Rigidity of compact Riemannian spin Manifolds with Boundary

In this article, we prove new rigidity results for compact Riemannian spin manifolds with boundary whose scalar curvature is bounded from below by a non-positive constant. In particular, we obtain generalizations of a result of Hang-Wang \cite{hangwang1} based on a conjecture of Schroeder and Strake \cite{schroeder}.Comment: English version of "G\'eom\'etrie spinorielle extrins\`eque et rigidit\'es", Corollary 6 in Section 3 added, to appear in Letters Math. Phy

The Dirac operator on untrapped surfaces

We establish a sharp extrinsic lower bound for the first eigenvalue of the Dirac operator of an untrapped surface in initial data sets without apparent horizon in terms of the norm of its mean curvature vector. The equality case leads to rigidity results for the constraint equations with spherical boundary as well as uniqueness results for constant mean curvature surfaces in Minkowski space.Comment: 16 page

Optimal eigenvalue estimate for the Dirac-Witten operator on bounded domains with smooth boundary

Eigenvalue estimate for the Dirac-Witten operator is given on bounded domains (with smooth boundary) of spacelike hypersurfaces satisfying the dominant energy condition, under four natural boundary conditions (MIT, APS, modified APS, and chiral conditions). This result is a generalisation of Friedrich's inequality for the usual Dirac operator. The limiting cases are also investigated.Comment: 2007, 18 pages, submitted 02 June 200

Auditors perceptions towards the effectiveness of the international standard on auditing 240 Red Flags : evidence from Lebanon

Most of the studies on auditors’ perceptions towards the effectiveness of the international standard on auditing 240 Red Flags (RF) were conducted in developed economies. This research, therefore, fills the gap by aiming to determine whether RF can be helpful for Lebanon certified public accountant (LCPA) working in auditing firms by detecting fraudulent financial reporting (FFR). Data were collected using a questionnaire that was distributed to a random sample of 130 LCPA. The results support that there is a positive significant association between pressures and FFR occurrence in Lebanon. However, there were no support for opportunities and attitudes to be associated with FFR occurrence. Moreover, the findings provide a strong evidence that ISA 240 RF for FFR can help external auditors in detecting material mis-statement (MM) due to fraud in Lebanon. Therefore, the current research recommends LCPA working in the audit firms in Lebanon to focus their efforts more on high quality RF, which will in turn facilitate fraud detection in the financial statements.peer-reviewe

Determinants Of The Voluntary Formation Of A Company Audit Committee: Evidence From Palestine

Drawing on agency theory, this paper investigates the determinants of voluntary audit committee (AC) formation among non-bank firms listed on the Palestine Stock Exchange (PSE). We used the annual reports of nearly all non-bank companies listed on the PSE as well as the company guides issued by the PSE for the period between 2010 and 2012. Logistic regression analysis was performed to identify the influence of a set of corporate governance mechanisms, ownership structures and company characteristics on the voluntary formation of ACs among non-bank Palestinian firms. The result of the analysis demonstrated that the AC is influenced by foreign ownership, institutional ownership, board diligence and external auditor type. This paper adds to the limited AC literature in Middle Eastern countries in general and in the Arab World in particular. This paper not only examines the determinants of the voluntary formation of ACs but also attempts to theorise about this formation

On a spin conformal invariant on manifolds with boundary

On a n-dimensional connected compact manifold with non-empty boundary equipped with a Riemannian metric, a spin structure and a chirality operator, we study some properties of a spin conformal invariant defined from the first eigenvalue of the Dirac operator under the chiral bag boundary condition. More precisely, we show that we can derive a spinorial analogue of Aubin's inequality.Comment: 26 page

A Reilly formula and eigenvalue estimates for differential forms

We derive a Reilly-type formula for differential p-forms on a compact manifold with boundary and apply it to give a sharp lower bound of the spectrum of the Hodge Laplacian acting on differential forms of an embedded hypersurface of a Riemannian manifold. The equality case of our inequality gives rise to a number of rigidity results, when the geometry of the boundary has special properties and the domain is non-negatively curved. Finally we also obtain, as a by-product of our calculations, an upper bound of the first eigenvalue of the Hodge Laplacian when the ambient manifold supports non-trivial parallel forms.Comment: 22 page

Nonexistence of Generalized Apparent Horizons in Minkowski Space

We establish a Positive Mass Theorem for initial data sets of the Einstein equations having generalized trapped surface boundary. In particular we answer a question posed by R. Wald concerning the existence of generalized apparent horizons in Minkowski space

Segunda fractura de fémur por insuficiencia en pacientes tratada con risedronato

Presentamos un caso clínico de fractura por insuficiencia en fémur en una paciente con antecedentes de fractura de fémur contralateral de características similares y diagnosticada de osteoporosis severa, que recibió tratamiento con risedronato durante cuatro años, en el intervalo de tiempo entre ambas fracturas. A diferencia de los casos publicados de fracturas de fémur por insuficiencia, atribuidas a tratamiento prolongado con alendronato, en nuestro caso ambas fracturas pueden atribuirse a la misma evolución de la osteoporosis.We report a case of insufficiency fracture in the femur in a patient with a history of contralateral femoral fracture similar characteristics and diagnosed with severe osteoporosis that were treated with risedronate for four years, the time interval between fractures. Unlike the reported cases of insufficiency femoral fractures, attributed to prolonged alendronate therapy, in our case both fractures can be attributed to the same development of osteoporosis

Description and Predictive Factors of individual outcomes in a refugee camp based mental health intervention (Beirut, Lebanon)

There is little evidence on the effectiveness of services for the care of people with mental disorders among refugee populations. Médecins sans Frontières (MSF) has established a mental health centre in a mixed urban-refugee population in Beirut to respond to the significant burden of mental health problems. Patients received comprehensive care through a multidisciplinary team. A cohort of people with common and severe mental disorders has been analysed between December 2008 and June 2011 to evaluate individual outcomes of treatment in terms of functionality