Beyond Schur's Conjecture

Schur 4] conjectured that the maximum length N of consecutive quadratic nonresidues modulo a prime p is less than root p if p is large enough. This was proved by Hummel in 2003. In this note, we outline a clear improvement over Hummel's bound for p > 23.

Beyond Schur's Conjecture

Schur 4] conjectured that the maximum length N of consecutive quadratic nonresidues modulo a prime p is less than root p if p is large enough. This was proved by Hummel in 2003. In this note, we outline a clear improvement over Hummel's bound for p > 23.

Estados Unidos : ��ante una suba de tasas de inter��s en 2015?

Introducci��n: A ra��z de la crisis de hipotecas sub-prime de 2008 en Estados Unidos, tanto la Reserva Federal (FED) como los dem��s bancos centrales del mundo (en especial, el Banco Central Europeo y el de Jap��n actualmente) comenzaron a aplicar un continuo est��mulo monetario v��a bajas tasas de inter��s (cercanas a cero en los tres casos). Dicha pol��tica monetaria activa fue efectiva, en el caso de Estados Unidos, para otorgar liquidez al mercado y actuar sobre las expectativas de los agentes. De este modo, adem��s de generarse una importante recuperaci��n de valor en los activos y un colapso en las yields de la parte larga de la curva de bonos soberanos, se comenz�� a observar una muy gradual mejora en la econom��a real, la cual viene siendo cada vez m��s robusta a juzgar por ciertos indicadores que se ver��n m��s adelante en este ensayo...

Informe de Econom��a e Instituciones

Resumen: En su quinto n��mero el Informe de Econom��a e Instituciones cuenta con tres columnas que abordan cuestiones te��ricas y de pol��tica econ��mica relacionadas con la tem��tica de la econom��a y las instituciones. En la primera columna, La crisis financiera y el debate regulatorio, presenta una explicaci��n institucional a la crisis hipotecaria actual en Estados Unidos. Seg��n el autor en el origen de la inestabilidad del sistema financiero, que produjo consecutivos efectos de ���burbujas��� burs��tiles se encuentra la revoluci��n tecnol��gica y una desregulaci��n imprudente de los sistemas financieros desde los a��os 1980. Con respecto a las soluciones en curso se resalta que las medidas que no incluyan, aparte de soluciones coyunturales como los rescates de entidades bancarias y financieras, una reformulaci��n de las regulaciones no podr��n atacar el problema en toda su magnitud. En la segunda columna, Causas institucionales de la crisis econ��mica mundial, se enfoca en las causas de la crisis actual, que seg��n el autor provienen de notorias fallas institucionales. El vac��o de reglas prudenciales en las hipotecas sub-prime produjo primero una ���burbuja��� en el precio de los inmuebles y luego, al colapsar ��sta, condujo a elevados porcentajes de incobrabilidad. Un rasgo en la organizaci��n institucional de la sociedad es evitar que alguien sea ���juez y parte��� en un tema, evitando asimetr��as en la informaci��n y lobbies. Por ��ltimo, se comenz�� a transferir a los ahorristas el riesgo crediticio, esto transforma esencialmente la funci��n del sector bancario de evaluadores de riesgos a vendedores de bonos. En la tercera columna, Los subsidios estatales en un contexto de vac��o institucional, se puntualiza que la absoluta discrecionalidad de que gozan los gobiernos para disponer la asignaci��n de dineros p��blicos v��a subsidios es una constante hist��rica, que en los pa��ses m��s avanzados a comenzado a revertirse. El crecimiento explosivo de los subsidios en nuestro pa��s durante los ��ltimos a��os, en un marco de vac��o de reglas jur��dicas que fijen ciertos criterios imperativos para el gobierno, ha conducido a situaciones de marcada ineficiencia. Existen muchas recetas para revertir tal escenario, pero lo complejo es encontrar la llave para torcer la natural resistencia de los gobiernos a crear sistemas que los limiten en ese terreno.

Materia, forma y privaci��n en el op��sculo de ���Principiis naturae��� de Santo Tom��s de Aquino

Resumen: En este trabajo seguimos la presentaci��n de la materia, la forma y la privaci��n realizada por Santo Tom��s de Aquino en los dos primeros cap��tulos del De principiis naturae. Identificados como los principios de la naturaleza, son la clave para entender las definiciones de generaci��n de las que nos provee el Aquinate. ��l entiende la generaci��n, protagonista de los cambios del mundo material, en sus principios, descubiertos en sus relaciones acto-potenciales. Completa esta presentaci��n la distinci��n entre las substancias y los accidentes y sus consecuencias en el campo de los cambios de los cuerpos. Luego, Santo Tom��s extiende los an��lisis de la privaci��n y de la materia. La privaci��n, entonces, es bien distinguida de la negaci��n, porque el Aquinate muestra su dimensi��n potencial. La materia, por otro lado, se descubre en su pluralidad de sentidos y nos permite hablar de una participaci��n de la materia, a partir de la principal��sima materia ex qua o primera. Por ��ltimo, tomamos nota de las fuentes secundarias de este texto, revisando pasajes de San Agust��n y Averroes.

Microstructure Evolution of Laser Pulse processed Ductile Iron Surface

Pulsed laser beam was used to modify surface processing for ductile iron. The microstructures of processed specimen were observed using optical microscope (OM). Nanoindentation and micro-hardness of microstructures were measured from surface to inner of sample. The experimental results show that, modification zone is consisted of light melted zone, phase transformation hardening area and transient area. The light melt area is made up of coarse dendrite crystalline with a thickness less than 20um, phase transformation hardening area mainly of laminal or acicular martensite, retained austenite and graphite, i.e. M+A prime+ G. The cow-eye microstructure around graphite sphere always is formed in phase transformation hardening area zone, which consisting of a variety structure with the distance from the surface. So, it maybe as a obvious sign distinguishing modification zone border. Finally, the microstructures evolution of laser pulse processed ductile iron was analyzed coupling with beam energy distribution in space and laser pulse heating procession characteristics. The analysis shows that energy distribution of laser pulse has an important effect on microstructure during laser pulse modified ductile iron. Multi-scale and interlace arrangement are the important features for laser pulse modified ductile iron. Of microstructure.

Management of northern fur seals on the Pribilof Islands, Alaska, 1786-1981

This paper includes information about the Pribilof Islands since their discovery by Russia in 1786 and the population of northern fur seals, Cailorhinus ursinus, that return there each summer to bear young and to breed. Russia exterminated the native population of sea Oilers, Enhydra lulris, here and nearly subjected the northern fur seal to the same fate before providing proper protection. The northern fur seal was twice more exposed to extinction following the purchase of Alaska and the Pribilof Islands by the United States in 1867. Excessive harvesting was stopped as a result of strict management by the United States of the animals while on land and a treaty between Japan, Russia, Great Britain (for Canada), and the United States that provided needed protection at sea. In 1941, Japan abrogated this treaty which was replaced by a provisional agreement between Canada and the United States that protected the fur seals in the eastern North Pacific Ocean. Japan, the U.S.S.R., Canada, and the United States again insured the survival of these animals with ratification in 1957 of the "Interim Convention on the Conservation of North Pacific Fur Seals," which is still in force. Under the auspices of this Convention, the United States launched an unprecedented manipulation of the resource through controlled removal during 1956-68 of over 300,000 females considered surplus. The biological rationale for the reduction was that production of fewer pups would result in a higher pregnancy rate and increased survival, which would, in turn, produce a sustained annual harvest of 55,000-60,000 males and 10,000-30,000 females. Predicted results did not occur. The herd reduction program instead coincided with the beginning of a decline in the number of males available for harvest. Suspected but unproven causes were changes in the toll normally accounted for by predation, disease, adverse weather, and hookworms. Depletion of the animals' food supply by foreign fishing Heets and the entanglement of fur seals in trawl webbing and other debris discarded at sea became a prime suspect in altering the average annual harvest of males on the Pribilof Islands from 71,500 (1940-56) to 40,000 (1957-59) to 36,000 (1960) to 82,000 (1961) and to 27,347 (1972-81). Thus was born the concept of a research control area for fur seals, which was agreed upon by members of the Convention in 1973 and instituted by the United States on St. George Island beginning in 1974. All commercial harvesting of fur seals was stopped on St. George Island and intensive behavioral studies were begun on the now unharvested population as it responds to the moratorium and attempts to reach its natural ceiling. The results of these and other studies here and on St. Paul Island are expected to eventually permit a comparison between the dynamics of unharvested and harvested populations, which should in turn permit more precise management of fur seals as nations continue to exploit the marine resources of the North Pacific Ocean and Bering Sea. (PDF file contains 32 pages.)

Cage culture in reservoirs in India (a handbook)

This document is part of a series of 5 technical manuals produced by the Challenge Program Project CP34 ���Improved fisheries productivity and management in tropical reservoirs���. The reservoirs of India have a combined surface area of 3.25 million hectares (ha), mostly in the tropical zone, which makes them the country����s most important inland water resource, with huge untapped potential. The prime objective of cage culture discussed here is to rear fingerlings measuring >100 millimetres (mm) in length, especially carp, for stocking reservoirs. The manual discusses various aspects of cage culture from site selection to its economic benefits. (PDF contains 27 pages)

Malaria Vaccine Adjuvants: Latest Update and Challenges in Preclinical and Clinical Research

There is no malaria vaccine currently available, and the most advanced candidate has recently reported a modest 30% efficacy against clinical malaria. Although many efforts have been dedicated to achieve this goal, the research was mainly directed to identify antigenic targets. Nevertheless, the latest progresses on understanding how immune system works and the data recovered from vaccination studies have conferred to the vaccine formulation its deserved relevance. Additionally to the antigen nature, the manner in which it is presented (delivery adjuvants) as well as the immunostimulatory effect of the formulation components (immunostimulants) modulates the immune response elicited. Protective immunity against malaria requires the induction of humoral, antibody-dependent cellular inhibition (ADCI) and effector and memory cell responses. This review summarizes the status of adjuvants that have been or are being employed in the malaria vaccine development, focusing on the pharmaceutical and immunological aspects, as well as on their immunization outcomings at clinical and preclinical stages.

Enhanced Operation of Electricity Distribution Grids Through Smart Metering PLC Network Monitoring, Analysis and Grid Conditioning

Low Voltage (LV) electricity distribution grid operations can be improved through a combination of new smart metering systems' capabilities based on real time Power Line Communications (PLC) and LV grid topology mapping. This paper presents two novel contributions. The first one is a new methodology developed for smart metering PLC network monitoring and analysis. It can be used to obtain relevant information from the grid, thus adding value to existing smart metering deployments and facilitating utility operational activities. A second contribution describes grid conditioning used to obtain LV feeder and phase identification of all connected smart electric meters. Real time availability of such information may help utilities with grid planning, fault location and a more accurate point of supply management.

A review of the population structure of yellowfin tuna, Thunnus albacares, in the Eastern Pacific Ocean

ENGLISH: Since its inception in 1950 by agreement between the Republic of Costa Rica and the United States of America, the Inter-American Tropical Tuna Commission has been engaged in studies of the biology, ecology and population dynamics of yellowfin tuna in the eastern Pacific Ocean. Prime consideration has been given to the evaluation of the effects of fishing pressure on the yellowfin tuna in this area in order to estimate the maximum sustainable yield. A portion of the eastern Pacific has been defined by the Inter-American Tropical Tuna Commission (1963) as a regulatory area for yellowfin tuna (Figure 1). SPANISH: Desde su incepci��n en 1950, por un acuerdo entre la Rep��blica de Costa Rica y los Estados Unidos de Am��rica, la Comisi��n Interamericana del At��n Tropical ha estado ocupada en los estudios de la biolog��a, ecolog��a y din��mica de las poblaciones del at��n aleta amarilla en el Oc��ano Pac��fico Oriental. Se consider�� primariamente la evaluaci��n de los efectos de la presi��n de la pesquer��a sobre el at��n aleta amarilla en esta ��rea, para poder estimar el rendimiento m��ximo sostenible. Una parte del Pac��fico Oriental ha sido definida por la Comisi��n Interamericana del At��n Tropical (1963), como ��rea de reglamentaci��n del at��n aleta amarilla (Figura 1). (PDF contains 60 pages.)

La informaci��n televisiva en campa��a electoral. An��lisis de las noticias en ETB y TVE durante las elecciones municipales y auton��micas de mayo de 2003

401 p.

Nutrients and biological production in lakes

This paper is a review of studies on effects of nutrients on biological productivity and efforts made so far at restoration of nutrients in lakes. It is to provide an understanding of the basis scientific process accruing in lakes, therefore of prime importance in maintaining water quality standards for propagation of effective lake management

On the Mumford-Tate conjecture for Abelian varieties with reduction conditions

<p>In this thesis we study Galois representations corresponding to abelian varieties with certain reduction conditions. We show that these conditions force the image of the representations to be "big," so that the Mumford-Tate conjecture (:= MT) holds. We also prove that the set of abelian varieties satisfying these conditions is dense in a corresponding moduli space. </p> <p>The main results of the thesis are the following two theorems. </p> <p>Theorem A: Let A be an absolutely simple abelian variety, End�� (A) = k : imaginary quadratic field, g = dim(A). Assume either dim(A) ��� 4, or A has bad reduction at some prime ��, with the dimension of the toric part of the reduction equal to 2r, and gcd(r,g) = 1, and (r,g) ��� (15,56) or (m -1, m(m+1)/2). Then MT holds. </p> <p>Theorem B: Let M be the moduli space of abelian varieties with fixed polarization, level structure and a k-action. It is defined over a number field F. The subset of M(Q) corresponding to absolutely simple abelian varieties with a prescribed stable reduction at a large enough prime �� of F is dense in M(C) in the complex topology. In particular, the set of simple abelian varieties having bad reductions with fixed dimension of the toric parts is dense. </p> <p>Besides this we also established the following results: </p> <p> (1) MT holds for some other classes of abelian varieties with similar reduction conditions. For example, if A is an abelian variety with End�� (A) = Q and the dimension of the toric part of its reduction is prime to dim( A), then MT holds. </p> <p> (2) MT holds for Ribet-type abelian varieties. </p> <p> (3) The Hodge and the Tate conjectures are equivalent for abelian 4-folds. </p> <p> (4) MT holds for abelian 4-folds of type II, III, IV (Theorem 5.0(2)) and some 4-folds of type I. </p> <p> (5) For some abelian varieties either MT or the Hodge conjecture holds. </p>

Arithmetic of cyclotomic fields and Fermat-type equations

<p>Let l be any odd prime, and �� a primitive l-th root of unity. Let C_l be the l-Sylow subgroup of the ideal class group of Q(��). The Teichm��ller character w : Z_l ��� Z^*_l is given by w(x) = x (mod l), where w(x) is a p-1-st root of unity, and x ��� Z_l. Under the action of this character, C_l decomposes as a direct sum of C^((i))_l, where C^((i))_l is the eigenspace corresponding to w^i. Let the order of C^((3))_l be l^h_3). The main result of this thesis is the following: For every n ��� max( 1, h_3 ), the equation x^(ln) + y^(ln) + z^(ln) = 0 has no integral solutions (x,y,z) with l ��� xyz. The same result is also proven with n ��� max(1,h_5), under the assumption that C_l^((5)) is a cyclic group of order l^h_5. Applications of the methods used to prove the above results to the second case of Fermat's last theorem and to a Fermat-like equation in four variables are given.</p> <p>The proof uses a series of ideas of H.S. Vandiver ([Vl],[V2]) along with a theorem of M. Kurihara [Ku] and some consequences of the proof of lwasawa's main conjecture for cyclotomic fields by B. Mazur and A. Wiles [MW]. In [V1] Vandiver claimed that the first case of Fermat's Last Theorem held for l if l did not divide the class number h^+ of the maximal real subfield of Q(e^(2��i/i)). The crucial gap in Vandiver's attempted proof that has been known to experts is explained, and complete proofs of all the results used from his papers are given.</p>