8,612 research outputs found
The use of performance information case studies in local social services departments
New Public Management (NPM) is the commonly used label for the growing popularity of businesslike control tools in governmental organisations. NPM includes several dimensions of change, such as divisionalisation, visible and active control and a prominent role for performance measurement. Developments in Dutch local government demonstrate several of these elements of NPM. Pollitt and Bouckaert (2000) and Pollitt (2002) defined four levels of NPM change: (1) discourse; (2) decisions; (3) practices and (4) results. This paper focuses on performance measurement. The politicians and managers at the top of the investigated municipalities took the decision to adopt instruments that generate performance information. This paper seeks to explain the extent to which the information resulting from these instruments is actually being used in the management practices at work floor level. It investigates two categories of explanations for information use: characteristics of the available information (such as its contents, amount and quality) and characteristics of the organization and its routines. The paper thus analyses how decisions taken by politicians and top managers to adopt NPM relate practices at work floor level.
The robustness of proofreading to crowding-induced pseudo-processivity in the MAPK pathway
Double phosphorylation of protein kinases is a common feature of signalling
cascades. This motif may reduce cross-talk between signalling pathways, as the
second phosphorylation site allows for proofreading, especially when
phosphorylation is distributive rather than processive. Recent studies suggest
that phosphorylation can be `pseudo-processive' in the crowded cellular
environment, as rebinding after the first phosphorylation is enhanced by slow
diffusion. Here, we use a simple model with unsaturated reactants to show that
specificity for one substrate over another drops as rebinding increases and
pseudo-processive behavior becomes possible. However, this loss of specificity
with increased rebinding is typically also observed if two distinct enzyme
species are required for phosphorylation, i.e. when the system is necessarily
distributive. Thus the loss of specificity is due to an intrinsic reduction in
selectivity with increased rebinding, which benefits inefficient reactions,
rather than pseudo-processivity itself. We also show that proofreading can
remain effective when the intended signalling pathway exhibits high levels of
rebinding-induced pseudo-processivity, unlike other proposed advantages of the
dual phosphorylation motif.Comment: To appear in Biohys.
Decline and decadence in Iraq and Syria after the age of Avicenna? : ʿAbd al-Laṭīf al-Baghdādī (1162–1231) between myth and history
‘Abd al-Laṭīf al-Baghdādī’s (d. 1231) work Book of the Two Pieces of Advice (Kitāb al Nasīḥatayn) challenges the idea that Islamic medicine declined after the twelfth century AD. Moreover, it offers some interesting insights into the social history of medicine. ‘Abd al-Laṭīf advocated using the framework of Greek medical epistemology to criticize the rationalist physicians of his day; he argued that female and itinerant practitioners, relying on experience, were superior to some rationalists. He lambasted contemporaneous medical education because it
put too much faith in a restricted number of textbooks such as the Canon by Ibn Sīnā (Avicenna, d. 1037) or imperfect abridgments
Periodic Structure of the Exponential Pseudorandom Number Generator
We investigate the periodic structure of the exponential pseudorandom number
generator obtained from the map that acts on the set
Denominators of Bernoulli polynomials
For a positive integer let where
runs over all primes and is the sum of the base digits of .
For all we prove that is divisible by all "small" primes
with at most one exception. We also show that is large, has
many prime factors exceeding , with the largest one exceeding
. We establish Kellner's conjecture, which says that the number of
prime factors exceeding grows asymptotically as for some constant with . Further, we
compare the sizes of and , leading to the
somewhat surprising conclusion that although tends to infinity
with , the inequality is more frequent
than its reverse.Comment: 25 page
Applications of atomic ensembles in distributed quantum computing
Thesis chapter. The fragility of quantum information is a fundamental constraint faced by anyone trying to build a quantum computer. A truly useful and powerful quantum computer has to be a robust and scalable machine. In the case of many qubits which may interact with the environment and their neighbors, protection against decoherence becomes quite a challenging task. The scalability and decoherence issues are the main difficulties addressed by the distributed model of quantum computation. A distributed quantum computer consists of a large quantum network of distant nodes - stationary qubits which communicate via flying qubits. Quantum information can be transferred, stored, processed and retrieved in decoherence-free fashion by nodes of a quantum network realized by an atomic medium - an atomic quantum memory. Atomic quantum memories have been developed and demonstrated experimentally in recent years. With the help of linear optics and laser pulses, one is able to manipulate quantum information stored inside an atomic quantum memory by means of electromagnetically induced transparency and associated propagation phenomena. Any quantum computation or communication necessarily involves entanglement. Therefore, one must be able to entangle distant nodes of a distributed network. In this article, we focus on the probabilistic entanglement generation procedures such as well-known DLCZ protocol. We also demonstrate theoretically a scheme based on atomic ensembles and the dipole blockade mechanism for generation of inherently distributed quantum states so-called cluster states. In the protocol, atomic ensembles serve as single qubit systems. Hence, we review single-qubit operations on qubit defined as collective states of atomic ensemble. Our entangling protocol requires nearly identical single-photon sources, one ultra-cold ensemble per physical qubit, and regular photodetectors. The general entangling procedure is presented, as well as a procedure that generates in a single step Q-qubit GHZ states with success probability p(success) similar to eta(Q/2), where eta is the combined detection and source efficiency. This is signifcantly more efficient than any known robust probabilistic entangling operation. The GHZ states form the basic building block for universal cluster states, a resource for the one-way quantum computer
Reconciling the observed star-forming sequence with the observed stellar mass function
We examine the connection between the observed star-forming sequence (SFR
) and the observed evolution of the stellar mass function
between . We find the star-forming sequence cannot have a slope
0.9 at all masses and redshifts, as this would result in a
much higher number density at by
than is observed. We show that a transition in the slope of the star-forming
sequence, such that at and
({Whitaker} {et~al.} 2012) at
, greatly improves agreement with the
evolution of the stellar mass function. We then derive a star-forming sequence
which reproduces the evolution of the mass function by design. This
star-forming sequence is also well-described by a broken-power law, with a
shallow slope at high masses and a steep slope at low masses. At , it is
offset by 0.3 dex from the observed star-forming sequence, consistent
with the mild disagreement between the cosmic SFR and recent observations of
the growth of the stellar mass density. It is unclear whether this problem
stems from errors in stellar mass estimates, errors in SFRs, or other effects.
We show that a mass-dependent slope is also seen in other self-consistent
models of galaxy evolution, including semi-analytical, hydrodynamical, and
abundance-matching models. As part of the analysis, we demonstrate that neither
mergers nor hidden low-mass quiescent galaxies are likely to reconcile the
evolution of the mass function and the star-forming sequence. These results are
supported by observations from {Whitaker} {et~al.} (2014).Comment: 17 pages, 13 figures, accepted to ApJ Oct 31st 201
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