Aging and sexual health: getting to the problem

Erectile dysfunction (ED) is one of the most common disorders in male and is often associated with other age-related comorbidities. The aging process affects the structural organization and function of penile erectile components such as smooth muscle cell and vascular architecture. These modifications affect penile hemodynamics by impairing cavernosal smooth muscle cell relaxation, reducing penile elasticity, compliance and promoting fibrosis. This review aims to identify the mechanisms of ED in the penile aging process in experimental and clinical data. It also highlights areas that are in need of more research. The search strategies yielded total records screened from PubMed. Clarification of the molecular mechanisms that accompanies corpus cavernosum aging and aging-associated ED will aid new perspectives in the development of novel mechanism-based therapeutic approaches. Age is not a limiting factor for ED medical management, and it is never too late to treat. Hypogonadism should be managed regardless of age, and synergistic effects have been found during testosterone (T) replacement therapy when used along with oral phosphodiesterase-5 (PDE-5) inhibitors. Therefore, the clinical management of ED related to aging can be done by therapeutic interventions that include PDE-5 inhibitors, and other pharmacological treatments.     

Language shift and the family: Questions from the Sri Lankan Tamil diaspora1

Fishman's Graded Intergenerational Disruption Scale (GIDS) emphasizes the family in maintaining the heritage languages of immigrant communities. This study uses interview data from Sri Lankan Tamil communities in the U.S.A., U.K., and Canada to explain how families account for the rapid loss of Tamil in the diaspora. It shows how the positive valuation of English since British colonization, the need to make up for past deprivations because of caste, religious, and gender inequality, the pressure for migrants to join the social mainstream, and the need to resolve intergenerational tensions influence the family to forego language maintenance goals. The findings encourage us to situate the family in macro‐social institutions, power, and history in order to understand the prospects for language maintenance. The article provides an inside view of the Sri Lankan Tamil migrant families to explain how they resolve the tensions of valuing cultural identity and yet disregarding heritage language proficiency.     

Two-Event Model for Carcinogenesis: Biological, Mathematical, and Statistical Considerations

A two-mutation model for carcinogenesis is reviewed. General principles in fitting the model to epidemiologic and experimental data are discussed, and some examples are given. A general solution to the model with time-dependent parameters is developed, and its use is illustrated by application to data from an experiment in which rats exposed to radon developed lung tumors.     

Investment in Shared Suppliers: Effect of Learning,Spillover, and Competition

We investigate the optimal strategies for firms to invest in their suppliers when the benefits of such investments can spillover to other firms who also source from the same suppliers. We consider two Bayesian firms that can invest in improving the quality of their shared supplier; the firms do not have complete information on the true quality of the supplier, but they update their beliefs based on the supplier's performance. We formulate the problem as an investment game and obtain Markov perfect equilibria characterized by the investment thresholds of both firms. The equilibrium investment strategies of the two firms are characterized by a region of preemption and a region of war of attrition. We also examine how the interplay between spillover, competition, and returns from the investment at shared suppliers affect the investment threshold and the time to the leader's investment, and identify the conditions under which competition delays or hastens the first investment in a shared supplier.     

Diesel Engine Exhaust and Lung Cancer Mortality: Time‐Related Factors in Exposure and Risk

To develop a quantitative exposure‐response relationship between concentrations and durations of inhaled diesel engine exhaust (DEE) and increases in lung cancer risks, we examined the role of temporal factors in modifying the estimated effects of exposure to DEE on lung cancer mortality and characterized risk by mine type in the Diesel Exhaust in Miners Study (DEMS) cohort, which followed 12,315 workers through December 1997. We analyzed the data using parametric functions based on concepts of multistage carcinogenesis to directly estimate the hazard functions associated with estimated exposure to a surrogate marker of DEE, respirable elemental carbon (REC). The REC‐associated risk of lung cancer mortality in DEMS is driven by increased risk in only one of four mine types (limestone), with statistically significant heterogeneity by mine type and no significant exposure‐response relationship after removal of the limestone mine workers. Temporal factors, such as duration of exposure, play an important role in determining the risk of lung cancer mortality following exposure to REC, and the relative risk declines after exposure to REC stops. There is evidence of effect modification of risk by attained age. The modifying impact of temporal factors and effect modification by age should be addressed in any quantitative risk assessment (QRA) of DEE. Until there is a better understanding of why the risk appears to be confined to a single mine type, data from DEMS cannot reliably be used for QRA.     

Reanalysis of the DEMS Nested Case‐Control Study of Lung Cancer and Diesel Exhaust: Suitability for Quantitative Risk Assessment

The International Agency for Research on Cancer (IARC) in 2012 upgraded its hazard characterization of diesel engine exhaust (DEE) to “carcinogenic to humans.” The Diesel Exhaust in Miners Study (DEMS) cohort and nested case‐control studies of lung cancer mortality in eight U.S. nonmetal mines were influential in IARC's determination. We conducted a reanalysis of the DEMS case‐control data to evaluate its suitability for quantitative risk assessment (QRA). Our reanalysis used conditional logistic regression and adjusted for cigarette smoking in a manner similar to the original DEMS analysis. However, we included additional estimates of DEE exposure and adjustment for radon exposure. In addition to applying three DEE exposure estimates developed by DEMS, we applied six alternative estimates. Without adjusting for radon, our results were similar to those in the original DEMS analysis: all but one of the nine DEE exposure estimates showed evidence of an association between DEE exposure and lung cancer mortality, with trend slopes differing only by about a factor of two. When exposure to radon was adjusted, the evidence for a DEE effect was greatly diminished, but was still present in some analyses that utilized the three original DEMS DEE exposure estimates. A DEE effect was not observed when the six alternative DEE exposure estimates were utilized and radon was adjusted. No consistent evidence of a DEE effect was found among miners who worked only underground. This article highlights some issues that should be addressed in any use of the DEMS data in developing a QRA for DEE.     

How Sourcing of Interdependent Components Affects Quality in Automotive Supply Chains

In the automotive industry, many firms source key components from different suppliers, even though the components may function interdependently. In this study, we investigate how component level interdependence impacts quality performance and analyze how various operational factors moderate this relation. We synthesize information from several case studies to model the quality challenges faced by an automotive firm. For several sub‐assemblies that go into its products, the firm sourced key components from two different suppliers. The sub‐assemblies would fail whenever a component fails, but due to interdependent operations, failure of one component could cause the failure of the other. The firm found it challenging to improve the suppliers' quality performance as it was difficult to trace the failures to specific components. Our analysis reveals that – (i) the impact of interdependence is governed by the supply chain structure: reducing the interdependence between components improves quality when suppliers provide the components, but reducing interdependence worsens quality when the firm manufactures the entire sub‐assembly; and (ii) the relation between interdependence and quality performance is moderated by factors such as penalties, production costs, and interdependence costs. Additionally, we find that quality performance is lower when the firm outsources the components than when the firm manufactures the entire sub‐assembly. We identify coordinating mechanisms that leverage incentives and penalties to bridge the quality performance gap.     

Dilemmas in planning English/vernacular relations in post‐colonial communities

In the context of globalization and post‐modern discourses, the debate about the relative status of local and dominant languages poses serious policy problems for post‐colonial communities. Critics of minority language rights (MLR) generally point out that engineering a language shift on behalf of a vernacular language – motivated by the preservationist interests, collective rights and sentimental associations of an ethnic group – is futile, as the economic and social mobilities of individuals are bound to work against this enterprise. Proponents of MLR have gone to the other extreme of essentializing the linguistic identity of minority communities, generalizing their language attitudes, and treating local language rights as non‐negotiable. This article addresses this debate in the context of the attempts to promote Tamil by the military leadership in the North and East of Sri Lanka. The paper brings together data gathered in sociolinguistic studies for four years in the Jaffna society in order to understand the reception of the language policy in everyday life. The leadership recognizes that language policy is a symbolic statement for political purposes and tolerates certain inconsistencies in policy and practice. While the community assures itself of ethnic pride and linguistic autonomy with the stated policies, it negotiates divergent interests in the gaps between the policy/practice divide. Scholars should recognize the agency of subaltern communities to negotiate language politics in creative and critical ways that transcend the limited constructs formulated to either cynically sweep aside or unduly romanticize language rights.     

The Causes and Consequences of Immigrant Labour in the Construction Sector in Malaysia

Malaysian construction is highly dependant on immigrant labour; immigrants account for nearly 70 per cent of its workforce. Although they have aided the sector's rapid expansion, it has not been without costs. This paper examines the impact of immigrant labour on construction. The main finding is that immigrants, being largely unskilled, did not contribute to skill formation. Instead, they accumulated skills on‐the‐job, which were lost when they returned home. There was no evidence that immigrants displaced domestic workers since they were concentrated in jobs rejected by Malaysians. Furthermore, unlike in earlier periods, legal immigrants were no longer a cheap option, given the regulations governing their employment. They were not used to cut costs per se, but were used because domestic workers were not available in sufficient numbers. Despite the large immigrant presence, the general wage level increased, though admittedly not as rapidly as it might have in their absence. The reliance on immigrant workers has increased the need for supervision and quality control, thereby reducing the savings in cost; nonetheless, immigrants have helped keep costs in check. Surprisingly, rising wages and the continued shortage of labour have not led to a widespread adoption of labour‐saving methods. This is partly because productivity increases have managed to outpace wage increases, though this advantage is petering out. Also, immigrant presence has kept wages, as a proportion of total costs, manageable. The over reliance of the sector on immigrant labour is not desirable, especially since the majority is drawn from one source ‐ Indonesia. Any disruption of supply from this source can undermine the Malaysian economy. To avoid this, Malaysia must vary its source of immigrant labour and intensify efforts to attract domestic workers by improving conditions in construction.     

Optimal Ordering Policies for Stochastic Inventory Problems with Observed Information Delays

Information delays exist in an inventory system when it takes time to collect, process, validate, and transmit inventory/demand data. A general framework is developed in this paper to describe information flows in an inventory system with information delays. We characterize the sufficient statistics for making optimal decisions. When the ordering cost is linear, the optimality of a state‐dependent base‐stock policy is established even when information flows are allowed to cross over time. Additional insights into the problem are obtained via a comparison between our models and the models with stochastic order lead times. We also show that inventory can substitute for information and vice versa.