Interannual differences in the regressions of the polar caps of Mars

Analyses of the behavior of the Martian polar caps in the recent spacecraft and ground based observations seem to reveal the existence of year to year variations on their regressions. In order to investigate the interannual differences in the regressions of the polar caps, the earlier data by Fischbacher et al., were reexamined, which were based on the measurements of the large number of high quality photographic plates and films collected from 1905 to 1965 at the Lowell Observatory. The results are reported and discussed

Non-Thermal Continuum toward SGRB2(N-LMH)

An analysis of continuum antenna temperatures observed in the Green Bank Telescope (GBT) spectrometer bandpasses is presented for observations toward SgrB2(N-LMH). Since 2004, we have identified four new prebiotic molecules toward this source by means of rotational transitions between low energy levels; concurrently, we have observed significant continuum in the GBT spectrometer bandpasses centered at 85 different frequencies in the range of 1 to 48 GHz. The continuum heavily influences the molecular spectral features since we have observed far more absorption lines than emission lines for each of these new molecular species. Hence, it is important to understand the nature, distribution, and intensity of the underlying continuum in the GBT bandpasses for the purposes of radiative transfer, i.e. the means by which reliable molecular abundances are estimated. We find that the GBT spectrometer bandpass continuum is consistent with optically-thin, non thermal (synchrotron) emission with a flux density spectral index of -0.7 and a Gaussian source size of ~143" at 1 GHz that decreases with increasing frequency as nu^(-0.52). Some support for this model is provided by high frequency Very Large Array (VLA) observations of SgrB2.Comment: Accepted for Publication in the Astrophysical Journal Letter

Exact Scale Invariance of Composite-Field Coupling Constants

We show that the coupling constant of a quantum-induced composite field is scale invariant due to its compositeness condition. It is first demonstrated in next-to-leading order in 1/N in typical models, and then we argue that it holds exactly.Comment: 4 page

Uma revisão da literatura sobre fatores que apoiam a mudança organizacional voltada para o Lean Thinking: A review of the literature on factors that support organization change focused on Lean Thinking

Este artigo tem como objetivo apresentar uma revisão da literatura sobre os fatores e estados de mudança que precisam ser observados para que a mudança organizacional para o Lean Thinking (LT) seja duradoura e incorporada à cultura empresarial. A contribuição desta pesquisa é apresentar, num único material, uma visão estruturada sobre esses fatores, para que pesquisadores e profissionais possam minimizar as possibilidades de retorno ao sistema organizacional anterior à mudanças. Entende-se que não há prescrição universal de fatores, pois estes agem/interagem dentro de contextos organizacionais e culturais característicos de cada empresa, porém, os mecanismos de influência podem ser analisados e utilizados em processos de implementação ou estabilização de organizações em transição para o LT

Estruturas organizacionais de empresas digitais: estudo de caso uma empresa ágil no ramo de seguros: Digital organization´s structure: a case of insurance agile company

As empresas digitais vêm transformando a percepção dos negócios atuais desde sua essência, até a forma de sua organização, cargos e atividades. Hoje com a tecnologia e informação como sendo protagonista de setores tradicionais, a busca pelo atendimento as necessidades dos clientes se tornam cada dia mais importante e as empresas procuram cada vez mais se tornarem ágeis e eficientes. As “insurtechs” são empresas digitais na área de seguros e vem transformando, em muitos sentidos, o ambiente tradicional de seguros em que as empresas estavam acostumadas e estagnadas. O presente trabalho vem colaborar com uma visão de organização ágil dentro do contexto das empresas de seguro, trazendo um estudo de caso da estrutura organizacional que se utiliza do ágil com foco no cliente e que busca esse diferencial para concorrer com as empresas tradicionais em um mercado ainda bastante tradicional

Formulação e implementação de estratégias aplicadas as decisões em simuladores de jogos de empresas: uma comparação com jogos gerais da teoria dos jogos -

O processo de aprendizagem cada vez mais se vale de recursos lúdicos para produzir o conhecimento dos conceitos ou técnicas do assunto em estudo. Esses recursos, no contexto atual, podem ser por meio de arquivos de áudio e vídeo ou simuladores que permitam a representação de uma realidade de mercado com o máximo de variáveis possíveis, cujas variáveis podem ser conhecidas pelo participante no seu todo ou em parte. Nesse estudo o recurso lúdico para produzir o conhecimento no processo de aprendizagem é um simulador organizacional que representa o modelo de ambiente organizacional que uma empresa se depara no seu dia a dia. Embora sejam formatados mediante programação e com certo número de variáveis controláveis em sua ação, constituem importante ferramenta lúdica no processo de aprendizagem de um gestor. A formulação de estratégias por parte do participante leva sempre em conta a relação de sucesso do evento, ou seja, na tomada de decisão para a formulação de preço, por exemplo, a estratégia adotada e sua implementação são consideradas boas, pois o resultado esperado é a melhoria do posicionamento da empresa no mercado, o aumento de sua lucratividade e reconhecimento da marca. Comparando com o jogo de soma zero da teoria dos jogos a estratégia é boa quando produz o melhor resultado para o evento, isto é a vitória de um dos participantes

Synchrotron emission from the T Tauri binary system V773 Tau A

The pre-main sequence binary system V773 Tau A shows remarkable flaring activity around periastron passage. Here, we present the observation of such a flare at a wavelength of 3 mm (90 GHz) performed with the Plateau de Bure Interferometer. We examine different possible causes for the energy losses responsible for the e-folding time of 2.3 hours of that flare. We exclude synchrotron, collisional, and inverse Compton losses because they are not consistent with observational constraints, and we propose that the fading of the emission is due to the leakage of electrons themselves at each reflection between the two mirror points of the magnetic structure partially trapping them. The magnetic structure compatible with both our leakage model and previous observations is that of a helmet streamer that, as in the solar case, can occur at the top of the X-ray-emitting, stellar-sized coronal loops of one of the stars. The streamer may extend up to 20 R and interact with the corona of the other star at periastron passage, causing recurring flares. The inferred magnetic field strength at the two mirror points of the helmet streamer is in the range 0.12 - 125 G, and the corresponding Lorentz factor, gamma, of the partially trapped electrons is in the range 20 < gamma < 632. We therefore rule out that the emission could be of gyro-synchrotron nature: the derived high Lorentz factor proves that the nature of the emission at 90 GHz from this pre-main binary system is synchrotron radiation. Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).Comment: 8 pages, 5 figures, A&A in pres

Sub-terahertz, microwaves and high energy emissions during the December 6, 2006 flare, at 18:40 UT

The presence of a solar burst spectral component with flux density increasing with frequency in the sub-terahertz range, spectrally separated from the well-known microwave spectral component, bring new possibilities to explore the flaring physical processes, both observational and theoretical. The solar event of 6 December 2006, starting at about 18:30 UT, exhibited a particularly well-defined double spectral structure, with the sub-THz spectral component detected at 212 and 405 GHz by SST and microwaves (1-18 GHz) observed by the Owens Valley Solar Array (OVSA). Emissions obtained by instruments in satellites are discussed with emphasis to ultra-violet (UV) obtained by the Transition Region And Coronal Explorer (TRACE), soft X-rays from the Geostationary Operational Environmental Satellites (GOES) and X- and gamma-rays from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The sub-THz impulsive component had its closer temporal counterpart only in the higher energy X- and gamma-rays ranges. The spatial positions of the centers of emission at 212 GHz for the first flux enhancement were clearly displaced by more than one arc-minute from positions at the following phases. The observed sub-THz fluxes and burst source plasma parameters were found difficult to be reconciled to a purely thermal emission component. We discuss possible mechanisms to explain the double spectral components at microwaves and in the THz ranges.Comment: Accepted version for publication in Solar Physic

The Formaldehyde Masers in NGC 7538 and G29.96-0.02: VLBA, MERLIN, and VLA Observations

The 6 cm formaldehyde (H2CO) maser sources in the compact HII regions NGC 7538-IRS1 and G29.96-0.02 have been imaged at high resolution (beams < 50 mas). Using the VLBA and MERLIN, we find the angular sizes of the NGC 7538 masers to be ~10 mas (30 AU) corresponding to brightness temperatures ~10^8 K. The angular sizes of the G29.96-0.02 masers are ~20 mas (130 AU) corresponding to brightness temperatures ~10^7 K. Using the VLA, we detect 2 cm formaldehyde absorption from the maser regions. We detect no emission in the 2 cm line, indicating the lack of a 2 cm maser and placing limits on the 6 cm excitation process. We find that both NGC 7538 maser components show an increase in intensity on 5-10 year timescales while the G29.96-0.02 masers show no variability over 2 years. A search for polarization provides 3-sigma upper limits of 1% circularly polarized and 10% linearly polarized emission in NGC 7538 and of 15% circularly polarized emission in G29.96-0.02. A pronounced velocity gradient of 28 km/s/arcsecond (1900 km/s/pc) is detected in the NGC 7538 maser gas.Comment: accepted to ApJ, 15 figures, 11 table

A near-infrared study of the NGC 7538 star forming region

We present sub-arcsecond (FWHM ~ 0".7), NIR JHKs-band images and a high sensitivity radio continuum image at 1280 MHz, using SIRIUS on UH 88-inch telescope and GMRT. The NIR survey covers an area of ~ 24 arcmin^2 with 10-sigma limiting mags of ~ 19.5, 18.4, and 17.3 in J, H, and Ks-band, respectively. Our NIR images are deeper than any JHK surveys to date for the larger area of NGC 7538 star forming region. We construct JHK CC and J-H/J and H-K/K CM diagrams to identify YSOs and to estimate their masses. Based on these CC and CM diagrams, we identified a rich population of YSOs (Class I and Class II), associated with the NGC 7538 region. A large number of red sources (H-K > 2) have also been detected around NGC 7538. We argue that these red stars are most probably PMS stars with intrinsic color excesses. Most of YSOs in NGC 7538 are arranged from the N-W toward S-E regions, forming a sequence in age: the diffuse H II region (N-W, oldest: where most of the Class II and Class I sources are detected); the compact IR core (center); and the regions with the extensive IR reflection nebula and a cluster of red young stars (S-E and S). We find that the slope of the KLF of NGC 7538 is lower than the typical values reported for the young embedded clusters, although equally low values have also been reported in the W3 Main star forming region. From the slope of the KLF and the analysis by Megeath et al. (1996), we infer that the embedded stellar population is comprised of YSOs with an age of ~ 1 Myr. Based on the comparison between models of PMS stars with the observed CM diagram we find that the stellar population in NGC 7538 is primarily composed of low mass PMS stars similar to those observed in the W3 Main star forming region.Comment: 36 pages, 13 figures in JPEG format. Accepted for the publication in ApJ. Report is also available at : http://www.tifr.res.in/~ojha/NGC7538.htm