One of the long-term goals of exoplanet science is the atmospheric characterization of dozens of small exoplanets in order to understand their diversity and search for habitable worlds and potential ...biosignatures. Achieving this goal requires a space mission of sufficient scale. We seek to quantify the exoplanet detection performance of a space-based mid-infrared nulling interferometer that measures the thermal emission of exoplanets. For this, we have developed an instrument simulator that considers all major astrophysical noise sources and coupled it with Monte Carlo simulations of a synthetic exoplanet population around main-sequence stars within 20 pc. This allows us to quantify the number (and types) of exoplanets that our mission concept could detect over a certain time period. Two different scenarios to distribute the observing time among the stellar targets are discussed and different apertures sizes and wavelength ranges are considered. Within a 2.5-year initial search phase, an interferometer consisting of four 2 m apertures with a total instrument throughput of 5% covering a wavelength range between 4 and 18.5 \(\mu\)m could detect up to ~550 exoplanets with radii between 0.5 and 6 R\(_\oplus\) with an integrated SNR\(\ge\)7. At least ~160 of the detected exoplanets have radii \(\le\)1.5 R\(_\oplus\). Depending on the observing scenario, ~25-45 rocky exoplanets (objects with radii between 0.5 and 1.5 \(_{\oplus}\)) orbiting within the empirical habitable zone (eHZ) of their host stars are among the detections. With an aperture size of 3.5 m, the total number of detections can increase to up to ~770, including ~60-80 rocky, eHZ planets. With 1 m aperture size, the maximum detection yield is ~315 exoplanets, including \(\le\)20 rocky, eHZ planets. In terms of predicted detection yield, such a mission can compete with large single-aperture reflected light missions. (abridged)
Male Sprague-Dawley rats were partially hemitransected at the mesodiencephalic junction and treated with nicotine (nicotine hydrogen (+)-tartrate) using Alzet minipumps implanted subcutaneously. ...Nicotine was delivered for 2 weeks in a dose of 0.125 mg/kg/h resulting in a serum nicotine level of 50.0 +/- 5.1 ng/ml. Three other groups of rats were analyzed: hemitransected rats receiving saline treatment and sham-operated animals receiving nicotine and saline, respectively. The effects of hemitransection and nicotine rostrally as well as caudally to the lesion were evaluated with image analysis of tyrosine hydroxylase (TH)-immunoreactive (IR) nerve cell body and dendrite profiles in the rostral and caudal substantia nigra and of TH-IR nerve terminal profiles in the striatum. Adjacent sections were taken to Nissl staining. 3HNicotine binding in the midbrain and forebrain was studied by means of receptor autoradiography on partially hemitransected rats receiving no treatment. Catecholamine (CA) levels in the frontal cortex were measured using high-performance liquid chromatography (HPLC). Striatal dopamine (DA) function was analyzed studying apomorphine-induced (1.0 mg/kg) ipsilateral rotational behavior. The spontaneous behavior of the rats was evaluated with a hole board. Furthermore, body temperature and body weight were measured. The results demonstrated a lesion-induced disappearance of TH-IR cell body and dendrite profiles in the substantia nigra and of TH-IR nerve terminal profiles in the striatum. Similar findings were seen after Nissl staining. A significant counteraction of this disappearance was found in the nicotine-treated animals. On the lesioned animals a marked reduction of 3Hnicotine binding in the striatum and the substantia nigra was found. In the functional experiments an enhancement of the apomorphine-induced ipsilateral rotational behavior was demonstrated. The degree of rotation was positively correlated with the serum nicotine level. The study on spontaneous activity in the hole board showed a slower restoration of total activity in the hemitransected nicotine-treated rats. All these results are compatible with the hypothesis that the protective action of nicotine on the mesostriatal DA system may be due to a desensitization of excitatory nicotine cholinoceptors located on the nigral DA nerve cells, leading to a reduction of firing rate and reduced energy demands. Such an action of nicotine could be of importance for a possible anti-parkinsonian effect.
Recent observations of resolved cold debris disks at tens of au have revealed that gaps could be a common feature in these Kuiper belt analogues. Such gaps could be evidence for the presence of ...planets within the gaps or closer-in near the edges of the disk. We present SPHERE observations of HD 92945 and HD 107146, two systems with detected gaps. We constrained the mass of possible companions responsible for the gap to 1-2 M Jup for planets located inside the gap and to less than 5 M Jup for separations down to 20 au from the host star. These limits allow us to exclude some of the possible configurations of the planetary systems proposed to explain the shape of the disks around these two stars. In order to put tighter limits on the mass at very short separations from the star, where direct imaging data are less effective, we also combined our data with astrometric measurements from Hipparcos and Gaia and radial velocity measurements. We were able to limit the separation and the mass of the companion potentially responsible for the proper motion anomaly of HD 107146 to values of 2-7 au and 2-5 M Jup , respectively.
In contrast to other bacterial species, mycobacteria were thus far considered to contain groEL and groES genes that are present on separate loci on their chromosomes, Here, by screening a ...Mycobacterium leprae lambda gt11 expression library with serum from an Ethiopian lepromatous leprosy patient, two DNA clones were isolated that contain a groEL gene arranged in an operon with a groES gene. The complete DNA sequence of this groESL operon was determined. The predicted amino acid sequences of the GroES and GroEL proteins encoded by this operon are 85-90% and 59-61% homologous to the sequences from previously characterized mycobacterial GroES and GroEL proteins. Southern blotting analyses with M. leprae groES- and groEL-specific probes demonstrate that similar groESL homologous DNA is present in the genomes of other mycobacteria, including Mycobacterium tuberculosis. This strongly suggests that mycobacteria contain a groESL operon in addition to a separately arranged second groEL gene. Using five T-cell clones from two leprosy patients as probes, expression of the M. leprae GroES protein in Escherichia coli after heat shock was demonstrated. Four of these clones recognized the same M. leprae-specific GroES-derived peptide in a DR2-restricted fashion. No expression of the groEL gene from this operon was detected in E. coli after heat shock, as tested with a panel of T-cell clones and monoclonal antibodies reactive to previously described GroEL proteins of mycobacteria.
Sirius-like systems are wide binaries composed of a white dwarf (WD) and a companion of a spectral type earlier than M0. The WD progenitor evolves in isolation, but its wind during the AGB phase ...pollutes the companion surface and transfers some angular momentum. Within SHINE survey that uses SPHERE at the VLT, we acquired images of HD2133, HD114174, and CD-567708 and combined this data with high resolution spectra of the primaries, TESS, and literature data. We performed accurate abundance analyses for the MS. We found brighter J and K magnitudes for HD114174B than obtained previously and extended the photometry down to 0.95 micron. Our new data indicate a higher temperature and then shorter cooling age (5.57+/-0.02 Gyr) and larger mass (0.75+/-0.03 Mo) for this WD than previously assumed. This solved the discrepancy previously found with the age of the MS star. The two other WDs are less massive, indicating progenitors of ~1.3 Mo and 1.5-1.8 Mo for HD2133B and CD-56 7708B, respectively. We were able to derive constraints on the orbit for HD114174 and CD-56 7708. The composition of the MS stars agrees fairly well with expectations from pollution by the AGB progenitors of the WDs: HD2133A has a small enrichment of n-capture elements, which is as expected for pollution by an AGB star with a mass <1.5 Mo; CD-56 7708A is a previously unrecognized mild Ba-star, which is expected due to pollution by an AGB star with a mass in the range of 1.5-3.0 Mo; and HD114174 has a very moderate excess of n-capture elements, which is in agreement with the expectation for a massive AGB star to have a mass >3.0 Mo. On the other hand, none of these stars show the excesses of C that are expected to go along with those of n-capture elements. This might be related to the fact that these stars are at the edges of the mass range where we expect nucleosynthesis related to thermal pulses.
In recent decades, thousands of substellar companions have been discovered with both indirect and direct methods of detection. In this paper, we focus our attention on substellar companions detected ...with the direct imaging technique, with the primary goal of investigating their close surroundings and looking for additional companions and satellites, as well as disks and rings. Any such discovery would shed light on many unresolved questions, particularly with regard to their possible formation mechanisms. To reveal bound features of directly imaged companions we need to suppress the contribution from the source itself. Therefore, we developed a method based on the negative fake companion (NEGFC) technique that first estimates the position in the field of view (FoV) and the flux of the imaged companion, then subtracts a rescaled model point spread function (PSF) from the imaged companion. Next it performs techniques, such as angular differential imaging (ADI), to further remove quasi-static patterns of the star. We applied the method to the sample of substellar objects observed with SPHERE during the SHINE GTO survey. Among the 27 planets and brown dwarfs we analyzed, we detected a possible point source close to DH Tau B. This candidate companion was detected in four different SPHERE observations, with an estimated mass of \(\sim 1\) M\textsubscript{Jup}, and a mass ratio with respect to the brown dwarf of \(1/10\). This binary system, if confirmed, would be the first of its kind, opening up interesting questions for the formation mechanism, evolution, and frequency of such pairs. In order to address the latter, the residuals and contrasts reached for 25 companions in the sample of substellar objects observed with SPHERE were derived. If the DH Tau Bb companion is real, the binary fraction obtained is \(\sim 7\%\), which is in good agreement with the results obtained for field brown dwarfs.
Unusual orthodontic retreatment Janson, Guilherme; Janson, Marcos R.; Cruz, Karina Santana ...
American journal of orthodontics and dentofacial orthopedics,
04/2003, Letnik:
123, Številka:
4
Journal Article
Recenzirano
This case report describes the retreatment of a patient with a Class II Division 1 malocclusion; she had the same anteroposterior discrepancy after undergoing fixed appliance treatment with ...extraction of 4 first premolars. (Am J Orthod Dentofacial Orthop 2003;123:468-75)
