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Some Open Problems in the Context of Skew PBW Extensions and Semi-graded Rings

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Communications in Mathematics and Statistics 2021年第3期9卷 347-378页

作者： Oswaldo lezama Seminario deÁlgebra Constructiva-SAC2 Departamento de MatemáticasUniversidad Nacional de ColombiaSede BogotáBogotáColombia

In this paper,we discuss some open problems of non-commutative algebra and noncommutative algebraic geometry from the approach of skew PBW extensions and semi-graded *** exactly,we will analyze the isomorphism arising in the investigation of the Gelfand–Kirillov conjecture about the commutation between the center and the total ring of fractions of an Ore *** Serre’s conjecture will be discussed for a particular class of skew PBW *** questions about the Noetherianity and the Zariski cancellation property of Artin–Schelter regular algebras will be reformulated for semi-graded *** for the solution of some of the problems are included.

关键词： Gelfand–Kirillov conjecture Serre’s conjecture Artin–Schelter regular algebras Zariski cancellation problem Skew PBW extensions Semi-graded rings

Extended Modules and Ore Extensions

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Communications in Mathematics and Statistics 2016年第2期4卷 189-202页

作者： Viacheslav Artamonov Oswaldo lezama William Fajardo Moscow State University MoscowRussia Universidad Nacional de Colombia BogotaColombia

In this paper,we study extended modules for a special class of *** will assume that R is a ring and A will denote the Ore extensionA:=R[X1,...,xn;σ]for whichσis an automorphism of R,xixj=xjxi and xir=σ(r)xi,for eve... 详细信息

关键词： Extended modules and rings Quillen-Suslin's methods Ore extensions

Complete temporal characterization of a single photon

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Light(Science & Applications) 2015年第1期4卷 337-342页

作者： Zhongzhong Qin Adarsh S Prasad Travis Brannan Andrew MacRae A lezama AI Lvovsky Institute for Quantum Science and Technology University of CalgaryAlberta T2N1N4Canada Quantum Institute for Light and Atoms State Key Laboratory of Precision SpectroscopyEast China Normal UniversityShanghai 200062China Department of Physics University of CaliforniaBerkeleyCA 94720USA Institute of Physics Faculty of EngineeringUniversity of the RepublicJ.Herrera y Reissig 565Montevideo 11300Uruguay Russian Quantum Centre 100 Novaya St.SkolkovoMoscow 143025Russia Canadian Institute for Advanced Research 180 Dundas Street WestTorontoOntario M5G 1Z8Canada

Precise information about the temporal mode of optical states is crucial for optimizing their interaction efficiency between themselves and/or with matter in various quantum communication *** we propose and experimentally demonstrate a method of determining both the real and imaginary components of a single photon’s temporal density matrix by measuring the autocorrelation function of the photocurrent from a balanced homodyne detector at multiple local oscillator *** test our method on single photons heralded from biphotons generated via four-wave mixing in an atomic vapor and obtain excellent agreement with theoretical predictions for several settings.

关键词： autocorrelation matrix polychromatic optical heterodyne tomography single photon temporal mode function

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World Journal of Gastroenterology 2006年第27期12卷 4392-4396页

作者： Andrés Duarte-Rojo Ana lezama-Barreda María Teresa Ramírez-Iglesias Mario Peláez-Luna Guillermo Robles-Díaz Department of Internal Medicine Vasco de Quiroga 15Sectión ⅩⅥTlalpanCP 14000MéxicoDFMéxico Department of Gastroenterology Instituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránVasco de Quiroga 15Sección ⅩⅥTlalpanCP 14000MéxicoDFMéxico Department of Experimental Medicine Facultad de MedicinaUniversidad Nacional Autónoma de MéxicoHospital General de MéxicoDr. Balmis 148 PB Colonia DoctoresCP 06726MexicoDFMéxico

AIM： To evaluate the relationship between leptin and systemic inflammation in acute pancreatitis. METHODS： Consecutive patients with acute pancreatitis were included. Body mass index and serum samples were obtained at admission. Leptin, TNF-α, IL-6, -8 and -10 levels were determined by ELISA. Severity was defined according to Atlanta criteria. RESULTS： Fifty-two （29 females） patients were studied. Overall body mass index was similar between mild and severe cases, although women with severe pancreatitis had lower body mass index （P = 0.04） and men showed higher body mass index （P = 0.05）. No difference was found in leptin levels regarding the severity of pancreatitis, but higher levels tended to appear in male patients with increased body mass index and severe pancreatitis （P = 0.1）. A multivariate analysis showed no association between leptin levels and severity. The strongest cytokine associated with severity was IL-6. Correlations of leptin with another cytokines only showed a trend for IL-8 （P = 0.058）. CONCLUSION： High body mass index was associated with severity only in males, which may be related to android fat distribution. Serum leptin seems not to play a role on the systemic inflammatory response in acute pancreatitis and its association with severe outcome in males might represent a marker of increased adiposity.

关键词： Leptin Cytokines Obesity Acute pancreatitis Prognosis

Dynamics of tree species ecological groups in logged and unlogged tropical forests in the Venezuelan western plains

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Journal of Life Sciences 2008年第5期2卷 57-64页

作者： RAMIREZ-ANGULO Hirma TORRES-lezama Armando Research Team BIODESUS lnstituto de lnvestigaciones Para el Desarrollo Forestal （1NDEFOR） Facultad de Ciencias Forestalesy Ambientales Universidad de Los Andes Via Los Chorros de Milla Mérida Venezuela

The study of tree mortality and recruitment contributes to the understanding of forest dynamics and, at the same time, supplies a baseline to evaluate the impact of human activities. The study site is a moist semi-deciduous forest located in the Caparo Forest Reserve, Venezuela. Tree data were obtained from permanent plots established in unlogged and logged stands. Successive measurements were taken during a 15 yr period. Tree species mortality and recruitment was analyzed for individuals with diameter at breast height （d）〉-- 10 cm. The species were classified according to their shade tolerance （low or intolerant, intermediate and high or tolerant） and the maximum height （hmax）（small〈15 m, medium： 15-30 m and large 〉30 m）. Palms were considered as a separate group. In the unlogged stands 307 and 274 trees ha-1 were found at the beginning and final time of the monitoring period, respectively. These trees were classified into 55 and 48 species, respectively. Among them predominate species from the shade intermediate tolerant and large size group and palms. Similarly, in the logged forest 155 and 207 trees ha^-1 were found, whereas 59 and 60 tree species were recorded. Only four species were found with 〉10 individuals had, the majority of these species belong to the functional group of shade intolerant medium size species, which may be partly explained by forest recovering after selective logging. In the unlogged stands the mean annual rate of tree mortality is 2.61% and the highest values corresponded to shade intermediate tolerant and intolerant small size species. Tree density was not significantly correlated to tree mortality in both forest conditions （logged and unlogged）. The recruitment rate in the unlogged forest was 1.33%, with the lowest values obtained for the same groups with highest mortality; whereas in the logged stands reached 2.58%, with the highest value for the shade tolerant small size species, followed by shade intermediate tolerant large size spe

关键词： ecosystem disturbance recruitment selectivelogging tree mortality tropical forest

Ferromagnetic Resonance in Gd/Co Multilayer

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Chinese Physics Letters 2001年第7期18卷 973-975页

作者： A.V.Svalov J.M.Barandiarán V.O.Vas’kovskiy G.V.Kurlyandskaya L.lezama N.G.Bebenin J.Gutiérrez D.Schmool Ural State University Lenin Ave.51620083 EkaterinburgRussia Universidad del PaIs Vasco UPV-EHU Facultad de Ciencias Apdo.64448080 BilbaoSpain Institute of Metal Physics Ural Division of RASKovalevskaya str.18GSP-170620219 EkaterinburgRussia Laboratory de Magnetisme et d’Optique ptique CNRSUniversitéde Versailles-Saint Quentin-CNRSBatiment Fermat45 Avenue des Etats-Unis78035 Versalles CedexFrance

Magnetometric and ferromagnetic resonance(MFR)measurements have been performed on the polycrystalline multilayered structure,[Gd(7.5 nm)/Co(3 nm)]*** temperature dependence of magnetization of the sample suggests a compensation temperature Tcomp in the region of 240 K,implying that the Co and Gd layers are antiferromagnetically *** FMR curves are strongly temperature dependent,particularly in the vicinity of Tcomp.

关键词： magnetization ferromagnetic polycrystalline

The Influence of Large-Scale Phenomena on La Paz Bay Hydrographic Variability

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Open Journal of Marine Science 2015年第1期5卷 146-157页

作者： Cristóbal Guevara-Guillén Bernardo Shirasago-Germán Edgar Leonardo Pérez-lezama Centro Interdisciplinario de Ciencias Marinas (CICIMAR-IPN) Colonia Playa Palo de Santa RitaLa Paz México

We analyzed the hydrographic variability of La Paz Bay, the largest coastal water body in the Gulf of California, and its relationship with Pacific large-scale phenomena, including the El Ni?o-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), Pacific-North America pattern (PNA), and North Pacific pattern (NP). We used several indices related to these phenomena and the hydrographic variability data of La Paz Bay, consisting of the annual sea surface temperature patterns from satellite imagery from 2000 to 2010 and the mixed layer depths measured with?in situ?data from 1994 to 2009. The results indicate the sea surface temperature fluctuated during the study period, with 2007 as the coldest year and 2009 as the warmest. Two periods were identified in the annual thermal cycle of the bay, one period of warmth from June to November, and one of cold from December to May. The sea surface temperature is primarily influenced by the ENSO. The mixed layer depth analysis showed its absence during August-September, while the deepest ones were in November-March. The unusual 100 m mixed layer depth noted during February 2002 and its absence in March 1996 and 2009 were related to uncommon atmospheric conditions in the annual patterns of the ENSO, PNA, and NP. The variability of the mixed layer depth is primarily related to the variability of the NP. We concluded that the hydrographic conditions of La Paz Bay are most influenced by the NP during the cold phase of its annual cycle, and by the ENSO during the warm phase.

关键词： Pacific Large-Scale Phenomena La Paz Bay Gulf of California Hydrography Annual Patterns

Comment:Comments on “How to repair the Hill cipher”

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第2期9卷 211-214页

作者： Y.RANGEL-ROMERO R.VEGA-GARCíA A.MENCHACA-MéNDEZ D.ACOLTZI-CERVANTES L.MARTíNEZ-RAMOS M.MECATE-ZAMBRANO F.MONTALVO-lezama J.BARRóN-VIDALES N.CORTEZ-DUARTE F.RODRíGUEZ-HENRíQUEZ Computer Science Department CINVESTAV-IPN Av.IPN No. 2508 Col. San Pedro Zacatenco Mexico City 07300 Mexico

A modification of the Hill cipher algorithm was recently proposed by Ismail et al.(2006),who claimed that their new scheme could offer more security than the original one due to an extra non-linearity layer introduced via an elaborated key gen-eration *** mechanism produces one different encryption key for each one of the plaintext ***,we show in this paper that their method still has severe security flaws whose weaknesses are essentially the same as that already found in the original Hill cipher scheme.

关键词： Hill cipher Symmetric encryption Image encryption

The Swirling Jet Generation Method and Its Effect on the Velocity Distribution

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Journal of Mechanics Engineering and Automation 2020年第1期10卷 16-26页

作者： Fernández Roque Tiburcio Correa Arredondo JoséArturo Mejía Carmona Alejandro Sandoval lezama Jorge Vázquez Flores JoséFélix Tiburcio Fernández Roque Instituto Politécnico Nacional Escuela Superior de Ingeniería Mecánica y Eléctrica Unidad TicomanAv.Ticoman No.600Col.San JoséTicomanAlcaldía Gustavo A.MaderoC.P.07340 México DFMéxico 不详

The wing tip vortex has a great similarity with the swirling *** these are generated of a simpler and more economic form in a laboratory,it is relevant to determine which the best method is for the generation of the swirling *** this paper,the velocity distribution obtained experimentally with the method of generation here proposed,which consists of the employment of an axial fan without stators,is compared with the velocity distribution of swirling jets generated with three different *** is observed that the velocity distribution obtained with the proposed method is similar with one of the methods found in the references,which uses fixed blades guides at the entry of the *** proposed method is suitable for the generation of the swirling jet and it is considered that it is simpler and more economic to use blades fixed guides.

关键词： Swirling jet velocity distribution swirl intensity wingtip vortex tangential velocity