Nonlinear spectroscopy in the strong-coupling regime of cavity QED

A nonlinear spectroscopic investigation of a strongly coupled atom-cavity system is presented. A two-field pump-probe experiment is employed to study nonlinear structure as the average number of intracavity atoms is varied from N̅≈4.2 to N̅≈0.8. Nonlinear effects are observed for as few as 0.1 intracavity pump photons. A detailed semiclassical simulation of the atomic beam experiment gives reasonable agreement with the data for N̅≳2 atoms. The simulation procedure accounts for fluctuations in atom-field coupling which have important effects on both the linear and nonlinear probe transmission spectra. A discrepancy between the simulations and the experiments is observed for small numbers of atoms (N̅≲1). Unfortunately, it is difficult to determine if this discrepancy is a definitive consequence of the quantum nature of the atom-cavity coupling or a result of the severe technical complications of the experiment

Geospatial Analysis and Comparison of Habitat Costs for Resident Sarasota Bay Bottlenose Dolphins (Tursiops truncatus)

The Sarasota Dolphin Research Program (SDRP) studies a resident Florida bottlenose dolphin population that faces many threats from human activities. These dolphins concentrate in different areas seasonally, possibly in response to changes in the distribution of prey or predators. Movement from one location to another involves certain “costs” to the dolphins, which are defined in this project as the potential for negative environmental interactions (natural and anthropogenic). Using an updated habitat map for the SDRP study area and a geoprocessing model, a cost analysis was performed in order to compare the cost values of eight primary habitat types. Results indicated that Mangrove and Channel are the most costly, while Open Bay and Pass are the least costly. I hypothesized that dolphins will use habitats with lower costs more frequently than habitats with higher costs, but previous research and SDRP photographic survey data show that these dolphins frequently use dredged channels to move between areas, and at the population level they do not use any habitat type disproportionately to its availability

On a one-sample distribution-free test statistic V

SUMMARY A table of exact critical values of a one-sample distribution-free test statistic V is presented for selected significance levels and sample sizes n = 3( 1) 20. It is shown that this test is computationally similar to the well-known Wilcoxon rank sum test statisti

Simulations and scattering functions of polyelectrolyte-macroion complexes

Using Monte Carlo simulations of complex formation between a polyelectrolyte chain and an oppositely charged macroion, we calculated the scattering function of the polyelectrolyte chain. We investigated the case of the isolated polyelectrolyte chain and studied the effect and influence of key parameters such as the ionic concentration of the solution, polyelectrolyte length and intrinsic rigidity on the scattering function. Then, we focused on the polyelectrolyte-macroion complex by calculating the structure factor S(q) of the adsorbed polyelectrolyte chain. Typical conformations ranging from coils, extended chains to solenoids are revealed and the corresponding S(q) analysed. The effects of ionic concentration, chain length and intrinsic rigidity and relative size ratio between the polyelectrolyte and the macroion are investigated. Important effects on the structure factor of the adsorbed polyelectrolyte are observed when the macroion is partially or totally wrapped by the polyelectrolyte. Distance correlations between the polyelectrolyte monomer positions at the surface of the macroion induce the formation of peaks in the fractal regime of S(q). For semiflexible chains, when solenoid conformations are observed, the position of the peaks in the fractal regime corresponds directly to the separation distance between the turns. The formation of a protruding tail in solution is also observed through the formation in the fractal regime of a linear domai

Near-field imaging with two transmission gratings for submicrometer localization of atoms

We show theoretically that an atomic pattern with period d can be obtained with 100% visibility even for an infinitely extended source by sending atoms through two transmission gratings with periods d and d/2, respectively, and separated by half the Talbot length LT/2=d^2/2λdB, where λdB is the atomic wavelength and the source is infinitely far away. For a finite source distance, as would be attainable in any real experiment, a small correction to the grating periods and separations restores the period-d pattern. This effect is closely related to the Talbot and Lau effects in classical optics and can be used to localize atoms to a submicrometer scale without a compromise in atomic flux. We first derive compact analytical formulas for the idealized case of a monochromatic source and large gratings and then verify numerically that a finite grating size and velocity dispersion in the beam do not decrease the fringe visibility considerably. Finally, we briefly present an experiment in preparation to exhibit this localization

Creació i desenvolupament d’un model de negoci d’una ONG per a la construcció de pous d’aigua potable a Àfrica

Aquest projecte consisteix en la creació d’una Associació Juvenil sense ànim de lucre que té com a objectiu el subministrament d’aigua potable a llocs on no tenen accés a aquest bé bàsic per la vida. Aquest projecte té com a objectiu principal realitzar tots els passos per arribar al moment de la creació de l’entitat. A més a més, es fa el disseny i pla d’instal·lació d’un projecte pilot, això és, la construcció del primer pou que subministri aigua potable a una població a prop d’Arusha, Tanzània. Per dur a terme la creació d’aquesta entitat, que té com a objectiu esdevenir una Organització No Governamental (ONG), en primer lloc es fa un anàlisi del mercat, manifestant la necessitat de negocis com el que es presenta al territori africà. S’ha realitzat un estudi geogràfic per tal de localitzar les zones on construir pous tenint en compte les següents tres condicions: La necessitat de la zona d’aigua potable, ja sigui per beure-la o pel sanejament personal, la presència d’aigües subterrànies, i la profunditat a la que es pot arribar a obtenir aigua potable. Com a indrets amb projecció, s’han seleccionat bàsicament països africans, ja siguin de la part occidental, de la part central o sobre tot de la part oriental, com n’és el país del projecte pilot. Amb el fi de plantejar una instal·lació d’un pou efectiu i sostenible, s’han realitzat els càlculs necessaris tenint com a font d’energia del bombeig de l’aigua un panell solar, el qual subministra energia renovable. Aquesta característica és vital, ja que davant de tot es tracta d’un projecte sostenible i respectuós amb el medi ambient. Sobre aquestes bases establertes, s’ha elaborat un pla de negoci detallat, definint així tots els aspectes necessaris previs a la creació de l’organització de manera oficial. S’ha realitzat un ampli pla de màrqueting, amb l’organització d’un torneig solidari, la creació de comptes a les xarxes socials d’Instagram i LinkedIn, i l’enviament d’una enquesta a més de dues centes persones, per tal de tenir dades verídiques i realitzar una corba de captació sobre la que sostenir el pla financer. També s’ha detallat l’estructura jurídica i organitzativa de l’associació, amb el disseny d’un organigrama per veure visualment el nombre de departaments i les responsabilitats que engloben cadascun d’ells. La motivació principal és la inquietud de dos joves estudiant d’enginyeria industrial, els quals tenen ganes d’emprendre un projecte que apliqui l’àmbit tècnic en l’ajuda humanitària i la cooperació internacional. El projecte caldrà que sigui el màxim veraç i proper a la realitat possible, ja que l’objectiu de fons és aplicar-lo a la realitat en un futur pròxim, quan es disposi del temps i els recursos necessaris

On the behaviour of a rumour process with random stifling

We propose a realistic generalization of the Maki-Thompson rumour model by assuming that each spreader ceases to propagate the rumour right after being involved in a random number of stifling experiences. We consider the process with a general initial configuration and establish the asymptotic behaviour (and its fluctuation) of the ultimate proportion of ignorants as the population size grows to $\infty$. Our approach leads to explicit formulas so that the limiting proportion of ignorants and its variance can be computed.Comment: 12 pages, to appear in Environmental Modelling & Softwar

Un paseo por la memoria histórica de Canarias

In this article you can do a tour of the Canary history through of the mdC (Memoria Digital de Canarias), a pioneer project from a Spanish university who was born in 2003 and keeps the intellectual production of the Canary archipelago for five centuries. Many of these works are ancient, rare and valuable because they are discataloged. Thanks to digitizacion, the deterioration of these documentation as a result of multiple manipulations has been avoived, so mdC (Memoria Digital de Canarias) currently contributes to the conservation of Canarian documentary heritag