Ginzburg - Landau equation from SU(2) gauge field theory

The dual superconductor picture of the QCD vacuum is thought to describe various aspects of the strong interaction including confinement. Ordinary superconductivity is described by the Ginzburg-Landau (GL) equation. In the present work we show that it is possible to arrive at a GL-like equation from pure SU(2) gauge theory. This is accomplished by using Abelian projection to split the SU(2) gauge fields into an Abelian subgroup and its coset. The two gauge field components of the coset part act as the effective, complex, scalar field of the GL equation. The Abelian part of the SU(2) gauge field is then analogous to the electromagnetic potential in the GL equation. An important aspect of the dual superconducting model is for the GL Lagrangian to have a spontaneous symmetry breaking potential, and the existence of Nielsen-Olesen flux tube solutions. Both of these require a tachyonic mass for the effective scalar field. Such a tachyonic mass term is obtained from the condensation of ghost fields.Comment: 7 pages, LATE

Solutions to the Conflict in Kashmir

This policy paper investigates the conflict between India and Pakistan over the region of Kashmir in order to weigh whether a political rather than military resolution can be found. Various proposals to resolve the conflict are examined and evaluated. On the one hand, the possibility of Kashmir’s autonomy is considered; on the other, the solution of joint governance or, as a third option, formal partition of Kashmir in an Indian and Pakistani territory are explored. The importance of resuming political talks between India and Pakistan represents a primary first goal in order to make any resolution possible

Climate Change and the Structural Resilience of the Doha Metro

In recent years, the Doha Metro has been the spearhead of Qatar's effort to expand and upgrade its transportation infrastructure. In its current phase it will comprise three lines of an approximate overall length of 76 km and 37 stations. It is self-explanatory that such a significant infrastructure project should be a resilient one. The requirement for a 120 years design life for its permanent civil works structures implies that they should be resilient not only against the current environmental conditions, but also against future conditions due to the ongoing climate change. Resilient means that they will be able to serve their purpose under foreseen climatic changes during their design life. It is expected that climate change will increase the occurrence and intensity of weather events, especially in the Middle East and North Africa region. As per the AR5 assessment report of the Intergovernmental Panel on Climate Change "Climate change will have profound impacts on a broad spectrum of infrastructure systems..." transport being one of them. Furthermore, since transportation is interconnected with the economic and social welfare of an area, it is evident that the metro is a critical infrastructure system of Doha. In this paper, the climate change related main hazards on the Doha Metro permanent assets are presented along with the mitigation measures that have been adopted through provisions in the structural design and the materials used. Furthermore, suggestions for future contingency measures are made

Is constant needle motion during soft tissue filler injections a safer procedure?:A theoretical mathematical model for evaluating patient safety

BackgroundThe safety rationale behind the constant needle motion injection technique is based on the assumption that due to the constant needle motion and simultaneous soft tissue filler material administration a smaller amount of product per area may be injected into an artery if an artery within the range of the moving needle is inadvertently entered.ObjectiveTo perform mathematical calculations for determining the probability for causing intra-arterial product administration when constantly moving the needle during facial aesthetic soft tissue filler injections.MethodsThis study was designed as a theoretical investigation into the probabilities for causing adverse events due to intravascular injection of soft tissue filler material when constantly moving a 27-G needle during facial soft tissue filler administration.ResultsIt was revealed that with a higher number of conducted injection passes a greater soft tissue area can be covered by the needle. The odds of encountering an artery within the covered soft tissue volume and the odds of injecting any volume greater than zero into the arterial blood stream increases with the number of performed injection passes. This increase is greatest between 1 and 10 performed injection passes.ConclusionThis model demonstrates that the constant needle motion technique increases the probability of encountering an artery within the treatment area and thus increases the odds for intra-arterial product administration. The constant needle motion technique does not increase safety but rather may increase the odds of causing intra-arterial product administration with the respective adverse consequences for the patient

Potential Use of Wind Energy in the Greek Islets

174 σ.Η παρούσα εργασία εξετάζει τις προοπτικές αξιοποίησης του αιολικού δυναμικού των βραχονησίδων της Ελλάδας. Σε πρώτο στάδιο επιχειρείται ο εντοπισμός και η αναλυτική καταγραφή και περιγραφή του συνόλου των βραχονησίδων της Ελληνικής επικράτειας, για τις οποίες προσδιορίζεται υπό ποιες προϋποθέσεις κρίνεται εφικτή η αξιοποίηση της αιολικής ενέργειας. Εν συνεχεία οι βραχονησίδες που καταρχήν κρίνονται κατάλληλες με βάση γεωγραφικά και πληθυσμιακά κριτήρια, αποτυπώνονται στον εθνικό χάρτη της Ελλάδας προκειμένου να εξεταστούν – προταθούν πιθανές διασυνδέσεις τους με ηλεκτρικά δίκτυα. Αφού παρατεθούν οι προτεινόμενες τοπολογίες διασύνδεσης, ακολουθεί η τεχνική περιγραφή της διασύνδεσης, δίνοντας έμφαση στα τεχνικά χαρακτηριστικά των υποβρυχίων καλωδίων, των οποίων επιχειρείται η διαστασιολόγηση και η προσέγγιση του κόστους. Τέλος, μέσω των δεδομένων που προκύπτουν από την διαδικασία που περιγράφηκε, και με την αξιοποίηση οικονομικών στοιχείων και δεικτών οικονομικής αποδοτικότητας, επιχειρείται η οικονομική ανάλυση ενός χαρακτηριστικού δείγματος περιπτώσεων ανάπτυξης αιολικών πάρκων σε βραχονησίδες μέσω υποβρύχιας διασύνδεσης. Σε αυτή την ανάλυση λαμβάνεται υπόψη η ευνοϊκή τιμολόγηση που προβλέπεται από τον νέο νόμο (3851/2010), και τα αποτελέσματα δείχνουν ότι η ανάπτυξη αιολικών πάρκων σε βραχονησίδες είναι υπό προϋποθέσεις οικονομικά βιώσιμη.This thesis discusses about the potential use of wind energy in the Greek Islets. Firstly we attempted to find and write down all the rock islands of Greece,of wich it is possible to exploit wind energy, defining certain cercumstances. Additionaly, the isue deals with the potential connection of the islets with electrical grids. Furthermore, a financial analysis is taking place. Finaly, the potential use of wind energy in the Greek Islets, considered profitable accordind to the results.Χαράλαμπος Β. Νικολή

Diffusion-enhanced exciton dissociation in single-material organic solar cells

Single-material organic solar cells have recently attracted research attention due to their simplicity, morphological robustness and high yield of exciton dissociation. Using α-sexithiophene as a model system, we show that the single-event probability of the exciton dissociation at the boundaries of polycrystalline domains with different molecular orientation is extremely low (∼0.5%), while a high efficiency of charge generation is gained via hundred-fold crossings of the domain boundaries due to the long exciton diffusion length (∼45 nm). This journal i

Miniaturized VIS-NIR Spectrometers Based on Narrowband and Tunable Transmission Cavity Organic Photodetectors with Ultrahigh Specific Detectivity above 1014 Jones

Spectroscopic photodetection plays a key role in many emerging applications such as context-aware optical sensing, wearable biometric monitoring, and biomedical imaging. Photodetectors based on organic semiconductors open many new possibilities in this field. However, ease of processing, tailorable optoelectronic properties, and sensitivity for faint light are still significant challenges. Here, the authors report a novel concept for a tunable spectral detector by combining an innovative transmission cavity structure with organic absorbers to yield narrowband organic photodetection in the wavelength range of 400–1100 nm, fabricated in a full-vacuum process. Benefiting from this strategy, one of the best performed narrowband organic photodetectors is achieved with a finely wavelength-selective photoresponse (full-width-at-half-maximum of ≈40 nm), ultrahigh specific detectivity above 1014 Jones, the maximum response speed of 555 kHz, and a large dynamic range up to 168 dB. Particularly, an array of transmission cavity organic photodetectors is monolithically integrated on a small substrate to showcase a miniaturized spectrometer application, and a true proof-of-concept transmission spectrum measurement is successfully demonstrated. The excellent performance, the simple device fabrication as well as the possibility of high integration of this new concept challenge state-of-the-art low-noise silicon photodetectors and will mature the spectroscopic photodetection into technological realities

Reverse dark current in organic photodetectors and the major role of traps as source of noise

Organic photodetectors have promising applications in low-cost imaging, health monitoring and near-infrared sensing. Recent research on organic photodetectors based on donor–acceptor systems has resulted in narrow-band, flexible and biocompatible devices, of which the best reach external photovoltaic quantum efficiencies approaching 100%. However, the high noise spectral density of these devices limits their specific detectivity to around 1013 Jones in the visible and several orders of magnitude lower in the near-infrared, severely reducing performance. Here, we show that the shot noise, proportional to the dark current, dominates the noise spectral density, demanding a comprehensive understanding of the dark current. We demonstrate that, in addition to the intrinsic saturation current generated via charge-transfer states, dark current contains a major contribution from trap-assisted generated charges and decreases systematically with decreasing concentration of traps. By modeling the dark current of several donor–acceptor systems, we reveal the interplay between traps and charge-transfer states as source of dark current and show that traps dominate the generation processes, thus being the main limiting factor of organic photodetectors detectivity