Experience, Memory and Narrative: A Biographical Analysis of Ethnic Identity

In the first part of this paper, we will introduce the theoretical framework for analyzing autobiographical narratives as it has been developed by the German sociologists Fritz Schütze and Gabriele Rosenthal3, and later has been adapted by Koleva, Popova and others.4 In the second part we will use this methodology to analyze empirical data that have been collected as part of our MICROCON study on ethnic identity and the risk of inter-ethnic conflict in Bulgaria. We focus on the question of how people belonging to the group of “ethnic Turks” in Bulgaria define their ethnicity, between the competing contexts of the past (in the form of their experience) and the present (in the form of what they remember and how they reactualize it in their biographical narratives). The paper is based on the analysis of two (out of a sample of 120) narrative autobiographic interviews.

Skew-cyclic codes

We generalize the notion of cyclic codes by using generator polynomials in (non commutative) skew polynomial rings. Since skew polynomial rings are left and right euclidean, the obtained codes share most properties of cyclic codes. Since there are much more skew-cyclic codes, this new class of codes allows to systematically search for codes with good properties. We give many examples of codes which improve the previously best known linear codes

Coupling ideality of integrated planar high-Q microresonators

Chipscale microresonators with integrated planar optical waveguides are useful building blocks for linear, nonlinear and quantum optical devices. Loss reduction through improving fabrication processes has resulted in several integrated micro resonator platforms attaining quality (Q) factors of several millions. However only few studies have investigated design-dependent losses, especially with regard to the resonator coupling section. Here we investigate design-dependent parasitic losses, described by the coupling ideality, of the commonly employed microresonator design consisting of a microring resonator waveguide side-coupled to a straight bus waveguide. By systematic characterization of multi-mode high-Q silicon nitride microresonator devices, we show that this design can suffer from low coupling ideality. By performing full 3D simulations to numerically investigate the resonator to bus waveguide coupling, we identify the coupling to higher-order bus waveguide modes as the dominant origin of parasitic losses which lead to the low coupling ideality. Using suitably designed bus waveguides, parasitic losses are mitigated, and a nearly unity ideality and strong overcoupling (i.e. a ratio of external coupling to internal resonator loss rate > 9) are demonstrated. Moreover we find that different resonator modes can exchange power through the coupler, which therefore constitutes a mechanism that induces modal coupling, a phenomenon known to distort resonator dispersion properties. Our results demonstrate the potential for significant performance improvements of integrated planar microresonators, achievable by optimized coupler designs.Comment: 8 pages, 3 figures, 1 tabl

Crosstalk regulation among group 2- Sigma factors in Synechocystis PCC6803

BACKGROUND: The cyanobacterium Synechocystis PCC6803 contains one group 1 (sigA) and four group 2 (sigB, sigC, sigD and sigE) sigma factors. The activity of these multiple sigma factors determines the transcriptional program of this bacterium. We wanted to study the role of the group 2 sigma factors in Synechocystis. We have therefore constructed mutants of each of the group 2 sigma factors and investigated their crosstalk. RESULTS: We used quantitative RT-PCR analysis to measure the relative abundance of the sig mRNAs in the four sigma mutants. Our data indicate that a network of mutual transcriptional regulation links the expression of the sigma genes. Accordingly, an environmental stress acting on only one of the sigma factors will indirectly modify the expression of most of the other sigma factors. This was confirmed by the transcriptional analysis of the sig mRNAs as a function of nitrogen starvation. CONCLUSION: Taken together, our observations suggest that the crosstalk regulation between all group 1 and group 2 genes could be important for the adaptation of the bacterium to different environmental and physiological conditions

Inferring the connectivity of a regulatory network from mRNA quantification in Synechocystis PCC6803

A major task of contemporary biology is to understand and predict the functioning of regulatory networks. We use expression data to deduce the regulation network connecting the sigma factors of Synechocystis PCC6803, the most global regulators in bacteria. Synechocystis contains one group 1 (SigA) and four group 2 (SigB, SigC, SigD and SigE) sigma factors. From the relative abundance of the sig mRNA measured in the wild-type and the four group 2 sigma mutants, we derive a network of the influences of each sigma factor on the transcription of all other sigma factors. Internal or external stimuli acting on only one of the sigma factors will thus indirectly modify the expression of most of the others. From this model, we predict the control points through which the circadian time modulates the expression of the sigma factors. Our results show that the cross regulation between the group 1 and group 2 sigma factors is very important for the adaptation of the bacterium to different environmental and physiological conditions

PROFILES OF RECREATIONAL ACTIVITIES OF DAILY LIVING (RADL) IN PATIENTS WITH MENTAL DISORDERS

Background: Activities of daily living, play a key role in the measurement of functional health as defined by the International Classification of Functioning, Disability and Health (ICF) and in prevention and treatment of mental or somatic illnesses. From a clinical context it is important to discriminate between basic “activities of daily living, ADL”, “intentional activities of daily living, IADL”, and “recreational activities of daily living, RADL”. While ADL and IADL have gained much attention in dementia, the elderly, or severe somatic illnesses, there is a lack of research on RADL, which are important in depression, anxiety, or other neurotic disorders. Subjects and methods: 154 unselected inpatients of a department of behavioral and psychosomatic medicine filled in the “Check List of Recreational Activities” to assess the rates and profiles of RADL. Results: Patients reported on average 19.3 (s.d. 7.0) activities (range 4 – 40), i.e. males 21.3 (s.d. 6.5, 9 – 34) and females 18.9 (s.d. 7.1, 4 – 40). Most frequent RADL were passive and unspecific activities like “watching tv” (93.4%). Least frequent were activities which need special skills or preparation like ”horse back riding” (0.7%). Low rates were also found for activities which are in the centre of inpatient occupational therapy like “ceramics” (4.7%) or “silk-painting” (2.6%). There are differences between sexes but not in respect to age (18 to 60), sick leave and unemployment, or diagnostic status. When patients were asked what they would like to do in the future, the same activity profile emerged as when looking at what they had done in the last month Conclusion: The data give a reference profile for recreational activities, help to define what can be considered a normal frequency and spectrum of RADL, and, by this, can guide therapeutic interventions

PROFILES OF RECREATIONAL ACTIVITIES OF DAILY LIVING (RADL) IN PATIENTS WITH MENTAL DISORDERS

Background: Activities of daily living, play a key role in the measurement of functional health as defined by the International Classification of Functioning, Disability and Health (ICF) and in prevention and treatment of mental or somatic illnesses. From a clinical context it is important to discriminate between basic “activities of daily living, ADL”, “intentional activities of daily living, IADL”, and “recreational activities of daily living, RADL”. While ADL and IADL have gained much attention in dementia, the elderly, or severe somatic illnesses, there is a lack of research on RADL, which are important in depression, anxiety, or other neurotic disorders. Subjects and methods: 154 unselected inpatients of a department of behavioral and psychosomatic medicine filled in the “Check List of Recreational Activities” to assess the rates and profiles of RADL. Results: Patients reported on average 19.3 (s.d. 7.0) activities (range 4 – 40), i.e. males 21.3 (s.d. 6.5, 9 – 34) and females 18.9 (s.d. 7.1, 4 – 40). Most frequent RADL were passive and unspecific activities like “watching tv” (93.4%). Least frequent were activities which need special skills or preparation like ”horse back riding” (0.7%). Low rates were also found for activities which are in the centre of inpatient occupational therapy like “ceramics” (4.7%) or “silk-painting” (2.6%). There are differences between sexes but not in respect to age (18 to 60), sick leave and unemployment, or diagnostic status. When patients were asked what they would like to do in the future, the same activity profile emerged as when looking at what they had done in the last month Conclusion: The data give a reference profile for recreational activities, help to define what can be considered a normal frequency and spectrum of RADL, and, by this, can guide therapeutic interventions

Photonic chip based optical frequency comb using soliton induced Cherenkov radiation

By continuous wave pumping of a dispersion engineered, planar silicon nitride microresonator, continuously circulating, sub-30fs short temporal dissipative solitons are generated, that correspond to pulses of 6 optical cycles and constitute a coherent optical frequency comb in the spectral domain. Emission of soliton induced Cherenkov radiation caused by higher order dispersion broadens the spectral bandwidth to 2/3 of an octave, sufficient for self referencing, in excellent agreement with recent theoretical predictions and the broadest coherent microresonator frequency comb generated to date. In a further step, this frequency comb is fully phase stabilized. The ability to preserve coherence over a broad spectral bandwidth using soliton induced Cherenkov radiation marks a critical milestone in the development of planar optical frequency combs, enabling on one hand application in e.g. coherent communications, broadband dual comb spectroscopy and Raman spectral imaging, while on the other hand significantly relaxing dispersion requirements for broadband microresonator frequency combs and providing a path for their generation in the visible and UV. Our results underscore the utility and effectiveness of planar microresonator frequency comb technology, that offers the potential to make frequency metrology accessible beyond specialized laboratories.Comment: Changes: - Added data (new Fig.4) on the first full phase stabilization of a dissipative Kerr soliton (or dissipative cavity soliton) in a microresonator - Extended Fig. 8 in the SI - Introduced nomenclature of dissipative Kerr solitons - Minor other change

All optical manipulation of a single nitrogen-vacancy centre in nanodiamond

The efficient interaction of photons with single quantum emitters like nitrogen vacancy (NV) centres is essential for the elaboration of future integrated quantum optical devices. A promising strategy towards this goal capitalizes on the latest advances of nano-optics to boost the interaction with single emitters as well as strengthen coupling between several of them. However, fully exploiting the capabilities of this marriage between NV centres and optical nanostructures requires suitable tools to accurately control their interaction. In this thesis, we use optical manipulation to trap and manipulate in 3D individual nanodiamonds containing a single NV. We first demonstrate the use of optical tweezers as a tool to achieve deterministic trapping and three-dimensional spatial manipulation of individual nanodiamonds hosting a single NV spin. Remarkably, we find that the NV axis is nearly fixed inside the trap and can be controlled in situ by adjusting the polarization of the trapping light. By combining this unique spatial and angular control with coherent manipulation of the NV spin and fluorescence lifetime measurements near an integrated photonic system, we demonstrate individual optically trapped NV centers as a novel route for both three-dimensional vectorial magnetometry and sensing of the electromagnetic local density of states. In a second step, our manipulation technique is further developed to deterministically position a single nanodiamond into the hotspot of a plasmonic antenna. The gradient force of electromagnetic field of the excited plasmon acts as localized optical tweezers to drive the functionalized nanodiamonds to the regions of largest field enhancement of the antenna, where they are adsorbed. The proximity of the immobilized NV to the nano-antenna is corroborated by the observed decrease in its fluorescence lifetime. Last but not least, we observe a NV fluorescence decrease upon near-infrared (NIR) illumination. We identify the promotion of the excited electron to a so far unknown dark band with a fast decay channel as the origin of the fluorescence decrease. This assumption is verified by the excellent agreement between our simple rate equation model and the experiment. With this mechanism we demonstrate that a single NV can operate as an efficient and fast optical switch controlled through an independent NIR gating laser. Furthermore the hybrid system formed by a single NV coupled to a gold gap antenna enhances the modulation depth. The results presented in this thesis show the ability to manipulate and position NV centres in nanodiamond with optical tweezers. This paves the way towards spin based magnetic field and temperature sensing in liquid environment. Furthermore, the control of positioning and coupling to photonic and plasmonic nanostructures may play a role for potential applications in all-optical circuits or quantum optical devices.La interacción de fotones con emisores cuánticos individuales como los centros de nitrógeno-vacante (NV) es esencial para la elaboración de futuros dispositivos integrados de óptica cuántica. Una estrategia prometedora para alcanzar este objetivo es de aprovechar de los últimos avances de la nano-óptica para aumentar la interacción con emisores individuales, así como fortalecer el acoplamiento entre varios de ellos. Sin embargo, para aprovechar al máximo las capacidades de este matrimonio entre centros de NV y nano-estructuras ópticas se requiere de herramientas adecuadas para controlar con precisión su interacción. En esta tesis, se utiliza la manipulación óptica para atrapar y manipular en 3D nano-diamantes individuales que contienen un solo centro de NV. En primer lugar, demostramos el uso de pinzas ópticas como una herramienta para lograr la captura precisa y manipulación espacial tridimensional de nano-diamantes individuales conteniendo un solo centro de NV. Sorprendentemente, encontramos que el eje del centro de NV está casi fija dentro de la trampa y puede controlarse in situ mediante el ajuste de la polarización de la luz del láser de captura. Combinamos este control espacial y angular con la manipulación coherente del espín del centro NV y con medidas de tiempo de vida de fluorescencia de un sistema fotónico integrado. Demostramos que los centros NV atrapados ópticamente pueden servir como una nueva ruta para ambos magnetometría vectorial tridimensional y de detección de la densidad local de estados electromagnéticos. En un segundo paso, nuestra técnica de manipulación se desarrolló aún más hacia el posicionamiento de un nano-diamante individual en una antena plasmónica. La fuerza de gradiente del campo electromagnético del plasmon excitado actúa como una pinza óptica local para atraer los nano-diamantes funcionalizados a las regiones de mayor aumento del campo de la antena, donde quedan adsorbidos. La proximidad del centro NV inmovilizado en la nanoantena es corroborado por la disminución observada del tiempo de vida de la fluorescencia. Por otra parte, se observa una disminución de la fluorescencia NV tras la iluminación infrarroja. Identificamos como origen de la disminución de la fluorescencia la promoción del electrón excitado a una banda, que tiene un canal de decaimiento rápido. Esta hipótesis es comprobada por el excelente acuerdo entre nuestro modelo simple de ecuación cinética y el experimento. Por último, demostramos que un centro NV puede funcionar como un interruptor óptico eficiente y rápido controlado a través de un láser de control infrarrojo independiente. Además, el sistema híbrido formado por un solo NV acoplado a una nano-antena de oro aumenta la profundidad de modulación. Los resultados presentados en esta tesis demuestran la capacidad de manipular y posicionar nano-diamantes conteniendo un centro NV con pinzas ópticas. Esto allana el camino hacia un sensor de campo magnético y de temperatura en ambiente liquido usando el espín del centro NV. Además, el control de posicionamiento y acoplamiento a nano-estructuras fotónicas y plasmónicas podría tener un impacto para aplicaciones potenciales en circuitos completamente ópticos o dispositivos de óptica cuántica