Israel Mtz - Academia.edu (original) (raw)
Papers by Israel Mtz
Acta Materialia, 1998
AbstractÐThe kinetics, morphologies, and mechanisms involved in Reactive Isothermal Solidi®cation... more AbstractÐThe kinetics, morphologies, and mechanisms involved in Reactive Isothermal Solidi®cation were investigated. Experiments involved the Ni±Sn binary system. Three types of samples were prepared: powder samples, samples for dipping experiments, and model multi-layer samples. The samples were heat treated for dierent durations at temperatures in the range 235±6008C. The following results were obtained. During solidi®cation, Ni 3 Sn 4 was the only phase detected by SEM, optical microscopy, and XRD. However, in electron diraction during TEM examination, the Ni 3 Sn phase was also found. When solidi®cation was complete, the other two equilibrium intermediate phases were detected by SEM and XRD. The Ni 3 Sn 4 grew mainly as a layer at the solid/liquid interface. The Ni 3 Sn 4 /liquid interface was not¯at, containing deep grain boundary grooves, and part of the layer had crumbled into the liquid. As the Ni 3 Sn 4 layer grows, lateral grain growth occurs. The time-dependence of the mean grain size obeys a parabolic law. In short-duration experiments, the growth kinetics of the Ni 3 Sn 4 layer, too, was found to be parabolic, and with an activation energy of 27.621.7 kJ/mol. This value corresponds to the activation energy for the diffusion of Ni in liquid Sn. In long-time experiments deceleration of the growth kinetics was observed. Simultaneously with the phase growth and the lateral grain growth the coarse Ni 3 Sn 4 layer grains crumble into the liquid, a process related to the grooving of the Ni 3 Sn 4 layer which takes place at the microstructural transition zone (MTZ). The crumbling as well as the lateral grain growth are considered to be the factors that aect the growth kinetics. #
Journal of Cellular and Molecular Medicine, 2004
BMC Developmental Biology, 2010
Background In embryos the maternal-to-zygotic transition (MTZ) integrates post-transcriptional re... more Background In embryos the maternal-to-zygotic transition (MTZ) integrates post-transcriptional regulation of maternal transcripts with transcriptional activation of the zygotic genome. Although the molecular mechanisms underlying this event are being clarified in Drosophila melanogaster, little is know about the embryogenic processes in other insect species. The recent publication of expressed sequence tags (ESTs) from embryos of the global pest species Ceratitis capitata (medfly) has enabled the investigation of embryogenesis in this species and has allowed a comparison of the embryogenic processes in these two related dipteran species, C. capitata and D. melanogaster, that shared a common ancestor 80-100 mya. Results Using a novel PCR-based sexing method, which takes advantage of a putative LTR retrotransposon MITE insertion on the medfly Y chromosome, the transcriptomes of individual early male and female embryos were analysed using RT-PCR. This study is focused on two crucial aspects of the onset of embryonic development: sex determination and cellular blastoderm formation. Together with the three known medfly genes (Cctransformer, Cctransformer2 and Ccdoublesex), the expression patterns of other medfly genes that are similar to the D. melanogaster sex-determination genes (sisterlessA, groucho, deadpan, Sex-lethal, female lethal d, sans fille and intersex) and four cellular blastoderm formation genes (Rho1, spaghetti squash, slow-as-molasses and serendipity-α) were analyzed, allowing us to sketch a preliminary outline of the embryonic process in the medfly. Furthermore, a putative homologue of the Zelda gene has been considered, which in D. melanogaster encodes a DNA-binding factor responsible for the maternal-to-zygotic transition. Conclusions Our novel sexing method facilitates the study of i) when the MTZ transition occurs in males and females of C. capitata, ii) when and how the maternal information of "female-development" is reprogrammed in the embryos and iii) similarities and differences in the regulation of gene expression in C. capitata and D. melanogaster. We suggest a new model for the onset of the sex determination cascade in the medfly: the maternally inherited Cctra transcripts in the female embryos are insufficient to produce enough active protein to inhibit the male mode of Cctra splicing. The slow rate of development and the inefficiency of the splicing mechanism in the pre-cellular blastoderm facilitates the male-determining factor (M) activity, which probably acts by inhibiting CcTRA protein activity.
Environmental Earth Sciences, 1986
Accelerated erosion of a desert cliff due to uncontrolled sewage water disposal was investigated ... more Accelerated erosion of a desert cliff due to uncontrolled sewage water disposal was investigated at the Sede Boqer Campus in the Negev, Israel An erosional cirque formed by this water was studied as a model simulating natural processes. The cliffs consist of loess and conglomerate underlain by soft marl, clay, and chalk. The rate of erosion is of the order of 5%–8% of the volume of water discharged. The rate of incision ranges from 10 2 to 13.3 m/yr and is several orders higher than that expected under normal rainfall conditions The introduction of this new hydrological factor resulted in a severe disturbance of the morphological balance in the vicinity of the cliffs, accelerated erosion, and generated circular slides
¿En que consiste el modelo dogmático? Es una técnica que permite que permite a la dogmática a for... more ¿En que consiste el modelo dogmático? Es una técnica que permite que permite a la dogmática a formular el derecho positivo adecuándolo a determinados ideales, si bien haciéndolo parecer esa formulación como si se tratara de una mera descripción de soluciones que el derecho encierra en forma latente, es la atribución al legislador de ciertas propiedades de racionalidad, o que sirven para garantizarla, que está muy lejos de caracterizar a los legisladores reales.
Acta Materialia, 1998
AbstractÐThe kinetics, morphologies, and mechanisms involved in Reactive Isothermal Solidi®cation... more AbstractÐThe kinetics, morphologies, and mechanisms involved in Reactive Isothermal Solidi®cation were investigated. Experiments involved the Ni±Sn binary system. Three types of samples were prepared: powder samples, samples for dipping experiments, and model multi-layer samples. The samples were heat treated for dierent durations at temperatures in the range 235±6008C. The following results were obtained. During solidi®cation, Ni 3 Sn 4 was the only phase detected by SEM, optical microscopy, and XRD. However, in electron diraction during TEM examination, the Ni 3 Sn phase was also found. When solidi®cation was complete, the other two equilibrium intermediate phases were detected by SEM and XRD. The Ni 3 Sn 4 grew mainly as a layer at the solid/liquid interface. The Ni 3 Sn 4 /liquid interface was not¯at, containing deep grain boundary grooves, and part of the layer had crumbled into the liquid. As the Ni 3 Sn 4 layer grows, lateral grain growth occurs. The time-dependence of the mean grain size obeys a parabolic law. In short-duration experiments, the growth kinetics of the Ni 3 Sn 4 layer, too, was found to be parabolic, and with an activation energy of 27.621.7 kJ/mol. This value corresponds to the activation energy for the diffusion of Ni in liquid Sn. In long-time experiments deceleration of the growth kinetics was observed. Simultaneously with the phase growth and the lateral grain growth the coarse Ni 3 Sn 4 layer grains crumble into the liquid, a process related to the grooving of the Ni 3 Sn 4 layer which takes place at the microstructural transition zone (MTZ). The crumbling as well as the lateral grain growth are considered to be the factors that aect the growth kinetics. #
Journal of Cellular and Molecular Medicine, 2004
BMC Developmental Biology, 2010
Background In embryos the maternal-to-zygotic transition (MTZ) integrates post-transcriptional re... more Background In embryos the maternal-to-zygotic transition (MTZ) integrates post-transcriptional regulation of maternal transcripts with transcriptional activation of the zygotic genome. Although the molecular mechanisms underlying this event are being clarified in Drosophila melanogaster, little is know about the embryogenic processes in other insect species. The recent publication of expressed sequence tags (ESTs) from embryos of the global pest species Ceratitis capitata (medfly) has enabled the investigation of embryogenesis in this species and has allowed a comparison of the embryogenic processes in these two related dipteran species, C. capitata and D. melanogaster, that shared a common ancestor 80-100 mya. Results Using a novel PCR-based sexing method, which takes advantage of a putative LTR retrotransposon MITE insertion on the medfly Y chromosome, the transcriptomes of individual early male and female embryos were analysed using RT-PCR. This study is focused on two crucial aspects of the onset of embryonic development: sex determination and cellular blastoderm formation. Together with the three known medfly genes (Cctransformer, Cctransformer2 and Ccdoublesex), the expression patterns of other medfly genes that are similar to the D. melanogaster sex-determination genes (sisterlessA, groucho, deadpan, Sex-lethal, female lethal d, sans fille and intersex) and four cellular blastoderm formation genes (Rho1, spaghetti squash, slow-as-molasses and serendipity-α) were analyzed, allowing us to sketch a preliminary outline of the embryonic process in the medfly. Furthermore, a putative homologue of the Zelda gene has been considered, which in D. melanogaster encodes a DNA-binding factor responsible for the maternal-to-zygotic transition. Conclusions Our novel sexing method facilitates the study of i) when the MTZ transition occurs in males and females of C. capitata, ii) when and how the maternal information of "female-development" is reprogrammed in the embryos and iii) similarities and differences in the regulation of gene expression in C. capitata and D. melanogaster. We suggest a new model for the onset of the sex determination cascade in the medfly: the maternally inherited Cctra transcripts in the female embryos are insufficient to produce enough active protein to inhibit the male mode of Cctra splicing. The slow rate of development and the inefficiency of the splicing mechanism in the pre-cellular blastoderm facilitates the male-determining factor (M) activity, which probably acts by inhibiting CcTRA protein activity.
Environmental Earth Sciences, 1986
Accelerated erosion of a desert cliff due to uncontrolled sewage water disposal was investigated ... more Accelerated erosion of a desert cliff due to uncontrolled sewage water disposal was investigated at the Sede Boqer Campus in the Negev, Israel An erosional cirque formed by this water was studied as a model simulating natural processes. The cliffs consist of loess and conglomerate underlain by soft marl, clay, and chalk. The rate of erosion is of the order of 5%–8% of the volume of water discharged. The rate of incision ranges from 10 2 to 13.3 m/yr and is several orders higher than that expected under normal rainfall conditions The introduction of this new hydrological factor resulted in a severe disturbance of the morphological balance in the vicinity of the cliffs, accelerated erosion, and generated circular slides
¿En que consiste el modelo dogmático? Es una técnica que permite que permite a la dogmática a for... more ¿En que consiste el modelo dogmático? Es una técnica que permite que permite a la dogmática a formular el derecho positivo adecuándolo a determinados ideales, si bien haciéndolo parecer esa formulación como si se tratara de una mera descripción de soluciones que el derecho encierra en forma latente, es la atribución al legislador de ciertas propiedades de racionalidad, o que sirven para garantizarla, que está muy lejos de caracterizar a los legisladores reales.