. This study demonstrates how a participatory design can serve to improve the clinical end-user's understanding of the technical aspects of an EHR implementation, as well as enhance the outcomes of such projects.
Physiologically Based Pharmacokinetic Modeling of 3 HIV Drugs in Combination and the Role of Lymphatic System after Subcutaneous Dosing. Part 1: Model for the Free-drug Mixture

Drug-combination nanoparticles (DcNP) is a nano-formulation of multiple HIV drugs in one injectable. DcNP demonstrated long-acting pharmacokinetics (PK) for all drugs in the blood and lymphatic system of nonhuman primates (NHP). Long-acting is due to stably circulating DcNP and a depot in the lymphatic system during subcutaneous absorption. Because the PK of each drug in DcNP evolves through two species, i.e., drugs that dissociate from DcNP and drugs retained in DcNP (Part 2, presented separately), we describe here a physiologically based PK model of the nanoparticle-free drugs featuring the role of the lymphatic system. The free drug model was built using subcutaneous injections of suspended lopinavir-ritonavir-tenofovir in NHP and validated by external experiments. The model, for the first time, introduces the lymphatic network as part of a whole-body PBPK system and singles out major lymphatic regions: cervical, axillary, hilar, mesenteric, and inguinal nodes. Although the scope of the free-drug modeling was to support the construction of the nanoparticle model (Part 2), such a detailed/regionalized description of the lymphatic system and mononuclear cells represent an unprecedented level of prediction that renders the free drug model extendible to other small-drug molecules targeting the lymphatic system at both the regional and cellular level.
Debt Overhang and Pay for Performance Sensitivity

This paper examines the empirical impact debt overhang has on CEO compensation. In particular, we study if pay-for-performance sensitivity is affected by debt overhang. We construct a novel empirical new measure of debt overhang using default probabilities from a hazard model, effectively expanding the number of firms on which debt overhang can be computed. In pay-for-performance regressions we find strong statistical evidence of a negative effect from debt overhang, where a one standard deviation increase in debt overhang reduces pay-for-performance sensitivity by as much as 17%.
Motor performance of girls from twelve through eighteen years of age.

Abstract Three hundred girls in Georgia ranging from 12 through 18 years of age and enrolled in physical education from the seventh grade through the freshman year in college were given eight motor performance test items to measure running, jumping, throwing, speed, and agility. The study was undertaken to test the hypothesis that girls do not improve in motor performance after the age of 13.5 years, and also to investigate whether significant differences existed in motor skills according to age-grade level. Analysis of variance was used to test the significance of variation on each of the eight test items for the seven age-grade groups. Significance of differences in means for each test for each age-grade group was also calculated. Since ninth-grade girls, with a mean age of 14.4 years, scored highest on two items, tenth-grade girls scored highest on four items, and college girls scored highest on two tests, the hypothesis that girls generally do not evidence improvement in motor skills after the age of ...
Investigating Attitudes Toward Physical Education: Validation Across Two Instruments

The Centers for Disease Control have suggested that physical education plays a role in promoting healthy lifestyles. Prior research suggests a link between attitudes toward physical education and physical activity outside school. The current study provides additional evidence of construct validity through a validation across two instruments measuring attitudes toward physical education by investigating their psychometric properties with a sample of 6th grade students (N = 377). Confirmatory factor analysis results indicate that the four-factor model fit the data well for both instruments based on fit indices, and a multitrait-multimethod analysis provides evidence of convergent and discriminant validity. Cross validation of these instruments permits longitudinal investigations on the role of attitudes toward physical education and their impact on physical activity.
The role of Schwann cells in the development of human peripheral nerves. An electron microscopic study.

The Schwann cells of the sciatic nerve and brachial plexuses of four human fetuses aged 12, 14, 16, and 22 weeks of intrauterine life, were studied with the electron microscope. Four stages were recognized in the development of these cells: (a) pseudosyncytial, (b) migration, (c) division of cells and separation of axons, and (d) myelination. During all stages of development of human peripheral nerves, Schwann cells seem to have, as a morphological and perhaps physiological function, the isolation of axons from the surrounding connective tissue elements. During the intermediate stages of development, the main function of Schwann cells appears to be the separation of the axon bundles into smaller and smaller bundles, until one single axon has been finally separated from a bundle. This is accomplished by the continued division of the Schwann cells. After axon isolation has been accomplished, the function of the Schwann cells is myelination (14–16 weeks). All axons, either isolated or in bundles, had a complete or almost complete envelope of Schwann cell cytoplasm. At all stages of development a basement membrane separated the Schwann cell axon complexes from the surrounding mesenchymal tissues. It was suggested that the continual formation of cytoplasmic processes and division of the Schwann cells may be determined, at least in part, by the intimate contact of these cells with progressively enlarging axons.
Studies of respiratory components and oxidative phosphorylation in mitochondria of mi-1 Neurospora crassa.

Oxidative phosphorylation has been demonstrated with mitochondria of the mi-1 respiratory mutant of Neurospora crassa. The P/O ratios observed with these mitochondria were approximately 0.8 with citrate and 0.4 with either externally added reduced nicotinamide adenine dinucleotide (NADH), succinate, or ascorbate-tetramethyl-p-phenylenediamine (TPD). These P/O ratios suggest that there are only two sites of phosphorylation in mitochondria isolated from young (20 to 24 h) cultures of the mi-1 mutant. The energy-dependent reduction of NAD+ with succinate and the phosphorylation associated with ascorbate-TPD oxidation indicate that the first and the third sites of energy coupling are present in this mutant. Difference spectra of mitochondria from young cultures of the mi-1 mutant revealed the presence of cytochrome c. Cytochromes b and a + a3 were not detected. However, in the presence of antimycin A, a small peak in the Soret region at 430 nm was observed. A carbon monoxide difference spectrum revealed the presence of a component of the respiratory chain with a spectrum similar to that of cytochrome o. It is of interest that respiratory inhibitors such as antimycin A, 2-n-nonylhydroxyquinoline N-oxide, and cyanide abolished phosphorylation but only partially inhibited oxidation. It is postulated that the mi-1 respiratory system contains two pathways of electron transport—the first is associated with a phosphorylating pathway, whereas the second is a non-phosphorylating electron transport pathway.
Outsourcing Postracialism: Voicing Neoliberal Multiculturalism in Outsourced

This study investigates the ideological construction of neoliberal multiculturalism in the National Broadcasting Company's series Outsourced, starring a White male lead that manages a call center in India. We argue that the show advances global capitalism by co-opting multiculturalism to provide moral authority for Western neoliberal capitalism in the context of an inequitable global exchange. Neoliberalism benefits from postracialism by privatizing racism, thereby muting calls for antiracist structural reform. Relying on the ideological interests of neoliberal multiculturalism, Outsourced advances old racial logics by presenting unchallenged stereotypes of Indians and Indian culture and promotes a system of economic exchange that favors the global North while cloaking inequality with the veil of multiculturalism and the advancement of Whiteness as normative.
Situação atual do processo de certificação orgânica no Brasil

O sistema de producao orgânico visa a producao de alimentos ecologicamente sustentaveis, economicamente viaveis e socialmente justos, capaz de integrar o homem ao meio ambiente. A adocao desse sistema de producao vem crescendo, tanto em area cultivada como em numero de produtores e mercado consumidor, embora ainda represente uma parcela pequena da agricultura. O crescimento da agricultura orgânica se deve ao fato da agricultura convencional basear-se na utilizacao intensiva de produtos quimicos, fazendo com que os consumidores vejam neste sistema de producao uma possibilidade de risco a saude e ao meio ambiente, buscando produtos isentos de contaminacao. Com isso, a agricultura orgânica tem se destacado como uma das alternativas de renda para os pequenos agricultores, devido a crescente demanda mundial por alimentos mais saudaveis. Os produtos orgânicos nao usam agrotoxicos, sao obtidos em sistemas sustentaveis, pois mantem os recursos naturais e a fertilidade do solo, e tem qualidade garantida por certificadoras. A agricultura orgânica considera a propriedade agricola como uma unidade, como um organismo, onde o solo, a planta, o animal e o homem interagem harmoniosamente com o meio ambiente, demonstrando vantagens economicas, sociais e ambientais dos sistemas de producao orgânico, tendo sempre em foco a importância da certificacao desses produtos de origem orgânica, que e um elemento importante para o direcionamento do sistema de producao orgânica. A certificacao orgânica padroniza e facilita a comunicacao entre os agentes responsaveis pelo processo de producao e o seu consumidor, promovendo a transparencia dos atributos intrinsecos relevantes do produto para o consumidor, que busca um produto de qualidade superior ao convencional, possibilitando a utilizacao do selo fornecido pelas certificadoras, que e a garantia que o consumidor tem de estar consumindo produtos orgânicos. Afinal, com o crescente interesse pela agricultura orgânica, surge a necessidade de uma verificacao segura, que garanta ao consumidor a certeza de estar adquirindo produtos orgânicos. O objetivo deste trabalho e a realizacao de uma abordagem sobre a situacao atual do processo de certificacao orgânica no Brasil.
Genetic complementation analysis of the Agrobacterium tumefaciens virB operon: virB2 through virB11 are essential virulence genes.

Abstract The Agrobacterium tumefaciens virB gene products are proposed to assemble into a transport system capable of exporting complexes of DNA and protein across the bacterial envelope en route to plant cells. Nonpolar null mutations were constructed in each of the 11 virB genes of the A. tumefaciens pTiA6NC plasmid. In tumorigenicity assays, delta virB1 mutants exhibited severely attenuated virulence and delta virB2 through delta virB11 mutants exhibited avirulence. NdeI restriction sites introduced at the predicted translational start sites of the virB genes were used to subclone each of the virB genes downstream of the lacZ or virB promoter on broad-host-range plasmids. virB gene expression plasmids were used to define promoter and general sequence requirements for genetic complementation of the deletion mutations. Whereas virB1 and virB2 complemented delta virB1 and delta virB2, respectively, only when expressed in trans from the virB promoter, virB3 through virB11 complemented the corresponding deletion mutations when expressed in trans from either the lacZ or virB promoter. Several virB genes required additional upstream or downstream sequences for complementation: (i) virB2 complemented the delta virB2 mutation only when the complementing plasmid coexpressed virB1 and virB2, (ii) virB6 and virB9 complemented the delta virB6 and delta virB9 mutations only when the complementing plasmids carried at most 55 and 230 bp of sequences residing 5' of these genes, respectively, and (iii) virB7 and virB8 complemented the delta virB7 and delta virB8 mutations only when the complementing plasmid coexpressed virB7 and virB8. These studies established that virB1 is an accessory virulence determinant and virB2 through virB11 are absolutely essential for the A. tumefaciens infection process.
Glucose as a regulator of glycogen phosphorylase in rat diaphragm: II. Effect of glucose and related compounds on phosphorylase phosphate

Abstract 1. 1. The mechanism by which glucose causes a decrease in phosphorylase a levels in isolated rat diaphragm was investigated. Although glucose is known to be an inhibitor of both phosphorylases a and b , the effect of glucose could not be explained by a direct inhibitory action of the hexose on these enzymes. In contrast, it has been found that glucose markedly activates phosphorylase phosphatase, thus decreasing the level of phosphorylase a . 2. 2. In addition to glucose, glycogen and Glc-6- P also enhanced phosphatase activity, while Fru-1,6- P 2 and P i were inhibitory. 3. 3. Possible mechanismsof glucose activation of diaphragm phosphorylase phosphatase were investigated. Results indicated that the observed effect cannot be explained by a change in the molecular form of the substrate, phosphprylase a . Glucose may alter the susceptibility of the substrate and/or its partially phosphorylated intermediates to phosphatase action. Alternatively, glucose may directly activate the phosphatase itself.
The p75 NGF Receptor Exposed

Neurotrophins such as nerve growth factor (NGF) are secreted growth factors that are important for neuronal survival and plasticity. In their Perspective, Zampieri and Chao discuss a new study (He and Garcia) that highlights some unusual features about the binding of NGF to the p75 receptor.
Temporal scaling of hydraulic head fluctuations: Nonstationary spectral analyses and numerical simulations

[1] Temporal scaling of the hydraulic head time series, h(t), was found in a previous analysis of hourly measured head data. This issue is further investigated in this paper with nonstationary spectral analyses and numerical simulations. The results show that temporal scaling may indeed exist in h(t), which fluctuates like a fractional Brownian motion in most aquifers. On the basis of a linear reservoir model with a white noise recharge input, we show that the variance and covariance of h(t) are functions of time: The head variance increases with time and approaches a constant limit as time progresses, while the covariance decreases with the separation time interval for a fixed time and approaches the typical exponential covariance as time increases. The spectra of the simulated h(t) using a one-dimensional transient groundwater flow model with a white noise recharge in both homogeneous and heterogeneous aquifers are shown to be proportional to f-β, where f is frequency and β ∼ 1.84 (or H = 0.42). Heterogeneity in the hydraulic conductivity may affect the fractal dimension of h(t) in highly permeable aquifers but not in the low permeable aquifer simulated in this study.
Prospective manometric evaluation with pharmacologic provocation of patients with suspected esophageal motility dysfunction

Thirty-four consecutive patients referred to a gastroenterology clinic with suspected esophageal motility abnormality as a cause of their chest pain or dysphagia, or both, were prospectively studied in an 18-mo period. Peristaltic response to 10 wet (5 ml H2O) swallows was recorded in all studies with a low-compliance infusion system. To provoke symptoms and motility abnormalities after baseline evaluation, all patients had acid infusions (0.1 N HCl) and administration of edrophonium (80 micrograms/kg i.v.), pentagastrin (6 micrograms/kg s.c.), and bethanechol (40 micrograms/kg s.c.). Tracings were coded, read, and interpreted blindly. Baseline tracings were abnormal in 23 of 34 patients (68%), including increased amplitude peristaltic contractions ("nutcracker esophagus") in 10 and nonspecific esophageal motor disorders in 13. Acid infusion produced substernal burning in 3 of 33 patients, in motility change in 1 patient. Edrophonium produced chest pain with manometric changes in 6 of 34 (18%) patients. Pentagastrin produced chest pain with manometric change in 1 patient. Bethanechol produced chest pain with manometric change in 2 patients. One patient with low amplitude had elevation of esophageal baseline and multiple simultaneous contractions but no chest pain (subsequently developed achalasia). It was concluded that (a) abnormal motility is a common finding in a symptomatic group of patients with presumed esophageal motility disorder, (b) the "nutcracker" esophagus is the most frequent defect, and (c) attempted provocation of symptoms with acid or drugs is not generally effective; however, edrophonium is the best tolerated and most effective of currently available drugs.
The development of the blood-brain barrier in alcohol-exposed rats

Abstract Circulating horseradish peroxidase (HRP) was used as a tracer to determine if the blood-brain barrier to protein was altered by dietary prenatal alcohol exposure. Animals were prepared for light microscopic visualization of HRP after HRP infusion on gestational days 16, 18, 20, 22 and postnatal day 4. There was no consistent evidence of HPR leakage through the BBB in hte alcohol-exposed animals compared to control animals. Capillary endothelial cells and perivascular astrocytic endfeet were morphologically characterized by electron microscopy in rat optic nerve and cerebellum following dietary prenatal and postnatal ethanol exposure. Photomontages of optic nerve capillaries from G20 and P5 animals and cerebellar capillaries from P15 animals were examined for evidences of effects of alcohol on the development of the capillaries and adjacent astroglial endfeet. There was no consistent evidence of any alcohol-induced effects that could indicate a disruption of the vessel, the endothelial tight junctions, the perivascular glial limiting membranes, or the extent of vascular ensheathment by astrocytic endfeet.
Spiders: Where are the Bugs

One of the clearest trends in asset management is the rapid increase in the amount of individual and institutional money invested in indexed products. By far the most popular index that investors want to replicate is the S&P 500 index. While many academic studies have examined the characteristics of two instruments frequently used to replicate the S&P, index funds and futures, very little has been written about the newest way to replicate the S&P 500 index: Standard and Poors Depository Receipts (SDPR) commonly referred to as Spiders. The purpose of this paper is to analyze Spiders and compare them to alternative investments.
Adsorption of lipid-functionalized poly(ethylene glycol) to gold surfaces as a cushion for polymer-supported lipid bilayers.

Inclusion of a polymer cushion between a lipid bilayer membrane and a solid surface has been suggested as a means to provide a soft, deformable layer that will allow for transmembrane protein insertion and mobility. In this study, the properties of a heterofunctional, telechelic PEG lipopolymer (1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-poly(ethylene glycol)-2000-N-[3-(2-(pyridyldithio)propionate]) (DSPE-PEG-PDP) adsorbed from ethanol and water solutions onto gold surfaces were studied using a variety of surface-sensitive techniques. X-ray photoelectron spectroscopy showed that the PEG molecules are tethered to the gold surface via thiolate bonds. When adsorbed from water, ethanol, or their mixtures, reflection−absorption infrared spectroscopy showed that amorphous PEG layers with disordered DSPE alkyl chains were formed, independent of adsorption time or solution concentration. On the basis of advancing and receding water and hexadecane contact angles on the lipopolymer films, the DSPE lipid grou...
Endomorphin1-like immunoreactivity in the limbic system of Syrian hamsters (Mesocricetus auratus).

Abstract Recently, endomorphin-1 (Tyr-Pro-Trp-Phe-NH 2 ; EM1), an endogenous peptide that has high affinity and selectivity for the μ-opiate receptor, has been shown to modulate emotional behavior in mice and social behavior in Syrian hamsters. Endomorphin-1 (EM1) is present throughout the central nervous system in rats, mice, and guinea pigs; however, the distribution of EM1 in hamsters has not been described. The purpose of the present study was to investigate the distribution of EM1-like immunoreactivity (EM1L-IR) in the limbic system of Syrian hamsters using immunocytochemistry. Perikarya containing EM1L-IR were present in the anterior area, dorsomedial, ventromedial, periventricular, posterior, and arcuate nuclei of the hypothalamus. Fibers expressing EM1L-IR were present in the nucleus accumbens, caudate putamen, septum, bed nucleus of the stria terminalis, amygdaloid complex, and hypothalamus. The distribution of EM1 suggests a potential endogenous role for this peptide in major processes modulated by opiates, including affective states and social behavior.
Can One Cell Influence Cancer Heterogeneity

Gliomas are the most common form of malignant brain tumor in adults and have generally poor clinical outcomes. Patients with the most aggressive form of glioma, glioblastoma multiforme (GBM), have a low 5-year survival rate ( 1 ). Progress has been made in characterizing the genetic lesions and cells of origin in GBM, both of which may contribute to disease pathogenesis. On page 1080 in this issue, Friedmann-Morvinski et al. ( 2 ) show that differentiated neuronal cells and glial cells in the mouse brain can revert to less mature states upon acquiring these genetic lesions. Thus, multiple different cell types in the central nervous system, and not just neural stem cells, can be transformed into GBM in an animal model that recapitulates important aspects of the human disease.
Global trace-element biogeochemistiry at the K/T boundary: Oceanic and biotic response to a hypothetical meteorite impact

Calculations of trace-element fluxes to the ocean associated with a hypothetical 10-km-diameter Cl chondrite indicate that the mass of certain elements contained in the bolide, such as Fe, Co, Mn, Al, Zn, Ni, Ge, Cr, Sn, Cd, Pb, Ag, Cu, Hg, and Se, are comparable to or larger than the world ocean burden. Consequently, the introduction of meteoritic elements, in the form of atmospheric aerosol particles, to the surface ocean after a large meteor impact, concurrent with various element-specific solubilities, could rapidly alter the geochemical balance of some oceanic trace elements. We believe that this hypothetical pulse of trace elements would have been of sufficient magnitude to perturb the biogeochemical cycles operative at 66.4 Ma, a possible time of meteorite impact. Through direct exposure and bioaccumulation, many trophic levels of the marine food chain would have been adversely affected by these meteoritic elements. Those organisms residing in the surface ocean would be exposed to high prolonged concentrations of toxic trace elements. Preferential extinctions as driven by species-specific tolerance of elevated trace-element levels in the ocean would occur. The trace-element aerosol flux associated with K/T boundary volcanism may also have contributed to elevated trace-element concentrations in the world ocean. The trace-element toxification hypothesis postulates a mechanism that may have contributed to the selective extinction of marine organisms during the enigmatic terminal Mesozoic event.
"No matter what i do they still want their family": Stressors for African American grandparents and other relatives

Grandparents and other relatives increasingly assume the role of primary caregiver to minor children. This study interviewed family members caring for children whose parents were not available due to parental incarceration, other involvement in the criminal justice system, and substance abuse-related issues. Interviews with 25 African American women examined the impact of caregiving including stress and depression. Stress included caregiver issues related to finances, time allocation, care responsibilities, and concerns about the absent parent, as well as issues specific to the children related to school concerns, child behavior, and emotional problems. These stresses were examined along with caregiver depression scores using the Center for Epidemiological Studies Depression Scale, which indicated more depression related to caregiver illnesses, older caregivers, and care for older and a larger number of children. This study suggests that caring for these children is both challenging and stressful, and car...
Synthesis of new lipophilic acyclic di-ionizable polyethers, bis(crown ethers) and macrocyclic diamides

Abstract A series of new lipophilic acyclic polyethers containing two carboxylic or hydroxamic acid groups have been prepared. From lipophilic acyclic polyether dicarboxylic acids 2, 9 and 13, the bis(crown ethers) 20–25 were synthesized. From lipophilic acyclic polyether dicarboxylic acids 10–12 and 14, the new macrocyclic diamides 26–32 were prepared in high yields without the use of high dilution techniques or template effects.