Low-noise high-voltage DC power supply for nanopositioning applications

Nanopositioning techniques currently applied to characterize physical properties of materials interesting for applications at the microscopic scale rely on high-voltage electronic control circuits that should have the lowest possible noise level. Here we introduce a simple, flexible, and custom-built power supply circuit that can provide +375\,V with a noise level below 10\,ppm. The flexibility of the circuit comes from its topology based on discrete MOSFET components that can be suitable replaced in order to change the polarity as well as the output voltage and current.Comment: 3 pages, 2 figure

Pastoral Conflict, Emerging Trends and Environmental Stress in Nyangatom, Southern Ethiopia

This study examined the dynamics of conflict, emerging trends and relationship between inter-pastoral conflicts and environmental changes in Nyangatom, Southern Ethiopia.  The study employed a qualitative approach and exploratory case study research design.  The study revealed that inter-pastoral conflicts stem from multiple and compounding dynamics. The environmental change has escalated intense inter-pastoralists’ contestation and conflicts, including cross-border conflict, on the scarce and fast-depleting natural resources. Indeed, there is a causal link between inter-pastoral conflicts and environmental changes. In this regard, the environmental factor has uniquely affected the Nyangatom due to the drying of Kibish River and rapid invasion of Prosopis–Juliflora in their key grazing lands. In response to environmental stresses as part of the traditional copying mechanism, the Nyangatom cross border deep into South-Sudan to their ethnic kin of Toposa and into Kenya that usually causes frequent cross-border conflicts with Turkana pastoralists. Irrespective of discernible risk of conflicts, they used to migrate to Mursi and Surma territories that caused conflict. And yet, the Nyangatom has often engaged in frequent conflicts with Dasanach. The study suggests alternative livelihood options and an understanding of the complex conflict dynamics in view of the cause-effect relationships for future management of inter-pastoral and cross-border conflicts in the region

Electron concentration effects on the Shastry-Sutherland phase stability in Ce_{2-x}Pd_{2+y}In_{1-z} solid solutions

The stability of a Shastry-Sutherland ShSu phase as a function of electron concentration is investigated through the field dependence of thermal and magnetic properties of the solid solution Ce_{2-x}Pd_{2+y}In_{1-z} in the antiferromagnetic branch. In these alloys the electronic (holes) variation is realized by increasing $Pd$ concentration. The AF transition T_M decreases from 3.5K to 2.8K as $Pd$ concentration increases from y=0.2 to y=0.4. By applying magnetic field, the ShSu phase is suppressed once the field induced ferromagnetic polarization takes over at a critical field B_{cr} which increases with $Pd$ content. A detailed analysis around the critical point reveals a structure in the maximum of the dM/dB derivative, which is related with incipient steps in the magnetization M(B) as predicted by the theory for the ShSu lattice. The crossing of M(B) isotherms, observed in ShSu prototype compounds, is also analyzed. The effect of $In$ substitution by $Pd$ is interpreted as an increase of the number of 'holes' in the conduction band and results in a unique parameter able to describe the variation of the magnetic properties along the studied range of concentration.Comment: 8 pages, 11 figure

Exploring high temperature magnetic order in CeTi_1-xSc_xGe

Most of magnetic transitions related to Ce ordering are found below T_ord~12K. Among the few cases exceeding that temperature, two types of behaviors can be distinguished. One of them is related to the rare cases of Ce binary compounds formed in BCC structures, with a quartet ground state, whose degeneracy is reduced by undergoing different types of transitions mostly structural. The other group shows evidences of itinerant character with the outstanding example of CeRh_3B_2 showing the highest T_ord=115K. The second highest ordering temperature has been reported for CeScGe with T_ord=47K, but the nature of this magnetic state has not been investigated very deeply. In order to shed more light into this unusual high temperature ordering we studied the structural, magnetic, transport and thermal properties of CeTi_1-xSc_xGe alloys in the stability range of the CeScSi-type structure 0.25<x<1 This system presents a rich variety of magnetic behaviors along this concentration range, with the magnetic ordering growing from ferromagnetic (FM) T_C~7K up to an antiferromagnetic (AFM) transition at T_N=47K. The different regions show the following characteristics: i) on the Ti rich side (0.25<x<0.50) it exhibits a FM ground state (GS) with large saturation magnetization values M_sat up to ~1.15 mu_B. ii) Around x=0.60, the first crystal electric field excited doublet starts to contribute to the GS magnetic properties. Furthermore an AFM component with a connected metamagnetic transition appears. iii) At x=0.65 a clear change in the GS nature is associated to a critical point above which the GS properties can be described like for an itinerant system (with decreasing M_sat) and an effective GS degeneracy N_eff=4. iv) For x>0.65, the magnetic phase boundary splits into two transitions, with an intermediate phase presenting incommensurate spin density waves features.Comment: 8 pages, 10 figure

A propósito de dar clase, devolución y pago

En el siguiente texto doy cuenta resumida del objetivo del libro ¿Qué clase de dar es el dar clase?, partiendo de la conversación con la ética de Lévinas y de la articulación entre filosofía y educación. En función de estas relaciones analizo formas de devolución -a la sociedad y como forma de pago- que se vinculan a esta excedencia o “resto” de la educación que, según se sostiene, es del orden de lo que “no tiene precio” y, precisamente, por ello debería (la educación) tener un reconocimiento social y material que no tiene.Dossier: La enseñanza universitaria a 100 años de la Reforma: legados, transformaciones y compromisosEspecialización en Docencia Universitari

A propósito de dar clase, devolución y pago

En el siguiente texto doy cuenta resumida del objetivo del libro ¿Qué clase de dar es el dar clase?, partiendo de la conversación con la ética de Lévinas y de la articulación entre filosofía y educación. En función de estas relaciones analizo formas de devolución -a la sociedad y como forma de pago- que se vinculan a esta excedencia o “resto” de la educación que, según se sostiene, es del orden de lo que “no tiene precio” y, precisamente, por ello debería (la educación) tener un reconocimiento social y material que no tiene.Dossier: La enseñanza universitaria a 100 años de la Reforma: legados, transformaciones y compromisosEspecialización en Docencia Universitari