7,489 research outputs found

    Some inequalities for the Euclidean operator radius of two operators in Hilbert CC^{\ast}-Modules space

    Full text link
    The Euclidean operator radius of two bounded linear operators in the Hilbert CC^*-module over \A is given some precise bounds. Their relationship to recent findings in the literature that offer precise upper and lower bounds on the numerical radius of linear operators is also established.Comment: 12 page

    Testing collapse models with levitated nanoparticles: the detection challenge

    Get PDF
    We consider a nanoparticle levitated in a Paul trap in ultrahigh cryogenic vacuum, and look for the conditions which allow for a stringent noninterferometric test of spontaneous collapse models. In particular we compare different possible techniques to detect the particle motion. Key conditions which need to be achieved are extremely low residual pressure and the ability to detect the particle at ultralow power. We compare three different detection approaches based respectively on a optical cavity, optical tweezer and a electrical readout, and for each one we assess advantages, drawbacks and technical challenges

    An estimate for the numerical radius of the Hilbert space operators and a numerical radius inequality

    Full text link
    We provide a number of sharp inequalities involving the usual operator norms of Hilbert space operators and powers of the numerical radii. Based on the traditional convexity inequalities for nonnegative real numbers and some generalize earlier numerical radius inequalities, operator. Precisely, we prove that if \A_i,\B_i,\X_i\in\bh (i=1,2,,ni=1,2,\cdots,n), mNm\in\N, p,q>1p,q>1 with 1p+1q=1\frac{1}{p}+\frac{1}{q}=1 and ϕ\phi and ψ\psi are non-negative functions on [0,)[0,\infty) which are continuous such that ϕ(t)ψ(t)=t\phi(t)\psi(t)=t for all t[0,)t \in [0,\infty), then \begin{equation*} w^{2r}\bra{\sum_{i=1}^{n}\X_i\A_i^m\B_i}\leq \frac{n^{2r-1}}{m}\sum_{j=1}^{m}\norm{\sum_{i=1}^{n}\frac{1}{p}S_{i,j}^{pr}+\frac{1}{q}T_{i,j}^{qr}}-r_0\inf_{\norm{x}=1}\rho(\xi), \end{equation*} where r0=min{1p,1q}r_0=\min\{\frac{1}{p},\frac{1}{q}\}, S_{i,j}=\X_i\phi^2\bra{\abs{\A_i^{j*}}}\X_i^*, T_{i,j}=\bra{\A_i^{m-j}\B_i}^*\psi^2\bra{\abs{\A_i^j}}\A_i^{m-j}\B_i and \rho(x)=\frac{n^{2r-1}}{m}\sum_{j=1}^{m}\sum_{i=1}^{n}\bra{\seq{S_{i,j}^r\xi,\xi}^{\frac{p}{2}}-\seq{T_{i,j}^r\xi,\xi}^{\frac{q}{2}}}^2.Comment: No comment

    Loss Cone Profile on the Imaginary Surface Just Enclosing the Resonance Surface in 14.4 GHz ECR Ion Source

    Get PDF

    Entrepreneurship through Bricolage. A Study of Displaced Entrepreneurs at Times of War and Conflict

    Get PDF
    War and conflict brings about adverse changes for those who are displaced. How do entrepreneurial individuals respond to such adversity to either set-up, or continue with their existing entrepreneurial endeavours that would improve their own livelihood or that of others who have been affected? Whilst previous studies have found local knowledge, networks and resources to be crucial in the development of ventures in the war and conflict context, alienation from mainstream society within the host location often means that to succeed, those who are displaced require alternative strategies and approaches. Through examining the entrepreneurship ventures of six internally displaced entrepreneurs in Pakistan, our study identifies that entrepreneurial individuals find different ways to adapt to the new order, with both internal and external bricolage becoming the key strategies deployed to either re-establish their previous business(es) or to develop new endeavour(s) in the host location. To compensate for lack of local knowledge, networks and resources, we found that entrepreneurs followed closely their previous paths in their bricolage attempts, relying on reconfigurations of their pre-existing competencies, as well as utilising pre-established and clandestine networks

    Hydrophobicity properties of graphite and reduced graphene oxide of the polysulfone (PSf) mixed matrix membrane

    Get PDF
    Hydrophobicity properties of graphite and reduced graphene oxide (rGO) (from exfoliated graphite/rGO) towards PSf polymer membrane characteristic and properties at different additives weight concentrations (1, 2, 3, 4 and 5 wt. %) were investigated. Both PSF/graphite and PSf/rGO membranes were characterized in term of hydrophobicity, surface bonding, surface roughness and porosity. FTIR peaks revealed that membrane with graphite and reduced graphene oxide nearly diminished their O-H bonding which was opposite to the graphene oxide peak that shows a strong O-H bonding as increased exfoliated times. These results were in line with the contact angle results that showed strong hydrophobicity of graphite and reduced graphene oxide membranes as increased these additives concentration. The effect of strong hydrophobicity in these membranes also has resulted in smoother surface roughness compared to pristine PSf membrane. Further investigation of the performance of water flux also proved that both above membranes have strong hydrophobic effect, with the lowest pure water flux rate (L/m2h) was given by PSf/rGO 3% membrane at 19.2437 L/m2h

    Study of the superconducting properties of the Bi-Ca-Sr-Cu-O system

    Get PDF
    High Temperature Superconductivity in the Bi-Ca-Sr-Cu-O System has been observed and has attracted considerable attention in 1988. The 80 K superconductivity phase has been identified to have a composition of Bi2CaSr2Cu2Ox, while the 110 K phase as reported in the literature has a possible composition of Bi2Ca2Sr2Cu3Ox. Researchers present here a study of the electrical properties of bulk samples of the slowly cooled and rapidly quenched 2:1:2:2 system. The samples used in this study were prepared from appropriate amounts of Bi2O3, CuO, SrCO3, CaCO3
    corecore