249 research outputs found
The Bark Beetles (Coleoptera: Scolytidae) of the Maltese Islands (Central Mediterranean)
The bark beetle fauna of the Maltese Islands is reviewed, based on
literature records and examination of collected material. A total of twenty-one species
have been recorded of which seventeen species represent new records from the Maltese
archipelago. These include Hylurgus micklitzi, Kissophagus hederae, Phloeosinus
thujae, Liparthrum mori, Scolytus amygdali, Scolytus rugulosus, Scolytus sulcifrons,
Pityogenes calcaratus, Orthotomicus erosus, Thamnurgus characiae, Coccotrypes
dactyliperda, Crypturgus cylindricollis, Crypturgus numidicus, Xyleborinus saxesenii,
Hypocryphalus scabricollis comb. nov., Hypothenemus eruditus and Hypothenemus
leprieuri. The earlier citation of Scolytus scolytus is incorrect and should refer to S.
sulcifrons whereas the citation of Cryphalus piceae is definitely incorrect due to the
absence of its host-plants in Malta. Additionally, two species, Xyleborus ferrugineus
and X. volvulus were collected alive on logs originating from Tropical Africa and
intended for the timber industry. So far, there were no local records of establishment
of these two species in Malta.peer-reviewe
Structural anomalies, spin transitions and charge disproportionation in LnCoO3
The diamagnetic-paramagnetic and insulator-metal transitions in LnCoO3
perovskites (Ln = La, Y, rare earths) are reinterpreted and modeled as a
two-level excitation process. In distinction to previous models, the present
approach can be characterized as a LS-HS-IS (low-high-intermediate spin)
scenario. The first level is the local excitation of HS Co3+ species in the LS
ground state. The second excitation is based on the interatomic electron
transfer between the LS/HS pairs, leading finally to a stabilization of the
metallic phase based on IS Co3+. The model parameters have been quantified for
Ln = La, Pr and Nd samples using the powder neutron diffraction on the thermal
expansion of Co-O bonds, that is associated with the two successive spin
transitions. The same model is applied to interpret the magnetic susceptibility
of LaCoO3 and YCoO3.Comment: 52.Conference on Magnetism and Magnetic Materials, November 2007,
Tamp
Problematic advice from suicide prevention experts
Based on a 10-year systematic review of suicide prevention strategies, 29 suicide prevention experts from 17 European countries recommend four allegedly evidence-based strategies to be included in national suicide prevention programs. One of the recommended strategies is pharmacological treatment of depression. This recommendation is deeply problematic for several reasons.
First, it is based on a biased selection and interpretation of available evidence.
Second, the authors have failed to take into consideration the widespread corruption in the research on antidepressants.
Third, the many and serious side effects of antidepressants are not considered.
Thus, the recommendation may have deleterious consequences for countless numbers of people, and, in fact, contribute to an increase in the suicide rate rather than a decrease
Kreativitet og perversion
Janine Chasseguet-Smirgel: Kreativitet og perversionOversat fra engelsk af Lis Haugaard.Efterskrift af Tania Ørum.Rævens Sorte Bibliotek, 196 sider, Udsalgspris 175 kr.Janine Chasseguet-Smirgel: Kreativitet og perversionOversat fra engelsk af Lis Haugaard.Efterskrift af Tania Ørum.Rævens Sorte Bibliotek, 196 sider, Udsalgspris 175 kr
Phase transition in Pr0.5Ca0.5CoO3 and related cobaltites
We present an extensive investigation (magnetic, electric and thermal
measurements and X-ray absorption spectroscopy) of the Pr0.5Ca0.5CoO3 and
(Pr1-yYy)0.7Ca0.3CoO3 (y=0.0625-0.15) perovskites, in which a peculiar
metal-insulator (M-I) transition, accompanied with pronounced structural and
magnetic anomalies, occurs at 76 K and 40-132 K, respectively. The inspection
of the M-I transition using the XANES data of Pr L3-edge and Co K-edge proofs
the presence of Pr4+ ions at low temperatures and indicates simultaneously the
intermediate spin to low spin crossover of Co species on lowering the
temperature. The study thus definitively confirms the synchronicity of the
electron transfer between Pr3+ ions and Co^(3+/4+)O3 subsystem and the
transition to the low-spin, less electrically conducting phase. The large
extent of the transfer is evidenced by the good quantitative agreement of the
determined amount of the Pr4+ species, obtained either from the temperature
dependence of the XANES spectra or via integration of the magnetic entropy
change over the Pr4+ related Schottky peak in the low-temperature specific
heat. These results show that the average valence of Pr3+/Pr4+ ions increases
(in concomitance with the decrease of the formal Co valence) below TMI for
(Pr0.925Y0.075)0.7Ca0.3CoO3 up to 3.16+ (the doping level of the CoO3 subsystem
decreases from 3.30+ to 3.20+), for (Pr0.85Y0.15)0.7Ca0.3CoO3 up to 3.28+ (the
decrease of doping level from 3.30+ to 3.13+) and for Pr0.5Ca0.5CoO3 up to
3.46+ (the decrease of doping level from 3.50+ to 3.27+).Comment: 19 pages, 11 figure
On the microscopic origin of the magneto-electronic phase separation in Sr doped LaCoO3
The nanoscopic magneto-electronic phase separation in doped La1-xSrxCoO3
perovskites was studied with local probes. The phase separation is directly
observed by M\"ossbauer spectroscopy in the studied doping range of 0.05 <= x
<= 0.25 both at room-temperature as well as in the low temperature magnetic
phase. Extended with current synchrotron based X-ray spectroscopies, these data
help to characterize the volume as well as the local electric and magnetic
properties of the distinct phases. A simple model based on a random
distribution of the doping Sr ions describes well both the evolution of the
separated phases as well as the variation of the Co spin state. The experiments
suggest that Sr doping initiates small droplets and a high degree of doping
driven cobalt spin-state transition, while the Sr-free second phase vanishes
rapidly with increasing Sr content
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