Single-shot implementation of dispersion-scan for the characterization of ultrashort laser pulses

We demonstrate a novel, single-shot ultrafast diagnostic, based on the dispersion-scan (d-scan) technique. In this implementation, rather than scanning wedges to vary the dispersion as in standard d-scan, the pulse to be measured experiences a spatially varying amount of dispersion in a Littrow prism. The resulting beam is then imaged into a second-harmonic generation crystal and an imaging spectrometer is used to measure the two-dimensional trace, which is analyzed using the d-scan retrieval algorithm. We compare the single-shot implementation with the standard d-scan for the measurement of sub-3.5-fs pulses from a hollow core fiber pulse compressor. We show that the retrieval algorithm used to extract amplitude and phase of the pulse provides comparable results, proving the validity of the new single-shot implementation down to near single-cycle durations.Comment: 6 pages, 4 figure

A possible origin of superconducting currents in cosmic strings

The scattering and capture of right-handed neutrinos by an Abelian cosmic string in the SO(10) grand unification model are considered. The scattering cross-section of neutrinos per unit length due to the interaction with the gauge and Higgs fields of the string is much larger in its scaling regime than in the friction one because of the larger infrared cutoff of the former.The probability of capture in a zero mode of the string accompanied by the emission of a gauge or Higgs boson shows a resonant peak for neutrino momentum of the order of its mass. Considering the decrease of number of strings per unit comoving volume in the scaling epoch the cosmological consequences of the superconducting strings formed in this regime will be much smaller than those which could be produced already in the friction one.Comment: 14 pages Latex, 4 figues/ep

Reguladores de crecimiento y sustratos naturales para la aclimatación de vitro-plántulas de piña ananas comosus (l.) merr.

Con el propósito de obtener tecnologías para la etapa de adaptación de plántulas de piña, mediante el cultivo de tejidos, se experimentaron los sustratos arena amarilla de río, suelo natural y escoria de carbón, simultáneamente con las auxinas: AIA, AIB y ANA en concentraciones de 0,500, 1.000 y 1.500 ppm. Se registraron los parámetros vegetales número de raíces, longitud de la raíz y el peso seco de la raíz. En general ypara todo el ensayo, el sustrato arena amarilla de río fue el de mejor resultado, los otros dos manifestaron respuestas, generalmente, bajas y sin una tendencia clara. La hormona que mejor desempeño tuvo, cuando se combinó con el sustrato arena amarilla de río, fue la AIB, en concentraciones de 1000 y 1500 ppm.The aclimatizacion stage is the critical step during the development of tissue cultures in crops. It was evaluated the response of vitro-plants from pineapple Ananas comosus (L.) Merr., to the applications of the hormones: AlA, AIB and ANA in dos es 0-500-1000 and 1500 ppm at the medium: yellow river sand, natural soil and charcoal-scoria. The number of roots, root length and dry weigh root were recorded in the vitro-plants. In general, the yellow river sand was the medium that showed the best results. The natural soil and the charcoal - scoria had low response without a clear tendency. The AIB hormone presented a very good behaviour with the combination yellow river sand at 1000 and 1500 ppm dose

The effect of three-dimensional visualisation on performance in endoscopic sinus surgery:A clinical training study using surgical navigation for movement analysis in a randomised crossover design

Objectives: Endoscopic imaging techniques and endoscopic endonasal surgery (EES) expertise have evolved rapidly. Only few studies have assessed the effect of three-dimensional (3D) endoscopy on endoscopic sinus surgery (ESS). The present study aimed to objectively and subjectively assess the additional value of 3D high-definition (HD) endoscopy in ESS. Design: A randomized crossover study of endoscopic surgery performance, using five ESS tasks of varying complexity, performed on Thiel embalmed human specimens. Setting: Simulated surgical environment. Participants: Thirty participants, inexperienced in ESS. Main outcome measures: Performance was assessed using video imaging, surgical navigation and questionnaires. Main outcome measures were as follows: efficiency (defined by time to task completion), distance covered inside the nose, average velocity towards target, accuracy (measured by error rate), and subjective assessment of endoscope characteristics. Results: During ESS tasks, both efficiency and accuracy did not differ significantly between 2D HD and 3D HD endoscopy. Subjectively, imaging characteristics of the 3D HD endoscope were rated significantly better. Conclusions: ESS performance of inexperienced participants was not significantly improved by the use of 3D HD endoscopy during ESS tasks, although imaging characteristics of the 3D HD endoscope were rated significantly better. Surgical field characteristics and surgical techniques are likely to influence any additional value of 3D HD endoscopy

Atg21p is essential for macropexophagy and microautophagy in the yeast Hansenula polymorpha

AbstractATG genes are required for autophagy-related processes that transport proteins/organelles destined for proteolytic degradation to the vacuole. Here, we describe the identification and characterisation of the Hansenula polymorpha ATG21 gene. Its gene product Hp-Atg21p, fused to eGFP, had a dual location in the cytosol and in peri-vacuolar dots. We demonstrate that Hp-Atg21p is essential for two separate modes of peroxisome degradation, namely glucose-induced macropexophagy and nitrogen limitation-induced microautophagy. In atg21 cells subjected to macropexophagy conditions, sequestration of peroxisomes tagged for degradation is initiated but fails to complete

The Spiderweb galaxy: a forming massive cluster galaxy at z~2

We present a deep image of the radio galaxy MRC 1138-262 taken with the Hubble Space Telescope (HST) at a redshift of z = 2.2. The galaxy is known to have properties of a cD galaxy progenitor and be surrounded by a 3 Mpc-sized structure, identified with a protocluster. The morphology shown on the new deep HST/ACS image is reminiscent of a spider's web. More than 10 individual clumpy features are observed, apparently star-forming satellite galaxies in the process of merging with the progenitor of a dominant cluster galaxy 11 Gyr ago. There is an extended emission component, implying that star formation was occurring over a 50 times 40 kpc region at a rate of more than 100 M_sun/yr. A striking feature of the newly named ``Spiderweb galaxy'' is the presence of several faint linear galaxies within the merging structure. The dense environments and fast galaxy motions at the centres of protoclusters may stimulate the formation of these structures, which dominate the faint resolved galaxy populations in the Hubble Ultra Deep Field. The new image provides a unique testbed for simulations of forming dominant cluster galaxies.Comment: 5 pages, 2 figures (reduced to grayscale); ApJ Letter

Different susceptibility of osteosarcoma cell lines and primary cells to treatment with oncolytic adenovirus and doxorubicin or cisplatin

Despite improvements in treatment regimens for osteosarcoma (OS) patients, survival rate has not increased over the last two decades. New treatment modalities are therefore warranted. Preclinical results with conditionally replicative adenoviruses (CRAds) to treat OS are promising. One type of CRAd that was effective against OS cells is Ad5-Δ24RGD. In other types of cancer, CRAds have been shown to interact synergistically with chemotherapeutic agents. Chemotherapy for OS often includes doxorubicin and cisplatin. Therefore, we explored combination treatment of OS cell lines and primary OS cell cultures with Ad5-Δ24RGD and doxorubicin or cisplatin. On OS cell lines, combination treatment was additive to synergistic. Surprisingly, however, on seven of eight primary OS samples no such combination effects were observed. In contrast, in many cases chemotherapy even inhibited CRAd-mediated cell killing. The inhibitory effect of doxorubicin on Ad5-Δ24RGD in primary OS cells appeared to correlate with slow cell growth rate; reduced viral replication and absence of chemotherapy-induced G2 cell cycle arrest. Our results point to the possibility that, at least for OS, virotherapy and chemotherapy should best not be performed simultaneously. In general, our work underscores the importance of testing new genetic anticancer agents and treatment regimens on primary cancer specimens