Extending multi-tenant architectures: a database model for a multi-target support in SaaS applications

Multi-tenant architectures (MTAs) are considered a cornerstone in the success of Software as a Service as a new application distribution formula. Multi-tenancy allows multiple customers (i.e. tenants) to be consolidated into the same operational system. This way, tenants run and share the same application instance as well as costs, which are significantly reduced. Functional needs vary from one tenant to another; either companies from different sectors run different types of applications or, although deploying the same functionality, they do differ in the extent of their complexity. In any case, MTA leaves one major concern regarding the companies’ data, their privacy and security, which requires special attention to the data layer. In this article, we propose an extended data model that enhances traditional MTAs in respect of this concern. This extension – called multi-target – allows MT applications to host, manage and serve multiple functionalities within the same multi-tenant (MT) environment. The practical deployment of this approach will allow SaaS vendors to target multiple markets or address different levels of functional complexity and yet commercialise just one single MT application. The applicability of the approach is demonstrated via a case study of a real multi-tenancy multi-target (MT²) implementation, called Globalgest.     

Gender segregation and earnings differences in the Spanish labour market

This article analyses the effects of different types of gender segregation on the gender wage differential for the Spanish labour market. Matched employer–employee data from a sample of 226,535 workers are used. These workers are employed in 61 occupations within 26,492 establishments in 51 different industries. Workers belonging to the same industry, establishment or job share common factors which cannot be observed and these factors affect wages. If these unobservable variables are correlated with the explanatory variables, their estimated effects will be biased. For this reason, we estimate the effects of each type of gender segregation on the wage gap using a robust specification to these possible correlations. We obtain that industrial segregation by gender explains a lower part of the wage gap between men and women than previous researches found using standard regressions, while the contributions of establishment segregation and occupational segregation within each establishment are greater.     

The impact of multiple structural changes on mortality predictions

Most mortality models proposed in recent literature rely on the standard ARIMA framework (in particular: a random walk with drift) to project mortality rates. As a result the projections are highly sensitive to the calibration period. We therefore analyse the impact of allowing for multiple structural changes on a large collection of mortality models. We find that this may lead to more robust projections for the period effect but that there is only a limited effect on the ranking of the models based on backtesting criteria, since there is often not yet sufficient statistical evidence for structural changes. However, there are cases for which we do find improvements in estimates and we therefore conclude that one should not exclude on beforehand that structural changes may have occurred.     

Efficient delays in a stochastic model of bargaining

Summary. We consider a k-player sequential bargaining model in which both the cake size and the identity of the proposer are determined by a stochastic process. For the case where the cake is a simplex (of random size) and the players share a common discount factor, we establish the existence of a unique stationary subgame perfect payoff which is efficient and characterize the conditions under which agreement is delayed. We also investigate how the equilibrium payoffs depend on the order in which the players move and on the correlation between the identity of the proposer and the cake size.Received: November 5, 1996; revised version: December 31, 1996This revised version was published online in February 2005 with corrections to the cover date.     

Explanatory factors of the inflation news impact on stock returns by sector: The Spanish case

We study the short run response of daily stock prices on the Spanish market to the announcements of inflation news at an industrial level, deepening the potential explanatory factors of this response (risk-free interest rate, risk premium and growth expectations). We observe a positive and significant response of the stock returns in case of “bad news” (total inflation rate higher than expected one) in recession, and also in case of negative inflation surprises (“good news”) in non-economic recession. This behaviour is consistent with the evolution of the company dividend growth expectations, since we observe that the relationship between this theoretical component of the stock price and the unexpected inflation, to a large extent, seems to explain the observed behaviour.     

Social and organizational capital: Building the context for innovation

In the light of the key role intellectual capital has for firms' innovation capability, this paper analyzes the influence of two of their dimensions, organizational capital and social capital, on firms' product innovation, and the moderating role of radicalness. Unlike previous studies, the unit of analysis will not be the firm, but the R&D department. Thus, our research, conducted with a sample of Spanish industrial companies, provides a new insight with interesting results. First, our findings show that social capital favours firms' product innovation, especially under radical innovations. Second, organizational capital has an indirect effect on product innovation through positive influence on social capital. This implies that firms can stimulate communication and interaction among people, and therefore innovative activity, by means of explicit and codified knowledge (organizational capital).     

Power politics and the expansion of US exports, 1879–1938

In this article, we present quantitative evidence for the first time of the effect of US power politics on the expansion of its export market from the late nineteenth century to the eve of the Second World War. Like other empires, US imperial policy was expressed through annexation, gunboat policies, and asymmetrical trade agreements. We find that US exports to territories that became colonies or protectorates and those involved in other US military interventions grew more than three times faster between 1880–5 and 1934–8 than in the rest of the world. Our most relevant contribution to this discussion relies on a new geographically extensive database with information on bilateral trade flows, market size, trade costs, and variables that capture US political and military power. We first estimate a gravity equation to see the relationship between our power politics variables and US exports. Then, we present causal evidence of the role played by the colonies and protectorates in the expansion of US exports through an event study and the estimation of a generalized difference-in-differences model.     

The entrepreneurial motivation in academia: a multidimensional construct

In this paper we propose a model to analyse the motivation of academic entrepreneurs that comprises six dimensions: personal, relating to the entrepreneurial opportunity, to scientific knowledge, to the availability of resources, to the incubator organization, and to the social environment. The model is tested based on information from a survey administered to 152 Spanish academic entrepreneurs. Our results show that entrepreneurial opportunity is not part of the entrepreneurial motivation, but is of the utmost importance to academic entrepreneurs. Also, we find the scientific knowledge is the main driver of entrepreneurial activity in the academia.