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Derived algebraic geometry, determinants of perfect complexes, and applications to obstruction theories for maps and complexes
Get PDFAbstract A quasi-smooth derived enhancement of a Deligne-Mumford stack X naturally endows X with a functorial perfect obstruction theory in the sense of Behrend-Fantechi. We apply this result to moduli of maps and perfect complexes on a smooth complex projective variety. For moduli of maps, for X = S an algebraic K3-surface, g ∈ N, and β = 0 in H 2 (S, Z) a curve class, we construct a derived stack RM red g,n (S; β) whose truncation is the usual stack M g,n (S; β) of pointed stable maps from curves of genus g to S hitting the class β, and such that the inclusion M g (S; β) → RM red g (S; β) induces on M g (S; β) a perfect obstruction theory whose tangent and obstruction spaces coincide with the corresponding reduced spaces of Okounkov-Maulik-Pandharipande-Thomas [O-P2, M-P, M-P-T]. The approach we present here uses derived algebraic geometry and yields not only a full rigorous proof of the existence of a reduced obstruction theory -not relying on any result on semiregularity maps -but also a new global geometric interpretation. We give two further applications to moduli of complexes. For a K3-surface S we show that the stack of simple perfect complexes on S is smooth. This result was proved with different methods by Inaba ([In]) for the corresponding coarse moduli space. Finally, we construct a map from the derived stack of stable embeddings of curves (into a smooth complex projective variety X) to the derived stack of simple perfect complexes on X with vanishing negative Ext's, and show how this map induces a morphism of the corresponding obstruction theories when X is a Calabi-Yau threefold. An important ingredient of our construction is a perfect determinant map from the derived stack of perfect complexes to the derived stack of line bundles whose tangent morphism is given by Illusie's trace map for perfect complexes
Exploring Strategies to Address Obesity with Eat Smart, Move More North Carolina
Get PDFAbstract More than two-thirds of adults and almost one-third of children in North Carolina are overweight or obese. These high rates are of great concern, because overweight and obesity are related to increased risk of chronic disease and decreases in life expectancy, productivity, and quality of life. To address these issues, a state organization called Eat Smart, Move More North Carolina (ESMMNC) is working to make the healthy choice the easy choice through the promotion of policy change as well as change in physical and social environments. ESMMNC recently published North Carolina's Plan to Address Obesity: Healthy Weight and Healthy Communities 2013-2020 as a physical activity and healthy eating strategy guide for organizations in particular settings. The purpose of this public service project was to assist the ESMMNC Executive Committee in tracking the progress of the 2013-2020 Plan so they could consider how to better support the work of ESMMNC Leadership Team member organizations. For this public service project, I worked with the ESMMNC Executive Committee to create and distribute an online survey, and in the coming month, I will analyze and report on the results. Survey results will show which strategies from the 2013-2020 Plan have been adopted most, have not been adopted at all, are most difficult to implement, and which provide the greatest impact or benefit to organizations in certain settings. Through this project, I have learned about the importance of and barriers to communication and collaboration in a state-level organization while improving my own skills in communication and research. I have also gained a greater understanding of obesity as a multifaceted issue, influenced by numerous factors and therefore demanding comprehensive approaches in order to affect positive change
Linear Matrix Inequality Formulation of Spectral Mask Constraints With Applications to FIR Filter Design
Get PDFAbstract-The design of a finite impulse response (FIR) filter often involves a spectral "mask" that the magnitude spectrum must satisfy. The mask specifies upper and lower bounds at each frequency and, hence, yields an infinite number of constraints. In current practice, spectral masks are often approximated by discretization, but in this paper, we will derive a result that allows us to precisely enforce piecewise constant and piecewise trigonometric polynomial masks in a finite and convex manner via linear matrix inequalities. While this result is theoretically satisfying in that it allows us to avoid the heuristic approximations involved in discretization techniques, it is also of practical interest because it generates competitive design algorithms (based on interior point methods) for a diverse class of FIR filtering and narrowband beamforming problems. The examples we provide include the design of standard linear and nonlinear phase FIR filters, robust "chip" waveforms for wireless communications, and narrowband beamformers for linear antenna arrays. Our main result also provides a contribution to system theory, as it is an extension of the wellknown Positive-Real and Bounded-Real Lemmas
ANTENATAL TREATMENT WITH GLUCOCORTICOIDS AND THE HYPOTALAMIC-PITUITARY-ADRENAL AXIS ANTENATALNA TERAPIJA GLUKOKORTIKOIDIMA I HIPOTALAMO-HIPOFIZNO-ADRENALNA OSOVINA
Get PDFSummary Fetal development is a critical period in the life cycle which is why the placenta provides a structural and physiological barrier that protects the fetus from the outer fluctuations and inner disturbances. A variety of influences from the environment, however, might induce fetal overexposure to glucocorticoids that target the fetal hypothalamic-pituitaryadrenal (HPA) axis and influence the fetal growth trajectory. Development of the HPA axis starts in the early stages of pregnancy, but the timing of HPA axis maturation and the glucocorticoid receptor (GR) expression in relation to birth is highly species-specific. The functional state of the fetal HPA axis plays a key role in the maturation of many organs necessary for intrauterine development and existence after birth. A functional HPA axis in near-term fetuses provides an adequate response to stress and also affects the timing of parturition. Due to their potent effect on the maturation of fetal tissues, synthetic glucocorticoids are used in human pregnancy at risk of preterm delivery. Dexamethasone and betamethasone, as the ones most commonly used, cross the placental enzymatic barrier (11b-hydroxysteroid dehydrogenase type 2 -11b-HSD2) and have 25-fold higher affinity to the GR than endogenous glucocorticoids, stimulating many aspects of fetal maturation. Despite the numerous positive effects, exposure to synthetic glucocorticoids during fetal development may result in intrauterine growth retardation and fetal programming of the HPA axis function which is associated with cardiovascular, metabolic and psychiatric disorders manifested later in life. Long-term consequences indicate the need for the implementation of new studies that will pro- Kratak sadr`aj Fetalni razvoj predstavlja kriti~an period tokom `ivotnog ci klusa, zbog ~ega placenta obezbe|uje strukturnu i fiziolo{ku barijeru koja {titi fetus od spolja{njih kolebanja i unutra{njih poreme}aja. Brojni uticaji iz okru`enja mogu dovesti do izlaganja fetusa povi{enoj koncentraciji glukokor tikoida koji deluju na fetalnu hipotalamo-hipofiznoadrenalnu (HPA) oso vinu i uti~u na rast. Razvoj HPA osovine po~inje veoma rano tokom gestacije, ali vreme njenog sazrevanja i ekspresije glukokortikoidnog receptora (GR) u odnosu na ro|enje je specifi~no za svaku vrstu. Fetalna HPA osovina ima klju~nu ulogu u sazrevanju brojnih organa tokom intrauterinog raz voja neophodnih za pre`ivljavanje nakon ro|enja, obezbe |uje adekvatan odgovor fetusa na stres, a uti~e i na vreme poro|aja. Usled sna`nog uticaja na sazrevanje fetalnih tkiva, sintetski glukokortikoidi se upotrebljavaju tokom rizi~nih trudno}a kod kojih postoji opasnost od prevremenog poro|aja. Deksametazon i betametazon, kao naj~e{}e kori{}eni lekovi u antenatalnoj terapiji, prolaze enzimsku placentalnu barijeru (11b-hidroksisteroid dehidrogenaza tip 2 -11b-HSD2) i imaju 25 puta ve}i afinitet vezivanja za GR u odnosu na endogene gluko kortikoide, stimuli{u}i mnoge procese sazrevanja fetusa. Uprkos brojnim pozitivnim efektima, izlaganje sintetskim glukokortikoidima tokom fetalnog razvoja mo`e rezultirati retardacijom rasta fetusa i programiranjem fetalne HPA funkcije. Nastale promene su povezane sa kardiovaskular nim, metaboli~kim i psihijatrijskim poreme}ajima, koji se mogu manifestovati tokom `ivotnog ciklusa. Dugotrajne posledice antenatalnog tretmana ukazuju na potrebu za novim studijama, koje bi obezbedile bolje razumevanje veze izme|u izlo`enosti povi{enim koncentracijama gluko -308 Manojlovi}-Stojanoski et al.: Antenatal therapy Pregnancy and the HPA axis In adults, psychological or physical stress activates the hypothalamic-pituitary-adrenal (HPA) axis. Hypothalamic corticotrophin-releasing hormone (CRH) stimulates adrenocorticotropic hormone (ACTH) release from the anterior pituitary, which, in turn, causes the release of adrenal glucocorticoids. Adrenal glucocorticoids are dominantly involved in protein, carbohydrate and lipid metabolism, and strongly affect immune response with the primary goal of achieving homeostasis. An elevated glucocorticoid level provoked by chronic stress exposure exerts longterm changes in negative feedback control at the hypothalamic and pituitary level, while rapid glucocorticoid feedback suppression of basal and stressinduced HPA axis activity is controlled through a central site of action and involves activation of the glucocorticoid receptor (GR) (1). During pregnancy, numerous adaptations of maternal anatomy and physiology provide optimal conditions and maximal security for the developing fetus, from the environmental fluctuations and inner disturbances (2). The placenta represents a fetomaternal exchange barrier to many of the maternal factors, although sufficient amounts of nutrients and oxygen are delivered to the developing fetus, whereas fetal metabolic excretion products are removed, enabling optimal fetal growth (3). Although the placenta shows broad species-specific differences, the common histological structure includes the maternal blood vessels endothelium (endometrium) and the fetal blood vessels endothelium (chorion). At the earliest stage of development, the principal precursor of the fetal part of the placenta is the trophoblast, evident as a thin cellular layer surrounding the blastocyst. During implantation, the trophoblast becomes the chorion, which is in direct contact with uterine endometrial connective tissue and differentiates into syncytiotrophoblast, a multinucleated cytoplasmic mass or syncytium that arises from the fusion of separate cells of the underlying cytotrophoblast. The functional part of maternal placenta evolves from the uterine epithelium. The placental exchange area is villous in primates and sheep, and has the form of a labyrinth in mice, rats and guinea pigs (4). Placental endocrine function creates a unique endocrine milieu providing the production of hypothalamic and pituitary hormones, as well as growth factors. The quantity of synthesized adrenal and gonadal hormones, using substrates of maternal and fetal origin, indicates intensive steroidogenic activity in the placenta. Placental CRH is secreted in large amounts into the maternal and fetal circulation influencing the maternal and fetal HPA axis function. In human CRH immunoreactivity was present in hypothalamic paraventricular nuclei (PVN) as early as at 12 weeks of gestation, but intensive hypothalamic stimulation of pituitary corticotropes started from week 16-30 of gestation (4, 5). Further trophic support of the adrenal gland growth and differentiation by the released ACTH becomes evident from around mid gestation towards the term, but there is no clear correlation between the level of plasma ACTH and glucocorticoid concentrations, suggesting immaturity of the negative feedback regulation during fetal development. In rats, significant hypothalamic support of ACTH synthesis and release and promotion of adrenal gland growth and functional differentiation started later, during the last third of gestation. The functioning of negative feedback control was verified by the decreased CRH expression before birth (4, 6). Contrary to the hypothalamic CRH, placental CRH is positively stimulated by the increasing cortisol level that additionally up-regulates CRH gene expression establishing a feed forward loop (4). Circulating CRH influences fetal pituitary ACTH production and directly stimulates dehydroepiandrosterone (DHEA), dehydroepiandrosteronesulphate (DHEAS) and cortisol output from the fetal adrenals. The secreted DHEAS serves as a substrate for placental estrogen production due to aromatase activity. The created estrogen/progesterone ratio forces interconversion of the biologically active cortisol to inactive cortisone, thereby decreasing negative feedback drive of the higher control centers, and consequently hypothalamic CRH and pituitary ACTH output are enhanced and further stimulate the growth of fetal adrenal glands (7). In humans and primates, this mechanism has enabled the size of near-term adrenal glands to surpass several times the relative size of adult ones, primarily due to the enormously developed fetal zone, while the quantity of synthesized steroids 5 times surpasses the stimulated steroid production in adults. On the other hand, a centrally positioned fetal zone, responsible for androgen production during pregnancy, disappears during the postnatal period. In newborns, dramatic shrinkage of adrenal glands takes place due to involution of the fetal zone caused by apoptotic cell death Keywords: programming, fetal development, HPA axis, dexamethasone, betamethasone, antenatal therapy kortikoida tokom fetalnog perioda i {tetnih posledica u odraslom dobu. Klju~ne re~i: programiranje, fetalni razvoj, HPA osovina, deksametazon, betametazon, antenatalna terapija J Med Biochem 2014; 33 (4) 309 pus luteum and in the fetal gonads (10). Thus, the placenta and the fetal adrenals make a unique fetoplacental functional unit that controls and adjusts HPA axis functioning during in utero development. HPA axis function during development Prenatal presence of the GR has been demonstrated in the tissue derivatives of all three germ layers using in situ hybridization and immunocytochemical techniques. Strictly defined temporal and spatial expression of the GR, in fact, defines the target tissues and periods of glucocorticoid sensitivity during development. The established increase in GR mRNA amount just before the final differentiation step for each glucocorticoid target tissue, and the following decrease in GR mRNA amount upon differentiation, suggest that maturational events are controlled by glucocorticoids (11). Activity of the fetal HPA axis and the released glucocorticoids direct the fetal growth trajectory to a considerable extent, according to the maternal energy resources. Glucocorticoids promote fetal maturation, as they affect the developmental and maturational processes of a variety of tissues and organs, in order to enable functional adaptations requested for extrauterine survival. Under constantly changing environmental conditions, the survival of newborns depends on the maintenance of homeostasis, thermogenesis and a stable energy supply, in view of the transition from placental to enteral nutrition (12). To achieve this, glucocorticoids influence the timely differentiation of vital organ systems, including the central nervous system, gastrointestinal system, as well as other endocrine axes and tissue hormones sensitivity. Fetal lung maturation and surfactant production, enhancement of gluconeogenic enzyme activities in the liver and glycogen deposition, as well as adaptive thermogenesis in brown adipose tissue are also controlled by glucocorticoid action Like in adults, where stress implicates an HPA axis response, adverse intrauterine conditions in fetuses also provoke fetal HPA axis activation (15). For example, fetal hypoxemia leads to an increase in the fetal ACTH concentration with up-regulation of mRNAs of the ACTH receptor and steroid-synthesizing enzymes in the adrenals that result in selective increase of cortisol synthesis in fetal sheep (16). Negative feedback control of the HPA axis by glucocorticoids begins to operate near the term, suggesting that active control of the glucocorticoid level is indispensable even during fetal development (17). Coordinative activity of the HPA axis and the placenta in fetuses plays an important role in determining gestation length, which is certainly closely related to the maturation level of numerous organ systems. Although the exact mechanism remains unclear, an increase in fetal HPA activity has been established in humans and primates during late gestation. An increased cortisol concentration, that is generated locally in the placenta or derived systemically, stimulates prostaglandin synthesis, decreasing its metabolism, which results in an enhanced prostaglandin output. Huge amounts of DHEAS, produced by the fetal adrenals, undergo aromatization in the placenta and subsequently lead to elevated circulating estrogen levels (18). The created hormonal milieu and enhanced output of prostaglandins induce the expression of oxytocin receptors indispensable for uterine contractility. Late in gestation, an increase in unbound CRH fraction intensifies circulation in the feto-placental unit, potentiating the effects of local mediators and hormones that further up-regulate myometrial contractility and represent an important step in the initiation of birth (4, 19). Antenatal treatment Fetal growth and the development of fetal tissues and organs are dependent on many factors, including the hormonal environment. As mentioned, endogenous glucocorticoids produced by the fetal adrenal glands have a crucial role in these processes and exert beneficial effects on the maturation of fetal tissues where GR have been located. The timing of HPA axis maturation and expression of the genes encoding GR in relation to birth is highly species-specific. In species with a long gestational period (sheep, guinea pigs, primates and humans) that give birth to mature young, maximal brain growth and many aspects of neuroendocrine maturation take place in utero. But in species with short gestational periods (rats, rabbits and mice) that give birth to immature offspring, much of the neuroendocrine development, GR genes expression as well as the final maturation of endocrine axes occur in the postnatal period (20). Under normal circumstances, glucocorticoid levels are significantly lower in the fetus than in the mother and transplacental glucocorticoid diffusion is normally limited by the actions of the placental barrier enzyme, 11b-hydroxysteroid dehydrogenase type 2 (11b-HSD2) (21). This enzyme plays a key role in regulating glucocorticoid concentrations in the fetal circulation by inactivating maternal glucocorticoids at the level of the placenta, and protects fetuses from glucocorticoid overexposure. In a rat and human study, it has been demonstrated that attenuated activity of 11b-HSD2 due to carbenoxolone application, maternal exposure to stress or antenatal treatment with synthetic glucocorticoids may expose the fetus to inappropriately high levels of glucocorticoids, which leads to reduced fetal growth followed by long-lasting consequences (12). Due to their potency in maturating tissues and organs, synthetic glucocorticoids have been used for more than 40 years in human pregnancies at risk of preterm delivery. Antenatal glucocorticoid administra-310 Manojlovi}-Stojanoski et al.: Antenatal therapy tion is perhaps one of the most effective prenatal interventions for the prevention of complications related to preterm birth, which include respiratory distress syndrome (RSD), intraventricular hemorrhage and, most importantly, neonatal mortality. The origin of this practice comes from Liggins and Howie (22), whose preliminary results indicated a reduction in the incidence of RSD and mortality in humans after maternal betamethasone treatment. Subsequent trials have confirmed the efficacy of this treatment in the reduction of complications associated with preterm delivery (23). According to the National Institutes of Health (NIH), all the fetuses between 24 and 34 weeks of gestation at risk of preterm delivery are potential candidates for antenatal glucocorticoid treatment. The recommended treatment consists of two doses of 12 mg betamethasone administered intramuscularly 24 h apart, or four doses of 6 mg dexamethasone every 12 h. They cross the placental barrier, have 25-fold higher affinity to the GR than endogenous glucocorticoids, and act in accordance with its nuclear transcription factor function (24). The question of the relative risk and benefit of repetitive courses of prenatal glucocorticoid administration is still open. Antenatal glucocorticoid therapy is indicated in women with premature rupture of membranes and women with progestational or gestational diabetes at risk of preterm delivery, but contraindicated in cases of maternal systemic infections including tuberculosis (24). During gestation, synthetic glucocorticoids are also used to treat several other clinical conditions of the mother, such as autoimmune diseases, allergies and asthma. The incidence of congenital adrenal hyperplasia (CAH) in fetuses is rare, but treatment with glucocorticoids is necessary to improve later outcome. In contrast to antenatal therapy applied in preparation for preterm birth, treatment under these clinical conditions often begins early in the pregnancy and lasts throughout gestation (25). Despite the mentioned positive effects, repeated doses of antenatal glucocorticoids have potentially negative effects on fetal growth and adverse effects on brain growth and development in animals and humans. Impaired intrauterine growth and low birth weight, as markers of an adverse in utero environment, are associated with hypertension, glucose intolerance, insulin resistance, type 2 diabetes, dyslipidaemia, obesity, reproductive and brain disorders in adulthood Antenatal glucocorticoid therapy reduces mortality and morbidity in preterm babies and at the same time increases the risks of dysregulation of the metabolic function and endocrine axes, including stress response, growth and reproduction (12). More randomized human follow-up studies are needed to better understand the short-term benefits and long-term consequences of antenatal exposure to synthetic glucocorticoids on development and health. Antenatal treatment and fetal HPA axis function Results from animal and human studies demonstrate that fetal glucocorticoid overexposure results in fetal growth retardation that persists for a prolonged period after birth. The developing HPA axis is especially sensitive to glucocorticoid overexposure, as they strongly affect the establishment of HPA axis structure and function (29). Glucocorticoids control the proliferative activity of cells at all the HPA axis levels, and influence the gene expression of receptors, enzymes, ion channels, as well as cytoarchitectural proteins. All these changes at the cellular and molecular level result in altered set points of the delicate hormonal feedback mechanisms that become evident during the life cycle, under basal or stress circumstances The hippocampus has a central role in the negative-feedback regulation of HPA axis by glucocorticoids which interact with the abundantly expressed GR and mineralocorticoid receptors (MR). Application of synthetic glucocorticoids during pregnancy provokes a sex-specific influence according to hippocampal mRNA GR and MR levels in fetuses. Single maternal Dx exposure results in significant increases in MR and GR mRNA in the CA1-2 region of the hippocampus, and MR mRNA in the dentate gyrus in female fetuses, while changes are absent in male guinea pig fetuses (31). After multiple maternal treatment with Dx, marked increases in MR mRNA level in the hippocampus of female fetuses were recorded, while in males enhancement of GR mRNA was shown in limbic structures indicating changed hippocampal feedback sensitivity to glucocorticoids, natural or synthetic (32). Quantitative in situ hybridization demonstrated that the MR mRNA level is transiently decreased after a single Dx injection in the mouse fetus (33). Synthetic glucocorticoids applied during pregnancy lead to reduction in brain weight in fetuses. Literature data show similar effects of fetal glucocorticoid overexposure in different species, including mice, rhesus macaques and humans, such as reduced hippocampal volume with a reduced number of pyramidal neurons and pronounced degeneration of neuronal perikarya and dendrites, resulting in a decreased number of synaptic contacts The hypothalamus, as the main site for glucocorticoid negative feedback, represents a regulatory place where the stress response starts and terminates. Neurons in the parvocellular division of the hypothalamic paraventricular nuclei (PVN) synthesize both CRH and AVP, or only CRH, and their axons project to the median eminence where the produced neuropeptides are released. Repeated fetal glucocorticoid exposure to synthetic glucocorticoids, dexamethasone or betamethasone, inhibits fetal HPA function, as significantly decreased levels of CRH mRNA in the hypothalamic PVN in both male and female fetuses were established (32). Delay of CRH release in the external zone of the median eminence, shown by immunocytochemistry, might further confirm the decreased synthetic activity of CRH neurons in the fetus and neonatal offspring after fetal Dx exposure (37). Delicate cellular and molecular changes caused by the changed glucocorticoid milieu during development become evident at the level of hypothalamic neurosecretory cells morphometric parameters in fetuses and during the neonatal period (38). Analysis of neurosecretory parvocellular and magnocellular PVN neurons suggested that the area and diameter of neurosecretory cells nuclei at the levels were CRH neurons are dominantly positioned are significantly changed under the influence of dexamethasone, but the range of changes depends on the timetable and dosage of dexamethasone applied (39). As a consequence of the antenatal treatment, the quantity and time profile of hypothalamic CRH released into the hypophyseal portal blood along with other ACTH secretagogues such as AVP change, and this reflects on the differentiation and activity of anterior pituitary corticotropes and the secreted ACTH. Prenatal glucocorticoid exposure also directly influences the fetal pituitary, as GR are present in pituitary primordial cells. Again, the timing and regime of fetal glucocorticoid exposure in utero will determine the outcome, as regards the establishment of hormoneproducing cell populations in the ante
Policing culture, cultural policing: law and social order
Get PDFThis study transgresses the received distinction between two genres: the scholarly essay and the grant proposal. An extended reflection on a research endeavor still in progress, it interrogates the methodological and conceptual questions raised, ab initio, by the effort to explore and explain an unusually perplexing phenomenon: the dramatic rise, in postapartheid South Africa, of witchcraft killings-and of their policing, both formal and informal, which has produced distinctly hybrid styles of cultural justice. Our objective is to address a number of interrelated questions concerning the description, interpretation, and analysis of (1) occult-related violence, itself legitimized locally by populist appeals to ''culture'' and (2) its regulation by a secular modernist state committed to, yet challenged by, the constitutional recognition of cultural difference. It is our thesis that this ''epidemic'' of occultrelated violence, and the kinds of cultural policing that accompany it, are stark expressions of a structural contradiction within the ''new'' South Africa, a contradiction evinced in all postcolonies-and, increasingly, in other nation-states as well Our objective here is somewhat unusual. Rather than an ethnographic analysis or a theoretical discussion, what follows is an extended reflection on a research endeavor still in its early stages. We are concerned to shar
No full textAbstract The Yellow-footed Gull (Larus livens) is one of the few members of the genus Larus inhabiting the Gulf of California. Its breeding biology, nest phenology, and behavior have been long studied but little is known about seasonal changes in its diet. In this study, we tested if the diet of Yellow-footed Gull differed between reproductive (April and July) and non-reproductive (December). The frequency of occurrence of food items in gull's pellets and food niche breadth (FNB) and Levin's diversity (B est ) indexes for each sampling period (April, July, and December), as well as Pianka's dietary overlap (O%) and Morisita's (MI) dietary similarity indices between periods were estimated. We identified 9 taxa classes, whose frequency of occurrence varied significantly between all comparisons (April and December, July and December, April and July), and between reproductive (April-July) and non-reproductive seasons. FNB and B est diversity indexes indicated that Yellow-footed Gull has a broader niche spectrum during the breeding season (April-July), while dietary overlap estimators (O% and MI) were higher between July vs. December and April vs. December, but lower in April vs. July. Results are contrasted with previous studies of gull's feeding ecology, and possible effects of local human activity are discussed. All Rights Reserved © 2015 Universidad Nacional Autónoma de México, Instituto de Biología. This is an open access item distributed under the Creative Commons CC License BY-NC-ND 4.0. Keywords: Gull pellets; Feeding ecology; Larus livens; Food niche breadth Resumen La gaviota de patas amarillas (Larus livens) es uno de los pocos miembros del género Larus que habitan el Golfo de California. Su biología reproductiva, fenología de nido y comportamiento se han estudiado durante mucho tiempo, pero poco se sabe acerca de los cambios estacionales en su dieta. En este estudio se probó si la dieta de la gaviota de patas amarillas fue diferente entre temporadas reproductivas (abril y julio) y no reproductivas (diciembre). Se evaluó la frecuencia de presencia en egagrópilas, la amplitud de nicho trófico (FNB) y el índice de diversidad de Levi
Amnesia and Homicide: The Padola Case and a Study of Thirty Cases Historical Overview and the Padola Case
No full text2010): “Employment Growth and International Trade: A Small Open
No full textAbstract In this paper, we use a detailed dataset containing information about all international trade transactions of the population of Danish firms over more than a decade to analyze the relationship between export and import decisions and employment growth. We further distinguish between imports of final goods and imports of intermediate products. We find that both imports and exports decisions are positively related to employment growth. Interestingly, both finished goods and intermediate goods imports have a positive link. We also control for the re-exporting process, i.e. firms importing final goods to re-export them afterwards
Mandatory Labeling of Genetically Modified Foods: Does it Really Provide Consumer Choice?
No full textPerception With Compensatory Devices: From Sensory Substitution to Sensorimotor Extension
No full textAbstract Sensory substitution devices provide through an unusual sensory modality (the substituting modality, e.g., audition) access to features of the world that are normally accessed through another sensory modality (the substituted modality, e.g., vision). In this article, we address the question of which sensory modality the acquired perception belongs to. We have recourse to the four traditional criteria that have been used to define sensory modalities: sensory organ, stimuli, properties, and qualitative experienc