623 research outputs found
Currency Unions in Prospect and Retrospect
We critically review the recent literature on currency unions, and discuss the methodological challenges posed by the empirical assessment of their costs and benefits. In the process, we provide evidence on the economic effects of the euro. In particular, and in contrast with estimates of the trade effect of other currency unions, we find that the impact of the euro on trade has been close to zero. After reviewing the costs and benefits, we conclude with some open questions on normative and positive aspects of the theory of currency unions, emphasizing the need for a unified welfare-based framework to weigh their costs and gains.Currency union, Integration, Exchange Rage, Trade
Trading Partners and Trading Volumes: Implementing the Helpman-Melitz-Rubinstein Model Empirically
Helpman, Melitz, and Rubinstein (2008)-HMR-present a rich theoretical model to study the determinants of bilateral trade flows across countries. The model is then empirically implemented through a two-stage estimation procedure. This note seeks to clarify some econometric aspects of the estimation approach used by HMR and explore the consequences of possible departures from the maintained distributional assumptions.Gravity equation, Heteroskedasticity, Jensens inequality
On the Existence of the Maximum Likelihood Estimates for Poisson Regression
We note that the existence of the maximum likelihood estimates for Poisson regression depends on the data configuration. Because standard software does not check for this problem, the practitioner may be surprised to find that in some applications estimation of the Poisson regression is unusually difficult or even impossible. More seriously, the estimation algorithm may lead to spurious maximum likelihood estimates. We identify the signs of the non-existence of the maximum likelihood estimates and propose a simple empirical strategy to single out the regressors causing this type of identification failure.Poisson estimation, gravity equation
Is it different for zeros? Discriminating between models for non-negative data with many zeros
In many economic applications, the variate of interest is non-negative and its distribution is characterized by a mass-point at zero and a long right-tail. Many regression strategies have been proposed to deal with data of this type. Although there has been a long debate in the literature on the appropriateness of different models, formal statistical tests to choose between the competing specifications, or to assess the validity of the preferred model, are not often used in practice. In this paper we propose a novel and simple regression-based specification test that can be used to test these models against each other.
Estimating the Extensive Margin of Trade
Understanding and quantifying the determinants of the number of sectors or firms exporting in a given country is of relevance for the assessment of trade policies. Estimation of models for the number of sectors, however, poses a challenge because the dependent variable has both a lower and upper bound, implying that the partial effects
of the explanatory variables on the conditional mean of the dependent variable cannot be constant and must approach zero as the dependent variable approaches the bounds.
We argue that ignoring these bounds by using OLS or count-data models that ignore the upper bound can lead to erroneous conclusions due to the model's misspecification.
We propose a flexible specification that accounts for the doubly-bounded nature of the dependent variable. We empirically investigate the problem and the proposed solution, and find significant differences between estimates obtained with the proposed estimator and those obtained with standard approaches
Vlasništvo nad nekretninama crkvenih i samostanskih ustanova na orebićkome području u 19. stoljeću
U radu se na temelju katastarske dokumentacije nastale u sklopu zemljišne izmjere, koju je Austrija provela u prvoj polovici 19. stoljeća, analizira vlasništvo nad nekretninama crkava i samostanskih ustanova na orebićkome području. Iako su dubrovačke
zakonske odredbe od polovice 14. stoljeća ograničile oporučno ostavljanje nekretnina svim crkvenim ustanovama, mnoge su od njih kupovinama, donacijama ili oporučnim legatima došle u posjed pozamašnoga broja nekretnina. U 19. stoljeću samostanski redovi bilježe mnogo veće posjede u vlasništvu od crkava, a na orebićkome
području najveći broj građevinskih objekata i najveće zemljišne posjede ima dominikanski samostan iz Dubrovnika
Hypercholesterolemia promotes early renal dysfunction in apolipoprotein E-deficient mice
<p>Abstract</p> <p>Background</p> <p>Aging and dyslipidemia are processes which can lead to deleterious consequences to renal function. Therefore, the aim of this study was to determine the effects of both hypercholesterolemia and aging on renal function in mice.</p> <p>Methods</p> <p>Male hypercholesterolemic apolipoprotein E-deficient mice (ApoE, n = 13) and age-matched C57BL/6 control mice (C57, n = 15) were studied at 2 (young) and 8 (adult) month-old. At each time point, animals were placed in metabolic cages for 24 hours to urine volume and urinary creatinine quantification. Blood samples were collected for serum cholesterol, urea and creatinine measurements. Glomerular filtration rate (GFR) was estimated through creatinine clearance determination. Mesangial expansion was evaluated by Periodic Acid Schiff staining, renal fibrosis was determined through Masson's trichrome staining and neuronal nitric oxide synthase (nNOS) expression in the kidney was performed by Western Blotting. To statistical analysis two-way ANOVA followed by Fisher's <it>post hoc </it>test was used.</p> <p>Results</p> <p>Total plasma cholesterol was increased about 5-fold in ApoE mice at both time points compared to C57 animals. At 2-month-old, GFR was already markedly reduced in ApoE compared to C57 mice (187 ± 28 vs 358 ± 92 μL/min, p < 0.05). Adult C57 (-77%) and ApoE (-50%) mice also presented a significant reduction of GFR. In addition, serum urea was significantly increased in young ApoE animals compared to C57 mice (11 ± 1.3 vs 7 ± 0.9 mmol/L, p < 0.01). A significant mesangial expansion was observed at 2-month old ApoE mice compared to C57 mice (35 ± 0.6 vs 30 ± 0.9%, respectively, p < 0.05), which was aggravated at 8-month old animals (40 ± 3 and 35 ± 3%, respectively). Tubulointersticial fibrosis was augmented at both young (17 ± 2%, p < 0.05) and adult (20 ± 1%, p < 0.05) ApoE mice compared to respective C57 age controls (8 ± 1 and 12 ± 2%, respectively). The expression of nNOS was markedly reduced in a time-dependent manner in both strains.</p> <p>Conclusions</p> <p>These data show that both hypercholesterolemia and aging contribute to the loss of renal function in mice.</p
Crotoxin from Crotalus durissus terrificus venom: In vitro cytotoxic activity of a heterodimeric phospholipase A2 on human cancer-derived cell lines
Accepted manuscriptCrotoxin (CTX), a heterodimeric phospholipase present in venom of snakes of the genus Crotalus, has demonstrated a broad spectrum of pharmacological properties, such as antimicrobial, hemostatic, and antitumoral. However, the precise mechanism of its cytotoxicity and antitumoral properties remains to be determined. Therefore, in the present study, we isolated crotoxin (F1 CTX) through two steps DEAE-Sepharose and Heparin-Sepharose FF chromatography. The C-terminal sequence of the A- and B-chain protein fragment was determined by LC-MS/MS mass spectrometry, which showed 100% identity to crotoxin structure. In order to investigate its cytotoxic effects, we demonstrated that the F1 CTX fraction at 0-30 μg/mL concentrations for 72 h presented a heterogeneous response profile on nine human cancer-derived cell lines from four tumor types (pancreatic, esophagus, cervical cancer, and glioma). The glioma (GAMG and HCB151) and pancreatic (PSN-1 and PANC-1) cancer cells showed a higher sensitivity with IC50 of <0.5, 4.1, 0.7 and < 0.5 μg/mL, respectively. Conversely, F1 CTX does not reduce the viability of normal cells. On the other hand, cervical (SiHa) and esophagus (KYSE270) cancer cell lines presented higher resistance, with IC50 higher than 30.2 and 8.7 μg/mL, respectively. Moreover, F1 CTX did not affect cell cycle distribution under the conditions evaluated and seems to be more cytotoxic than cytostatic. The pro-apoptotic effect of F1 CTX treatment was demonstrated in glioma (HCB151) cell line. In addition, crotoxin revealed a potential to initiate cell responses such as DNA damage in glioma (HCB151) and pancreatic cancer by H2AX activity induction. Conversely, F1 CTX does not reduce the viability of normal cells. Importantly, the comparison of F1 CTX effect with standard chemotherapeutic agents demonstrated a greater cytotoxic potential in the majority of tumor types (glioma, pancreatic, and cervical cancer). On the other hand, F1 CTX was less cytotoxic in esophageal cell lines compared to the gemcitabine agent used in clinical practice. Therefore, this work showed that F1 CTX has a cytotoxic activity and pro-apoptotic potential, contributing to the knowledge about the F1 crotoxin properties as well as its possible use in cancer research, particularly in glioma and pancreatic cancer cell lines.FAPESP, the Hermínio Ometto University Center, the Hospital de Cancer de Barretos and FINEP (MCTI/FINEP/MS/SCTIE/DECIT-01/2013 - FPXII-BIOPLAT). We acknowledge the Mass Spectrometry Laboratory of the Brazilian Biosciences National Laboratory, CNPEM, Campinas, Brazil, for providing support on mass spectrometry analysisinfo:eu-repo/semantics/publishedVersio
Physical training improves cardiopulmonary functional capacity and increases cytokine IL-10 levels in individuals with Chagas disease
Purpose: To evaluate cardiopulmonary functional capacity and the production of cytokines in patients with and without Chagas disease, and with and without hypertension, after short and long-term exercise.Methods: In a case-controlled study, 56 participants who attended the Chagas Disease Laboratory at the State University of Maringa (LDC/UEM) and Basic Health Units (UBS) in Maringa that agreed to participate. The participants were divided into the following groups: 16 with Chagas disease (CHD group), 21 with systemic arterial hypertension (SAH group) and 19 normal individuals without these morbidities (NI group). Each participant performed the 6-min walk test (6MWT), and a 12-week physical training program. Pro-inflammatory and anti-inflammatory cytokines were measured before and after physical training.Results: The CHD group presented good performance in the 6MWT, with no significant differences in distance traveled or perceived exertion (p > 0.05) compared with the NI group. After physical training, the 6MWT results were significantly better, with significant decreases in systolic and diastolic blood pressure, in the SAH group (p = 0.0409; and p = 0.0377, respectively) and NI group (p = 0.0180; and p = 0.0431, respectively) and a significant increase in the levels of the anti-inflammatory cytokine interleukin-10 (IL-10; p < 0.05) in all three groups. The NI group exhibited a significant increase (p < 0.05) in the serum levels of the pro-inflammatory cytokines IL-6, IL-17 and tumor necrosis factor (all p< 0.05).Conclusion: All of the participants presented improvements in cardiopulmonary functional capacity and good prognosis, indicating the protective effect of IL-10 production and the benefits of physical training.Keywords: Chagas disease, Six-minute walk test, Physical training, Cytokines, Cardiopulmonary function capacity, Hypertensio
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