Does Openness to Trade Make Countries More Vulnerable to Sudden Stops, or Less? Using Gravity to Establish Causality

Openness to trade is one factor that has been identified as determining whether a country is prone to sudden stops in capital inflows, crashes in currencies, or severe recessions. Some believe that openness raises vulnerability to foreign shocks, while others believe that it makes adjustment to crises less painful. Several authors have offered empirical evidence that having a large tradable sector reduces the contraction necessary to adjust to a given cut-off in funding. This would help explain lower vulnerability to crises in Asia than in Latin America. Such studies may, however, be subject to the problem that trade is endogenous. Using the gravity instrument for trade openness, which is constructed from geographical determinants of bilateral trade, this paper finds that openness indeed makes countries less vulnerable, both to severe sudden stops and currency crashes, and that the relationship is even stronger when correcting for the endogeneity of trade.

Role of Peptide Backbone Conformation on Biological Activity of Chemotactic Peptides

To investigate the role of peptide backbone conformation on the biological activity of chemotactic peptides, we synthesized a unique analog of N-formyl-Met-Leu-Phe-OH incorporating the C α,α disubstituted residue, dipropylglycine (Dpg) in place of Leu. The conformation of the stereochemically constrained Dpg analog was examined in the crystalline state by x-ray diffraction and in solution using NMR, IR, and CD methods. The secretagogue activity of the peptide on human neutrophils was determined and compared with that of a stereochemically constrained, folded type II β-turn analog incorporating 1-aminocyclohexanecarboxylic acid (Ac6c) at position 2 (f-Met- Ac6c -Phe-OMe), the parent peptide (f-Met-Leu-Phe-OH) and its methyl ester derivative (f-Met-Leu-Phe-OMe). In the solid state, the Dpg analog adopts an extended β-sheet-like structure with an intramolecular hydrogen bond between the NH and CO groups of the Dpg residue, thereby forming a fully extended (C5) conformation at position 2. The ϕ and ψ values for Met and Phe residues are significantly lower than the values expected for an ideal antiparallel beta conformation causing a twist in the extended backbone both at the N and C termini. Nuclear magnetic resonance studies suggest the presence of a significant population of the peptide molecules in an extended antiparallel β conformation and the involvement of Dpg NH in a C5 intramolecular hydrogen bond in solutions of deuterated chloroform and deuterated dimethyl sulfoxide. IR studies provide evidence for the presence of an intramolecular hydrogen bond in the molecule and the antiparallel extended conformation in chloroform solution. CD spectra in methanol, trifluoroethanol, and trimethyl phosphate indicate that the Dpg peptide shows slight conformational flexibility, whereas the folded Ac6c analog is quite rigid. The extended Dpg peptide consistently shows the highest activity in human peripheral blood neutrophils, being approximately 8 and 16 times more active than the parent peptide and the folded Ac6c analog, respectively. However, the finding that all four peptides have ED50 (the molar concentration of peptide to induce half-maximal enzyme release) values in the 10(-8)-10(-9) M range suggests that an induced fit mechanism may indeed be important in this ligand-receptor interaction. Moreover, it is also possible that alterations in the backbone conformation at the tripeptide level may not significantly alter the side chain topography and/or the accessibility of key functional groups important for interaction with the receptor

Field Localization and Enhancement of Phase Locked Second and Third Harmonic Generation in Absorbing Semiconductor Cavities

We predict and experimentally observe the enhancement by three orders of magnitude of phase mismatched second and third harmonic generation in a GaAs cavity at 650nm and 433nm, respectively, well above the absorption edge. Phase locking between the pump and the harmonics changes the effective dispersion of the medium and inhibits absorption. Despite hostile conditions the harmonics become localized inside the cavity leading to relatively large conversion efficiencies. Field localization plays a pivotal role and ushers in a new class of semiconductor-based devices in the visible and UV ranges

Factors associated with survival during high frequency oscillatory ventilation in children

Our aim is to determine indicators of survival in children with severe hypoxic respiratory failure (HRF) after transition to high-frequency oscillatory ventilation (HFOV). Single-center retrospective examination of children with HRF transitioned to HFOV. Blood gases and ventilator settings 24 hours prior to and 48 hours after HFOV in survivors and nonsurvivors were evaluated. Sixty-two children with mean age of 7 years and mean weight of 26 kg were included with an observed mortality of 29%. Mean airway pressures (Paw), oxygenation index (OI), arterial oxygen partial pressure (PaO2)/fraction of inspired oxygen (FiO2) (P/F) ratio, pH, bicarbonate, and arterial carbon dioxide partial pressure were similar prior to HFOV in survivors and nonsurvivors. During HFOV, mean OI and P/F ratio improved in both groups with an average Paw increase of ∼10 cm H2O. Survivors had lower OI than nonsurvivors (21 ± 0.9 vs. 26.5 ± 2.2; p 200. Survivors had higher pH than nonsurvivors at 36 hours (7.40 ± 0.01 vs. 7.32 ± 0.02; p < 0.05), higher bicarbonate levels (27.1 ± 0.7 vs. 23.9 ± 1.3 mEq/L), and similar arterial carbon dioxide partial pressure with less oscillatory support (i.e., hertz and amplitude). Inhaled nitric oxide was used in 53% of patients with improvements in oxygenation but with no effect on mortality. HFOV improves oxygenation in children with severe HRF. Nonsurvivors can be distinguished from survivors at 24 to 36 hours during HFOV by higher OI, metabolic acidosis, and higher oscillatory support. These data may assist in prognostication or timing of initiating alternative therapies, such as extracorporeal membrane oxygenation

IRQX: A Framework for Information Retrieval Algorithms Using Query Expansion Techniques

The number of information retrieval users and their operations are continuously increasing with the rapid growth of internet technologies. Information Retrieval is one of the most prevalent operations that is frequently used by the Internet users. The process of Information Retrieval may cause two problems. First, the search engine may retrieve irrelevant documents and second it may fail to retrieve the relevant documents. Many approaches have been proposed to improve the query representation by reformulating the queries. Among them, Query Expansion (QE) is one of the most effective approaches. In Information Retrieval, Query Expansion is referred to as the techniques or algorithms that reformulate the original query by adding or modifying new terms into the query, in order to achieve better retrieval results. This paper contributed to the process of information retrieval algorithms using query expansion techniques to improve the precision and recall. The proposed framework Information Retrieval algorithms using Query Expansion (IRQX) facilitates the users to select their choice of algorithms based on their need

Modular networks emerge from multiconstraint optimization

Modular structure is ubiquitous among complex networks. We note that most such systems are subject to multiple structural and functional constraints, e.g., minimizing the average path length and the total number of links, while maximizing robustness against perturbations in node activity. We show that the optimal networks satisfying these three constraints are characterized by the existence of multiple subnetworks (modules) sparsely connected to each other. In addition, these modules have distinct hubs, resulting in an overall heterogeneous degree distribution.Comment: 5 pages, 4 figures; Published versio

Assessment of Mechanical Problems for Centrifugal Pumps in Eastern Uttar Pradesh, India

Centrifugal pumps are vital property of the agriculture sector. A good quality pump can assure uninterrupted water supply to irrigate crops. The consumer of agriculture sector is largely illiterate and shortcoming of the pumps is faced by farmers in the terms of wastage of money. The study has carried out to grow awareness about the technique among the farmers. In such cases reliable functioning of the pump is an absolute necessity. The major objective of this paper is the analysis of the component life and frequency of occurrence of problem in a centrifugal pump. A survey was conducted among the farmers of tube well irrigated areas and subsequently analyzed. It was found that frequency of occurrence of leakage and excessive noise are 3.17 and 3.11 years which is the most frequent shortcoming found under study. It was also found that the mean life of centrifugal pump components i.e. Bearing, Packing, Impeller, shaft and casing was found as 3.56 , 3.18 , 3.61, 4.20 and 4.64 years respectively. The package of seal has longest life for the operation of centrifugal pump. For the frequency of occurrence of these problems, four the category scale has also chosen. Value 1 refers to always occurs, 2 most frequent occurs, 3 occasionally occurs, 4 – rarely occurs. Under the study a centrifugal pump for irrigating crop has treated as vital input, which is also a key factor in boosting productivity, for the national development and food security

Chirped pulse Raman amplification in plasma: high gain measurements

High power short pulse lasers are usually based on chirped pulse amplification (CPA), where a frequency chirped and temporarily stretched ``seed'' pulse is amplified by a broad-bandwidth solid state medium, which is usually pumped by a monochromatic ``pump'' laser. Here, we demonstrate the feasibility of using chirped pulse Raman amplification (CPRA) as a means of amplifying short pulses in plasma. In this scheme, a short seed pulse is amplified by a stretched and chirped pump pulse through Raman backscattering in a plasma channel. Unlike conventional CPA, each spectral component of the seed is amplified at different longitudinal positions determined by the resonance of the seed, pump and plasma wave, which excites a density echelon that acts as a "chirped'" mirror and simultaneously backscatters and compresses the pump. Experimental evidence shows that it has potential as an ultra-broad bandwidth linear amplifier which dispenses with the need for large compressor gratings

Tunneling Study of the Charge-Ordering Gap on the Surface of La0.350_{0.350}Pr0.275_{0.275}Ca0.375_{0.375}MnO3_3 Thin Films

Variable temperature scanning tunneling microscopy/spectroscopy studies on (110) oriented epitaxial thin films of La$_{0.350}$Pr$_{0.275}$Ca$_{0.375}$MnO$_3$ are reported in the temperature range of 77 to 340 K. The films, grown on lattice matched NdGaO$_3$ substrates, show a hysteretic metal-insulator transition in resistivity at 170 K. The topographic STM images show step-terrace morphology while the conductance images display a nearly homogeneous surface. The normalized conductance spectra at low temperatures (T$<$150 K) show an energy gap of 0.5 eV while for T$\geq$180 K a gap of 0.16 eV is found from the activated behavior of the zero bias conductance. The presence of energy gap and the absence of phase separation on the surface over more than 2 $\mu$m$\times$2 $\mu$m area contradicts the metallic behavior seen in resistivity measurements at low temperatures. We discuss the measured energy gap in terms of the stabilization of the insulating CO phase at the film surface.Comment: 5 pages, 5 figures To appear in Phys. Rev.