Controlled delocalization of electronic states in a multi-strand quasiperiodic lattice

Finite strips, composed of a periodic stacking of infinite quasiperiodic Fibonacci chains, have been investigated in terms of their electronic properties. The system is described by a tight binding Hamiltonian. The eigenvalue spectrum of such a multi-strand quasiperiodic network is found to be sensitive on the mutual values of the intra-strand and inter-strand tunnel hoppings, whose distribution displays a unique three-subband self-similar pattern in a parameter subspace. In addition, it is observed that special numerical correlations between the nearest and the next-nearest neighbor hopping integrals can render a substantial part of the energy spectrum absolutely continuous. Extended, Bloch like functions populate the above continuous zones, signalling a complete delocalization of single particle states even in such a non-translationally invariant system, and more importantly, a phenomenon that can be engineered by tuning the relative strengths of the hopping parameters. A commutation relation between the potential and the hopping matrices enables us to work out the precise correlation which helps to engineer the extended eigenfunctions and determine the band positions at will.Comment: 8 pages, 6 figure

DYSREGULATION OF CALCIUM SIGNALING IN PHOTORECEPTOR SYNAPSES OF EAE MICE, A MULTIPLE SCLEROSIS ANIMAL MODEL

Ribbon synapses are specialized chemical synapses. Unlike conventional chemical synapses, they remain continuously active, responding tonically in a graded fashion to varying strengths of the relevant stimuli, over a broad range of intensities. Sustained continuous vesicle release in ribbon synapses is ascribed to a special electron-dense presynaptic structure, called the ribbon. In photoreceptor ribbon synapses light-induced changes in membrane potential are transformed into graded continuous neurotransmitter release. The main building component of the synaptic ribbon is the protein RIBEYE. The ribbon is anchored at the active zone and associated with many release-ready vesicles. Depolarization-induced opening of Cav channels, at the active zone, triggers synaptic vesicle exocytosis and the subsequent release of neurotransmitter contents into the synaptic cleft. Various active zone proteins, including the RIMs, control Cav channel localization and function. ER-resident SERCA pump and plasma membrane-resident Ca2+ ATPases (PMCAs) play a crucial role in maintaining Ca2+ homeostasis in the presynaptic terminal by extruding elevated Ca2+ levels from the cytosol in an ATP-dependent manner. Ca2+ homoestasis is important for controlling the basal sustained neurotransmitter release at ribbon synapses. Multiple sclerosis (MS) is a severe neuroinflammatory, degenerative disease of the central nervous system (CNS), in which the immune system attacks the myelin sheath of myelinated axons, leading to demyelination. However, the damage is not restricted to white matter alone. Evidences of early grey matter cortical lesions in the brain and retinal layer thinning indicate a more complex immunopathology. The retina is also an unmyelinated tissue. Experimental autoimmune encephalitis (EAE), a well established mouse model of MS, shows retinal ganglion cell death and retinal nerve fibre layer (RNFL) thinning in its preclinical stage. Interestingly Dembla et al., 2018 observed a significantly decreased synaptic vesicle cycling in photoreceptor synapses in EAE mice at a pre-clinical phase. Since Ca2+ ions play a crucial role in synaptic vesicle cycling, I analysed for possible malfunctions in Ca2+ signaling in photoreceptor ribbon synapses of EAE mice in its preclinical stage. Immunofluorescence assay of Cav1.4 α1F, the pore forming subunit, show decreased fluorescence intensity at photoreceptor synapses in the OPL of MOG/CFA (EAE) mice retinal sections in comparison to control sections with no significant reduction in the number of punctas in a defined length of the OPL. However, the average size of the Cav punctas in EAE was significantly smaller as judged by super-resolution structured illumination microscopy (SR-SIM). Similar results were also obtained for the β subunits of Cav1.4 channels. These findings indicate that although the number of Cav channel clusters remain unaltered in EAE preclinical phase, the number of channels in each cluster decrease. Western blot analyses using CFA and MOG/CFA mice retinal lysates showed similar levels of α1F protein in the two groups, implying that it is clustering of the Cav1.4 channels, which is primarily affected and not the total expression of the Cav protein. Interestingly Cavβ2 shows a significant reduction in EAE in Western blot analyses. Recent studies show that β subunits can also operate as a separate entity independent of the other Cav subunits, which might explain the different changes of Cav1.4 alpha and beta relative to each other. Immunofluorescence assay for RIMs that are crucially important for Cav channel localization and regulation showed a similar finding as the Cav1.4 proteins. RIM2 immunosignals (at the active zone of photoreceptor synapses) exhibited a highly significant reduction in their intensities in MOG/CFA photoreceptor synapses with the count for the number of punctas remaining unchanged compared to the control (CFA). Western blot analyses also exhibited a highly significant loss in total protein content of RIMs 1 and 2 in EAE retinal lysates. Thus, Cav channels and their regulators, RIMs, both are found to be adversely affected in photoreceptor synapses of EAE mice at a preclinical stage. Ca2+ influx measurements in CFA and MOG/CFA retinal slices using FURA2-AM, showed that depolarization-evoked Ca2+ influx at the OPL in MOG/CFA slices was reduced in amplitude and slowed in kinetics of Ca2+ increase. During my Fura2 imaging studies, I found additional alterations of Ca2+ homeostasis. The basal Ca2+ concentrations were elevated in preclinical EAE mice photoreceptor synapses. To find possible mechanisms for the increased basal Ca2+, I analyzed key components of Ca2+ extrusion mechanisms in photoreceptor terminals. PMCA2, the more efficient PMCA isoform with higher Ca2+ affinity, showed a significant reduction in its synaptic expression in EAE retina. The decreased synaptic expression of PMCA2 could result in a decreased cytosolic Ca2+ clearance and thus to the observed increase in basal Ca2+. PMCA1 and another protein PSD95, a photoreceptor presynaptic marker for synaptic integrity, remained unaltered in immunofluorescence studies. Thus, in preclinical phase of EAE, synaptic Ca2+ signaling is affected at various levels and could contribute to the recently discovered dysfunctions of synaptic vesicle cycling.Ribbonsynapsen sind spezialisierte chemische Synapsen. Im Gegensatz zu herkömmlichen chemischen Synapsen sind sie kontinuierlich aktiv und reagieren über eine enorme Bandbreite an Reizintensitäten mit graduierten Antworten. Die Fähigkeit zur kontinuierliche Vesikelfreisetzung der Ribbonsynapsen wird einer speziellen elektronendichten präsynaptischen Struktur, dem sogenannten Ribbon, zugeschrieben. In Photorezeptorribbonsynapsen werden lichtinduzierte Änderungen des Membranpotentials in abgestufte kontinuierliche Neurotransmitterfreisetzung umgewandelt. Der Hauptbestandteil des Ribbons ist das Protein RIBEYE. Der Ribbon ist in der aktiven Zone verankert und mit vielen, Freisetzungskompetenten Vesikeln verbunden. Die durch Depolarisation induzierte Öffnung von Cav- Kanälen in der aktiven Zone löst die Exozytose aus und setzt Neurotransmitter aus den synaptischen Vesikeln in den synaptischen Spalt frei. Verschiedene Proteine der aktiven Zonen, einschließlich der RIM-Proteine, steuern die Lokalisierung und Funktion dieser Cav Kanälen. Weiterhin spielen eine am ER-befindliche SERCA-Pumpe und in der Plasmamembran lokalisierte Ca2+-ATPasen (PMCAs) eine entscheidende Rolle bei der Aufrechterhaltung der Ca2+ -Homöostase in der präsynaptischen Terminale. PMCA’s schleusen Ca2+ ATP-abhängig aus der präsynaptischen Terminale. Die Aufrechterhaltung der Ca2+ Homöostase ist für die Steuerung der basalen verzögerten Freisetzung an den Ribbonsynapsen wichtig. Die Multiple-Sklerose (MS) ist im Wesentlichen eine neuroinflammatorische, degenerative Erkrankung des Zentralnervensystems (ZNS), bei der das Immunsystem die Myelinscheide von Axonen angreift, was zu der Demyelinisierung der Axone führt. Der Schaden ist jedoch nicht ausschließlich auf die weiße Substanz des ZNS beschränkt. Wachsende Hinweise auf frühe Schädigungen der grauen Substanz, wie z.B. kortikale Gehirnläsionen oder die Dickenabnahme der Netzhautschichten deuten auf eine deutlich komplexere Immunopathologie hin. Die Netzhaut ist ein nicht-myelinisierter Abschnitt des ZNS. Die experimentelle autoimmune Encephalomyelitis (EAE), ein gut etabliertes Mausmodell für MS, zeigt das Absterben retinaler Ganglienzellen und das Ausdünnen der RNFL (retinalen Nervenfaserschicht) bereits in der präklinischen Phase. Interessanterweise beobachteten Dembla et al., 2018 , einen signifikant verringerten synaptischen Vesikelzyklus in Photorezeptor-Synapsen von EAE-Mäusen in der vorklinischen Phase. Da Ca2+ Ionen eine entscheidende Rolle beim synaptischen Vesikelzyklus spielen, untersuchte ich mögliche Störungen des Ca2+ Signals in Photorezeptor-Synapsen von EAE-Mäusen im präklinischen Stadium.Immunfluoreszenzuntersuchungen der porenbildenden Kanaluntereinheit Cav1.4 α1F zeigten verringerte Immunsignale in Netzhautschnitten von behandelten (MOG/CFA) im Vergleich zu solchen von Kontrolltieren (CFA alleine), wobei die Anzahl der Immunsignale je gegebener Länge OPL unverändert war. Wie durch hochauflösende strukturierte Beleuchtungsmikroskopie (SR-SIM) gezeigt werden konnte, war die durchschnittliche Größe der Cav Immunsignale unter EAE-Bedingungen signifikant geringer, als die der Kontrolltiere. Ähnliche Ergebnisse wurden auch für die β Untereinheiten der Cav1.4-Kanälen erhalten. Diese Ergebnisse zeigen, dass die Anzahl der Cav Kanal-Cluster in der präklinischen Phase der EAE unverändert bleibt, die Anzahl der Kanäle in dem Cluster jedoch abnimmt. Western-Blot-Analysen von Retina-Lysaten der CFA und MOG/CFA-Mäusen zeigten vergleichbare Mengen an α1F-Protein in den beiden Gruppen. Dies deutet darauf hin, dass weniger die Proteinexpression (gleiche Menge an Gesamtprotein) als vielmehr die Clusterbildung der Cav1.4 Kanäle betroffen ist. Im Gegensatz dazu zeigten Western Blot Analysen der Cavβ2-Untereinheit eine deutlich reduzierte Proteinmenge unter EAE-Bedingungen. Neuere Studien zeigen , dass die Cavβ2-Untereinheiten auch als eigenständige Einheit unabhängig von den anderen Cav-Untereinheiten, arbeiten kann, was möglicherweise die. Unterschiede in derim Gesamtproteingehalt von Cav1.4α und Cavβ2 relativ zueinander unter EAE-Bedingungen erklärt. Immunfluoreszenzuntersuchungen der RIM Proteine, die für die Lokalisierung und Regulation von Cav Kanälen von entscheidender Bedeutung sind, führten zu ähnliche Ergebnisse wie für die Cav1.4-Proteine gezeigt. RIM2-Immunsignale (in der aktiven Zone der Photorezeptor-Synapsen) zeigten eine sehr signifikante Verringerung ihrer Intensitäten in MOG/CFA-Photorezeptor-Synapsen, wobei die Anzahl der Signale gegenüber der Kontrolle (CFA) unverändert blieb. Western-Blot-Analysen zeigten eine sehr deutliche Reduktion des Gesamtproteingehalts an RIMs 1 und 2 in EAE-Retina-Lysaten. Somit konnte ich zeigen, dass sowohl die Cav Kanäle als auch ihre Regulatoren, die RIMs, beide bereits in der vorklinischen EAE Phase nachteilig beeinflusst werden. Ca2+-Messungen mittels FURA2AM in CFA- und MOG/CFA-Retina-Schnitten zeigten, dass der durch Depolarisation hervorgerufene Ca2+-Einstrom in der OPL von MOG/CFA Retina-Schnitten in der Amplitude verringert war und die Kinetik des Ca2+ Anstiegs reduziert war. Während meiner Fura2-Untersuchungen fand ich zusätzliche Veränderungen der Ca2+-Homöostase. Die basalen Ca2+-konzentrationen waren bei präklinischen EAE-Mäuse-Photorezeptor-Synapsen erhöht. Um mögliche Mechanismen für das erhöhte Basal Ca2+ zu finden, analysierte ich Schlüsselkomponenten der Ca2+-Extrusionsmechanismen in Fotorezeptorendgeräten. PMCA2, die effizientere PMCA-Isoform mit höherer Ca2+ Affinität, zeigte eine signifikante Reduktion der synaptischen Expression in der EAE-Retina. Die verminderte synaptische Expression von PMCA2 könnte zu einer verminderten zytosolischen Ca2+-Clearance und damit zu einer beobachteten Erhöhung des Basal Ca2+ führen. PMCA1 und ein anderes Protein PSD95, ein präsynaptischer Photorezeptor-Marker für die synaptische Integrität, blieb in Immunfluoreszenzstudien unverändert. In der präklinischen Phase der EAE können die gestörten Ca2+-Signale zu den kürzlich entdeckten Funktionsstörungen des synaptischen Vesikelzyklus beitragen

Outage Analysis for SWIPT-Enabled Two-Way Cognitive Cooperative Communications

In this paper, we study a cooperative cognitive radio network (CCRN) where the secondary user-transmitter (SU-Tx) assists bi-directional communication between a pair of primary users (PUs) following the principle of two-way relaying. In return, it gets access to the spectrum of the PUs to enable its own transmission to SU-receiver (SU-Rx). Further, in order to support sustainable operation of the network, SU-Tx is assumed to harvest energy from the RF signals received from the PUs, using the technique of simultaneous wireless information and power transfer (SWIPT). Assuming a decode-and-forward behaviour and power-splitting based relaying protocol at SU-Tx, closed form expressions for outage probability of PU and SU are obtained. Simulation results validate our analytical results and illustrate spectrum-efficiency and energy-efficiency advantages of the proposed system over one-way relaying.Comment: 15 pages, 5 figures, Submitted to IEEE Transactions on Vehicular Technolog

Patterns of Alcohol Consumption among Male Adults at a Slum in Kolkata, India

Globally, alcohol-abuse is a major cause of mortality and morbidity. Consumption of alcohol has increased in India in the recent decades. It is imperative to know the patterns of alcohol consumption among different types of consumers to launch a well-planned nationwide programme for the prevention and control of this devastating social pathology. This community-based, cross-sectional study was undertaken to identify the patterns of alcohol intake among different types of alcohol consumers and to assess the clinical signs of chronic harmful alcohol-use. A predesigned, pretested, semi-structured alcohol-use disorders identification test (AUDIT) questionnaire was used for interviewing males, aged >18 years, selected by random sampling from an updated household list of a randomly-selected sector of the service area of the Urban Health Centre in Chetla, Kolkata, West Bengal, India. Written informed consents were obtained from all the respondents. Relevant clinical examination for chronic harmful alcohol-use was done according to the AUDIT clinical screening procedures. The results revealed that 65.8% (150/228) were current consumers of alcohol; 14% were alcohol-dependents; 8% were hazardous or harmful consumers, and 78% were non-hazardous non-harmful consumers. The mean age of the respondents at the initiation of drinking alcohol was 20.8+5.9 years. Eighty-six percent of dependents (n=21) took both Indian-made foreign liquor and locally-made alcoholic beverages. The proportions of alcohol consumers who drank alone among alcohol-dependents, hazardous or harmful consumers, and non-hazardous non-harmful consumers were 71.4%, 50%, and 7.7% respectively, and the difference was significant (p<0.01). Forty-one percent of the consumers drank at public places and workplaces, which may be socially harmful. About 38% of the dependents purchased alcohol from unlicensed liquor shops. Only 16% expressed concerns for their drinking habit mainly to the past illness. The proportion of the concerned respondents was higher in the hazardous and harmful drinking patterns than in the non-hazardous non-harmful drinking pattern, and the difference was significant (p<0.05). About 62% of the dependents had clinical signs of chronic alcohol consumption. The presence of a considerable proportion of alcohol-dependents, the low mean age at initiation of drinking alcohol, and the habit of drinking in public places and workplaces are the main areas that need special emphasis by intervention programmes

Flux driven and geometry controlled spin filtering for arbitrary spins in aperiodic quantum networks

We demonstrate that an aperiodic array of certain quantum networks comprising magnetic and non-magnetic atoms can act as perfect spin filters for particles with arbitrary spin state. This can be achieved by introducing minimal quasi-one dimensionality in the basic structural units building up the array, along with an appropriate tuning of the potential of the non-magnetic atoms, the tunnel hopping integral between the non-magnetic atoms and the backbone, and, in some cases, by tuning an external magnetic field. This latter result opens up the interesting possibility of designing a flux controlled spin demultiplexer using quantum networks. The proposed networks have close resemblance with a family of recently developed photonic lattices, and the scheme for spin filtering can thus be linked, in principle, to a possibility of suppressing any one of the two states of polarization of a single photon, almost at will. We use transfer matrices and a real space renormalization group scheme to unravel the conditions under which any aperiodic arrangement of such topologically different structures will filter out any given spin projection. Our results are analytically exact, and corroborated by extensive numerical calculations of the spin polarized transmission and the density of states of such systems

Improving yield, quality and economic potential of strawberries grown in high tunnels for Kansas

Master of ScienceDepartment of Horticulture and Natural ResourcesEleni PliakoniCary L RivardInterest in spring day-neutral strawberry production in high tunnels is increasing in the Midwest. Although day-neutral cultivars have a much longer fruiting period than June-bearing cultivars, it is not clear if they will thrive in the summer climatic conditions in Kansas. High temperatures can reduce fruit yield and quality, potentially resulting in poorer fruit marketability and profitability for growers. A recent study at Kansas State University saw that heat-tolerant cultivars could be grown in high tunnels in Kansas when shade cloth was used. Different colored plastic mulches could also be used to change the soil temperature and light intensity, which can help to improve productivity and fruit quality. The goal of this thesis was to determine the best color for plastic mulch for a high tunnel system in regard to productivity, fruit quality, and profitability. A split-plot randomized complete block design was used in trials conducted at the Kansas State University Olathe Horticulture Research and Extension Center in 2020 and 2021. Six plastic mulches (black, white, black stripe, silver, red, and green) were employed, as well as two-day neutral cultivars, ‘Albion’ and ‘Portola’. Throughout the season, soil temperature, UV-A, and UV-B were measured in each plastic plot. All input costs were recorded throughout the growing season to calculate the production budget and profitability of the production system based on crop price and marketability. Three harvests were analyzed for quality, and mature fruit (90% to 100% red) and fruit yield was measured by harvesting strawberry plants twice per week. At harvest and for up to four days of storage, visual quality, respiration, flesh firmness, color, soluble solids content (SSC), titratable acidity (TA), and SSC/TA ratio were measured as well as nutritional quality (total phenolic, antioxidant, and anthocyanin). In our study, total and marketable strawberry fruit yields were greater in 2020 than 2021. In comparison to the (standard) black mulch, the silver mulch had a higher fruit yield, likely due to a reduced temperature range and lower UV-B irradiation capacity (P<0.0001). Strawberries grown with silver mulch had 38 % and 33% higher total and marketable fruit weight per plant, respectively (P<0.0001). The ‘Portola’ plants grown with the green mulch had 7% higher marketability compared to the ones grown with black plastic mulch. ‘Portola’ showed significantly higher total (1.68 lb/plant) and marketable (1.04 lb/plant) yield compared to ‘Albion’, which produced 1.08 lb/plant and 0.76 lb/plant, respectively (P< 0.0001). Strawberry size, soluble solid content, SSC/TA ratio, color, firmness, and total anthocyanin content were not affected by plastic mulch color. ‘Albion’ fruit grown with silver mulch had greater TA, FRAP and total phenolics than those grown with black mulch when measured at harvest (P < 0.0001). In contrast, ‘Portola’ fruit grown with the black plastic mulch had the greatest FRAP concentration (1020 mol 100 g-1) compared to the other plastic mulch. According to our findings, the use of silver mulch enhanced yield for both cultivars and antioxidant content for ‘Albion.’ The economic analysis revealed that silver mulch was also the most profitable mulch for ‘Albion’, while the black stripe mulch performed the best for ‘Portola’, which had the lowest breakeven prices of $2.18/lb and$1.92/lb, in 2020. The average percent marketability ([marketable fruit yield / total fruit yield] x 100) observed in our trials was 69.4 %, which is estimated to provide $870/1000ft2 in net revenue at$2.80/lb. When the selling price was projected at $3.02/lb for ‘Portola’ and$4/lb for ‘Albion’, it was estimated that the profit was equal to the investment cost (100% ROI). The results of this work indicate that the use of silver and other reflective mulches may be a low-cost way to effectively increase strawberry yield and quality. The economic analysis also suggests that the production of day-neutral strawberries can be a profitable enterprise for high tunnel growers in the region. As growers integrate this crop into their production system, careful consideration to the cultivar, growing methods, and marketing will be critical for success