12,683 research outputs found
A NICMOS Direct Imaging Search for Giant Planets around the Single White Dwarfs in the Hyades
We report preliminary results from our search for massive giant planets (6-12
Jupiter masses) around the known seven single white dwarfs in the Hyades
cluster at sub-arcsec separations. At an age of 625 Myr, the white dwarfs had
progenitor masses of about 3 solar masses, and massive gaseous giant planets
should have formed in the massive circumstellar disks around these ex-Herbig A0
stars, probably at orbital separations similar or slightly larger than that of
Jupiter. Such planets would have survived the post-Main-Sequence mass loss of
the parent star and would have migrated outward adiabatically to a distance of
about 25 AU. At the distance of the Hyades (45 pc) this corresponds to an
angular separation of 0.5 arcsec. J and H magnitudes of these giants are in the
range of 20.5-23.3 mag, which can be resolved with NICMOS. The achieved
sensitivities and contrast ratios agree well with simulations. Preliminary
evaluation of the NICMOS data set did not reveal any evidence for neither
planetary mass companions with masses down to about 10 Jupiter masses nor brown
dwarfs around any of the seven white dwarfs for separations larger than 0.5
arcsec.Comment: 14th European Workshop on White Dwarf
Orbits and masses in the young triple system TWA 5
We aim to improve the orbital elements and determine the individual masses of
the components in the triple system TWA 5.
Five new relative astrometric positions in the H band were recorded with the
adaptive optics system at the Very Large Telescope (VLT). We combine them with
data from the literature and a measurement in the Ks band. We derive an
improved fit for the orbit of TWA 5Aa-b around each other. Furthermore, we use
the third component, TWA 5B, as an astrometric reference to determine the
motion of Aa and Ab around their center of mass and compute their mass ratio.
We find an orbital period of 6.03+/-0.01 years and a semi-major axis of
63.7+/-0.2 mas (3.2+/-0.1 AU). With the trigonometric distance of 50.1+/-1.8
pc, this yields a system mass of 0.9+/-0.1 Msun, where the error is dominated
by the error of the distance. The dynamical mass agrees with the system mass
predicted by a number of theoretical models if we assume that TWA5 is at the
young end of the age range of the TW Hydrae association.
We find a mass ratio of M_Ab / M_Aa = 1.3 +0.6/-0.4, where the less luminous
component Ab is more massive. This result is likely to be a consequence of the
large uncertainties due to the limited orbital coverage of the observations.Comment: 9 pages, 8 figures, accepted by Astronomy and Astrophysic
Dynamical stability analysis of the HD202206 system and constraints to the planetary orbits
Long-term precise Doppler measurements with the CORALIE spectrograph revealed
the presence of two massive companions to the solar-type star HD202206.
Although the three-body fit of the system is unstable, it was shown that a 5:1
mean motion resonance exists close to the best fit, where the system is stable.
We present here an extensive dynamical study of the HD202206 system aiming at
constraining the inclinations of the two known companions, from which we derive
possible ranges of value for the companion masses.
We study the long term stability of the system in a small neighborhood of the
best fit using Laskar's frequency map analysis. We also introduce a numerical
method based on frequency analysis to determine the center of libration mode
inside a mean motion resonance.
We find that acceptable coplanar configurations are limited to inclinations
to the line of sight between 30 and 90 degrees. This limits the masses of both
companions to roughly twice the minimum. Non coplanar configurations are
possible for a wide range of mutual inclinations from 0 to 90 degrees, although
configurations seem to be favored. We also confirm the
5:1 mean motion resonance to be most likely. In the coplanar edge-on case, we
provide a very good stable solution in the resonance, whose does not
differ significantly from the best fit. Using our method to determine the
center of libration, we further refine this solution to obtain an orbit with a
very low amplitude of libration, as we expect dissipative effects to have
dampened the libration.Comment: 14 pages, 18 figure
Characterization of a rare analphoid supernumerary marker chromosome in mosaic
Abstract publicado em: Chromosome Research. 2015;23(Suppl 1):67-8. doi:10.1007/s10577-015-9476-6Analphoid supernumerary marker chromosomes (SMCs) are a rare subclass of SMCs C-band-negative
and devoid of alpha-satellite DNA. These marker chromosomes cannot be identified unambiguously by conventional banding techniques alone being necessary to apply molecular cytogenetic methods in favour of a detailed characterization. In this work we report an analphoid SMC involving the terminal long arm of chromosome 7, in 9 years-old boy with several dysmorphic features and severe development delay.
Cytogenetic analysis revealed a mosaic karyotype with the presence of an extra SMC, de novo, in 20 %
of lymphocytes and 73 % of fibroblast cells. FISH analysis with alpha-satellite probes for all chromosomes, whole chromosome painting probe for chromosome 7, and D7S427 and TelVysion 7q probes, allowed
establishing the origin of the SMC as an analphoidmarker resulting of an invdup rearrangement of 7q36-qter region. Affimetrix CytoScan HD microarray analysis, redefined the SMC to arr[hg19] 7q35(143696249-159119707)×2~3, which correspond to a gain of 15.42 Mb and encloses 67 OMIM genes, 16 of which are associated to disease. This result, combined with detailed clinical description, will provide an important means for better genotype-phenotype correlation and a more suitable genetic counselling to the patient and his parents, despite the additional difficulty resulting from being a mosaic (expression varies in different tissues). Analphoid SMCs derived from chromosome 7 are very rare, with only three cases reported so far. With this case we hope contribute to a better understanding of this type of chromosome rearrangements which are difficult for genetic counselling
OnabotulinumtoxinA for hemicrania continua: open label experience in 9 patients
BACKGROUND:
Hemicrania continua is a strictly unilateral, continuous headache, typically mild to moderate in severity, with severe exacerbations commonly accompanied by cranial autonomic features and migrainous symptoms. It is exquisitely responsive to Indomethacin. However, some patients cannot tolerate treatment, often due to gastrointestinal side effects. Therapeutic alternatives are limited and controlled evidence lacking.
METHODS:
We present our experience of nine patients treated with OnabotulinumtoxinA for hemicrania continua. All patients were injected using the PREEMPT (Phase 3 REsearch Evaluating Migraine Prophylaxis Therapy) protocol for migraine.
RESULTS:
Five of nine patients demonstrated a 50% or more reduction in moderate to severe headache days with OnabotulinumtoxinA with a median reduction in moderate to severe headache days of 80%. Patient estimate of response was 80% or more in five subjects. The median and mean duration of response in the five responders was 11 and 12 weeks (range 6-20 weeks). Improvements were also seen in headache-associated disability
CONCLUSIONS:
OnabotulinumtoxinA adds a potential option to the limited therapeutic alternatives available in hemicrania continua
Access to General Practitioners during the second year of the COVID-19 pandemic in Portugal: a nationwide survey of doctors
BackgroundThe Portuguese National Health System (NHS) provides universal coverage and near-free health care, but the population has high out-of-pocket expenses and unmet care needs. This suggests impaired accessibility, a key dimension of primary care. The COVID-19 pandemic has further affected access to health care. Understanding General Practitioners' (GP) experiences during the pandemic is necessary to reconfigure post-pandemic service delivery and to plan for future emergencies. This study aimed to assess accessibility to GPs, from their perspective, evaluating determinants of accessibility during the second pandemic year in Portugal.MethodsAll GPs working in NHS Family Practices in continental Portugal were invited to participate in a survey in 2021. A structured online self-administered anonymous questionnaire was used. Accessibility was assessed through waiting times for consultations and remote contacts and provision of remote access. NHS standards were used to assess waiting times. Descriptive statistics were used to characterize the study sample. Associations between categorical variables were tested using the chi 2 statistic and the Student t-test was used to compare means of continuous variables.ResultsA total of 420 GPs were included (7% of the target population). Median weekly working hours was 49.0 h (interquartile range 42.0-56.8), although only 14% reported a contracted weekly schedule over 40 h. Access to in-person consultations and remote contacts was reported by most GPs to occur within NHS time standards. Younger GPs more often reported waiting times over these standards. Most GPs considered that they do not have enough time for non-urgent consultations or for remote contacts with patients.ConclusionsMost GPs reported compliance with standards for waiting times for most in-person consultations and remote contacts, but they do so at the expense of work overload. A persistent excess of regular and unpaid working hours by GPs needs confirmation. If unpaid overtime is necessary to meet the regular demands of work, then workload and specific allocated tasks warrant review. Future research should focus on younger GPs, as they seem vulnerable to restricted accessibility. GPs' preferences for more in-person care than was feasible during the pandemic must be considered when planning for the post-pandemic reconfiguration of service delivery
Financial constraint and foreign direct investment of SMEs: evidence from Portugal
This work aims to explore the financing constraints perceived by Portuguese small and medium-sized enterprises (SMEs) carrying out productive foreign direct investment (FDI). It relies on primary data, presenting an explorative empirical analysis. The results evidence a strong dependence on internal funds and give little support to market failures in financing FDI, as no remarkable differences were found in financing constraints between domestic and foreign investments, but this reluctance of Portuguese SMEs towards external financing does not match with a willingness to open the social capital to new shareholders. Portuguese entrepreneurs lack knowledge of alternative financing sources to relieve dependence on domestic funds to FDI. Banks and government could relevantly contribute in this field, we also recommend further financial literacy in Portguese SMEs. This work is limited by its sample and qualitative nature. Although there is abundant literature on the access to economic agents' financing, to this day this work is the first to focus on Portuguese SMEs analysing primary data, hence its originality. Reporting SMEs’ reluctance towards external financing, it can enhance external financers to best capture such clients.Restricción financiera e inversión extranjera directa de las PYME: evidencia de PortugalEste trabajo intenta explorar las limitaciones de financiación percibidas por las pequeñas y medianas empresas (PYMES) portuguesas que realizan inversiones directas extranjeras (IED) productivas. Se basa en datos primarios y presenta un análisis empÃrico exploratorio. Los resultados demuestran una fuerte dependencia de los fondos internos y ligero énfasis en las deficiencias del mercado en la financiación de la IED, no reportando diferencias notables en las limitaciones de financiación entre las inversiones nacionales y extranjeras, pero esta renuencia de las PYMES portuguesas a la financiación externa no se corresponde con la voluntad de abrir el capital social a nuevos accionistas. Los empresarios portugueses no conocen alternativas para aliviar la dependencia de los fondos nacionales a la IED. Los bancos y el gobierno podrÃan contribuir en este campo, también recomendamos una mayor alfabetización financiera en las PYMES portuguesas. Este trabajo está limitado por su muestra y su naturaleza cualitativa. Aunque existe abundante literatura sobre el acceso a la financiación de los agentes económicos, hasta el dÃa de hoy este trabajo es el primero que se centra en las PYMES portuguesas a través de datos primarios, de ahà su originalidad. Al informar sobre la reticencia de las PYMES a la financiación externa, puede mejorar la capacidad de los financiadores externos en captar esos clientes.
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