SOMATIC EMBRYOGENESIS AND PLANT REGENERATION FROM CALLUS AND SUSPENSION CULTURES OF IPHIONA MUCRONATA (FORSSK)

A protocol was designed for plant regeneration of Iphiona mucronata from embryogenic callus via somatic embryogenesis to enable micro propagation of this endangered plant. The embryogenic callus was induced using seedling cultured for nine months on Murashig and Skoog medium (MS) supplemented with 0.1 mg l-1 naphthalene acetic acid (NAA), 0.1 mg l-1 kinetin (Kn) and 5 mg l-1 ascorbic acid and incubated in the dark followed by growing on hormone free medium. Transfer of developed embryos to MS medium supplemented with 0.5 mg l-1 kinetin induced shoot formation. Four treatments were further tried for plant development by using indole acetic acid (IAA) or indole butyric acid (IBA) alone or in combination with kinetin. The results showed that 2 mg l-1 IAA was the best for in vitro plantlet regeneration. Embryogenic suspension was induced by transfer of embryogenic callus to liquid medium having the same composition followed by hormone free medium where different stages of embryos were monitored. Shoots were developed upon transfer to liquid medium supplemented with 0.5 mg l-1 Kn. However, no further development appeared upon transfer to semi solid medium containing different phytohormones. Embryogenic callus showed the highest phenolic contents when compared with embryogenic suspension, regenerated plantlets and the parent plant while flavonoids were detected only in embryogenic callus

Reversing Ostwald Ripening

The phenomenon of Ostwald Ripening is generally considered a limiting factor in the monodisperse production of nanoparticles. However, by analysing the free energy of a binary AB solution with precipitated A particles we show that there is a region in the parameter space of component concentrations and interaction energies where smaller particles are more stable than bigger ones. The strong binding of B species to surfaces of A particles significantly decreases the particle effective surface energy, making it negative. The global minimum of free energy in such a system is thus reached when mass is transferred from bigger particles to the smaller ones, such that all particles become identical in size. The process of mass transfer is opposite to Ostwald ripening, and can be used for generating monodisperse arrays of nanoparticles.Comment: 11 pages and 4 figures of the main text plus 4 pages and 1 figure supporting materia

Seismic Microzonation of Central Khartoum, Sudan

A preliminary seismic microzonation of Central Khartoum, Sudan is proposed. Khartoum, the capital of Sudan, is located at the confluence of White and Blue Niles. The city is heavily populated. The Central Khartoum with its high rise buildings is the center of governmental and business activities and is located on strip adjacent to the Blue Nile. Geological and geotechnical data indicated that the subsoil conditions at Central Khartoum are characterized by alluvial deposits underlain by Nubian Sandstone below a depth of 20 m. The alluvial deposits locally known as Gezira formations, consist of clays grading into silt and sand with depth. Macro seismic zonation of Sudan and its vicinities, developed by the authors, gave the ground acceleration at the bed rock surface. The effect of alluvial deposits at Central Khartoum on propagation of seismic motion parameters to the ground surface is investigated in this study. Correlations are proposed for pertinent cyclic soil properties such as shear modulus, damping, and shear wave velocity. The classical shear beam model developed by Idriss and Seed is used to study the effect of local soil conditions on ground motion parameters. In absence of strong motion records, artificial time histories of ground motion parameters are used. Plots showing the time histories of ground motion parameters at the ground surface are obtained. The results indicated amplification of ground acceleration of up to 1.15. Because of the presence of saturated loose to medium dense sand at some locations within Central Khartoum, the risk of earthquake-induced liquefaction is evaluated. The susceplity of subsoils in Central Khartoum to liguefaction is evaluated probabilistically by modifying the classical method developed by Seed and Idriss. The risk of earthquake-induced liquefaction is computed by combining the seismic hazard and the conditional probability of liquefaction. The study showed that the risk of liquefaction is low

Studies on charge production from Cs2Te photocathodes in the PITZ L-band normal conducting radio frequency photo injector

This paper discusses the behavior of electron bunch charge produced in an L-band normal conducting radio frequency cavity (RF gun) from Cs2Te photocathodes illuminated with ps-long UV laser pulses when the laser transverse distribution consists of a flat-top core with Gaussian-like decaying halo. The produced charge shows a linear dependence at low laser pulse energies as expected in the quantum efficiency limited emission regime, while its dependence on laser pulse energy is observed to be much weaker for higher values, due to space charge limited emission. However, direct plug-in of experimental parameters into the space charge tracking code ASTRA yields lower output charge in the space charge limited regime compared to measured values. The rate of increase of the produced charge at high laser pulse energies close to the space charge limited emission regime seems to be proportional to the amount of halo present in the radial laser profile since the charge from the core has saturated already. By utilizing core + halo particle distributions based on measured radial laser profiles, ASTRA simulations and semi-analytical emission models reproduce the behavior of the measured charge for a wide range of RF gun and laser operational parameters within the measurement uncertainties.Comment: 15 pages, 16 figures, 2 table

BERLinPro A Compact Demonstrator ERL for High Current and Low Emittance Beams

The HZB previously BESSY was the first institution in Germany to build and operate a dedicated synchrotron light source BESSY I . About 10 years ago BESSY II, a third generation synchrotron light source, was commissioned and is very successfully running since that time. Due to its expertise in development and operation of accelerator facilities HZB is ideally suited to realize new accelerator concepts. Therefore HZB is proposing to build a demonstrator ERL facility BERLinPro that will realize high current and low emittance operation at 100 MeV. BERLinPro is intented to bring ERL technology to maturity. This paper presents an overview of the project and the key components of the facilit

Long-range transfer of electron-phonon coupling in oxide superlattices

The electron-phonon interaction is of central importance for the electrical and thermal properties of solids, and its influence on superconductivity, colossal magnetoresistance, and other many-body phenomena in correlated-electron materials is currently the subject of intense research. However, the non-local nature of the interactions between valence electrons and lattice ions, often compounded by a plethora of vibrational modes, present formidable challenges for attempts to experimentally control and theoretically describe the physical properties of complex materials. Here we report a Raman scattering study of the lattice dynamics in superlattices of the high-temperature superconductor $\bf YBa_2 Cu_3 O_7$ and the colossal-magnetoresistance compound $\bf La_{2/3}Ca_{1/3}MnO_{3}$ that suggests a new approach to this problem. We find that a rotational mode of the MnO$_6$ octahedra in $\bf La_{2/3}Ca_{1/3}MnO_{3}$ experiences pronounced superconductivity-induced lineshape anomalies, which scale linearly with the thickness of the $\bf YBa_2 Cu_3 O_7$ layers over a remarkably long range of several tens of nanometers. The transfer of the electron-phonon coupling between superlattice layers can be understood as a consequence of long-range Coulomb forces in conjunction with an orbital reconstruction at the interface. The superlattice geometry thus provides new opportunities for controlled modification of the electron-phonon interaction in complex materials.Comment: 13 pages, 4 figures. Revised version to be published in Nature Material

Statistically induced phase transitions and anyons in 1D optical lattices

Anyons-particles carrying fractional statistics that interpolate between bosons and fermions-have been conjectured to exist in low-dimensional systems. In the context of the fractional quantum Hall effect, quasi-particles made of electrons take the role of anyons whose statistical exchange phase is fixed by the filling factor. Here we propose an experimental setup to create anyons in one-dimensional lattices with fully tuneable exchange statistics. In our setup, anyons are created by bosons with occupation-dependent hopping amplitudes, which can be realized by assisted Raman tunnelling. The statistical angle can thus be controlled in situ by modifying the relative phase of external driving fields. This opens the fascinating possibility of smoothly transmuting bosons via anyons into fermions and of inducing a phase transition by the mere control of the particle statistics as a free parameter. In particular, we demonstrate how to induce a quantum phase transition from a superfluid into an exotic Mott-like state where the particle distribution exhibits plateaus at fractional densities

Quantum Computing and Quantum Simulation with Group-II Atoms

Recent experimental progress in controlling neutral group-II atoms for optical clocks, and in the production of degenerate gases with group-II atoms has given rise to novel opportunities to address challenges in quantum computing and quantum simulation. In these systems, it is possible to encode qubits in nuclear spin states, which are decoupled from the electronic state in the $^1$S$_0$ ground state and the long-lived $^3$P$_0$ metastable state on the clock transition. This leads to quantum computing scenarios where qubits are stored in long lived nuclear spin states, while electronic states can be accessed independently, for cooling of the atoms, as well as manipulation and readout of the qubits. The high nuclear spin in some fermionic isotopes also offers opportunities for the encoding of multiple qubits on a single atom, as well as providing an opportunity for studying many-body physics in systems with a high spin symmetry. Here we review recent experimental and theoretical progress in these areas, and summarise the advantages and challenges for quantum computing and quantum simulation with group-II atoms.Comment: 11 pages, 7 figures, review for special issue of "Quantum Information Processing" on "Quantum Information with Neutral Particles

Complicated small bowel tumors – limits and possibilities in emergency

Spitalul Clinic de Urgență ”Sfântul Pantelimon”, București, România, Al XI-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova și cea de-a XXXIII-a Reuniune a Chirurgilor din Moldova „Iacomi-Răzeșu” 27-30 septembrie 2011Tumorile intestinului subțire sunt rare, reprezentând aproximativ 1-2% din neoplasmele gastrointestinale. Prognosticul lor este rezervat din cauza diagnosticului dificil preoperator și descoperirea lor în stadii avansate, însoțite frecvent de complicații. Materiale și metodă: Studiul este descriptiv, retrospectiv, efectuat pe o perioadă de 5 ani (2006-2010) și include 13 bolnavi operați în clinica noastră. Studiul evaluează elementele demografice ale lotului, mijloacele diagnostice folosite și eficiența lor și atitudinea terapeutică. Rezultate: Lotul a fost alcătuit din 13 bolnavi cu o medie de vârstă de 66 de ani, dintre care 8 de sex masculin și 5 de sex feminin. Cazurile au fost internate în regim de urgență datorită complicațiilor: 8 bolnavi s-au prezentat în ocluzie intestinală, 4 bolnavi s-au prezentat cu anemie severă și hematochezie sau melenă, iar 1 caz a prezentat pneumoperitoneu. Radiografia abdominală simplă a indicat intervenția chirurgicală de urgență în 9 cazuri (prezența de nivele hidro-aerice sau pneumoperitoneu) fără să aducă informații suplimentare legate de etiologie, stadiu evolutiv. Endoscopia digestivă superioară a exclus patologia gastro-duodenală la bolanvii prezentați cu hemoragie digestivă. La acești bolnavi intervenția chirurgicală a fost recomandată de cantitatea mare de transfuzii necesară pentru menținerea hemodinamică a bolnavilor. Soluția terapeutică a fost reprezentată de enterectomia segmentară și anastomoză primară în 13 cazuri și colectomie asociată în două cazuri; în două cazuri a fost necesară o derivație digestivă, în amonte, de protecție. 4 cazuri au prezentat metastaze la distanță. Concluzii: În ciuda arsenalului diagnostic și imagistic existent, diagnosticul tumorilor de intestin subțire se pune în majoritatea cazurilor la momentul explorării chirurgicale. Prezența complicațiilor îngreunează actul chirurgical și managementul postoperator al bolnavului, mărind mortalitatea.Small bowel tumors are a rare entity, accounting for about 1-2% of gastrointestinal tumors. Their prognosis is poor because of the difficult preoperative diagnosis and their discovery in advanced stages, frequently associated with complications. Materials and method: The study is descriptive, retrospective, over a 5 year period (2006- 2010) and includes 13 patients operated on in our clinic. The study evaluates the demographical characteristics of the group, the diagnostic tools that were used and the therapeutic approach. Results: The group was made up of 13 patients, with an average age of 66 years, 8 male and 5 female. The cases were admitted on arrival because of complications: 8 patients presented with intestinal obstruction, 4 with severe anemia and melena or hematochezia and one patient presented with pneumoperitoneum. Plain abdominal x-rays prompted immediate surgery in 9 cases (free air under the diaphragm or air-fluid levels) without bringing further information regarding etiology or disease stage. Upper gastrointestinal endoscopy excluded gastro-duodenal pathology in the patients presented with digestive bleeding. Surgery was performed, in these patients, owing to the large amount of blood transfusion necessary to stabilize them. The procedure performed was segmentary enterectomy with primary anastomosis in 13 patients, associated with colectomy in 2 cases; in two cases we associated a by-pass of the tumoral segment. Metastatic disease was found in four patients. Conclusions: Despite the sophisticated imaging and diagnostic modalities, diagnosis of a small bowel tumor is often achieved only at the time of surgical exploration. The presence of complications makes surgical and postoperative therapy difficult and increases mortality