Friends and Partners: The Impact of Network Ties

How does a high-tech entrepreneur find the most qualified engineer for her startup? How does a scientific inventor acquire funding or recruit the best partner for his project? In chapter 1 I develop a discrete matching model with heterogeneous values and an undirected social network to address these questions. My model offers a framework to study how relative network positions affect payoffs and incentives. While an entrepreneur's expected return increases with the size of her own network, the network externalities from competing entrepreneurs are more complex. There is a tradeoff between the size of an entrepreneur's network and the competitive externality she exerts. When an entrepreneur's network increases, her closest competitors are hurt, but her less similar competitors may actually have a better chance of finding a suitable partner. In a more connected network, fewer frictions interfere with compatible matches. Results are consistent with observable patterns in high-tech and biotechnology in Silicon Valley and Massachusetts, as well as the turn of the 20th century German synthetic dye manufacturing. Initiatives to promote social networks within innovative sectors are critical and deserve future research. In Chapter 2 I consider a two-period endogenous network search model in which entrepreneurs build relationships with specialists. The model includes a period of costly network search and applies results from my companion paper. In the presence of network externalities, entrepreneurs over-invest in networking. Networks in which is it not costly to build new relationships are the least efficient. While positive externalities reduce this problem some negative inefficiencies will likely prevail. Networks in which participation is cheap - such as online career networks LinkedIn or Monster.com - have limited information about individual specialists and are the most inefficient. A network that is costly to participate in, but is more effective at targeting entrepreneur's search for qualified candidates results in a more compatible and, likely, efficient partnership. These networks might include alumni groups, trade associations or head-hunters. This chapter provides one explanation for the varied successes of government programs in fostering effective business networks. Efficient networks foster fewer, more specific relationships

Bronchiolitis. Analysis of 10 consecutive epidemic seasons

Bronchiolitis is the leading cause of hospitalization in infants under 12 months. Our aims were to analyze epidemiological characteristics of infants with bronchiolitis over 10 consecutive seasons and to evaluate whether there are any clinical differences between infants hospitalized for bronchiolitis during epidemic peak months and infants in non-peak months. We enrolled consecutive enrolled 723 previously healthy term infants hospitalized at the Paediatric Emergency Department, "Sapienza" University of Rome over the period 2004-2014. Fourteen respiratory viruses were detected from nasopharyngeal aspirates by molecular methods. Clinical and demographic data were extracted from clinical charts. Viruses were detected in 351 infants (48.5%): RSV in 234 (32.4%), RV in 44 (6.1%), hBoV in 11 (1.5%), hMPV in 12 (1.6%), co-infections in 39 (5.4%), and other viruses in 11 (1.5%). Analyzing the 10 epidemic seasons, we found higher incidence for bronchiolitis every 4 years with a peak during the months December-January. Infants hospitalized during peak months had lower family history for asthma (P = 0.003), more smoking mothers during pregnancy (P = 0.036), were slightly higher breastfed (0.056), had lower number of blood eosinophils (P = 0.015) and had a higher clinical severity score (P = 0.017). RSV was detected mostly during peak months, while RV was equally distributed during the seasons. We found some variations in bronchiolitis incidence during epidemics, and discriminative characteristics in infants hospitalized for bronchiolitis during peak months and in non-peak months, that might reflect two different populations of children. Pediatr Pulmonol. 2016; 9999:XX-XX. © 2016 Wiley Periodicals, Inc

Modifiable risk factors associated with bronchiolitis

Background: We sought to clarify possibly modifiable risk factors related to pollution responsible for acute bronchiolitis in hospitalized infants. Methods: For this observational study, we recruited 213 consecutive infants with bronchiolitis (cases: median age: 2 months; age range: 0.5-12 months; boys: 55.4%) and 213 children aged <3 years (controls: median age: 12 months; age range: 0.5-36 months; boys: 54.5%) with a negative medical history for lower respiratory tract diseases hospitalized at 'Sapienza' University Rome and IRCCS Bambino Gesù Hospital. Infants' parents completed a standardized 53-item questionnaire seeking information on social-demographic and clinical characteristics, indoor pollution, eating habits and outdoor air pollution. Multivariate logistic regression analyses were run to assess the independent effect of risk factors, accounting for confounders and effect modifiers. Results: In the 213 hospitalized infants the questionnaire identified the following risk factors for acute bronchiolitis: breastfeeding 3/43 months (OR: 2.1, 95% confidence interval [CI]: 1.2-3.6), presence of older siblings (OR: 2.8, 95% CI: 1.7-4.7), 3/44 cohabitants (OR: 1.5, 95% CI: 1.1-2.1), and using seed oil for cooking (OR: 1.7, 95% CI: 1.2-2.6). Having renovated their home in the past 12 months and concurrently being exposed daily to smoking, involving more than 11 cigarettes and two or more smoking cohabitants, were more frequent factors in cases than in controls (p = 0.021 and 0.05), whereas self-estimated proximity to road and traffic was similar in the two groups. Conclusions: We identified several risk factors for acute bronchiolitis related to indoor and outdoor pollution, including inhaling cooking oil fumes. Having this information would help public health authorities draw up effective preventive measures - for example, teach mothers to avoid handling their child when they have a cold and eliminate exposure to second-hand tobacco smoke

L’ecografia polmonare per il pediatra

L’ecografia polmonare si sta dimostrando una metodica di grande interesse e negli ultimi anni si è assistito ad un fiorire di pubblicazioni sull’argomento. In particolar modo, la sua semplicità d’uso e d’apprendimento ne stanno garantendo una forte diffusione. Se paragonata poi alla radiografia del torace, la più diffusa indagine di imaging in pneumologia pediatrica, l’ecografia polmonare appare molto promettente. In questo articolo ci prefiggiamo di fornire alcune informazioni basilari sull’ecografia polmonare che possono però diventare un importante spunto per la comprensione di questa innovativa metodica.The lung ultrasound is object of a strong interest and in the lasts years there has been a huge increase in the number of publications on the topic. Its simplicity of use and learning are ensuring it an increasingly widespread use. If compared to the chest radiograph, the most used imaging technique in pediatric pulmonology, lung ultrasound appears very promising. In this article we aim to provide some basic information on lung ultrasound that can become an important start point for understanding this innovative technique

Incidence and predisposing factors for severe disease in previously healthy term infants experiencing their first episode of bronchiolitis

Aim: To determine the incidence and predisposing factors for severe bronchiolitis in previously healthy term infants 0.8 mg/dL) and pulmonary consolidation on chest X-ray were more common among infants with severe disease. Severity was independently associated with younger age on admission < 30 days, respiratory syncytial virus (RSV) infection and lymphocyte counts < 3200/mu L. No significant differences were found between epidemiologic variables. Conclusions: Severe bronchiolitis is uncommon in previously healthy term infants < 12 months of age and when present develops soon after disease onset. Severity is predicted by young age and RSV carriage, whereas epidemiologic variables seem less likely to intervene

Indoor pollution, demographic characteristics and bronchiolitis. A pilot study

Distribution of identities between plant helitron RPAs and eukaryotic “core” RPAs. (PDF 274 kb