29 research outputs found
Fabrication of HighâQuality Thin SingleâCrystal Diamond Membranes with Low Surface Roughness
Certain aspects before and during the fabrication of single-crystal diamond (SCD) membranes are highlighted, which are decisive to obtain high-quality membranes with low surface roughness values around 0.2 nm on a small area scale. In addition to the requirements for the starting material, including a high planarity and a moderate surface roughness, the importance of cleaning processes to minimize particles and impurities before and during the structuring is emphasized. With the help of a planarization procedure, consisting of a combination of different Ar/Cl recipes with low etch rates, surface defects like grooves due to polishing are minimized and smooth surfaces are acquired. Severe micromasking can be prevented by the application of a cyclic Ar/Cl + O recipe, allowing finally the fabrication of defect-minimized and planarized SCD membranes in the thickness range between few microns and a few hundred nanometers. The high quality of the structured SCD membranes is evidenced with a morphological as well as an optical characterization via fiber-based microcavity measurements
Does adult ADHD interact with COMT val 158 met genotype to influence working memory performance?
Peer reviewedPostprin
Scanning cavity microscopy of a single-crystal diamond membrane
Spin-bearing color centers in the solid state are promising candidates for
the realization of quantum networks and distributed quantum computing. A
remaining key challenge is their efficient and reliable interfacing to photons.
Incorporating minimally processed membranes into open-access microcavities
represents a promising route for Purcellenhanced spin-photon interfaces: it
enables significant emission enhancement and efficient photon collection,
minimizes deteriorating influence on the quantum emitter, and allows for full
spatial and spectral tunability, key for controllably addressing suitable
emitters with desired optical and spin properties. Here, we study the
properties of a high-finesse fiber Fabry-P\'erot microcavity with integrated
single-crystal diamond membranes by scanning cavity microscopy. We observe
spatially resolved the effects of the diamond-air interface on the cavity mode
structure: a strong correlation of the cavity finesse and mode structure with
the diamond thickness and surface topography, significant transverse-mode
mixing under diamond-like conditions, and mode-character-dependent
polarization-mode splitting. Our results reveal the influence of the diamond
surface on the achievable Purcell enhancement, which helps to clarify the route
towards optimized spin-photon interfaces
Scanning cavity microscopy of a single-crystal diamond membrane
Spin-bearing color centers in the solid state are promising candidates for the realization of quantum networks and distributed quantum computing. A remaining key challenge is their efficient and reliable interfacing to photons. Incorporating minimally processed membranes into open-access microcavities represents a promising route for Purcellenhanced spin-photon interfaces: it enables significant emission enhancement and efficient photon collection, minimizes deteriorating influence on the quantum emitter, and allows for full spatial and spectral tunability, key for controllably addressing suitable emitters with desired optical and spin properties. Here, we study the properties of a high-finesse fiber Fabry-PĂ©rot microcavity with integrated single-crystal diamond membranes by scanning cavity microscopy. We observe spatially resolved the effects of the diamond-air interface on the cavity mode structure: a strong correlation of the cavity finesse and mode structure with the diamond thickness and surface topography, significant transverse-mode mixing under diamond-like conditions, and mode-character-dependent polarization-mode splitting. Our results reveal the influence of the diamond surface on the achievable Purcell enhancement, which helps to clarify the route towards optimized spin-photon interfaces
Fabrication and Characterization of Single-Crystal Diamond Membranes for Quantum Photonics with Tunable Microcavities
The development of quantum technologies is one of the big challenges in modern research. Acrucial component for many applications is an efficient, coherent spinâphoton interface, and coupling single-color centers in thin diamond membranes to a microcavity is a promising approach. To structure such micrometer thin single-crystal diamond (SCD) membranes with a good quality, it is important to minimize defects originating from polishing or etching procedures. Here, we report on the fabrication of SCD membranes, with various diameters, exhibiting a low surface roughness down to 0.4 nm on a small area scale, by etching through a diamond bulk mask with angled holes. A significant reduction in pits induced by micromasking and polishing damages was accomplished by the application of
alternating Ar/Cl2 + O2 dry etching steps. By a variation of etching parameters regarding the Ar/Cl2 step, an enhanced planarization of the surface was obtained, in particular, for surfaces with a higher initial surface roughness of several nanometers. Furthermore, we present the successful bonding of
an SCD membrane via van der Waals forces on a cavity mirror and perform finesse measurements which yielded values between 500 and 5000, depending on the position and hence on the membranethickness. Our results are promising for, e.g., an efficient spinâphoton interface
Sympathy for the Devil: A Conservation Strategy for Devil and Manta Rays
Background International trade for luxury products, medicines, and tonics poses a threat to both terrestrial and marine wildlife. The demand for and consumption of gill plates (known as Peng Yu Sai, âFish Gill of Mobulid Rayâ) from devil and manta rays (subfamily Mobulinae, collectively referred to as mobulids) poses a significant threat to these marine fishes because of their extremely low productivity. The demand for these gill plates has driven an international trade supplied by largely unmonitored and unregulated catches from target and incidental fisheries around the world. Scientific research, conservation campaigns, and legal protections for devil rays have lagged behind those for manta rays despite similar threats across all mobulids.
Methods To investigate the difference in attention given to devil rays and manta rays, we examined trends in the scientific literature and updated species distribution maps for all mobulids. Using available information on target and incidental fisheries, and gathering information on fishing and trade regulations (at international, national, and territorial levels), we examined how threats and protective measures overlap with species distribution. We then used a species conservation planning approach to develop the Global Devil and Manta Ray Conservation Strategy, specifying a vision, goals, objectives, and actions to advance the knowledge and protection of both devil and manta rays.
Results and Discussion Our literature review revealed that there had been nearly 2.5-times more âmantaâ-titled publications, than âmobulaâ or âdevil rayâ-titled publications over the past 4.5 years (January 2012âJune 2016). The majority of these recent publications were reports on occurrence of mobulid species. These publications contributed to updated Area of Occupancy and Extent of Occurrence maps which showed expanded distributions for most mobulid species and overlap between the two genera. While several international protections have recently expanded to include all mobulids, there remains a greater number of national, state, and territory-level protections for manta rays compared to devil rays. We hypothesize that there are fewer scientific publications and regulatory protections for devil rays due primarily to perceptions of charisma that favour manta rays. We suggest that the well-established species conservation framework used here offers an objective solution to close this gap. To advance the goals of the conservation strategy we highlight opportunities for parity in protection and suggest solutions to help reduce target and bycatch fisheries
Fabrication and Characterization of Single-Crystal Diamond Membranes for Quantum Photonics with Tunable Microcavities
The development of quantum technologies is one of the big challenges in modern research. A crucial component for many applications is an efficient, coherent spin–photon interface, and coupling single-color centers in thin diamond membranes to a microcavity is a promising approach. To structure such micrometer thin single-crystal diamond (SCD) membranes with a good quality, it is important to minimize defects originating from polishing or etching procedures. Here, we report on the fabrication of SCD membranes, with various diameters, exhibiting a low surface roughness down to 0.4 nm on a small area scale, by etching through a diamond bulk mask with angled holes. A significant reduction in pits induced by micromasking and polishing damages was accomplished by the application of alternating Ar/Cl2 + O2 dry etching steps. By a variation of etching parameters regarding the Ar/Cl2 step, an enhanced planarization of the surface was obtained, in particular, for surfaces with a higher initial surface roughness of several nanometers. Furthermore, we present the successful bonding of an SCD membrane via van der Waals forces on a cavity mirror and perform finesse measurements which yielded values between 500 and 5000, depending on the position and hence on the membrane thickness. Our results are promising for, e.g., an efficient spin–photon interface
Stathmin and Cluster C personality disorders, panic disorder and agoraphobia
Es wurde bereits mehrfach vermutet, dass das auf dem Chromosomabschnitt 1p36.11 lokalisierte Stathmin-Gen, welches durch seine Funktion als Regulator der Mikrotubulidynamik fĂŒr die neuronale PlastizitĂ€t bei Vertebraten eine entscheidende Rolle spielt, fĂŒr die Angstentstehung von essentieller Bedeutung sein könnte. Zum einen wurde von Shumyatsky und Kollegen der Befund erbracht, dass Stathmin-defiziente MĂ€use weder angeborene noch erlernte Furcht zeigten. Zum anderen konnten Brocke und Mitarbeiter fĂŒr gesunde Probanden nachweisen, dass zwei Promotor-SNPs rs182455 und rs213641 mit der Induktion von Angst und psychosozialem Stress assoziiert sind. Aus diesen GrĂŒnden, die Stathmin zu einem ausgezeichneten Kandidatengen fĂŒr angstrelevante Erkrankungen machen, wurde in der vorliegenden Arbeit eine Fall-Kontroll-Studie durchgefĂŒhrt, die den oben genannten rs182455 und einen neu identifizierten Promotor-Polymorphismus in Form eines STR-Bereichs analysierte. Das untersuchte Patientenkollektiv bestand aus 642 Patienten mit Persönlichkeitsstörungen, von denen 115 eine âĂ€ngstlicheâ Cluster C Persönlichkeitsstörung aufwiesen. Des Weiteren wurden 239 Patienten mit einer Panikstörung und komorbider Agoraphobie und eine Kontrollgruppe aus 239 gesunden Blutspendern analysiert. Methodisch wurde hierbei zunĂ€chst eine Sequenzierung des Stathmin-Gens zur genaueren Analyse des STR-Bereichs durchgefĂŒhrt. Die Genotypisierung des STR-Bereichs erfolgte anschlieĂend mit Hilfe drei verschiedener PCR-AnsĂ€tze und einer Kapillar-Gelelektrophorese. Die Genotypisierung des rs182455 wurde mittels PCR, einem nachfolgenden Restriktionsverdau und einer Gelelektrophorese durchgefĂŒhrt. AbschlieĂend wurden die Allelfrequenzen des rs182455 und des STR-Bereichs auf eine mögliche Assoziation mit Persönlichkeitseigenschaften, Persönlichkeitsstörungen und Panikstörung und Agoraphobie statistisch untersucht. Die in dieser Arbeit durchgefĂŒhrten Assoziationsanalysen von rs182455 zeigen zum einen eine signifikante Assoziation mit der TPQ Dimension âreward dependenceâ (p=0,009), insbesondere mit der Subskala âBindungâ, mit der NEO-PI-R Dimension Extraversion (p=0,035), insbesondere mit den Facetten âWĂ€rmeâ und âGeselligkeit/Zusammenlebenâ. BezĂŒglich der NEO-PI-R Dimension Neurotizismus ergab sich bei geschlechtsgetrennten Analysen eine signifikante Assoziation fĂŒr die Facette âĂngstlichkeitâ bei Frauen (p=0,026). Zum anderen wurde bei geschlechtsgetrennten Analysen eine signifikante Assoziation mit Cluster C Persönlichkeitsstörungen bei weiblichen Patienten (p=0,025) nachgewiesen. DarĂŒber hinaus zeigte sich eine signifikante Assoziation des rs182455 mit der Panikstörung, wobei diese Assoziation insbesondere auf die Patienten mit Agoraphobie zurĂŒckzufĂŒhren ist (p=0,041). Die Assoziationsanalysen des STR-Bereichs, der aus einem ATC-Insertionspolymorphismus und einer TAA-Trinukleotidwiederholung besteht, ergaben bezĂŒglich der NEO-PI-R Dimension Neurotizismus im Hinblick auf die Facette âĂngstlichkeitâ ebenfalls eine signifikante Assoziation (p=0,011) mit dem ATC-Insertionspolymorphismus. Im Hinblick auf Cluster C Persönlichkeitsstörungen zeigte sich bei geschlechtsgetrennten Analysen eine signifikante Assoziation des ATC-Insertionspolymorphismus (p=0,019) bei weiblichen Patienten und eine signifikante Assoziation mit der Trinukleotid-Wiederholung TAA (p=0,031). BezĂŒglich des ATC-Insertionspolymorphismus wurde darĂŒber hinaus eine signifikante Assoziation des STR-Bereichs mit der Panikstörung (p=0,020) und komorbider Agoraphobie (p=0,024) nachgewiesen. Diese Resultate bestĂ€tigen die Annahme, dass dem Stathmin-Gen fĂŒr die Angstentstehung und fĂŒr die Genese angstrelevanter Erkrankungen möglicherweise eine Bedeutung zukommt. Die Assoziation mit den Persönlichkeitseigenschaften âĂngstlichkeitâ, âBindungâ, âWĂ€rmeâ und âGeselligkeit/Zusammenlebenâ, die eventuell als maternale Eigenschaften gewertet werden können, entspricht ebenfalls dem Modell der Stathmin-defizienten Maus, da auĂer dem Nichtvorhandensein angeborener oder erlernter Furcht weibliche Stathmin-defiziente MĂ€use die Aufzucht der Jungtiere vernachlĂ€ssigen. Dies könnte auch eine mögliche ErklĂ€rung fĂŒr den Geschlechtereffekt im Sinne einer Frauenwendigkeit darstellen, der sich insbesondere fĂŒr die genannten Persönlichkeitseigenschaften und fĂŒr die Cluster C Persönlichkeitsstörungen, aber auch fĂŒr die Panikstörung und Agoraphobie detektieren lieĂ. Zusammenfassend sprechen diese Daten fĂŒr die Hypothese, dass es sich bei Stathmin um ein geschlechtsspezifisches SuszeptibiltĂ€tsgen fĂŒr Cluster C Persönlichkeitsstörungen und die Panikstörung und Agoraphobie handelt.Stathmin, a gene located on chromosome 1p36.11 and enriched in the amygdala, seems to control learned and innate fear and to play also a role in maternal behaviours in mice. Two recent studies argued for stathmin as a regulator of affective control processes and especially anxiety processing in humans. A case-control study of one of these SNPs (rs182455) as well as another polymorphism in the transcriptional control region of stathmin was conducted in 642 patients with personality disorders, 115 of them suffered from Cluster C personality disorders, in 239 patients suffering from panic disorder and agoraphobia and in 239 controls. Both promoter polymorphisms were specifically and significantly associated with panic disorder and agoraphobia as well as with Cluster C personality disorders, however the rs182455 only yielded a significant association within the female subsample. Furthermore both polymorphisms were significantly associated with the Revised NEO Personality Inventory (NEO-PI-R) neuroticism facet âanxietyâ and the rs182455 again only yielded a significant association within the female subsample. Rs182455 also showed a significant association with the NEO-PI-R dimension âextraversionâ and especially with the facets âwarmthâ and âgregariousnessâ and the Tridimensional Personality Questionnaire (TPQ) dimension âreward dependenceâ especially with the subscale âattachmentâ. The stathmin variation is associated with Cluster C personality disorders and âanxietyâ as well as with âwarmthâ, âgregariousnessâ and âattachmentâ, which may be considered as maternal traits. All the results showed a gender effect, some even only yielded significant results in the female subsample. In conclusion stathmin may constitute a susceptibility gene with a gender effect for panic disorder and agoraphobia and for Cluster C personality disorders