Purchasing Power Parity and Country Characteristics: Evidence from Time Series Analysis

This paper investigates the relationships between country characteristics and the validity of PPP. We use three alternative time series methods to test for the stationarity of real exchange rates for each of the 72 countries over the period from 1976 to 2005. Our result shows that the evidence of PPP exhibits geographic difference. It is most likely to find stationary real exchange rates for European countries, whereas it is least likely to obtain the result of supporting PPP for Asian countries. We then use a probit regression model to examine if county characteristics are related to the validity of PPP. The probit regression result reveals that the validity of PPP decreases with inflation rate and increases with nominal exchange rate volatility.Purchasing power parity, Country characteristics, Unit root tests

Mixture Selection, Mechanism Design, and Signaling

We pose and study a fundamental algorithmic problem which we term mixture selection, arising as a building block in a number of game-theoretic applications: Given a function $g$ from the $n$-dimensional hypercube to the bounded interval $[-1,1]$, and an $n \times m$ matrix $A$ with bounded entries, maximize $g(Ax)$ over $x$ in the $m$-dimensional simplex. This problem arises naturally when one seeks to design a lottery over items for sale in an auction, or craft the posterior beliefs for agents in a Bayesian game through the provision of information (a.k.a. signaling). We present an approximation algorithm for this problem when $g$ simultaneously satisfies two smoothness properties: Lipschitz continuity with respect to the $L^\infty$ norm, and noise stability. The latter notion, which we define and cater to our setting, controls the degree to which low-probability errors in the inputs of $g$ can impact its output. When $g$ is both $O(1)$-Lipschitz continuous and $O(1)$-stable, we obtain an (additive) PTAS for mixture selection. We also show that neither assumption suffices by itself for an additive PTAS, and both assumptions together do not suffice for an additive FPTAS. We apply our algorithm to different game-theoretic applications from mechanism design and optimal signaling. We make progress on a number of open problems suggested in prior work by easily reducing them to mixture selection: we resolve an important special case of the small-menu lottery design problem posed by Dughmi, Han, and Nisan; we resolve the problem of revenue-maximizing signaling in Bayesian second-price auctions posed by Emek et al. and Miltersen and Sheffet; we design a quasipolynomial-time approximation scheme for the optimal signaling problem in normal form games suggested by Dughmi; and we design an approximation algorithm for the optimal signaling problem in the voting model of Alonso and C\^{a}mara

Assembling a cellulase cocktail and a cellodextrin transporter into a yeast host for CBP ethanol production

Background: Many microorganisms possess enzymes that can efficiently degrade lignocellulosic materials, but donot have the capability to produce a large amount of ethanol. Thus, attempts have been made to transform suchenzymes into fermentative microbes to serve as hosts for ethanol production. However, an efficient host for aconsolidated bioprocess (CBP) remains to be found. For this purpose, a synthetic biology technique that cantransform multiple genes into a genome is instrumental. Moreover, a strategy to select cellulases that interactsynergistically is needed.Results: To engineer a yeast for CBP bio-ethanol production, a synthetic biology technique, called “promoter-basedgene assembly and simultaneous overexpression” (PGASO), that can simultaneously transform and express multiplegenes in a kefir yeast, Kluyveromyces marxianus KY3, was recently developed. To formulate an efficient cellulasecocktail, a filter-paper-activity assay for selecting heterologous cellulolytic enzymes was established in this study andused to select five cellulase genes, including two cellobiohydrolases, two endo-β-1,4-glucanases and onebeta-glucosidase genes from different fungi. In addition, a fungal cellodextrin transporter gene was chosen totransport cellodextrin into the cytoplasm. These six genes plus a selection marker gene were one-step assembledinto the KY3 genome using PGASO. Our experimental data showed that the recombinant strain KR7 could expressthe five heterologous cellulase genes and that KR7 could convert crystalline cellulose into ethanol.Conclusion: Seven heterologous genes, including five cellulases, a cellodextrin transporter and a selection marker,were simultaneously transformed into the KY3 genome to derive a new strain, KR7, which could directly convertcellulose to ethanol. The present study demonstrates the potential of our strategy of combining a cocktailformulation protocol and a synthetic biology technique to develop a designer yeast host

TGF-β inhibits IL-1β-activated PAR-2 expression through multiple pathways in human primary synovial cells

To investigate the mechanism how Transforming growth factor-β(TGF-β) represses Interleukin-1β (IL-1β)-induced Proteinase-Activated Receptor-2 (PAR-2) expression in human primary synovial cells (hPSCs). Human chondrocytes and hPSCs isolated from cartilages and synovium of Osteoarthritis (OA) patients were cultured with 10% fetal bovine serum media or serum free media before treatment with IL-1β, TGF-β1, or Connective tissue growth factor (CTGF). The expression of PAR-2 was detected using reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting. Collagen zymography was performed to assess the activity of Matrix metalloproteinases-13 (MMP-13). It was demonstrated that IL-1β induces PAR-2 expression via p38 pathway in hPSCs. This induction can be repressed by TGF-β and was observed to persist for at least 48 hrs, suggesting that TGF-β inhibits PAR-2 expression through multiple pathways. First of all, TGF-β was able to inhibit PAR-2 activity by inhibiting IL-1β-induced p38 signal transduction and secondly the inhibition was also indirectly due to MMP-13 inactivation. Finally, TGF-β was able to induce CTGF, and in turn CTGF represses PAR-2 expression by inhibiting IL-1β-induced phospho-p38 level. TGF-β could prevent OA from progression with the anabolic ability to induce CTGF production to maintain extracellular matrix (ECM) integrity and to down regulate PAR-2 expression, and the anti-catabolic ability to induce Tissue inhibitors of metalloproteinase-3 (TIMP-3) production to inhibit MMPs leading to avoid PAR-2 over-expression. Because IL-1β-induced PAR-2 expressed in hPSCs might play a significantly important role in early phase of OA, PAR-2 repression by exogenous TGF-β or other agents might be an ideal therapeutic target to prevent OA from progression

Carbon Dioxide Angiography in Lower Limbs: A Prospective Comparative Study With Selective Iodinated Contrast Angiography

This was a prospective comparison of the accuracy and image quality of carbon dioxide digital subtraction angiography (CO2 DSA) and iodinated contrast digital subtraction angiography (ICDSA) in evaluating lower extremity arteries and patient tolerance of the procedures. Selective DSA was performed in 14 Taiwanese patients who were diagnosed with peripheral artery occlusive disease (PAOD). Both contrast materials were administered through mechanical injectors. Post-processing of the image used pixel shifting. Images of vessels were divided into 22 anatomic segments and evaluated by two experienced radiologists. A four-point scale was used to classify diseased vessels. Two interpreters rated the CO2 DSA image against the ICDSA image on a three-point scale. Patient tolerance was assessed from verbal descriptions. Cohen's kappa was used to determine interobserver agreement and descriptive statistics were used to summarize patient experience. Interobserver agreement ranged from fair to excellent, with most being good or excellent. Three patients (21.4%) could not tolerate the whole procedure and nine patients (64.3%) reported discomfort during the CO2 DSA procedure. CO2 DSA image quality was better for the thigh than the distal runoff and pelvic regions. Our results showed that selective CO2 DSA cannot replace ICDSA as a routine diagnostic tool for PAOD because it does not give images of comparative quality

Late onset of large benign ductus arteriosus aneurysm presented with increased nuchal translucency and cystic hygroma at first trimester Down syndrome screening

AbstractObjectiveFetal ductus arteriosus aneurysm (DAA) is a rare but potentially risky congenital heart disease. It is often not diagnosed until the third trimester because of its asymptomatic nature and late onset. In rare occasions, DAA may result in serious complications; therefore, prenatal diagnosis is helpful.Case ReportHerein, we report the case of a foetus with cystic hygroma and increased nuchal translucency in the first trimester (but regressed at 20-week anomalous scan). Karyotyping indicated a 46 XY genotype. A large vascular mass was noted at the apex of the left lung by Doppler ultrasound at 38 weeks of gestation, with a diameter of 12.5 mm. After birth, echocardiography showed a patent ductus arteriosus with aneurysmal dilatation (17 mm as the largest diameter); thus, DAA was impressed. Chest computed tomography and three-dimensional angiography confirmed the large aneurysmal dilatation of the ductus arteriosus with a closed end at the pulmonary arterial side.ConclusionThe male infant survived, but presented mild respiratory distress at birth. He was discharged at 24 days of age. At that time, DAA had regressed partially (diameter of 8.5 mm and much less blood flow), and it fully regressed at 40 days of age