bluuebunny/crossref_metadata_2025_split huggingface dataset:
Motion of a Test Particle According to the Scalar Ether Theory of Gravitation and Application to its Celestial Mechanics
Authors: Arminjon Mayeul , Winkler Rainer Wolfgang 
Published: January 2019

AbstractThe standard interpretations of special relativity (Einstein–Minkowski) and general relativity (GR) lead to a drastically changed notion of time: the eternalism or block universe theory. This has strong consequences for our thinking about time and for the development of new fundamental theories. It is therefore important to check this thoroughly. The Lorentz–Poincaré interpretation, which sees the relativistic effects as following from a “true” Lorentz contraction of all objects in their motion through the ether, uses a conservative concept of time and is in the absence of gravitation indistinguishable from the standard interpretation; but there exists currently no accepted gravitation theory for it. The scalar ether theory of gravitation is a candidate for such a theory; it is presented and discussed. The equations of motion for a test particle are derived; the case of a uniformly moving massive body is discussed and then specialized to the case of spherical symmetry. Formulas for the acceleration of test particles are given in the preferred frame of the ether and in the rest frame of the massive body that moves with velocityVwith respect to the ether. When the body rests in the ether (V=0), the acceleration is up to orderc−2identical to GR. The acceleration of a test particle forV≠0is given; this makes it possible to fit observations in celestial mechanics to ephemerides withVas a free parameter. The current status of such fits (although to ephemerides and not to observations) is presented and discussed.
Cell Cycle-Regulated Transcription of CENP-A by the MBF Complex Ensures Optimal Level of CENP-A for Centromere Formation
Authors: Aristizabal-Corrales David , Yang Jinpu , Li Fei 
Published: January 2019

AbstractIn most eukaryotes, the histone H3 variant CENP-A serves as the epigenetic mark for centromeres. CENP-A transcription is subject to cell-cycle regulation, but the molecular mechanism underlying the regulation remains elusive. Through a genetic screen...The centromere plays an essential role in chromosome segregation. In most eukaryotes, centromeres are epigenetically defined by the conserved histone H3 variant CENP-A. Proper centromere assembly is dependent upon the tight regulation of CENP-A level. Cell cycle regulation of CENP-A transcription appears to be a universal feature across eukaryotes, but the molecular mechanism underlying the temporal control of CENP-A transcription and how such regulation contributes to centromere function remains elusive. CENP-A in fission yeast has been shown to be transcribed before S phase. Using various synchronization methods, we confirmed that CENP-A transcription occurs at G1, leading to an almost twofold increase of the protein during S phase. Through a genetic screen, we identified the MBF (MluI box-binding factors) complex as a key regulator of temporal control of CENP-A transcription. The periodic transcription of CENP-A is lost in MBF mutants, resulting in CENP-A mislocalization and chromosome segregation defects. We identified the MCB (MluI cell cycle box) motif in the CENP-A promoter, and further showed that the MBF complex binds to the motif to restrict CENP-A transcription to G1. Mutations of the MCB motif cause constitutive CENP-A expression and deleterious effects on cell survival. Using promoters driving transcription to different cell cycle stages, we found that timing of CENP-A transcription is dispensable for its centromeric localization. Our data instead indicate that cell cycle-regulated CENP-A transcription is a key step to ensure that a proper amount of CENP-A is generated across generations. This study provides mechanistic insights into the regulation of cell cycle-dependent CENP-A transcription, as well as its importance on centromere function.
Manejo de la vegetación, domesticación de plantas y origen de la agricultura en Mesoamérica
Authors: Casas Alejandro , Caballero Javier , Mapes Cristina , Zárate Sergio 
Published: January 2019

A model of domestication of plants in Mesoamerica based on selective management of plant populations and communities by silvicultural practices is analyzed. Archaeological and ethnobotanical information suggests that intentional manipulation of vegetation by Mesoamerican peoples has occurred in past and present times in order to control availability of useful plants. Forms of management of plant communities or populations have included tolerance, protection and enhancement of individual plants of particular species during clearance of vegetation and other ways of perturbation. Processes of artificial selection (selection in situ) may be carried out through these forms of plant management. These processes may cause significant morphological differences between wild and managed populations as illustrated by the cases discussed here of Anoda cristata, Crotalaria pumila, Leucaena esculenta and Stenocereus stellatus. Processes of artificial selection in situ are mechanisms of incipient domestication of plants which appear to have been carried out in Mesoamerica, perhaps since pre-agricultural times, and that could contribute to explain the processes that led to the origins of agriculture in this region.
Pérdida secundaria de la fotosíntesis: el caso de las algas incoloras y de algunos parásitos
Authors: Gutiérrez-Cirios-Madrid Emma Berta 
Published: January 2019

This review pretends to illustrate a very interesting phenomenon in nature: the secondary loss of the photosynthetic function and its effects in chloroplast and mitochondrial DNA. Here it is described how plastid DNA has been reduced loosing those genes which encode for photosynthetic proteins. An example of the mitochondrial DNA of a colouress alga is also explained. An hypothesis is proposed where the number o f mitochondrial genes is maintained in this colourless organisms due to the energetic demand on the organelle.
Efecto de la transformación de la selva a pradera sobre la dinámica de los nutrientes en un ecosistema tropical estancional en México
Authors: García-Oliva Felipe , Maass José Manuel 
Published: January 2019

The effects of conversion of tropical deciduous forest into pasture were examined on the Central Pacific Coast of Mexico. Under forested conditions two situations of nutrient cycles were determined: 1] hilltop locations where biological processes of soil were dominant; and 2] midslope locations where topographic characteristics were the main factor. When the forest cover was cut and burned, grasses were introduced for continuous cattle grazing, which led to changes in physical and chemical soil properties. Each topographic position responded differently to the conversion. The hilltop locations had higher nutrient retention capacity, which related strongly to higher soil organic matter content. In contrast, the midslope locations had a low nutrient protection capacity. After 11 years of use as pasture, the hilltop locations lost 700 kg N ha-1, 2,500 kg Ca ha-1 and 500 kg P ha-1, similar to the midslope locations losses.
Origen, variación y tendencias evolutivas del Henequén (<em>Agave fourcroydes</em> Lem.)
Authors: Colunga-García Marín Patricia 
Published: January 2019

Henequen was domesticated by the Maya people, from A. angustifolia, since pre-Hispanic times. It is one of the most important natural hard fibers worldwide because of its good quality and adaptation to ecologically restricted agrohabitats. This cultivar has maintained great economic and cultural value in the state of Yucatan. Ethnobotanical, morphological, and isozyme evidence were compiled to discuss the origin and evolution of henequen by human selection, the germplasm diversity available in the cultivated populations and that of the wild populations from which it could have arisen. Results suggested the occurrence of a drastic erosion of the genetic diversity maintained by the Maya, as a consequence of its cultivation under large plantations established at the beginning of this century for the cordage industry. At present, only three varities are cultivated: Sak ki (SK), Yaax ki (YK) and Kitam ki (KK), these last two in very small populations. SK and YK differ from wild populations in four syndromes of domestication: gigantism, greater fibrosity, less thorniness, and less reproductive capacity. KK is very similar to the wild types. Isozyme analysis indicated that wild populations have relatively high levels of variation, whereas all individuals of each henequen variety were identical. A parsimony analysis indicated two lineages: that of SK and YK, cultivated cordage plants selected for stronger and longer fibers, whose sister group is the tropical deciduous forest ecotype (SF); and that of ali other wild populations, which also included KK, the cultivated textile plants selected for finer fibers, and nearly extint in Yucatan. These results support the hypothesis of the yucatecan origin of SK and YK from the SF ecotype, as well as the recent introduction of KK. Methodology used is discussed as well as research perspectives in this theme.
La vegetación escletófila perennifolia del Valle de Tehuacán, Puebla y sus similitudes con la vegetación esclerófila de climas mediterráneos
Authors: Flores-Hernández Noe , Valiente-Banuet Alfonso , Dávila Patricia , Villaseñor José Luis 
Published: January 2019

The evergreen sclerophyllous vegetation of the Tehuacán Valley is described and compared with 4 of the 5 zones with Mediterranean-type climates. In the vegetation description structural aspects such as cover, height, frequency and life forms spectrum were considered. This vegetation type called Mexical has a close similarity in life forms spectrum with annuals predominance with the Mediterranean-type vegetation. Therefore, the evergreen sclerophyllous vegetation distribution within the tropics not only is explained in relation with mediterranean-type climates, and also because by historical factors .
Los Géneros <em>Docidium, Penium, Haplotaenium, Pleurotaenium, Tetmemorus y Triploceras</em> (Desmidiales, Chlorophyta) en Cuba
Authors: Martínez-Almeida Víctor M. 
Published: January 2019

This is a further contribution to the knowledge of the desmid flora of Cuba. One hundred and sixty samples collected from the most important regions in regard to occurrence of desmids and diversity of mi croalgae species in Cuba (Pinar del Río, Isla de la juventud, Ciénaga de Zapata, Matanzas and San Felipe, Camagüey), were examined. Emphasis was made on the taxonomic survey of those cylindrical" representative genera. 22 infrageneric taxa belonging to 17 species were identified, 18 of which are new records from the country. Some populations examined showed a wide morphological variability. Each taxon is briefly described based on Cuban material. Original drawings and comments about distribution and synonymy according to the available taxonomic literature are included.
La vegetación de la Reserva Ecológica Lomas del Seminario, Ajusco, México
Authors: González-Hidalgo Beatriz , Orozco-Segovia Alma , Diego-Pérez Nelly 
Published: January 2019

El presente trabajo fue realizado en la Reserva Ecológica Lomas del Seminario, Ajusco Medio, México, Distrito Federal, con la finalidad de conocer el estado actual de la vegetación. Se reconocieron 2 tipos de vegetación primaria: matorral xerófilo y bosque de Quercus, además de 2 tipos de vegetación secundaria: matorral de Quercus asociado a Sedum y matorral xerófilo asociado a Sedum. Se elaboró un mapa de vegetación de la zona y se determinó la composición florística y la estructura de la vegetación.
Estructura, composición y diversidad de la selva baja caducifolia del Cerro Verde, Nizanda (Oaxaca), México
Authors: Gallardo-Cruz José A. , Meave Jorge A. , Pérez-García Eduardo A. 
Published: January 2019

En este estudio se describe la estructura, la composición florística y los patrones de diversidad de la selva baja caducifolia del Cerro Verde, localizado en Nizanda (Istmo de Tehuantepec, Oaxaca, México). En 30 parcelas de 100 m2 se censaron las plantas leñosas con DAP ??1 cm (estrato alto), y en cinco subcuadros de 4 m2 dentro de cada una se censaron las plantas con DAP < 1 cm, pero con altura > 30 cm (estrato bajo). Se encontraron 194 especies distribuidas en 52 familias. La riqueza de especies fue idéntica en ambos estratos (145 especies), y cada uno aportó de manera exclusiva ca. 25% de la riqueza total registrada. Leguminosae fue la familia más rica en especies (27), seguida por Asteraceae (20) y Euphorbiaceae (18). Las especies más frecuentes fueron Bursera simaruba + B. aff. cinerea (no distinguidas en el campo), Euphorbia schlechtendalii, Pilosocereus collinsii y Capparis verrucosa. La riqueza específica promedio por cuadro fue de 30 especies. Los índices basados en la riqueza y la abundancia de las especies (Berger-Parker = 0.20; Simpson = 0.09; [de Fisher = 9.47; Shannon = 2.78; equitatividad = 0.82) indican una alta diversidad y una consecuente baja dominancia en esta selva. Los valores extrapolados mostraron una densidad total (estratos alto + bajo) de 23,950 ind. ha-1 (830 ind. ha-1 con DAP ? 10 cm), una cobertura de 446.7%, y un área basal de 53 m2 ha-1. La altura promedio del 10% de los árboles más altos fue 9.1 m. La estructura de la selva baja del Cerro Verde es semejante a la de otras comunidades vegetales del trópico seco de México y denota un buen estado de conservación. Este hecho, aunado a su particular composición florística, enfatiza la pertinencia de su conservación formal.
Estructura y composición de la vegetación ribereña de la barranca del río Tembembe, Morelos, México
Authors: Camacho-Rico Fernando , Trejo Irma , Bonfil Consuelo 
Published: January 2019

Structure and composition of the riparian vegetation of the middle-upper basin of the Tembembe river, in the state of Morelos, was analyzed. Height, diameter at breast height, crown area and taxonomic identity of each individual having a DBH 1 cm were recorded in 23 quadrats of 100 m2 each. A total of 74 species and 516 individuals were found. Mean density was 2,148 ind. ha-1, mean basal area was 88.39 m2 ha-1, and mean height (of individuals with DBH 20 cm) w as 10.5 m. Classification analysis allowed the discrimination of three communities whose distribution was associated to the altitudinal gradient: the first (G1) in the upper part (1,700 - 1,650 m a.s.l.) was dominated by species (like Alnus acuminata) having a holartic affinity; the second (G2) at an intermediate altitude (1,640 - 1,340 m a.s.l.) was dominated by Trema micrantha; and the third (G3) in the lower portion (1,210 - 1,110 m a.s.l.) dominated by species (like Daphnopsis salicifolia) having a tropical affinity. Diversity, density and crown cover did not differ among them, but mean basal area was largest in the highest and lowest communities than in the intermediate one. Mean height of the tree layer decreased with altitude. This study contributes to the knowledge of the riparian vegetation in Morelos state and provides basic ecological information for future restoration programs of the riparian vegetation of the Tembembe river
Germinación y establecimiento de plántulas de Pterocereus gaumeri , una cactácea columnar, rara y endémica de Yucatán, México
Authors: Méndez Martha , Dorantes Alfredo , Dzib Gabriel , Argáez Jorge , Durán Rafael 
Published: January 2019

Se evaluó el nodricismo y la depredación sobre la germinación y el establecimiento de nuevos individuos de Pterocereus gaumeri . Se realizó un experimento de campo con diseño factorial, considerando el factor asociación con cinco niveles (cuatro nodrizas y claros), el factor depredación con dos (protegidas y expuestas) y el factor orientación con cuatro (cuatro puntos cardinales). No hubo diferencias significativas en la germinación entre claros y bajo las nodrizas, ni entre especies, pero sí entre semillas protegidas de la depredación y las expuestas. Para el factor orientación no se encontraron diferencias en ningún caso. La supervivencia de las plántulas bajo nodrizas fue significativamente mayor que en los claros y se presentó una gran depredación de plántulas. Estos resultados sugieren que el reclutamiento de nuevos individuos a las poblaciones de P. gaumeri es una fase crítica de su ciclo de vida y contribuyen a explicar la rareza de esta cactácea amenazada.
Flora de la costa de Oaxaca, México (2): lista florística comentada del Parque Nacional Huatulco
Authors: Salas-Morales Silvia H. , Schibli Leo , Nava-Zafra Arturo , Saynes-Vásquez Alfredo 
Published: January 2019

Se presenta la lista de especies, incluyendo algunas de sus características, así como la descripción florística de los tipos de vegetación del Parque Nacional Huatulco. El estudio consistió en 18 recorridos de campo durante los cuales se recolectaron 4,382 números de plantas vasculares, en altitudes entre 0 y 200 m. De estas colecciones se han determinado 3,312 muestras y hasta el momento se tienen 91 familias, 391 géneros y 736 especies. Las familias dominantes por su riqueza de especies son Leguminosae (146), Euphorbiaceae (48), Asteraceae (42) y Convolvulaceae (37). Los tipos de vegetación reconocidos en las 6,374.98 ha del Parque son: bosque de galería, manglar, sabana, selva baja caducifolia, selva baja espinosa, selva mediana subcaducifolia, vegetación de dunas costeras y vegetación secundaria.
Los Hongos micorrizógenos arbusculares de la región de Nizanda, Oaxaca, México
Authors: Guadarrama-Chávez Patricia , Camargo-Ricalde Sara Lucía , Hernández-Cuevas Laura , Castillo-Argüero Silvia 
Published: January 2019

Se reportan 25 especies y siete géneros de esporas de hongos micorrizógenos arbusculares (HMA) para la región de Nizanda, Oaxaca, México. Para ello, se tomaron al azar muestras de suelo, en lluvia y secas, incluyendo parcelas de cultivo de maíz, áreas de vegetación secundaria y selva baja caducifolia. Se aislaron las esporas, se identificaron y se montaron macetas de propagación. La familia Glomeraceae aportó 44% de las especies, seguida de Acaulosporaceae (24%) y Gigasporaceae (20%). Se encontraron 13 especies en el maizal, 24 en vegetación secundaria y 12 en selva baja caducifolia. De éstas, Glomus dussi, G. verruculosum, Pacispora scintillans y Scutellospora erythropa son nuevos registros para México. G. constrictum se encontró sólo en el cultivo de maíz, mientras que Acaulospora delicata, A. foveata, A. mellea, A. scrobiculata, Entrophospora infrequens, Gigaspora decipiens, Glomus claroideum, G. fulvum y G. geosporum estuvieron presentes en los tres ambientes estudiados. No se encontraron especies restringidas únicamente a la selva baja caducifolia.
Using Karaoke Videos to Teach Japanese Vocabulary to Taiwanese University Students
Authors: Sasi Abolfazl Shirban , Haga Toshinari 
Published: January 2019

This paper reports the usage of Japanese karaoke films in order to enhance learning Japanese vocabulary among students in a university in Taiwan. A pretest-posttest control-group design was implemented in which the treatment students (55 girls and 48 boys) were given Japanese vocabulary lessons via listening to and watching two karaoke films, while the control group (62 girls and 47 boys) received their Japanese vocabulary lessons through only listening to the same songs (N=212, P ≤ 0.05). The treatment lasted for six consecutive regular general Japanese classes in which the last 20 minutes of the session was allocated to this experiment. The statistical independent samples T-tests used for each of the three comparisons in this study revealed a significant higher gain scores for the girls treatment group, while the boys treatment and control, as well as the general (all) students treatment and control groups did not show any significant difference. Given the ever-growing usage of karaoke in many countries such as Taiwan, the authors believe that addressing the possible and potential capabilities of such a favorable activity, particularly among the youth, can prove effective and helpful in teaching/learning Japanese and other languages.
The Significance of English Language Development for Future Asian Tourism and Hotel Management Professionals
Authors: Zou Jia Hui , Ramirez Stephanie Isabel Molina , Erazo Mayra Alexandra Cuenca , Encalada Maria Asuncion Rojas 
Published: January 2019

The present study is a systematic review that explores existent research on the significance of developing English at schools and universities, and the impact of English for Specific Purposes (ESP) courses to acquire specialized English for businesses, mainly on the Asian Tourism and Hotel Management sector. Because of ESP complexity, it is recommended to be taught to students of intermediate-advanced English level. Consequently, future professionals will be capable of communicating in the target language around the world and be ready to take these specialized English courses. It also considers the advantages of having appropriate English fluency in the Tourism and Hotel Management sector, and the disadvantages of not having English fluency in this field.
The Self and the Other in "The Land of Dreams"
Authors: Khrais Sura M. , Daana Hana A. 
Published: January 2019

This paper is a study of the post-colonial polarity of the Self/the Other in Hanan Al Shaykh's short story "The Land of Dreams". It investigates the sub-textual tensions between her admiration of the European model (the Self) and her status as an Arab writer representing the Other. Thus, Al Shaykh presents a prejudiced text in which the Other is misrepresented and rather stereotypically portrayed. While the Self is civilised and a savior-like figure, the Other (Yemini men and women) is primitive, superstitious and ignorant. Furthermore, the researcher will show that what seems to be a meaningful connection across the racial line where the Self (Ingrid; the civilised European) and the Other (Yemini people) find a contact zone is no more than an illogical oversimplification of the relationship. While Hanan Al Shaykh introduces this model of racial liberation through unification of the Self and the Other, the question remains to what extent would that relationship sustain the pressures of the primitive culture of the Other? Indeed, Al Shaykh tends to simplify and generalise the relationship to the point of producing romantic and idealised images of a human contact beyond cultural and racial gaps, which strikes the reader as naïve and unrealistic.
Clinical study on postpartum eclampsia
Authors: J. Madhu , Shankar Priya 
Published: January 2019

Background: Eclampsia constitutes one of the deadly triad along with malnutrition and anemia which authors encounter in the present tertiary hospital Karnataka Institute of Medical Sciences, Hubli. This study was done to study the epidemiological factors associated with postpartum eclampsia, correlation with neuroimaging and the maternal outcome. The objective of the present study was retrospective study of postpartum eclampsia over a period of 22 months.Methods: A retrospective study conducted over a period 22 months from June 2015 to March 2017 in a tertiary care hospital, Karnataka Institute of Medical Sciences, Hubli. Case records of all postpartum eclampsia patients admitted during the period were analyzed.Results: This study showed that incidence of postpartum eclampsia in our hospital was 1.4%. It is more common in age group of 20-25 years, more common in primipara (67.24%), commonest mode of delivery was vaginal route (86.2%), the occurrence of convulsion was more common within 24hrs after delivery. Most common CT scan finding was normal study (51.72%) followed by cerebral infarct (15.5%), cerebral edema (13.72%), PRES (10.34%). There were no cases of maternal mortality due to postpartum eclampsia during study period.Conclusions: Eclampsia still remains a major cause of maternal morbidity, CT scan of brain gives valuable intracerebral information, and aids in a better management.