A combined transmission spectrum of the Earth-sized exoplanets TRAPPIST-1 b and c

Three Earth-sized exoplanets were recently discovered close to the habitable zone of the nearby ultracool dwarf star TRAPPIST-1. The nature of these planets has yet to be determined, since their masses remain unmeasured and no observational constraint is available for the planetary population surrounding ultracool dwarfs, of which the TRAPPIST-1 planets are the first transiting example. Theoretical predictions span the entire atmospheric range from depleted to extended hydrogen-dominated atmospheres. Here, we report a space-based measurement of the combined transmission spectrum of the two inner planets made possible by a favorable alignment resulting in their simultaneous transits on 04 May 2016. The lack of features in the combined spectrum rules out cloud-free hydrogen-dominated atmospheres for each planet at 10-$\sigma$ levels; TRAPPIST-1 b and c are hence unlikely to harbor an extended gas envelope as they lie in a region of parameter space where high-altitude cloud/haze formation is not expected to be significant for hydrogen-dominated atmospheres. Many denser atmospheres remain consistent with the featureless transmission spectrum---from a cloud-free water vapour atmosphere to a Venus-like atmosphere.Comment: Early release to inform further the upcoming review of HST's Cycle 24 proposal

mGluR5 receptor availability is associated with lower levels of negative symptoms and better cognition in male patients with chronic schizophrenia

Consistent findings postulate disturbed glutamatergic function (more specifically a hypofunction of the ionotropic NMDA receptors) as an important pathophysiologic mechanism in schizophrenia. However, the role of the metabotropic glutamatergic receptors type 5 (mGluR5) in this disease remains unclear. In this study, we investigated their significance (using [11 C]ABP688) for psychopathology and cognition in male patients with chronic schizophrenia and healthy controls. In the patient group, lower mGluR5 binding potential (BPND ) values in the left temporal cortex and caudate were associated with higher general symptom levels (negative and depressive symptoms), lower levels of global functioning and worse cognitive performance. At the same time, in both groups, mGluR5 BPND were significantly lower in smokers (F[27,1] = 15.500; p = .001), but without significant differences between the groups. Our findings provide support for the concept that the impaired function of mGluR5 underlies the symptoms of schizophrenia. They further supply a new perspective on the complex relationship between tobacco addiction and schizophrenia by identifying glutamatergic neurotransmission-in particularly mGluR5-as a possible connection to a shared vulnerability. Keywords: chronic schizophrenia; cognition; mGluR5 receptor; negative symptoms; positron emission tomography

Transcriptomic profile of host response in Japanese encephalitis virus infection

<p>Abstract</p> <p>Background</p> <p>Japanese encephalitis (JE) is one of the leading causes of acute encephalopathy with the highest mortality rate of 30-50%. The purpose of this study was to understand complex biological processes of host response during the progression of the disease. Virus was subcutaneously administered in mice and brain was used for whole genome expression profiling by cDNA microarray.</p> <p>Results</p> <p>The comparison between viral replication efficiency and disease progression confirms the active role of host response in immunopathology and disease severity. The histopathological analysis confirms the severe damage in the brain in a time dependent manner. Interestingly, the transcription profile reveals significant and differential expression of various pattern recognition receptors, chemotactic genes and the activation of inflammasome. The increased leukocyte infiltration and aggravated CNS inflammation may be the cause of disease severity.</p> <p>Conclusion</p> <p>This is the first report that provides a detailed picture of the host transcriptional response in a natural route of exposure and opens up new avenues for potential therapeutic and prophylactic strategies against Japanese encephalitis virus.</p

Dielektrische Resonatoren mit Hochtemperatur-Supraleiter Abschirmung zur Oszillatorstabilisierung

In der vorliegenden Arbeit wurden kompakte dielektrische Resonatoren mit einer Abschirmung aus HTSL-Filmen untersucht. Die Resonatoren bestehen aus jeweilseinem Zylinder aus einkristallinem Saphir oder LaAlO$_{3}$, der zentralsymmetrisch zwischen zwei epitaktischen YBa$_{2}$Cu$_{3}$O$_{7-\delta}$-Filmen angeordnet ist. Die Abmessungen dieser Resonatoren sind deutlich kleiner als bei Hohlraumresonatoren gleicher Resonanzfrequenz. Zur Optimierung der Resonatoren wurden die Hochfrequenzeigenschaften der supraleitenden Abschirmung und des Dielektrikums untersucht. Die Messung des Hochfrequenz-Oberflächenwiderstandes R$_{s}$ in Abhängigkeit der Temperatur erfolgte in dielektrisch beladenen Mikrowellenresonatoren bei 19 GHz und 37 GHz. Zur Untersuchung der Frequenzabhängigkeit wurde der Oberflächenwiderstand bei 19 GHz, 37 GHz und 87 GHz bestimmt. Daraus ergab sich eine Frequenzabhängigkeit des Oberflächenwiderstandes von etwa R$_{s}$ $\varpropto \omega^{1.7}$, die im Rahmen eines Drude- Zweiflüssigkeitenmodells mit einer temperaturabhängigen Streurate der Quasiteilchen $\tau^{-1}$ (T) erklärt werden kann. Zusätzlich wurde der Oberflächenwiderstand als Funktion der Frequenz und der Hochfrequenz-Magnetfeldstärke in Zusammenarbeit mit dem Massachusetts Institute of Technologie (MIT) mit Hilfe eines Streifenleitungsresonators an strukturierten YBa$_{2}$Cu$_{3}$O$_{7-\delta}$-Schichten auf LaAlO$_{3}$ Substraten im Frequenzbereich von 1.5 GHz bis 20 GHz gemessen. Für Feldstärken unter 80 kA/rn weist R$_{s}$ bei 4 K nur eine schwache Abhängigkeit von der Hochfrequenzfeldstärke auf. Mit Hilfe des coupled grain-Modells läßt sich daraus ein Restwiderstand von etwa 7 $\mu \Omega$ abschätzen. In einem dielektrischen Resonator bestehend aus einem einkristallinen LaAlO$_{3}$-Zylinder mit 7 mm Durchmesser zwischen zwei 20 mm großen YBa$_{2}$Cu$_{3}$O$_{7-\delta}$-Filmen konnten bei 4.2 K Gütefaktoren Q$_{0}$ von 4.5 $\cdot$ 10$^{5}$ bei 11.6 GHz im TE$_{011}$-Mode bzw. 6 $\cdot$ 10$^{5}$ bei 18 GHz im TE$_{021}$-Mode erzielt werden. Bei 77 K wurden Güten von 1 $\cdot$ 10$^{5}$ bei 11.6 GHz sowie 1.2 $\cdot$ 10$^{5}$ bei 18 GHz gemessen. Solch hohe Güten lassen sich mit normalleitenden Resonatoren gleicher Größe nicht erzielen. Ein dielektrischer Resonator aus LaAlO$_{3}$ mit einer Resonanzfrequenz von 5.6 GHz im TE$_{011}$-Mode wurde mit zwei YBa$_{2}$Cu$_{3}$O$_{7-\delta}$-Dünnfilmen mit 30 mm Durchmesser aufgebaut. Dabei hat sich gezeigt, daß die erreichbaren Güten stark von den Herstellungsparametern und der Struktur der Zwillingsdomänen des verwendeten LaAlO$_{3}$-Zylinders abhängen. Mit einem nach dem Verneuill-Verfahren hergestellten LaAlO$_{3}$-Zylinder wurden Leerlaufgüten von 8.5 $\cdot$ 10$^{5}$ bei 4.2 K und 2.5 $\cdot$ 10$^{5}$ bei 77 K erreicht. Mit einem mit Hilfe des Czochralsky-Verfahrens gewachsenem LaAlO$_{3}$-Einkristall wurden Leerlaufgüten oberhalb von 2 $\cdot$ 10$^{6}$ bei [...

Dielektrische Resonatoren mit Hochtemperatur-Supraleiter Abschirmung zur Oszillatorstabilisierung

In der vorliegenden Arbeit wurden kompakte dielektrische Resonatoren mit einer Abschirmung aus HTSL-Filmen untersucht. Die Resonatoren bestehen aus jeweils einem Zylinder aus einkristallinem Sphir oder LaALO_3, der zentralsymmetrisch zwischen zwei epitaktischen YBa_2Cu_3O_7_-_#delta#-Filmen angeordnet ist. Zur Optimierung der Resonatoren wurden die Hochfrequenzeigenschaften der supraleitenden Abschirmung und des Dielektrikums untersucht. (orig./MM)Compact dielectric resonators provided with a shielding made of HTSC thin films are examined. The resonators consist of a cylinder made of monocrystalline sapphire or LaAlO_3, placed at central symmetry between two epitactic YBa_2Cu_3O_7_-_#delta# films. For optimization of the resonators, the high-frequency properties of the superconducting shielding and the dielectricum are examined. (orig./MM)SIGLEAvailable from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Alternative headphones for patient noise protection and communication in PET-MR studies of the brain

IntroductionDue to the high noise emission generated by the gradients in magnetic resonance imaging (MRI), an efficient method of noise protection is mandatory. In addition to providing hearing protection, appropriate headphone systems also serve to facilitate communication between the operator and the patient. However, in combined PET-MR devices, use of common pneumatic headphones, as delivered by the manufacturer, is problematic due to the potential generation of attenuation artefacts in the PET measurement. Furthermore, modern multichannel head coils rarely provide space for conventional headphones. This work presents an alternative system, which aims to address these limitations while still being appropriate for both patient noise protection and communication in PET-MR.Material and methodsAs an alternative to the standard headphones supplied with the PET-MR (3T MR-BrainPET, Siemens), the possibility of using earphones built out of commercially available earplugs has been investigated. The air channel (E-A-RLink) of the earplug is connected to the tubes of the original headphones. The attenuation characteristics of the conventional headphones and of the modified earphones were measured using a dedicated PET system with a 68Ge transmission source. For this purpose, the headphones, and then the earphones, were attached to a non-radioactive head phantom. To investigate the influence of the different phones on PET emission images, measurements of the head phantom, filled with 18F solution, were performed in the PET-MR. A measurement of the head phantom without headphones or earphones was used as a reference.ResultsThe linear attenuation coefficient of the headphones was 0.11 cm-1 and that of the head phantom 0.10 cm-1. The earphones were not identifiable in the transmission image. The emission image showed an activity underestimation of 10% near the headphones, compared to the reference image, whereas the earphones did not affect the image. Communication with the patient via the earphones was successful, and the noise protection—as confirmed by investigated subjects—was satisfying.ConclusionThe presented earphones, which can be connected to the existing patient communication system, are a preferable alternative to the conventional headphones, as, in contrast to the use of headphones, qualitative and quantitative errors in the PET images can be avoided. Patient acceptance of the earphones was high, despite the increase in preparation time before the PET-MR study

MR-Based PET Motion Correction Procedure for Simultaneous MR-PET Neuroimaging of Human Brain

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