Entrepreneurial workaround practices in severe institutional voids: Evidence from Kenya

Entrepreneurs in developing economies try to cope with weak or absent formal institutions – often referred to as ‘institutional voids’ – by relying extensively on intermediary organizations such as business incubators and development organizations or informal institutions such as political, kinship, or family relationships. However, in many African countries, intermediary support is limited and informal institutions are also unreliable, adding risks and costs to doing business and increasing the severity of institutional voids in the surrounding ecosystem. We investigate the practices followed by 47 commercial entrepreneurs in Kenya to ‘work around’ these severe institutional voids to achieve their goals of business creation and growth. We find that severe institutional voids stimulate the hybridization of goals to include social value creation, create a need for a more strategic orchestration of business relationships, and motivate entrepreneurs to proactively cross-brace the institutional infrastructure around them. We contribute by unveiling the important role of entrepreneurs as microinstitutional agents in developing economies and by detailing how commercial and social goals become intertwined in the context of African entrepreneurship

Nucleosynthesis in Advective Accretion Disks Around Galactic and Extra-Galactic Black Holes

We compute the nucleosynthesis of materials inside advective disks around black holes. We show that composition of incoming matter can change significantly depending on the accretion rate and accretion disks. These works are improvements on the earlier works in thick accretion disks of Chakrabarti, Jin & Arnett (1987) in presence of advection in the flow.Comment: Latex pages including figures. Kluwer Style files included. Appearing in `Observational Evidence for Black Holes in the Universe', ed. Sandip K. Chakrabarti, Kluwer Academic Publishers (DORDRECHT: Holland

The New Transverse-Facial Artery Musculomucosal Flap for Intraoral Reconstructions

Head/neck cancer resections often require reconstruction to restore form and function. Small-to-medium size intraoral defects can be successfully reconstructed by local pedicled flaps, such as the facial artery musculomucosal (FAMM) flap,1 which encompasses different layers: cheek mucosa and submucosa, the underlying layer of the buccinator muscle, a portion of the orbicularis oris close to the labial commissure, and the facial artery.2 The flap is usually outlined longitudinally over the facial artery course, and average size is 5 × 2.5 cm. We describe here an innovative flap design and dissection, apt to treat larger defects than the usual ones. Go to: METHODS In a 50-year-old patient with squamous carcinoma of the soft palate involving also surrounding oral soft tissue, after oncological resection, we designed on the cheek mucosa an 8 × 3 cm flap with a squamous carcinoma orientation. The flap axis was crossing about 90 degrees the projection of the facial vessels. Dissection was carried out in anteroposterior direction and the facial artery skeletonized in continuity 3.5 cm superiorly and inferiorly the flap entrance (Fig. ​(Fig.1).1). Once the vascular pedicles had been mobilized and the labial artery ligated, the transverse (t)-FAMM flap was transposed superoposteriorly and sutured to the residual mucosa of the hard palate. A contralateral t-FAMM flap was harvested and transposed. The whole soft palate was then reconstructed by suturing the 2 flaps together

Sailing as Stroke Rehabilitation Strategy

Stroke (brain attack), is a serious global public health problem and the main cause of many forms of disability. The majority of stroke survivors are mostly left with motor (muscle movement or mobility) impairments. Although remarkable developments have been made in drug treatment, post-stroke care continues to rely on rehabilitation interventions mostly. On the other hand, the presence of post-stroke depression has been associated with decreases in functional recovery, social activity and cognition. Therefore, this project aims to improve the quality of people’s lives after a stroke by introducing sailing as outdoor mobility rehabilitation. It is intended to increase the patients’ motivation and engagement in the rehabilitation process by a more enjoyable and relaxing intervention than the existing ones especially for long term periods. The project, based on a haptic system installed on the deck of NYTEC 28 sailing boat, aim to monitoring rehab process development in post-stroke during normal sailing activity

On the Azimuthal Stability of Shock Waves around Black Holes

Analytical studies and numerical simulations of time dependent axially symmetric flows onto black holes have shown that it is possible to produce stationary shock waves with a stable position both for ideal inviscid and for moderately viscous accretion disks. We perform several two dimensional numerical simulations of accretion flows in the equatorial plane to study shock stability against non-axisymmetric azimuthal perturbations. We find a peculiar new result. A very small perturbation seems to produce an instability as it crosses the shock, but after some small oscillations, the shock wave suddenly transforms into an asymmetric closed pattern, and it stabilizes with a finite radial extent, despite the inflow and outflow boundary conditions are perfectly symmetric. The main characteristics of the final flow are: 1) The deformed shock rotates steadily without any damping. It is a permanent feature and the thermal energy content and the emitted energy vary periodically with time. 2) This behavior is also stable against further perturbations. 3) The average shock is still very strong and well defined, and its average radial distance is somewhat larger than that of the original axially symmetric circular shock. 4) Shocks obtained with larger angular momentum exhibit more frequencies and beating phenomena. 5) The oscillations occur in a wide range of parameters, so this new effect may have relevant observational consequences, like (quasi) periodic oscillations, for the accretion of matter onto black holes. Typical time scales for the periods are 0.01 and 1000 seconds for black holes with 10 and 1 million solar mass, respectively.Comment: 15 pages, 7 figures, accepted by the Astrophysical Journa

Clearing the hurdles for nanotechnology: In vivo inhalation effects

Nanoparticle Poster SessionINTRODUCTION: Nanoparticles of many types have been created for industrial and medical applications. Among these nanoparticles, single-walled carbon nanotubes (SWCNT) are of high interest for their physicochemical properties and application in electronics, drug delivery and other areas. With the rapid expansion in SWCNT-based new technologies, a full understanding of their safety and risks for human exposure must be considered. Because of the potential human risk of nanoparticle exposure we have developed an animal model to study the effects of nanoparticle exposure on lung tissue. Using this rat model we hypothesized that an acute nanoparticle exposure would result in an inflammatory response in lung tissue. METHODS: Particle instillation (intratracheal under direct visualization) of 50 μL pediatric surfactant containing 500 micrograms SWCNT (or surfactant alone) was performed in 32 rats to date. Pulmonary histology and biochemical measures on bronchoalveolar lavage (BAL), pleural fluid, serum and lung cells was quantified. RESULTS: Very early (<30 minutes) eosinophilia developed in lung tissue following SWCNT instillation. Innate immune system sterile response, or Damage Associated Molecular Patterns (DAMPs) protein was released. Our dose proved sterile, <0.03 EU LPS, showing the effect was damage-induced not pathogen-induced. High mobility group box protein-1 (HMGB1), a nuclear chaperone and prototype DAMP was elevated (ELISA) following SWCNT exposure. A second DAMP, heatshock protein 70 (HSP-70), a cytoplasmic chaperone, was also quantified by ELISA. The response OF HSP-70 over time is similar to HMGB1. Western blots performed on time-harvested lungs exposed to SWCNT demonstrated a receptor for advanced glycation end products (RAGE), with a strong peak at 3 hours after pulmonary exposure. The inflammatory cytokine TNFα appeared in lung tissue and bronchial alveolar lavage (BAL) at 30 minutes, with the same timing as the HMGB1 and HSP-70 release. Flow cytometry of type II pneumocytes and pulmonary macrophages from SWCNT-exposed rats demonstrated secondary DAMP receptors. A potential chronic effect was noted at one month. HMGB1 and HSP-70 peaked acutely at approximately 24 hr and then slowly decreased at 1 to 2 weeks. At 1 month, however, a new increase was seen. CONCLUSIONS: The hydrophobic SWCNT, important industrial components, form bundles and fibers in the hydrophilic lung, creating an immediate cellular inflammatory response, measurable cellular necrosis and very rapid chemokine release. Early data suggests the potential for chronicity

Risk of internet addiction in adolescents: A confrontation between traditional teaching and online teaching

Background: The technological evolution has given the opportunities to develop new models of education, like online teaching. However, Internet Problematic Use and Internet Addiction are becoming frequently represented among adolescents with a prevalence that varies worldwide from 2% to 20% of the high school population. Objective: The aim of this study was to analyse the risk of Internet Addiction in a High Schools student sample comparing two different types of schools (online and traditional teaching) and analyzing the associations between pathological use of Internet and socio-demographic factors connected to the different educational orientations and to the daily usage of Internet. Methods: Students were enrolled from four different orientation school programs (different high school, technical and economical Institute, vocational schools). Each student completed a self-reported test to collect socio-demographic data and th Internet Addiction Test (IAT) from K. Young to assess the risk of Internet Addiction. The Mann-Whitney test for quantitative variables was used for statistical analysis. Results: 522 students were enrolled, 243 students from online teaching and 279 from traditional teaching schools. Internet Addiction was observed in 1,16% of the total sample, while 53.83% of subjects was at risk of development Internet Addiction. No significant difference was found between the two different types of teaching, nor considering gender. Considering the amount of time spent on the web in portion of the sample at risk of developing Internet Addiction, the Traditional Teaching group spent between 4 and 7 hours a day on the Web, while the Online Teaching group between 1 to 3 hours/daily. However, no statistically significant difference was found. Conclusion: Although our data demonstrate that there is no clear association between online education and problematic use of Internet, the excessive use of Internet is linked to a massive waste of personal energy in terms of time and social life

A simple model of radiative emission in M87

We present a simple physical model of the central source emission in the M87 galaxy. It is well known that the observed X-ray luminosity from this galactic nucleus is much lower than the predicted one, if a standard radiative efficiency is assumed. Up to now the main model invoked to explain such a luminosity is the ADAF (Advection-Dominated-Accretion-Flow) model. Our approach supposes only a simple axis-symmetric adiabatic accretion with a low angular momentum together with the bremsstrahlung emission process in the accreting gas. With no other special hypothesis on the dynamics of the system, this model agrees well enough with the luminosity value measured by Chandra.Comment: 11 pages, 6 figures, accepted for publication in The Astrophysical Journa

A conjectural extension of Hecke’s converse theorem

We formulate a precise conjecture that, if true, extends the converse theorem of Hecke without requiring hypotheses on twists by Dirichlet characters or an Euler product. The main idea is to linearize the Euler product, replacing it by twists by Ramanujan sums. We provide evidence for the conjecture, including proofs of some special cases and under various additional hypotheses

Modeling the time-resolved quasi-periodic oscillations in AGNs

Observation of the bright Seyfert 1 galaxy RE J1034+396 is believed to demonstrate a drift of the central period of the Quasi Periodic Oscillation (QPO) linearly correlated with the temporary X-ray luminosity. We show, using a specific scenario of the oscillation mechanism in black hole accretion disc, that modeling such correlated trends puts very strong constraints on the nature of this oscillation and the characteristic features of the hot flow in Active Galactic Nuclei (AGN). In our model, QPO oscillations are due to the oscillations of the shock formed in the low angular momentum hot accretion flow, and the variation of the shock location corresponds to the observed changes in the QPO period and the X-ray flux. In this scenario, change in the shock location caused by perturbation of the flow angular momentum is compatible with the trends observed in RE J1034+396, whereas the perturbation of the specific flow energy results in too strong flux response to the change of the oscillation period. Using a complete general relativistic framework to study the accretion flow in the Kerr metric, we discuss the role of the black hole spin in the period drift. Future missions are expected to bring more active galaxies with time-resolved quasi-periodic oscillations so similar quantitative study for other QPO scenarios will be necessary.Comment: Final version accepted for publication in MNRAS. Several modifications made. Eight pages. Six colour figure