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40 resultados encontrados para: TEMA: Análisis químico
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1.
Libro
Guía de muestreo en lagunas costeras / Luis M. Zabalegui Medin, Leticia Zendrero Moreno
Zabalegui Medina, Luis M. ; Zendrero Moreno, Leticia (coaut.) ;
México : Universidad Autónoma Metropolitana , s. f
Clasificación: 551.4609 / Z3
Bibliotecas: San Cristóbal
Cerrar
SIBE San Cristóbal
SAA001784 (Disponible)
Disponibles para prestamo: 1

2.
Artículo
Rat volatiles as an attractant source for the Asian tiger mosquito, Aedes albopictus
Díaz Santiz, Edvin (autor) ; Rojas, Julio C. (autor) ; Casas Martínez, Mauricio (autor) ; Cruz López, Leopoldo Caridad (autor) ; Malo Rivera, Edi Álvaro (autor) ;
Disponible en línea
Contenido en: Scientific Reports Volumen 10, número 1, artículo número 5832 (March 2020), p. 1-12 ISSN: 2045-2322
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Resumen en: Inglés |
Resumen en inglés

Aedes albopictus is a vector of dengue, chikungunya, and dirofilariasis. Volatile compounds are crucial for mosquitoes to locate their hosts. This knowledge has allowed the identification of attractants derived from human odours for highly anthropophilic mosquito species. In this study, we used rats as a experimental model to identify potential attractants for host-seeking Ae. albopictus females. Porapak Q extracts from immature female rats were more attractive to Ae. albopictus females than those from mature and pregnant females, and males. Phenol, 4-methylphenol, 4-ethylphenol, and indole were identified compounds in male, immature, mature, and pregnant female extracts. There were quantitative differences in these compounds among the extracts that likely explain the discrepancy in their attractiveness. Ae. albopictus females were not attracted to the single compounds when was compared with the four-component blend. However, the binary blend of 4-methylphenol  + 4-ethylphenol and the tertiary blend of 4-methylphenol + 4-ethylphenol + indole were as attractive as the four-component blend. In the field trials, BGS traps baited with the tertiary or quaternary blends caught more Ae. albopictus females and males than BGS traps without lures. This is the first laboratory and field study to identify compounds that mediate the attraction of Ae. albopictus to one of its hosts.


3.
- Artículo con arbitraje
Resumen en: Inglés |
Resumen en inglés

Organic livestock production uses low levels of external inputs and less fossil fuel than does conventional livestock production, and therefore it is more energy efficient, reduces contamination, provides healthy food and ecosystem services, and contributes to reducing and adapting to climate change. This article characterizes livestock production and evaluates the potential and limitations of organic conversion and the energy efficiency of conventional dual purpose (milk and meat) cattle production in a humid tropical region of Chiapas, Mexico. Our analysis indicates that for the Livestock Production Units (LPU) of the study region, the greater the organic livestock conversion index (OLCI, 0–100%), the lower the values for herd size, stocking rate, total feed supplement, annual cost of feed purchased for cattle, and production cost per cow; by contrast, those LPU with greater OLCI have greater economic efficiency. Furthermore, the greater the OLCI, the greater the values of the following indicators: Feeding management, Sustainable grassland management, Ecological weed control in grasses and crops, Veterinary prevention and care, Food safety, and Ecological farm management. A direct relationship exists between the potential for organic conversion (>OLCI) and energy and economic efficiency. Meanwhile, an inverse relationship was found between OLCI and energy efficiency on the one hand, and - on the other - use of direct and indirect energy, total energy input, energy output, and number of people that could be fed with the energy from milk and meat produced. Converting LPU to organic production and increasing their energy efficiency depends on farmers further developing their abilities to manage sustainable agricultural systems through advisory, technical assistance, and permanent financial support.


4.
Artículo
Resumen en: Inglés |
Resumen en inglés

•The induction of defences in response to herbivory is a key mechanism of plant resistance. While a number of studies have investigated the time course and magnitude of plant induction in response to a single event of herbivory, few have looked at the effects of recurrent herbivory. Furthermore, studies measuring the effects of the total amount and recurrence of herbivory on both direct and indirect plant defences are lacking. To address this gap, here we asked whether insect leaf herbivory induced changes in the amount and concentration of extrafloral nectar (an indirect defence) and concentration of leaf phenolic compounds (a direct defence) in wild cotton(Gossypium hirsutum). •We conducted a greenhouse experiment where we tested single event or recurrent herbivory effects on defence induction by applying mechanical leaf damage and caterpillar (Spodoptera frugiperda) regurgitant. •Single events of 25% and 50% leaf damage did not significantly influence extrafloral nectar production or concentration. Extrafloral nectar traits did, however, increase significantly relative to controls when plants were exposed to recurrent herbivory (two episodes of 25% damage). In contrast, phenolic compounds increased significantly inresponse to single events of leaf damage but not to recurrent damage. In addition, we found. that local induction of extrafloral nectar production was stronger than systemic induction, whereas the reverse pattern was observed for phenolics. •Together, these results reveal seemingly inverse patterns of induction of direct andindirect defences in response to herbivory in wild cotton.


5.
- Artículo con arbitraje
*Solicítelo con su bibliotecario/a
A framework approach for unravelling the impact of multiple factors influencing flooding
Gai, Lingtong (autora) ; Baartman, Jantiene E. M. (autora) ; Mendoza Carranza, Manuel (autor) ; Wang, Feng (autor) ; Ritsema, Coen J. (autor) ; Geissen Geissen, Violette (autora) ;
Disponible en línea
Contenido en: Journal of Flood Risk Management Vol. 11 (2018), p. 111-126 ISSN: 1753-318X
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

To have a better understanding of the in fluence of topographic, climatic, and, especially, anthropogenic factors on hydrological discharge and flooding, this study proposes a new framework approach using a set of methods to answer the questions why, where, when, and how flooding occurs. Including conditional inference tree (CIT), cross-correlation, and double-mass curves analysis, the approach is demonstrated in an application to the Wei River Basin, China. From the CIT analysis, dam construction period was identified as the most important factor (why), and the sub-catchment farthest upstream contributed the most to the flooding of the downstream floodplain (where). We then analysed the effect of the periods of dam construction on the time lag change (when) and the precipitation – discharge relationship (how) using cross-correlation analysis and double-mass curves analysis, respectively. The results suggested that the dam construction delayed the precipitation for 0.4 days on average compared to before the dam construction period, and the discharge at the outlet of the basin was reduced by 44%. This framework approach is promising as it can quantitatively evaluate the importance of multiple factors on multiple years of flooding, while many studies evaluate single flooding events.


6.
Capítulo de libro
Los homicidios en los estados fronterizos de México. Cambios y tendencias
Yanes Pérez, Maritel ; González Ramírez, Raúl Sergio (coaut.) ;
Contenido en: Diseño, implementación y evaluación de políticas públicas. Estudios de caso en México y América Latina Chetumal, Quintana Roo, México : Universidad de Quintana Roo, 2018 página 159-175 ISBN:978-607-9448-55-4
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Resumen en: Inglés |
Resumen en inglés

The propolis produced by bees are used in alternative medicine for treating inflammation, and infections, presumably due to its antioxidant properties. In this context, five propolis fromMéxico were investigated to determine their inhibitory lipid peroxidation properties. The ethyl acetate extract from a red propolis from Chiapas State (4-EAEP) was the most potent (IC50 = 1.42±0.07 μg/mL) in the TBARS assay, and selected for further studies. This extract afforded two new compounds, epoxypinocembrin chalcone (6), and an ε-caprolactone derivative (10), as well as pinostrobin (1), izalpinin (2), cinnamic acid (3), pinocembrin (4), kaempherol (5), 3,3-dimethylallyl caffeate in mixture with isopent-3-enyl caffeate (7a + 7b), 3,4-dimethoxycinnamic acid (8), rhamnetin (9) and caffeic acid (11). The HPLC profile, anti-mycobacterial, and antioxidant properties of this extract was also determined. Most of the isolated compounds were also tested by inhibition of reactive oxygen species (ROS) in challenged mouse bone marrow-derived mast cells (BMMCs), and DPPH. Their anti-inflammatory activity was evaluated by TPA, and MPO (myeloperoxidase) activity by ear edema test in mice. The most potent compounds were 7a + 7b in the TBARS assay (IC50 = 0.49±0.06 μM), and 2 which restored the ROS baseline (3.5 μM). Our results indicate that 4-EAEP has anti-oxidant, and anti-inflammatory properties due to its active compounds, suggesting it has anti-allergy and anti-asthma potential.

Human activities have changed and shaped landscape conditions of the Yucatán Peninsula for more than 4000 years. Several paleoecological studies showed the oldest pollen record of corn-based agriculture is from northern Belize, with an estimated age of 3300 BC. Several other studies report maize between 1500 and 3000 BC from northern Guatemala and the Mexican part of the Yucatán Peninsula. After 3500 cal yr BP several paleoecological studies showed a marked tendency to drier climatic conditions. In pollen records, increased drought is expressed as a reduced presence of fossil arboreal pollen. Pollen records with the presence of Zea mays also show other taxa, which are indicators of disturbance in different vegetation types.


8.
- Artículo con arbitraje
*Solicítelo con su bibliotecario/a
Variation in the cuticular hydrocarbons of the Mexican fruit fly Anastrepha ludens males between strains and age classes
Bosa Ochoa, Carlos Felipe ; Cruz López, Leopoldo Caridad (coaut.) ; Guillén Navarro, Griselda Karina (coaut.) ; Zepeda Cisneros, Cristina Silvia (coaut.) ; Liedo Fernández, Pablo (coaut.) ;
Contenido en: Archives of Insect Biochemistry and Physiology Vol. 99, no. 3, e21513 (November 2018), p. 1-13 ISSN: 1520-6327
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

In this study cuticular hydrocarbons (CHCs) were characterized from wings of individual unmated males of different Anastrepha ludens (Loew) mass‐reared strains of different ages (3 and 19‐day‐old): (a) a standard mass‐reared colony (control), (b) a genetic sexing strain, (c) a selected strain, (d) a hybrid strain, and (e) wild males. We found that the hydrocarbon profiles in all males included two n‐alkanes, five monomethyl alkanes, and two alkenes. CHCs ranged from C26 to C31. The most prominent peaks were 2‐ methyloctacosane (2‐Me‐C28), n‐nonacosene (C29:1), 2‐ methyltriacontane (2‐Me‐C30), and n‐hentriacontene (C31:1). Significant variations in the CHC amounts of the mass‐reared strains were observed from Day 9 and thereafter. Comparison of CHCs using multivariate and canonical analyses across ages and among mass‐reared strains and wild males revealed qualitative and quantitative differences. The relative amounts of C29:1 and 2‐Me‐C30 were significantly higher across age groups in the mass‐reared strains than those in the wild males. In contrast, amounts of n‐nonacosane (C29) significantly increased in wild males as they aged. Through statistical analyses, we inferred that CHC amounts vary with age. Wild males differed significantly from the mass‐reared strains in the amount of C29, and the genetic sexing strain Tap‐7 had significantly higher values for 2‐methylhexacosane (2‐Me‐C26). In contrast the selected and control strain differed from the other strains in amounts of C29:1 and 2‐Me‐C30. We suggest that differential profiles in hydrocarbon composition among the strains may be mainly due to environmental pressures.


Resumen en: Inglés |
Resumen en inglés

It has been demonstrated that the human biomonitoring of susceptible populations is a valuable method for the identification of critical contaminants. Therefore, the purpose of this study was to assess the exposure profile for arsenic (As), lead (Pb), mercury (Hg), 1-hydroxypyrene (1-OHP), 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (DDE), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs) in children living in Ciudad Juarez, Chihuahua, Mexico (a major manufacturing center in Mexico). In 2012, we evaluated a total of 135 healthy children living in Ciudad Juarez since birth. The total PBDEs levels ranged from nondetectable (< LOD) to 215 ng/g lipid, with a mean total PBDEs level of 29.5 ± 53.0 ng/g lipid (geometric mean ± standard deviation). The mean total PCBs level in the study participants was 29.0 ± 10.5 ng/g lipid (range 4.50–50.0 ng/g lipid). The mean concentration of total DDT (DDT + DDE) was 11.9 ± 6.70 ng/g lipid (range 3.00–26.0 ng/g lipid). The mean 1-OHP levels was 1.2 ± 1.1 µmol/mol creatinine (range <LOD to 3.90 µmol/mol creatinine). Regarding heavy metals levels, the mean urinary As levels was 19.5 ± 3.07 µg/g creatinine, for urinary mercury the levels ranged from <LOD to 11.5 µg/L, with a mean value of 2.10 µg/L, and finally, the mean blood lead level was 4.20 ± 3.80 µg/dL. In conclusion, our data indicate high exposure levels to chemicals analyzed in the children living in the study community. Therefore, a biomonitoring program for the surveillance of the child population in Ciudad Juarez is necessary.


10.
Libro
L'analyse qualitative en sciences humaines et sociales / Pierre Paillé, Alex Mucchielli
Paillé, Pierre ; Mucchielli, Alex (coaut.) ;
París, France : Armand Colin , 2016
Clasificación: 300.01 / P3
Bibliotecas: Chetumal
Cerrar
SIBE Chetumal
ECO030008534 (Disponible)
Disponibles para prestamo: 1
Resumen en: Frances |
Resumen en frances

Les méthodes qualitatives occupent une place grandissante en sciences humaines et sociales, constituant depuis leurs origines américaines un courant aussi riche que diversifié. Cet ouvrage, véritable manuel, permet d’appréhender aussi bien l’histoire que les enjeux épistémologiques et applications pratiques de ces méthodes dans leur diversité (analyses thématiques, à l’aide des catégories, en mode écriture…). Il cible toute la fécondité du dénominateur commun à ces méthodes : une démarche rigoureuse de reformulation, d’explicitation ou de théorisation des données d’enquête participant de la découverte et de la construction de sens. Cette 3e édition a été augmentée de deux nouveaux chapitres et a fait l'objet de profonds remaniements.