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The nucleus of the PN Lo4 is very hot and H-deficient and may be classified as a PG 1159 star (Werner 1992). Besides K 1–16, it is the second known pulsating central star. New spectra were taken between May 1991 and Febr. 1992. Within 18 days we witnessed a rapid decline of an emission line phase, which has begun less than 7 months ago. During this time Lo4 has changed its spectral type from PG 1159 to early WC (WC2 or WC3) and back to PG 1159. This phenomenon has never been observed before in hot post-AGB stars. The event is interpreted as an intrinsic phenomenon. Because of the short time scales, the variations are probably confined to the outermost stellar layers. It is known that the pulsation driving zones are close to the stellar surface and we speculate about a causal relation between enhanced mass-loss and possible variations in the pulsation behaviour. Spectral analysis was performed using NLTE model codes for spherically expanding atmospheres (Hamann et al. 1991) to analyze the WC-type spectrum and for plane-parallel static atmospheres (Werner 1992) to analyze the PG 1159 type spectrum. We find Teff=120kK and log g=5.5 during the PG 1159 phase. For the WC phase we obtain the same Teff and the mass-loss rate log (·/(M⊙/yr))=−7.3. The element abundances are typical for PG 1159 stars (He:C:O=46:43:ll, by mass) and v∞=:4000 km/s. More details can be found in Werner et al. (1992).
The compact radio and near-infrared (NIR) source Sagittarius A* has been observed in the context of two NIR triggered global VLT and VLBA campaigns at 43 GHz (7 mm) on May 16-18 2012 and October 4 2014. While on October 4 2014 Sgr A* remained in a quiescent state, a NIR flare on May 17 2012 is accompanied by an increase in flux density of 0.22 Jy at 7 mm delayed by 4.5±0.5 h. Additionally, Sgr A* seems to develop a weak secondary radio off-core component of 0.02 Jy at a position angle of 140° and an angular distance of 1.5 mas shortly before the peak of the flare. This spatial extension and the time delay are in the range of expected values for events casually connected by adiabatic expansion.
Time scales for post-AGB stellar evolution are still unclear. In order to study them it is useful to look for old PNe and compare nebula expansion and stellar evolutionary ages. We have selected very hot members from different white dwarf sub-classes. Many of them are objects recently discovered in the Hamburg-Schmidt Survey (Hagen et al. 1995). The sample includes three peculiar objects whose spectra show signatures of an extremely hot wind (≈ 106 K), namely absorption lines of ultra-high ionized metals, e.g. O VIII (Werner et al. 1995). A complete list is given in the table below. The search was performed by direct Hα narrow band imaging using a wide angle (20′ × 20′) CCD camera (WWFPP) attached to the Calar Alto 1.23m telescope (28.9.-3.10.1995).
Very hot central stars (CSPN) of highly excited planetary nebulae (PN) display directly the formation of white dwarfs. Only a few of these CSPN have been analyzed so far due to their low brightness and thus, the interpretation of their evolutionary status is hampered by statistical incompleteness. In the last decade many spectral analyses of very hot post-AGB stars by means of state-of-the-art NLTE model atmospheres have been performed (e.g. Rauch et al. 1996; Werner & Rauch 1994; Rauch & Werner 1995) and our picture of post-AGB evolution has been improved.
We present the results of a recent spectroscopic investigation of the cool DO white dwarf HD 149499 B in the EUV and FUV ranges. Observations were performed with the spectrograph of the EUVE satellite and the Berkeley EUV/FUV spectrometer of the ORFEUS space experiment. The analysis of the ORFEUS spectrum, performed with a grid of LTE model atmospheres, yielded the basic parameters Teff = 49500 ± 500 K and log g = 7.97 ± 0.08. This result is confirmed by the EUVE spectra. The photospheric hydrogen Lyman lines in the FUV spectrum indicate the presence of hydrogen: log nH/nHe = −0.65 ± 0.12. The implications of this finding for the spectral evolution of white dwarfs are discussed. A check of the LTE assumption was performed by a comparison with NLTE atmospheres calculated for appropriate parameters. The interstellar hydrogen column towards the HD 149499 system amounts to NH = (7 ± 2) · 1018 cm−2.
The eruptive variable V838 Mon was discovered on Jan 6, 2002. Due to a subsequent phase of almost constant brightness and a spectral appearance which is unlike classical novae, speculations have been made about its nature. Either it was a very peculiar, slow nova defining a new class, an eruptive event in an evolved star as in the case of Sakurai’s Object but in a much earlier phase, or something completely different.
A fast moving infrared excess source (G2) which is widely interpreted as a core-less gas and dust cloud approaches Sagittarius A* (Sgr A*) on a presumably elliptical orbit. VLT Ks-band and Keck K′-band data result in clear continuum identifications and proper motions of this ∼19m Dusty S-cluster Object (DSO). In 2002-2007 it is confused with the star S63, but free of confusion again since 2007. Its near-infrared (NIR) colors and a comparison to other sources in the field speak in favor of the DSO being an IR excess star with photospheric continuum emission at 2 microns than a core-less gas and dust cloud. We also find very compact L′-band emission (<0.1″) contrasted by the reported extended (0.03″ up to ∼0.2″ for the tail) Brγ emission. The presence of a star will change the expected accretion phenomena, since a stellar Roche lobe may retain a fraction of the material during and after the peri-bothron passage.
Understanding the interaction of group V impurities with intrinsic defects in ZnO is important for developing p-type material. We have studied N-doped ZnO thin films and N-doped bulk ZnO crystals, with positron annihilation spectroscopy, in contrast to earlier studies that have concentrated on N-implanted ZnO crystals. We show that the introduction of N impurities into ZnO, irrespective of whether it is done during the growth of thin films or bulk crystals or through implantation and subsequent thermal treatments, leads to the formation of stable vacancy clusters and negative ion-type defects. Interestingly, the stability of these vacancy clusters is found almost exclusively for N introduction, whereas single Zn vacancy defects or easily removable vacancy clusters are more typically found for ZnO doped with other impurities.
Neuroimaging research has demonstrated medial prefrontal cortex (mPFC) hyporesponsivity and amygdala hyperresponsivity to trauma-related or emotional stimuli in post-traumatic stress disorder (PTSD). Relatively few studies have examined brain responses to the recollection of stressful, but trauma-unrelated, personal events in PTSD. In the current study, we sought to determine whether regional cerebral blood flow (rCBF) abnormalities in mPFC and amygdala in PTSD could be observed during the recollection of trauma-unrelated stressful personal events.
Participants were 35 right-handed male combat veterans (MCVs) and female nurse veterans (FNVs) who served in Vietnam: 17 (seven male, 10 female) with current military-related PTSD and 18 (nine male, nine female) with no current or lifetime PTSD. We used positron emission tomography (PET) and script-driven imagery to study rCBF during the recollection of trauma-unrelated stressful versus neutral and traumatic events.
Voxelwise tests revealed significant between-group differences for the trauma-unrelated stressful versus neutral comparison in mPFC, specifically in the anterior cingulate cortex (ACC). Functional region of interest (ROI) analyses demonstrated that this interaction in mPFC represented greater rCBF decreases in the PTSD group during trauma-unrelated stressful imagery relative to neutral imagery compared to the non-PTSD group. No differential amygdala activation was observed between groups or in either group separately.
Veterans with PTSD, compared to those without PTSD, exhibited decreased rCBF in mPFC during mental imagery of trauma-unrelated stressful personal experiences. Functional neuroanatomical models of PTSD must account for diminished mPFC responses that extend to emotional stimuli, including stressful personal experiences that are not directly related to PTSD.
Defects introduced into single crystals of Al,Cu, and Fe by low temperature fast neutron irradiation were examined by diffuse scattering of X-rays. Structure and correlations of interstitials and vacancies were investigated after irradiation and during annealing. The primary defect structure is characterized by the correlation of defects in defect cascades. Size distributions for the arrangement of interstitials and vacancies were obtained. The evolution of the damage structure during recovery was followed and found to depend on the primary damage state. In Al we find large and dilute cascades with a mean radius of R-90Å, whereas in Cu small and dense cascades with R-20Å are produced. During recovery in Cu dislocation loops of interstitial and vacancy type are formed. In Al agglomeration of interstitials does not lead to loop formation. In Fe rather dilute cascades with R=60Å are observed. Here only small agglomerates of interstitials evolve during recovery in stages I and III.
Highly refractive amorphous TiO2 and Ta2O5 films with thicknesses between 270 and 514 nm were deposited on fused silica glass substrates by reactive evaporation and reactive ion plating. Density, hardness, and stiffness were investigated as a function of deposition process. The films were examined using Rutherford backscattering spectroscopy and were found to have densities between 72 and 100% of those of the corresponding bulk oxides. Nanoindentation studies indicated a strong correlation between density and both hardness and elastic stiffness of the oxide film materials. Hardness and modulus both varied by more than 40% over this density range.
We present results of a project aimed at establishing a set of 12 spectro-photometric standards over a wide wavelength range from 320 to 2500 nm. Currently no such set of standard stars covering the near-IR is available. Our strategy is to extend the useful range of existing well-established optical flux standards (Oke 1990, Hamuy et al. 1992, 1994) into the near-IR by means of integral field spectroscopy with SINFONI at the VLT combined with state-of-the-art white dwarf stellar atmospheric models (TMAP, Holberg et al. 2008). As a solid reference, we use two primary HST standard white dwarfs GD71 and GD153 and one HST secondary standard BD+17 4708. The data were collected through an ESO “Observatory Programme” over ~40 nights between February 2007 and September 2008.
Reducing herbicide rates can reduce production costs and the potential for carryover injury in subsequent crops, but may also compromise residual weed control. When used at the highest recommended rates (0.35 kg ai/ha), fomesafen may cause carryover injury on sweet corn. One of the most valuable attributes of fomesafen use in snap and dry beans is control of common ragweed. Field experiments were conducted in 1999, 2000, and 2002 to investigate both the residual ragweed control from fomesafen at 0.09, 0.18, and 0.36 kg ai/ha and the potential for a second application to extend the duration of residual control, while reducing the total amount applied per season. Results were significantly affected by weather conditions. In a very wet year (2000), with the greatest ragweed pressure, a single application of fomesafen at 0.20 kg/ha was predicted to provide at least 90% control of ragweed throughout snap and dry bean seasons. In the driest year (1999), 0.09 kg ai/ha provided greater than 90% control for the same period. Regardless of whether a single or double application was made, the total amount of fomesafen required per season was less than the manufacturer's recommended rate. Compared with making a single application, two low-rate applications did not reduce the total fomesafen rate required per season. To help insure at least 90% control of ragweed throughout the snap and dry bean seasons a grower should apply 0.20 kg ai/ha early in the season. Lower rates may be used, but in wet seasons, a second application may be needed to prevent yield loss or interference of ragweed with mechanical harvesting.
Acupuncture has been claimed to be associated with activation of the endogenous antinociceptive system. The analgesic effects of acupuncture have been ascribed to β-endorphin interacting with opioid receptors. However, firstly, the release of β-endorphin into the blood has been proven to be induced by stress, i.e. under dysphoric conditions, and, secondly, if released under stress, β-endorphin has been shown not to be analgesic. Our aim was to test whether β-endorphin immunoreactive material is released into the cardiovascular compartment during acupuncture comparing the most frequently used types of acupuncture with standard pain treatment under apparently low stress conditions.
This prospective study included 15 male patients suffering from chronic low back pain. β-Endorphin immunoreactive material and cortisol were measured in the plasma of patients who underwent, in randomorder, therapy according to a standard pain treatment, traditional Chinese acupuncture, sham acupuncture, electro acupuncture and electro acupuncture at non-acupuncture points before, at and after the treatment. Statistical analysis was performed using two-way ANOVA with repeated measures.
A decrease in plasma cortisol concentration measured over the five treatment protocols was highly significant (P < 0.001). The β-endorphin immunoreactive material concentrations in plasma were minimal at all times and in all treatment conditions. The influence of treatments by various acupuncture procedures on cortisol and β-endorphin immunoreactive material plasma concentrations over the three time points was not significantly different.
β-endorphin immunoreactive material in blood is not released by any type of acupuncture as tested under low stress conditions.
The manufacturer's recommended rate for fomesafen in snap beans, dry beans, and soybeans may cause carryover injury in sweet corn. A field experiment, a survey, and multiple greenhouse experiments were conducted to (1) estimate the fomesafen residue concentrations in the soil that might result from use of lower than registered rates, (2) estimate fomesafen residue concentrations in growers' fields and evaluate grower practices for their effects on carryover potential, and (3) investigate the effects of soil type and sweet corn variety on the potential for fomesafen to cause injury to sweet corn. Results of the dissipation study predicted average soil concentrations to be approximately 0.019 mg fomesafen/kg soil at the start of the sweet corn planting season. Half-life values ranged between 28 and 66 d, with an average of 50 d. Residues in grower fields were slightly less than those found in the dissipation study. Injury from fomesafen varied significantly by sweet corn variety and by soil type. Sweet corn grown in soils with high organic matter and low pH were most susceptible to injury from fomesafen. At high rates of fomesafen (0.12 mg/kg), reductions in dry weight of sweet corn varieties ranged from 5 to 60%. At rates of fomesafen slightly higher than those detected in field soils at the time of sweet corn planting (0.03 mg/kg), dry weight either increased slightly (variety trial) or decreased by 6 to 12% (soil-effect trial) depending on soil type. The risk of sweet corn yield losses because of fomesafen carryover appear relatively low. Growers can reduce the risk of carryover injury by planting tolerant varieties in fields where fomesafen was applied the preceding year.
Background. There is evidence that individuals with bipolar disorder exhibit neuropsychological impairments not only during episodes of depression or mania but also when they are euthymic. One of the most consistently reported cognitive problems in euthymic individuals with bipolar disorder is impairment in episodic memory. Learning and memory depend on individuals' ability to organize information during learning. A recent study by our group showed that verbal episodic memory impairments in euthymic patients with bipolar I disorder (BP-I) are mediated by difficulties in organizing verbal information appropriately during learning. The purpose of the present study was to determine whether memory impairments in euthymic individuals with BP-I extend to non-verbal memory and whether non-verbal memory impairments are mediated by difficulties in organizing non-verbal information during encoding.
Method. Study participants were 25 euthymic, remitted individuals with BP-I and 25 age, gender and education matched control participants. Participants completed the Rey-Osterrieth Complex Figure Test (RCFT), a well-established measure of non-verbal memory that enables assessment of organization during learning.
Results. Compared to control participants, BP-I participants showed impaired performance on the RCFT immediate recall. They also relied less on organizational strategies during encoding. Multiple regression modeling indicated that group differences between control and BP-I participants in long-delayed free recall did not remain statistically significant when effects of lower organization were partialled out.
Conclusions. Non-verbal memory problems in individuals with bipolar disorder, while euthymic, are mediated by poor use of non-verbal organization strategies during encoding, but do not appear to reflect deficits in retention of information.
The efficacies of bentazon and fomesafen in controlling annual weeds in dry and edible pod beans in New York State were investigated in greenhouse and field experiments. Dose responses to bentazon and fomesafen were studied for four weed species (ragweed, velvetleaf, eastern black nightshade, and hairy nightshade) under greenhouse conditions. Herbicides were applied at cotyledon to two-, two- to four-, and four- to six–true leaf stages, both with and without a crop oil concentrate (bentazon) or a nonionic surfactant (fomesafen). Field studies were conducted for 2 yr for all weed species except eastern black nightshade, for which no adequate field populations were found. Field studies confirmed greenhouse results, indicating that weed control could be improved by the use of an adjuvant, but there were exceptions. In general, adjuvant usage improved the efficacy of fomesafen more than it did with bentazon. The minimum rates of herbicide required for effective and consistent control was dependent on the particular combination of weed species, herbicide and its rate of application, growth stage at which the application was made, and adjuvant usage.