A model of Firm's Growth in a knowledge based economy

Abstract Knowledge-based economies use knowledge as an input of production to produce knowledge-intensive products and services. In such economies, a firm’s growth crucially depends on knowledge accumulation, technical change and the resulting innovation activities. To achieve sustained growth, a firm must keep on innovating. A firm’s core competence and its refinement and development over time play a crucial role in a firm’s innovation activities and its growth. In this paper, a conceptual framework of a firm’s innovation and growth in knowledge-based economy is presented. This framework is based on a firm’s core competence and its development over time within a firms’ cluster. This model is empirically estimated and evaluated, in a pilot study, via a data set from a manufacturing cluster of 128 firms operating in the North East England. The empirical results provide some support for the proposed framework. In particular, it is found that the conditional probability that a firm undertakes R&D activity to innovate in such a cluster of firms is over 70 %. Keywords Knowledge economy . Core competence . R&D activities . Cluster formation . Innovation polic

Disproportionate Correlation between Imaging and Outcome in an Infant with Cerebral Abscess

ObjectiveBrain abscesses represent organized foci of suppuration within the parenchyma. Here we report a 3 month-old girl with a very huge complicated cerebral abscess, and the course of treatment given. The patient's recovery was excellent. The follow up MRI showed only subtle porencephalic changes as the only parenchymal sequelae, which may be due to CNS plasticity in infants

A Multidisciplinary Technique Using Endonasal Endoscopic Approach with Intrathecal Fluorescin Under Neuronavigation Guidance in Patients with Cerebrospinal Fluid Leak

Background: Cerebrospinal fluid (CSF) is contained in an anatomic space, including cerebral ventricles and subarachnoid spaces and cisterns of brain and spine. Distraction of normal anatomy of any containing parts of this system will result in CSF leakage which could be associated with morbidity and mortality with variable degrees. In this study, we aimed to present 3 patients with history of blunt head trauma, who presented with delayed CSF leak and underwent endonasal endoscopic approach under image guided surgery using neuronavigation system with fluorescein illumination.Case Presentation: Three patients were referred to neurosurgery department of Shohada Tajrish Hospital with previous history of blunt head trauma, complained from CSF rhinorrhea. They underwent thin slice Computed Tomography scan and received intrathecal fluorescein for better visualization of leakage source under live endonasal endoscopic approach, using image guided neuronavigation technology. Autologous fat tissue and fascia was used to seal the leakage site. Clinical and imaging follow up at post-operative state as well as 1st, 2nd, 4th and 8th week revealed no post-operative complications and repeated CSF leakage.Conclusion: CSF rhinorrhea indicates abnormality in bony structure of skull base and is a major threat for ascending microbial infections and subsequent meningitis. Thus, identification of leakage site(s) and accurate surgical repair is necessary. We experienced a multidisciplinary approach which showed excellent results and no post-operative complications. Multidisciplinary approach with combination of endonasal endoscopic view under neuronavigation system improves accuracy and will minimize post-operative complications.

Posterior Fossa Tumor in Children

How to Cite this Article: Tabatabaei SM, Seddighi A, Seddighi AS. Posterior Fossa Tumor in Children. Iran. J. Child. Neurol 2012;6(2): 19-24. Objective Primary brain tumors are the most common solid neoplasms of childhood, representing 20% of all pediatric tumors. The best current estimates place the incidence between 2.76 and 4.28/100,000 children per year. Compared with brain tumors in adults, a much higher percentage of pediatric brain tumors arise in the posterior fossa. Infratentorial tumors comprise as many as two thirds of all pediatric brain tumors in some large series. Tumor types that most often occur in the posterior fossa include medulloblastoma, ependymoma, cerebellar astrocytoma and brainstem glioma. Materials & Methods All pediatric cases of posterior fossa tumor that were considered for surgery from 1981 to 2011 were selected and the demographic data including age, gender and tumor characteristics along with the location and pathological diagnosis were recorded. The surgical outcomes were assessed according to pathological diagnosis. Results Our series consisted of 84 patients (52 males, 32 females). Cerebellar symptoms were the most common cause of presentation (80.9%) followed by headache (73.8%) and vomiting (38.1%). The most common histology was medulloblastoma (42.8%) followed by cerebellar astrocytoma (28.6%), ependymoma (14.3%), brainstem glioma (7.2%) and miscellaneous pathologies (e.g., dermoid,  andtuberculoma) (7.2%). Conclusion The diagnosis of brain tumors in the general pediatric population remains challenging. Most symptomatic children require several visits to a physician before the correct diagnosis is made. These patients are often misdiagnosed for gastrointestinal disorders. Greater understanding of the clinical presentation of these tumors and judicious use of modern neuroimaging techniques should lead to more efficacious therapies.References 1. Mehta V, Chapman A, McNeely PD, Walling S, Howes WJ. 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Functional basis of posterior fossa symptoms and signs. eds. Posterior fossa tumours. New York: Springer Verlag; 1993;12-21. 15. Cohen ME, Duner PK. Tumours of the brain and spinal cord including leukemic infiltrates. In: Swaiman KF, editor. Pediatric neurology principles and practice. St. Louis: Mosby; 1991. p. 94550. 16. Bronstein KS. Epidemiology and classification of brain tumors. Crit Care Nurs Clin North Am 1995 Mar;7(1):79-89. 17. GOL A. Cerebellar astrocytomas in children. Am J Dis Child 1963 Jul;106:21-4. 18. Hojer C, Hildebrandt G, Lanfermann H, Schroder R, Haupt WF. Pilocyticastrocytomas of the posterior fossa. A follow-up study in 33 patients. Acta Neurochir (Wien) 1994;129(3-4):131-9. 19. Lassman LP, Arjona VE. Pontine gliomas of childhood. Lancet 1967 Apr 29;1(7496):913-5. 20. Reigel DH, Scarff TB, Woodford JE. Biopsy of pediatric brain stem tumors. Childs Brain. 1979;5(3):329-40. 21. Griwan MS, Sharma BS, Mahajan RK, Kak VK. Value of precraniotomy shunts in children with posterior fossa tumours. Childs Nerv Syst 1993 Dec;9(8):462-5. 22. Raimondi AJ, Tomita T. Hydrocephalus and infratentorial tumors. Incidence, clinical picture, and treatment. J Neurosurg 1981 Aug;55(2):17482. 23. Jamjoom AB, Jamjoom ZA, al-Rayess M. Intraventricular and leptomeningeal dissemination of a pilocytic cerebellar astrocytoma in a child with a ventriculoperitoneal shunt: case report Br J Neurosurg. 1998 Feb;12(1):568. 24. Vaquero J, Cabezudo JM, de Sola RG, Nombela L. Intratumoral hemorrhage in posterior fossa tumors after ventricular drainage. Report of two cases. J Neurosurg 1981 Mar;54(3):406-8. 25. Hoffman HJ, Hendrick EB, Humphreys RP. Metastasis via ventriculoperitoneal shunt in patients with medulloblastoma. J Neurosurg 1976 May;44(5):562-6. 26. Hirsch J, Renier D, Czernichow P, Benveniste L, PierreKahn A. Medulloblastoma in childhood: survival and functional results. Acta Neurochir 1979;48:1-15. 27. 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Use of Natural Instability For Enhancement of Flow Mixing in Annuli

A technique has been proposed to increase flow mixing in annuli by means of vortex generation. Corrugations in the form of axisymmetric ribs are placed at the walls of annulus to modulate the axial flow which can potentially induce vortex instabilities. Unlike other vortex generation methods which suffer from relatively high pressure losses, this technique is expected to cause less pressure drop. Spectral algorithm based on Fourier and Chebyshev expansions has been used to study the stationary state and its stability. Due to the irregularities of the boundaries, the immersed boundary conditions (IBC) method is used to enforce the flow boundary conditions. The effect of geometric and flow parameters on pressure losses and stability have been thoroughly investigated. Characteristics of vortex mode and travelling wave instabilities as well as region of dominance in each case are also determined. Moreover, it has been shown that effect of arbitrary ribs can be accurately captured using reduced geometry model

Public-Private-People Partnerships (4P) for Improving the Response to COVID-19 in Iran

Public-Private-People Partnership is a significant element in disaster response. COVID-19 as a pandemic has been the worst disaster in the last decades in Iran in terms of exposure and magnitude. In order to respond effectively, the Iranian government needs an extra capacity which may be provided by the private sector and people. This study aims to collect evidences of Public-Private-People partnerships pertaining to COVID-19 response in Iran from February to April 2020. Partnership case studies are classified into three categories as follows: 1) Public-private partnerships; 2) public-people partnerships; and 3) private-people partnerships. It was found that the Iranian government has removed or diminished some of the barriers to cooperation. There was also more cooperation between the people, the private sector, and the public sector than during normal times (vs disasters). People participated in the response procedure through some associations or groups, such as religious and ethnic communities, as well as through non-governmental organizations. It is showed that 4P is vital in disasters response and in particular to epidemics. The government can be more active in partnerships with private sector, and people in emergencies such as COVID-19 Pandemic. Enhancing social capital, institutionalization, and developing required infrastructures by the government will improve public-private partnerships