Discrete Morse theory for moment-angle complexes of pairs (D^n,S^{n-1})

For a finite simplicial complex K and a CW-pair (X,A), there is an associated CW-complex Z_K(X,A), known as a polyhedral product. We apply discrete Morse theory to a particular CW-structure on the n-sphere moment-angle complexes Z_K(D^{n}, S^{n-1}). For the class of simplicial complexes with vertex-decomposable duals, we show that the associated n-sphere moment-angle complexes have the homotopy type of wedges of spheres. As a corollary we show that a sufficiently high suspension of any restriction of a simplicial complex with vertex-decomposable dual is homotopy equivalent to a wedge of spheres.Comment: Corollary 1.2 and 1 reference added. Some formulations and arguments made more precis

Arrangements of symmetric products of spaces

Using the topological technique of diagrams of spaces, we calculate the homology of the union and the complement of finite arrangements of subspaces of the form $D + SP^{n-d}(X)$ in symmetric products $SP^n(X)$ where $D\in SP^d(X)$. As an application we include a computation of the homology of the homotopy end space of the open manifold $SP^n(M_{g,k})$, where $M_{g,k}$ is a Riemann surface of genus $g$ punctured at $k$ points, a problem which was originally motivated by the study of commutative $(m+k,m)$-groups.Comment: This is an updated version of the paper. In this version some results (Proposition 1.7., Theorem 1.8, Theorem 1.9, Theorem 1.11) are now reformulated in the greater generality (over integer coefficients). Moreover, we now interpret Theorems 1.8 and 1.11 as a generalization of classical Steenrod's theorem to the case symmetric products of (simple) diagrams of space

MPS and ACS with an atomic magnetometer

We show that a single atomic magnetometer in a magnetically unshielded environment can be used to perform magnetic particle spectroscopy (MPS) and AC susceptometry (ACS) on liquid-suspended magnetic nanoparticles. We demonstrate methods allowing a simultaneous recording of M(H) and dM/dH(H) dependences of samples containing down to 1 μg of iron. Our results pave the way towards an atomic magnetometer based MPI scanner

On-chip jitter measurement for true random number generators

Applications of true random number generators (TRNGs) span from art to numerical computing and system security. In cryptographic applications, TRNGs are used for generating new keys, nonces and masks. For this reason, a TRNG is an essential building block and often a point of failure for embedded security systems. One type of primitives that are widely used as source of randomness are ring oscillators. For a ring-oscillator-based TRNG, the true randomness originates from its timing jitter. Therefore, determining the jitter strength is essential to estimate the quality of a TRNG. In this paper, we propose a method to measure the jitter strength of a ring oscillator implemented on an FPGA. The fast tapped delay chain is utilized to perform the on-chip measurement with a high resolution. The proposed method is implemented on both a Xilinx FPGA and an Intel FPGA. Fast carry logic components on different FPGAs are used to implement the fast delay line. This carry logic component is designed to be fast and has dedicated routing, which enables a precise measurement. The differential structure of the delay chain is used to thwart the influence of undesirable noise from the measurement. The proposed methodology can be applied to other FPGA families and ASIC designs

M(H) dependence and size distribution of SPIONs measured by atomic magnetometry

We demonstrate that the quasistatic recording of the magnetic excitation function M(H) of superparamagnetic iron oxide magnetic nanoparticle (SPION) suspensions by an atomic magnetometer allows a precision determination of the sample’s iron mass contentmFe and the particle size distribution

En jämlik skola?

Grujic, Vladimir & Nilsson, Tatiana. (2006). En jämlik skola. En studie av hur samhällsklassrelaterade faktorer och könstillhörighet inverkar på elevers studieprestationer i grundskolan. (An equal school? A study of how social class related factors and gender affect the achievements of pupils in elementary school). Skolutveckling och ledarskap. Lärarutbildningen 60 poäng, Malmö Högskola. Syftet med följande arbete är att få en bild av vilka faktorer, samt i vilken grad, som inverkar på elevers prestationer i skolan. Vi avgränsar dessa faktorer till följande: Social och kulturell bakgrund, föräldrainverkan, krav från föräldrahåll, identifiering med närsamhället, kamratpåverkan, betyg samt influenser från media, d.v.s. tv, tidningar, musik. I vårt arbete undersöker vi i vilken grad elevernas prestationer är beroende av deras föräldrars utbildningsnivå, deras könstillhörighet samt deras olika intressen. Med hjälp av enkätundersökningar samt studier av aktuella statistiska data, relevanta för vår undersökning, söker vi finna signifikanta framgångsfaktorer. Undersökningsarbetet, konsultationen av teoretiska studier, samt undersökningar, påvisar att klasstillhörighet, och i ännu högre grad könstillhörighet inverkar påtagligt på elevers prestationer i skolan

An operad of 3-manifolds

A coloured operad whose operadic operations are 3-cobordisms is introduced in this paper. This operad is presented purely combinatorially through diagrams in handlebodies together with a calculus, which is a generalization of Kirby's calculus. Both integral and rational calculi are developed and a calculus consisting of finite set of local moves is presented in the paper.Comment: 30 pages, an appendix added, Sections "Introduction" and "The operad" are rewritte