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This paper develops an estimation methodology for network data generated from a system of simultaneous equations, which allows for network interdependencies via spatial lags in the endogenous and exogenous variables, as well as in the disturbances. By allowing for higher-order spatial lags, our specification provides important flexibility in modeling network interactions. The estimation methodology builds, among others, on the two-step generalized method of moments estimation approach introduced in Kelejian and Prucha (1998, Journal of Real Estate Finance and Economics 17, 99–121; 1999, International Economic Review 40, 509–533; 2004, Journal of Econometrics 118, 27–50). The paper considers limited and full information estimators, and one- and two-step estimators, and establishes their asymptotic properties. In contrast to some of the earlier two-step estimation literature, our asymptotic results facilitate joint tests for the absence of all forms of network spillovers.

This paper seeks to understand the forces determining the pattern of asset ownership in global value chains. We augment a standard model of vertical integration rooted in the property-rights theory to account for fixed integration costs and derive four channels of influence for the cross-country and cross-sector pattern of asset ownership: the relative investment intensity of sectors and countries; the relative density of markets; the relative reliance on and importance of supplying and producing country-sectors; and the relative importance of fixed integration costs. We confirm the relevance of these determinants for the observed pattern of asset ownership in a large panel of worldwide directed ownership linkages. ISSN:0014-2921 ISSN:1873-572X

This paper proposes a Bayesian estimation framework for panel data sets with binary dependent variables where a large number of cross-sectional units are observed over a short period of time and cross-sectional units are interdependent in more than a single network domain. The latter provides for a substantial degree of flexibility towards modeling the decay function in network neighborliness (e.g., by disentangling the importance of rings of neighbors) or towards allowing for several channels of interdependence whose relative importance is unknown ex ante. Besides the flexible parameterization of cross-sectional dependence, the approach allows for simultaneity of the equations. These features should make the approach interesting for applications in a host of contexts involving structural and reduced-form models of multivariate choice problems at micro-, meso-, and macro-economic levels. The paper outlines the estimation approach, illustrates its suitability by simulation examples, and provides an application to study exporting and foreign ownership among potentially interdependent firms in the specialized and transport machinery sector in the province of Guangdong., Journal of Applied Econometrics, 37 (7), ISSN:0883-7252, ISSN:1099-1255, ISSN:0021-8901, ISSN:1365-2664

This chapter assesses the role of a larger degree of common language use between the populations of two countries on the so-called extensive product margin of trade. We focus on the overlap of products exported or imported between any pair of countries. The results suggest that the effect of varying aspects of sharing a common language on the variety overlap is both positive and important. The effect of sharing a common spoken language exceeds the one of common native language, implying that a larger overlap in language proficiency is quantitatively more important than a higher cultural proximity.

Background: Patients with early or locally advanced breast cancer achieving a pathologic complete response (pCR) after neoadjuvant chemotherapy have a lower risk for recurrence or death compared to patients with residual invasive cancer. In the future, breast surgery might be avoided in patients in whom the presence of residual tumor after neoadjuvant therapy can be ruled out with very high confidence. Magnetic resonance imaging (MRI) has been shown to be the most accurate radiologic tool in breast cancer diagnostics and follow-up care. Therefore, we investigated the diagnostic accuracy of contrast-enhanced MRI to predict a pathological complete remission after neoadjuvant chemotherapy. Methods: This retrospective study included all non-metastatic breast cancer patients treated with neoadjuvant chemotherapy followed by a contrast-enhanced MRI and breast cancer surgery at our institution between 09/2006 and 05/2016. Three specialized breast radiologists, blinded to the clinical and pathological data, reevaluated all preoperative MRI scans and recorded the presence or absence of contrast enhancement as indicator for residual cancer. pCR was defined as no invasive tumor in breast and axilla (ypT0/is N0), however 3 alternative definitions were investigated as well (ypT0 N0, ypT0/is and ypT). Cross tables were used to calculate sensitivity, specificity, pCR-predictive value (PPV), non-pCR-predictive value (NPV) and accuracy. P-values reflecting PPV and NPV differences between various patient subgroups were calculated with Fisher's exact test. The Kaplan-Meier method was used for estimates of distant-recurrence-free survival (DRFS) and overall survival (OS). Results: In total, 246 patients fulfilled the inclusion criteria and were evaluated. Overall pCR and radiologic complete remission (rCR) rate were 29% and 45%, respectively. Only 48% of rCR corresponded to a pCR (PPV). Conversely, in 87% of cases, residual tumor in the MRI was pathologically confirmed (NPV). The sensitivity to detect a pCR was 75%, while specificity and accuracy were 67% and 69%, respectively. The diagnostic performance of MRI to predict treatment response varied between different histologic and molecular tumor subtypes, however there were little differences between the 4 pCR definitions. The PPV was significantly lower in the hormone-receptor(HR)-positive subgroup compared with the HR-negative subgroup (33% vs. 61%; P = 0.004), especially in luminal-A-like (7%) and lobular carcinomas (0%), respectively. Despite the low concordance (Kohens kappa -0.1), the prognostic value for distant recurrence-free survival was similar between rCR (HR 0.29) and pCR (HR 0.27), respectively. The median pathologic tumor size of residual disease in false-positive cases (rCR but no pCR) was 0.7 cm (SD 0.98 cm). Conclusion: Contrast-enhanced MRI does not accurately predict pCR after neoadjuvant chemotherapy in early or locally advanced breast cancer, especially in HR-positive tumors. However, in case of false rCR the dimension of residual disease is generally small. Since residual tumor tissue can be detected with high precision, preoperative breast MRI is still of value for operation planning. Citation Format: Gampenrieder SP, Peer A, Weismann C, Meissnitzer M, Rinnerthaler G, Webhofer J, Westphal T, Popovscaia M, Meissnitzer T, Reitsamer R, Hauser-Kronberger C, Egger H, Hergan K, Mlineritsch B, Greil R. Contrast-enhanced MRI does not accurately predict pathologic complete response (pCR) after neoadjuvant chemotherapy in early or locally advanced breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-02-02.

The relevance of mobile organic matter for the transport of Pb through soils has been shown through several studies. Up until this study, no investigation has been published on whether the adsorption of Pb alters the size and/or shape, and consequently the mobility, of organic substances. We hypothesize that the addition of Pb induces the formation of organic precipitates by intermolecular cross-linking. We extracted organic matter from forest floor samples and determined the size and shape of the organic colloids via small angle X-ray scattering (SAXS) and their zeta potential. Measurements were conducted at three Pb concentrations (0, 0.05 and 0.10 mmol l−1) and at varying pH values (2.5, 4, 7, and 8). Under neutral and alkaline conditions, we observed geometrically weakly defined colloids possessing a maximal dimension of 33 nm. Either decreasing the pH value or increasing the Pb concentration induced the formation of organic matter rods with a corresponding decrease in the maximal dimension to 24 nm. Zeta potential measurements indicate that this decrease is due to a reduction of the repulsion between functional groups of the natural polyelectrolytes. SAXS curves indicate the formation of polymolecular Pb–organic agglomerates at pH 4 and 0.1 mM Pb, which exhibit a high colloidal stability. We conclude from our results that Pb is not merely passively co-transported by organic matter in soils but that it may also accelerate its mobile sorbents through the compaction of organic molecules or by the formation of highly mobile organic colloids.

This paper assesses the role of intra-sectoral spillovers in total factor productivity across Chinese producers in the chemical industry. We use a rich panel data-set of 12,552 firms observed over the period 2004-2006 and model output by the firm as a function of skilled and unskilled labor, capital, materials, and total factor productivity, which is broadly defined. The latter is a composite of observable factors such as export market participation, foreign as well as public ownership, the extent of accumulated intangible assets, and unobservable total factor productivity. Despite the richness of our data-set, it suffers from the lack of time variation in the number of skilled workers as well as in the variable indicating public ownership. We introduce spatial spillovers in total factor productivity through contextual effects of observable variables as well as spatial dependence of the disturbances. We extend the Hausman and Taylor (1981) estimator to account for spatial correlation in the error term. This approach permits estimating the effect of time-invariant variables which are wiped out by the fixed effects estimator. While the original Hausman and Taylor (1981) estimator assumes homoskedastic error components, we provide spatial variants that allow for both homoskedasticity and heteroskedasticity. Monte Carlo results show, that our estimation procedure performs well in small samples. We find evidence of positive spillovers across chemical manufacturers and a large and significant detrimental effect of public ownership on total factor productivity.

This paper assesses the role of intra-sectoral spillovers in total factor productivity across Chinese producers in the chemical industry. We use a rich panel data-set of 12,552 firms observed over the period 2004-2006 and model output by the firm as a function of skilled and unskilled labor, capital, materials, and total factor productivity, which is broadly defined. The latter is a composite of observable factors such as export market participation, foreign as well as public ownership, the extent of accumulated intangible assets, and unobservable total factor productivity. Despite the richness of our data-set, it suffers from the lack of time variation in the number of skilled workers as well as in the variable indicating public ownership. We introduce spatial spillovers in total factor productivity through contextual effects of observable variables as well as spatial dependence of the disturbances. We extend the Hausman and Taylor (1981) estimator to account for spatial correlation in the error term. This approach permits estimating the effect of time-invariant variables which are wiped out by the fixed effects estimator. While the original Hausman and Taylor (1981) estimator assumes homoskedastic error components, we provide spatial variants that allow for both homoskedasticity and heteroskedasticity. Monte Carlo results show, that our estimation procedure performs well in small samples. We find evidence of positive spillovers across chemical manufacturers and a large and significant detrimental effect of public ownership on total factor productivity.

One of the oldest and largest literatures in empirical economics is concerned with the estimation of demand and supply of goods, services, and factors across national or subnational borders (see Leamer and Levinsohn, 1995). The respective empirical models specified and estimated are often referred to as gravity models, accruing to their functional-form similarity to Newton’s law of gravity in physics. As Newton’s model, gravity models of international trade or factor flows are (at least) double-indexed, involving a region or country of origin and a region or country of destination. Pooling such demand equations across pairs or regional units or even across cross-sectional units and time inevitably leads to a panel data structure of the data. This chapter is concerned with a host of issues that arise with the estimation of such models, respecting their panel econometric generic structure. The issues covered range from the estimation of double-indexed versus higher-indexed models, the estimation of fixed effects versus random effects models, issues of endogeneity, of approximation, estimation with missing or zero trade flow data, structural versus reduced-form estimation, the role of dynamics or cross-sectional dependence, and issues with specific applications.

In Zusammenarbeit zwischen zwei Betreibern und zwei Generatorherstellern wurden die Standerwicklungen von zwei hoch beanspruchten Motor-Generatorsatzen mit unterschiedlichen Online-Methoden untersucht. Die ausgewahlten Testmethoden spiegeln die verschiedenen Diagnosephilosophien dieser Gesellschaften wieder. Zusatzlich zu verschiedenen Teilentladungsmessystemen wurden Analysen der Kuhlluft hinsichtlich Ozon und anderen gasformigen Reaktionsprodukten sowie Korperschalldiagnosen angewendet. Um die Ubereinstimmung der Diagnosen zu uberprufen, wurden die Prufergebnisse unabhangig ausgewertet und getrennt in diesem Aufsatz kommentiert. Unterschiede wurden in einer gemeinsamen Schlussfolgerung diskutiert. Zufolge der verschiedenartigen Isolationsschaden ergaben sich interessante Erkenntnisse.

The synthesis and analysis of [14C]NVP VID4001, a specific vitamin D3-hydroxylase inhibitor is reported. The key intermediate is (R)-2-amino-1-phenyl-[1-14C]ethanol 9 synthesized in an effective, enantioselective approach using a borane reduction of phenacyl chloride 6 in the presence of (R)-oxazaborolidine-catalyst 2. After N-acylation of 9 the resulting amide 10 was converted to the oxazoline 12, which when treated with imidazole ring-opened to the title compound 1. Both reactions—ring-closure and ring-opening—went with complete configurational inversion. The secondary isotope effect induced splitting 13C-NMR signals enabling the quantification of the isotopic purity and thereby the specific activity of 1 Copyright © 1999 John Wiley & Sons, Ltd.

An engine plant in Salzgitter completed the plant-engineering in 1996 for a new manufacturing line for TDI-camshafts and - based on extensive cost evaluation - decided to invest into a heat treatment equipment, integrated into the manufacturing process. A special designed fixture-quench machine enables to quench the camshafts within tight tolerances (max. 0.1 mm axial distortion), which is well within the grinding stock. That installed fixture-quench technology led to the possibility, to completely eliminate a cold straithening operation, which -applied to such components of geometric complexity - would generate scrap rates of more than 10 % of the entire production.

Purpose: Surgical techniques, especially with a higher risk, must always critically considered. It is the objective of this paper to show that for complete removal of advanced pelvic endometriosis even partial bowel resection may be indicated to retain ovarian function. Material and Method: From February 1, 1985 through December 31, 1995 laparotomy was performed in 223 women at the Kreiskrankenhaus Neumarkt i.d.Opf. for advanced pelvic endometriosis. In 47 patients a complete section of the big bowel mostly including the sacrouterine ligaments had to be removed to resect all areas of endometriosis. In 12 of these patients the uterus together with a fallopian tube and some functional ovarian tissue was retained. All patients were clinically checked approximately eight weeks after surgery and were interviewed by telephone one to nine years later. Results: The analysis of pain as the cardinal symptom - we differetiated between lower abdominal pain in gener- al and dyspareunia and painful miction or defecation - resulted in an improvement in 2/3 to 3/4 of either group. Menstrual pain was lowered in 80% of the patients who underwent uterus-conserving surgery. The interval of menstrual bleeding was shortened in about 35% and extended in roughly 60%. Five pregnancies were achieved in eight patients who desired children. Two of these pregnancies resulted in early miscarriage, three in term delivery. Surgery was complicated by a rectovaginal fistula in one case. This fistula disappeared under conservative treatment. Conclusion: Inspite of new methods in the treatment of endometriosis radical surgery including the removal of bowel in advanced cases remains an important therapeutic option: Avoiding the disadvantages of hormonal withdrawal, satisfactory long-term results are achieved. In some cases women i desiring children may benefit from this therapy.

This paper considers a Hausman and Taylor (1981) panel data model that exhibits a Cliff and Ord (1973) spatial error structure. We analyze the small sample properties of a generalized moments estimation approach for that model. This spatial Hausman-Taylor estimator allows for endogeneity of the time-varying and time-invariant variables with the individual effects. For this model, the spatial effects estimator is known to be consistent, but its disadvantage is that it wipes out the effects of time-invariant variables, which are important for most empirical studies. Monte Carlo results show that the spatial Hausman-Taylor estimator performs well in small samples. Key Words: Hausman-Taylor estimator; Spatial random effects; Small sample properties JEL No. C23, 31