THE NEW ECONOMICS OF DISTANCE: LONG-TERM TRENDS IN INDEXES OF SPATIAL FRICTION

Distance-related costs have changed at different rates across categories of resource flows and across modes and media between 1960 and 1998. The cost of moving knowledge/information has dropped much faster than the costs of moving people or materials. The costs of processing and moving information have dropped by 98% and 92% respectively, in real terms since 1960. In addition, there are big differences in the rates of change within the real costs of moving people using different travel modes--just as big differences exist within the real costs of moving materials using different modes. For example, the real costs of moving materials by domestic rail and inland waterway have decreased by 58% and 42% in real terms, respectively, while inter-city trucking costs have not changed significantly in real terms since 1960. Thus, this paper suggests that the 'new economics of distance' is not about the disappearance of distance nor the demise of borders as factors in economics. Rather, 'the new economics of distance' is about the increasing role played by logistics management and the adjustment processes that are occurring as firms creatively seek to substitute between types of resources and between the modes and media for moving those resources.Industrial Organization,

STOCHASTIC CHARGE TRANSPORT IN MULTI-ISLAND SINGLE-ELECTRON TUNNELING DEVICES

The physics of the operation of singe-electron tunneling devices (SEDs) and singe-electron tunneling transistors (SETs), especially of those with multiple nanometer-sized islands, has remained poorly understood in spite of some intensive experimental and theoretical research. This computational study examines the current-voltage (IV) characteristics of multi-island single-electron devices using a newly developed multi-island transport simulator (MITS) that is based on semi-classical tunneling theory and kinetic Monte Carlo simulation. The dependence of device characteristics on physical device parameters is explored, and the physical mechanisms that lead to the Coulomb blockade (CB) and Coulomb staircase (CS) characteristics are proposed. Simulations using MITS demonstrate that the overall IV characteristics in a device with a random distribution of islands are a result of a complex interplay among those factors that affect the tunneling rates that are fixed a priori (e.g. island sizes, island separations, temperature, gate bias, etc.), and the evolving charge state of the system, which changes as the source-drain bias (VSD) is changed. With increasing VSD, a multi-island device has to overcome multiple discrete energy barriers (up-steps) before it reaches the threshold voltage (Vth). Beyond Vth, current flow is rate-limited by slow junctions, which leads to the CS structures in the IV characteristic. Each step in the CS is characterized by a unique distribution of island charges with an associated distribution of tunneling probabilities. MITS simulation studies done on one-dimensional (1D) disordered chains show that longer chains are better suited for switching applications as Vth increases with increasing chain length. They are also able to retain CS structures at higher temperatures better than shorter chains. In sufficiently disordered 2D systems, we demonstrate that there may exist a dominant conducting path (DCP) for conduction, which makes the 2D device behave as a quasi-1D device. The existence of a DCP is sensitive to the device structure, but is robust with respect to changes in temperature, gate bias, and VSD. A side gate in 1D and 2D systems can effectively control Vth. We argue that devices with smaller island sizes and narrower junctions may be better suited for practical applications, especially at room temperature

Asynchronous Games over Tree Architectures

We consider the task of controlling in a distributed way a Zielonka asynchronous automaton. Every process of a controller has access to its causal past to determine the next set of actions it proposes to play. An action can be played only if every process controlling this action proposes to play it. We consider reachability objectives: every process should reach its set of final states. We show that this control problem is decidable for tree architectures, where every process can communicate with its parent, its children, and with the environment. The complexity of our algorithm is l-fold exponential with l being the height of the tree representing the architecture. We show that this is unavoidable by showing that even for three processes the problem is EXPTIME-complete, and that it is non-elementary in general

Association of first trimester serum level of placental growth factor (PlGF) and cervical length with onset of preterm labour

Background: Preterm labour (PTL) or premature labour is defined as one where labour starts before the 37th completed week.  The incidence of preterm birth is around 5-10% and it is the leading cause of perinatal morbidity and mortality. Diagnosis and treatment of PTL is challenging. However, owing to the availability of effective strategies for prevention of preterm birth, risk identification and early prediction is even more essential. This may provide opportunity for intervention and better obstetric care. Various biochemical markers were studied for prediction of preterm labour, but the sensitivity and specificity were found to be low. This study focuses on determining whether serum level of PlGF and ultrasound measure of cervical length at 10 – 14 weeks period of gestation can be used for early prediction of preterm labour.Methods: 296 antenatal women participated in this prospective observational study carried out from Dec 2015 to Sep 2017 at a tertiary care hospital. Serum level of PlGF was determined at 10-14 weeks. In the same sitting, cervical length was measured by transvaginal sonography. All these patients were followed up in antenatal OPD for monitoring the onset of preterm labour.Results: Incidence of preterm labour was 6.76 %. Maternal characteristics and obstetric factors were comparable in cases and controls. Serum PlGF level and cervical length values were lower in preterm labour group than term deliveries. But this result was not statistically significant.Conclusions: Lower levels of PlGF and cervical length were seen in preterm labour group, although it was not found to be statistically significant

Preparation of Undoped and Phosphorus Doped μc-Si:H Films: Effect of Extended Period of Hydrogen Plasma Annealing in Interrupted Growth

Interrupted growth and H-plasma annealing of stacking layers of Si:H film resulted in a significant improvement in material properties towards microcrystallization. Increase of dark conductivity and reduction of optical absorption due to extended period of hydrogen plasma exposure was noted. An associated improvement in the network structure towards crystallinity was observed by Raman, TEM and XRD studies. Highly conducting ( σD ~ 6 × 10-3 s. cm-1) undoped mc-Si:H films have been prepared at significantly low thickness of 650 Å. P-doped mc-Si:H films having conductivity ~ 26.2 S.cm-1 were obtained from very low level of PH3 dilution. Large number of dopants introduce additional defects at the grain boundary and inhibits the crystallization process

Comparative Study of Ram Air Turbines based on Wind Tunnel Study for Specific Air Borne Energy Extraction

Ram Air Turbines (RAT) are used for emergency on-board power generation on aircraft and associated systems. Many studies on usage of RATs have shown promising results in terms of using RATs as a source of emergency on-board power generation. Many external podded systems on aircraft utilise RATs for self-sufficient adaptation. These pods generate their own power using RATs for their power requirements instead of depending on the mother aircraft power. Commercial cargo planes use RATs for generating emergency hydraulic power. A RAT was suggested to be used for emergency power, during failure of main alternator on a prototype aircraft. A specific requirement of the RAT was also to produce high drag for aerodynamic braking when deployed and concurrently generate electrical energy. Three models with different solidity were studied in wind tunnel at different wind speeds for suitability of this drag-energy combination. This paper presents the results of the study. Based on the results, a suitable RAT was selected for further analysis and ground trials

Maternal and fetal factors observed with late preterm births

Backround: Although neonatal morbidity and mortality rates are fallen in recent decades, the prevalence of preterm deliveries has increased especially late preterm births. Late preterm deliveries are at increased risk of various neonatal complications compared to term deliveries.This study was carried out to identify the maternal characteristics and co-morbidites found with late preterm births and feto-maternal outcome in terms of indication of delivery, route of delivery, Apgar score and NICU admissions.Methods: A retrospective study was conducted in a tertiary care teaching hospital of Indian armed forces between Jan 2011 to Dec 2012 where 248 late preterm deliveries were analysed.Results: 56% women had spontaneous late preterm births and 44% women were induced. 23% of patients had history of 1 or more prior abortion and 13% patients had previous fetal deaths among the patients had late preterm delivery. Common maternal morbidities in mother delivering late preterm were hypertensive disorders of pregnancy (20.6%), anaemia (14.5%) and preterm premature rupture of membrane (13.7%). 4.8% newborns had Apgar ≤ 7 and 10% newborns required NICU admissions.Conclusion: Higher incidences of hypertensive disorders of pregnancy, anaemia and preterm premature rupture of membrane were found with late preterm birth and 10% of newborns required NICU care.

Simulation of charge transport in multi-island tunneling devices: Application to disordered one-dimensional systems at low and high biases

Although devices have been fabricated displaying interesting single-electron transport characteristics, there has been limited progress in the development of tools that can simulate such devices based on their physical geometry over a range of bias conditions up to a few volts per junction. In this work, we present the development of a multi-island transport simulator, MITS, a simulator of tunneling transport in multi-island devices that takes into account geometrical and material parameters, and can span low and high source-drain biases. First, the capabilities of MITS are demonstrated by modeling experimentaldevices described in the literature, and showing that the simulated device characteristics agree well with the experimental observations. Then, the results of studies of charge transport through a long one-dimensional (1D) chain of gold nano-islands on an insulating substrate are presented. Current-voltage (IV) characteristics are investigated as a function of the overall chain-length and temperature. Under high bias conditions, where temperature has a minimal effect, the IV characteristics are non-Ohmic, and do not exhibit any Coulomb staircase (CS) structures. The overall resistance of the device also increases non-linearly with increasing chain-length. For small biases, IV characteristics show clear CS structures that are more pronounced for larger chain-lengths. The Coulomb blockade and the threshold voltage (Vth ) required for device switching increase linearly with the increase in chain length. With increasing temperature, the blockade effects are diminished as the abrupt increase in current at Vth is washed out and the apparent blockade decreases. Microscopic investigations demonstrate that the overall V characteristics are a result of a complex interplay among those factors that affect the tunneling rates that are fixed a priori (island sizes, island separations, temperature, etc.), and the evolving charge state of the system, which changes as the applied source-drain bias (VSD ) is changed. In a system of nano-islands with a broad distribution of sizes and inter-island spacings, the applied bias is divided across the junctions as one would expect of a voltage divider, with larger potential drops across the wider junctions and smaller drops across the narrower junctions. As a result, the tunneling resistances across these wider junctions decrease dramatically, relative to the other junctions, at high VSD thereby increasing their electron tunneling rates. IV behavior at high VSD follows a power-law scaling behavior with the exponent dependent on the length of the chain and the degree of disorder in the system

Knowledge and attitude of medical students towards bioethics- A cross sectional study from a medical college in northern Tamil Nadu

Studies have shown that a significant proportion of healthcare professionals were unaware of the universally recognized bioethical principles. The study was conducted to assess the knowledge and attitude towards bioethics among undergraduate medical students of a Medical College and also to find out the association of knowledge and attitude towards bioethics with other factors. This was a Cross Sectional study conducted at a medical college of Chengalpattu district between April to September of 2019. Study participants included medical undergraduate students from second academic year to fourth academic year of the medical college who had clinical exposure. Data was collected from a total of 224 subjects using a pretested, self-administered questionnaire. 89.3% of the respondents had poor knowledge about medical ethics.  The prevalence of good+excellent knowledge about bioethics was highest among 17-19 years age group (95.8%) and least among >22 (60%) years age group, highest among those with <12 months of clinical exposure (100%) and least among those with 25-36 months of exposure (57.8%) and both these associations were found to be statistically significant by Chi square test. (P= 0.048 and <0.001 respectively). Majority of the subjects (>58%) had a favourable attitude towards the correct ethical practices with respect to most of the issues (11/15). However, majority of them (>53.1%) also had a favorable attitude towards certain issues (4/15) which are debatable. The most preferred sources for learning about medical ethics were seminars (81.7%), clinical discussions (78.1%) and lectures (57.1%). Majority of the subjects had poor knowledge about bioethics. The knowledge was better among students of earlier years of course compared to those in the later part. Majority of the subjects had a favorable attitude towards the correct ethical practices in most of the cases. The most preferred sources for learning about medical ethics were seminars, clinical discussions and lecture

A scientific research study on the management of Manyasthamba (Cervical Spondylosis) with Nasya and Nasapana

The science of life Ayurveda, not only deals with the prevention of diseases by maintaining health but also with the alleviation of diseases. In this ultra modern era due to change in lifestyles, sedentary works and food habits, people are unable to follow the Dinacharya and Ritucharya as explained in the classics, which may lead to different diseases. Due to improper postural habits, weight bearing and other unwholesome diets and habits there are higher the chances of discomfort and disease pertaining to spinal cord. Manyasthambha is one such condition that disturbs a big population due to today’s alterations in lifestyle. Here an effort is made to study and understand the role of Nasya Karma, Nasaapana and Shamanaushadhi like Vyoshadi Guggulu in the treatment aspect of this disease. Nasya Karma and Nasaapana provided highly significant results in all the symptoms of Manyasthambha. As per the clinical data, ‘Nasaapana is found to be more effective than Nasya Karma’. So it can be concluded that better results can be obtained with Shaddharana Yoga as Amapachana, Nasaapana with Mashabaladi Kwatha followed by Vyoshadi Guggulu as Shamanoushadhi