Perpetual emulation threshold of PT-symmetric Hamiltonians

We describe a technique to emulate a two-level \PT-symmetric spin Hamiltonian, replete with gain and loss, using only the unitary dynamics of a larger quantum system. This we achieve by embedding the two-level system in question in a subspace of a four-level Hamiltonian. Using an \textit{amplitude recycling} scheme that couples the levels exterior to the \PT-symmetric subspace, we show that it is possible to emulate the desired behaviour of the \PT-symmetric Hamiltonian without depleting the exterior, reservoir levels. We are thus able to extend the emulation time indefinitely, despite the non-unitary \PT dynamics. We propose a realistic experimental implementation using dynamically decoupled magnetic sublevels of ultracold atoms.Comment: 15 pages, 8 figure

Repeated Measurements with Minimally Destructive Partial-Transfer Absorption Imaging

We demonstrate partial-transfer absorption imaging as a technique for repeatedly imaging an ultracold atomic ensemble with minimal perturbation. We prepare an atomic cloud in a state that is dark to the imaging light. We then use a microwave pulse to coherently transfer a small fraction of the ensemble to a bright state, which we image using in situ absorption imaging. The amplitude or duration of the microwave pulse controls the fractional transfer from the dark to the bright state. For small transfer fractions, we can image the atomic cloud up to 50 times before it is depleted. As a sample application, we repeatedly image an atomic cloud oscillating in a dipole trap to measure the trap frequency

Unconventional topology with a Rashba spin-orbit coupled quantum gas

Topological order can be found in a wide range of physical systems, from crystalline solids, photonic meta-materials and even atmospheric waves to optomechanic, acoustic and atomic systems. Topological systems are a robust foundation for creating quantized channels for transporting electrical current, light, and atmospheric disturbances. These topological effects are quantified in terms of integer-valued invariants, such as the Chern number, applicable to the quantum Hall effect, or the $\mathbb{Z}_2$ invariant suitable for topological insulators. Here we engineered Rashba spin-orbit coupling for a cold atomic gas giving non-trivial topology, without the underlying crystalline structure that conventionally yields integer Chern numbers. We validated our procedure by spectroscopically measuring the full dispersion relation, that contained only a single Dirac point. We measured the quantum geometry underlying the dispersion relation and obtained the topological index using matter-wave interferometry. In contrast to crystalline materials, where topological indices take on integer values, our continuum system reveals an unconventional half-integer Chern number, potentially implying new forms of topological transport

Realization of a fractional period adiabatic superlattice

We propose and realize a deeply sub-wavelength optical lattice for ultracold neutral atoms using $N$ resonantly Raman-coupled internal degrees of freedom. Although counter-propagating lasers with wavelength $\lambda$ provided two-photon Raman coupling, the resultant lattice-period was $\lambda/2N$, an $N$-fold reduction as compared to the conventional $\lambda/2$ lattice period. We experimentally demonstrated this lattice built from the three $F=1$ Zeeman states of a $^{87}{\rm Rb}$ Bose-Einstein condensate, and generated a lattice with a $\lambda/6= 132\ {\rm nm}$ period from $\lambda=790 \ {\rm nm}$ lasers. Lastly, we show that adding an additional RF coupling field converts this lattice into a superlattice with $N$ wells uniformly spaced within the original $\lambda/2$ unit cell.Comment: 5 pagesl 4 figure

Documento de posición sobre las necesidades y niveles óptimos de vitamina D

IntroducciónEn los últimos años se ha producido un notable interés por la vitamina D, no sólo por su importancia crucial en el metabolismo mineral óseo, sino también por los efectos extraóseos, cada vez mejor conocidos. Asi mismo, se ha constatado la existencia de valores séricos bajos de vitamina D, por debajo de lo deseable, en diferentes poblaciones, tanto sanas como enfermas, y se discute cuáles serían los niveles óptimos de vitamina D en sangre. Por todo ello, la Sociedad Española de Investigación Ósea y Metabolismo Mineral (SEIOMM), conjuntamente con todas las Sociedades Científicas implicadas en el estudio del metabolismo óseo, han elaborado el presente documento de posición sobre las necesidades y niveles óptimos de vitamina D

El trasplante autólogo de células mesoteliales como acelerador y modificador de la cicatrización cutánea en ratas Autologous mesothelial cells transplantation as accelerator and skin healing modifier in rats

El propósito del presente estudio fue comprobar si el autotrasplante de células mesoteliales peritoneales en heridas de espesor total en ratas acelera y modifica el proceso de cicatrización cutánea normal, basándonos en la teoría de que las células mesoteliales provenientes de tejidos como el peritoneo, pleura o pericardio, son responsables de uno de los procesos de cicatrización más rápidos y sintetizan varios factores estimulantes y quimiotácticos de la cicatrización (causantes de las adherencias intraabdominales), además de que poseen la capacidad de diferenciarse en otras series celulares (plasticidad). Diseñamos un estudio experimental, analítico, longitudinal, prospectivo y comparativo, en el Laboratorio de Cirugía Experimental del Centro Médico ABC Observatorio, México D.F. (México). Se emplearon 15 ratas cepa Wistar, divididas en 2 grupos: Grupo I (n=5) en el que previa anestesia general, se extirparon 3 mm. de diámetro de piel de la región dorsal mediante técnica microquirúrgica y cierre por segunda intención; y Grupo II (n=10) en el que se realizó minilaparotomía con escisión de peritoneo parietal, cierre primario de la misma, escisión de piel de espesor total en región dorsal de 3 mm. de diámetro y colocación del autoinjerto peritoneal en la herida dorsal. En el análisis histológico se revisaron 6 variables: colágeno, fibroblastos, número de vasos, macrófagos, células inflamatorias y grado de retracción, para puntualizar integralmente el tipo y características de la cicatrización en ambos grupos. El análisis estadístico de datos se elaboró con Statistical Package of Social Sciences 17.0. Se realizó estadística descriptiva por medio de medidas de frecuencia, de tendencia central y de dispersión. Los resultados mostraron que los individuos del Grupo I presentaron mayor inflamación, fibrosis y retracción, datos compatibles con una fase proliferaría de cicatrización. En el Grupo II se encontró menor inflamación y fibrosis, mayor colágeno y datos compatibles con una fase de remodelación. En conclusión, el autotrasplante de células mesoteliales peritoneales en heridas de espesor total acelera el proceso de cicatrización cutánea normal en ratas ya que disminuye la inflamación, la fibrosis y aumenta el colágeno.<br>The purpose of this study was to verify if the autologous peritoneal mesothelial cells in full thickness wounds on rats, speed up and adjust the normal skin healing process. Based on the theory that mesothelial cells from tissues such as peritoneum, pleura or pericardium, are responsible for one of the faster healing process and synthesize stimulating wound healing and chemotactical factors (hence the genesis of surgical adhesions), besides possessing the ability to differentiate into other cell series (plasticity). We designed a pilot, analytical, longitudinal, prospective and comparative study in the Laboratory of Experimental Surgery at The American British Cowdray Medical Center, Mexico City (México). Were used 15 Wistar rats which were divided into 2 groups: Group I (n = 5) where after general anesthesia, skin removed 3 mm in diameter with microsurgical technique in the back and was close by secondary intention; and Group II or experimental group (n = 10) where laparotomy was performed with excision of the parietal peritoneum and primary closure, excision of full thickness skin on the dorsal surface of 3mm diameter and peritoneal autograft placement on the dorsal wound. In histological analysis, were reviewed 6 variables: collagen, fibroblasts, number of vessels, macrophages, inflammatory cells and retraction, to point out fully the nature and characteristics of healing in both groups. For the statistical analysis we used Statistical Package for Social Sciences 17.0. The descriptive statistics was made using frequency measures of central tendency and dispersion. The results showed that the Group I rats, had increased inflammation, fibrosis and retraction, data support a proliferative phase of healing. In the Group II or experimental were found less inflammation and fibrosis, increased collagen and data consistent with a remodeling phase. In conclusion, we found that autologous peritoneal mesothelial cells in full thickness wounds accelerates the normal skin healing in rats by decreasing inflammation, fibrosis and increased collagen