Contracting and the division of the gains from trade

This paper examines the microstructure of import markets and the division of the gains from trade among consumers, importers and exporters. When exporters and importers transact through anonymous markets, double marginalization and business stealing among competing importers lead to lower profits. Trading parties can overcome these inefficiencies by investing in richer contractual arrangements such as bilateral contracts that eliminate double marginalization and joint contracts that also internalize business stealing. Introducing these contractual choices into a trade model with heterogeneous exporters and importers, we show that trade liberalization increases the incentive to engage in joint contracts, thus raising the profits of exporters and importers at the expense of consumer welfare. We examine the implications of the model for prices, quantities and exporter-importer matches in Colombian import markets before and after the US-Colombia free trade agreement. US exporters that started to enjoy dutyfree access were more likely to increase their average price, decrease their quantity exported and reduce the number of import partners

Modeling of Congestion: A Tool for Urban Traffic Management in Developing Countries

In order to formulate rational traffic management measures for urban roads, it is essential to understand the effect of different types of vehicle on congestion. The effect of different types of vehicle on congestion has been captured on the basis of marginal congestion. Using congestion models, the marginal congestions have been estimated for different road widths, traffic compositions and on-street parking levels. The peak hour vehicular composition and volume level vary for different roads in an urban area. Therefore, for assessing the operating conditions for different roads based on a comparable quantitative measure, the marginal congestion caused per Passenger Car Unit (PCU) of mixed traffic stream has been estimated and denominated ‘Marginal Congestion Index (MCI)’. The use of MCI for prioritization of management actions for different urban roads is discussed. It is shown that a congestion model explicitly accounts for the effects of traffic composition and volume level. Therefore, the effect of different types of vehicles on congestion at all traffic volumes could be estimated using congestion models. Altogether, modeling of congestion is established as a tool for formulating rational traffic management measures for urban roads in developing countries

Firm-to-firm connections in Colombian imports

The vast majority of world trade flows is between firms. Only recently has research in international trade started to emphasize the importance of the connections between exporters and importers both in aggregate trade flows and in the negative relationship between trade and geographic distance. This chapter documents the role of firm-to-firm connections in trade flows and the formation and duration of these importer-exporter relationships. Using customs data from Colombia for 1995-2014, we are able to identify both the Colombian importing firm and the foreign exporter in every Colombian import and export transaction. We document both the nature of these bilateral trading relationships and their evolution over time

Design of phase change Ge2Sb2Te5 based on-off electro-optic switch

Design of electro-optic ON-OFF switches based on well-known phase change material Ge2Sb2Te5(GST) is presented. The electro-optic switch is achieved by implementing by co-directional coupling between a 220 nm thick silicon nanowire and a silicon waveguide topped with ITO-GST-ITO layers at the 1.55μm wavelength. By introducing the electric field via the ITO electrodes, the GST layer can be changed between the amorphous and crystalline states. As the modal loss in the crystalline state is much higher than the amorphous state, through a rigorous modal analysis of the coupled silicon nanowire and GST waveguide by using the finite element method, the optimal ITO spacing is obtained at 75nm which is less sensitive to device parameter variations and thus offering better tolerances. The GST thickness is also optimized for the phase matching point at 25 nm in order to efficiently transfer power from silicon nanowire to GST waveguide to attain the OFF state. Once the device is phase matched in crystalline state, the power in the amorphous state will pass with very little interaction with the GST waveguide resulting in an ON state. The Eigenmode Expansion Method of Fimmprop is used as a junction analysis approach to calculate the optical power coupling efficiencies to the output silicon nanowire. The extinction ratio of the electro-optic switch and insertion loss in ON state at phase matching can be obtained as a function of the device length. A compact 1.75 μm long device shows a high extinction ratio of 22 dB with an insertion loss of only 0.56 dB

Proteomic Profiling and Neurodegeneration in West-Nile-Virus-Infected Neurons

West Nile virus, a mosquito-borne flavivirus, is a human, equine, and avian pathogen. High-resolution two-dimensional differential-gel electrophoresis (2D-DIGE) was used to characterize protein expression in primary rat neurons and to examine the proteomic profiling to understand the pathogenesis of West-Nile-associated meningoencephalitis. Three pH ranges, 3–10, 4–7, and 5–6, were used to analyze the protein spots. The proteins are labeled with fluorescent dyes Cy3 and Cy5 before being separated on the basis of charge and size respectively on a two-dimensional platform. About 55 proteins showed altered expression levels. These were then subsequently digested and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis using peptide mass fingerprinting and database searching. These cellular proteins could represent distinct roles during infection related to apoptosis. Our findings show that two-dimensional differential gel electrophoresis combined with mass spectrometry is a powerful approach that permits the identification of proteins whose expression was altered due to West Nile virus infection

Gradual distraction on hinged-based Ilizarov ring fixator to correct fixed flexion deformity of knee: description of the surgical technique

Knee deformity in flexion is the most disabling deformity. Surgical correction can be attempted with soft tissue release, osteotomy, or both. However, acute correction can cause serious complications. Ilizarov technique has become an appealing alternative to open surgery, where skeletal traction is used to distract the joint gradually and steadily in order to reduce the risk of skin problems or neurovascular injuries. Two patients and three limbs, male aged 28-42 (mean=35 years) with severe fixed flexion deformity were corrected by a hinged-based Ilizarov ring fixator. Mean flexion of the knee was pre-operatively 86.66 degrees (80-90 degrees). The mean extension angle at the last follow-up was 168.3 degrees (165-170). The mean knee society score (KSS) was 44.3 (35-50), mean KSS functional score was 43.3 (0-65). One patient had satisfactory outcomes and could stand without walking aids and walks on extended knee with walking aids. Arthrodesis of knee or creating a stiff knee in the most extended position may be most effective for severe, fixed contractures.With the gradual, calculated distraction, the Ilizarov apparatus is an effective tool for treating severe cases of knee contracture

Design of a Compact Low-Loss Phase Shifter Based on Optical Phase Change Material

We propose the design of a nonvolatile,low-lossopticalphase shifter based on optical phase change material(O-PCM).The opticalphase change material Ge2Sb2Se4Te1(GSST), which exhibitslow lossat telecommunication wavelength1.55 μmas compared to other commonly used O-PCMs, is usedin this work as the active material. Instead of direct interaction of the waveguide mode with the O-PCM, the design utilizescouplingbetween the primary SiN strip waveguide andawaveguide formed by O-PCM, in itsamorphous state.Thephase matching in the amorphous state inhibits theinteraction of the waveguide mode withGSST in itshighly lossy crystalline state resulting in low loss operation.Due to a high differential refractive index between the two states of GSST, the design requires a very small length of the phase shifter to accumulate the desired phase difference.The overall response of the Mach-Zehnder Interferometer (MZI) configurationusing the designedphase shiftershows that the design can be used to obtain optical switching with avery small insertion loss and crosstalk over the entire C-band

Associations between Overall and Abdominal Obesity and Suicidal Ideation among US Adult Women

Obesity is associated with increased risks for mental disorders. This study examined associations of obesity indicators including body mass index (BMI), waist circumference, and waist-height ratio with suicidal ideation among U.S. women. We analyzed data from 3,732 nonpregnant women aged ≥20 years who participated in the 2005–2008 National Health and Nutrition Examination Survey. We used anthropometric measures of weight, height, and waist circumference to calculate BMI and waist-height ratio. Suicidal ideation was assessed using the Item 9 of the Patient Health Questionnaire-9. Odds ratios with 95% conference intervals were estimated using logistic regression analyses after controlling for potential confounders. The age-adjusted prevalence of suicidal ideation was 3.0%; the prevalence increased linearly across quartiles of BMI, waist circumference, and waist-height ratio (P for linear trend <0.01 for all). The positive associations of waist circumference and waist-height ratio with suicidal ideation remained significant (P < 0.05) after adjustment for sociodemographics, lifestyle-related behavioral factors, and having either chronic conditions or current depression. However, these associations were attenuated after both chronic conditions and depression were entered into the models. Thus, the previously reported association between obesity and suicidal ideation appears to be confounded by coexistence of chronic conditions and current depression among women of the United States