535 research outputs found
An improvement's project model to foster sustainable continuous improvement
Continuous Improvement programs are constantly applied amongst companies to reach competitive advantages. However, it is known that companies struggle to sustain benefits of continuous improvement projects in long-Term periods. Indeed, there is not a common shared framework assessing which are the managerial variables that can guarantee improvement's projects success. This research presents a model and a pool of improvement's projects could be framed and carried out accordingly. The model and its enabler mechanisms foster the importance that the outstanding literature assign to human focused factors and soft practices to sustain continuous improvement benefits in the long-Term period. This study presents a first assessment analysis of the model, even if not statistically valid, highlighting its enablers and barriers for a correct application. Then, based on the first data collected on a sample of improvement's projects framed with the model described, the study draws some considerations about which are the critical success factors for improvement's projects
Three-State Complex Valued Spins Coupled to Binary Branched Polymers in Two-Dimensional Quantum Gravity
A model of complex spins (corresponding to a non-minimal model in the
language of CFT) coupled to the binary branched polymer sector of quantum
gravity is considered. We show that this leads to new behaviour.Comment: 3 pages, Latex2e, 2 eps figures, uses espcrc2 and epsf. Contribution
to LATTICE 97, to appear in the Proceeding
Probing molecular dynamics at the nanoscale via an individual paramagnetic center
Understanding the dynamics of molecules adsorbed to surfaces or confined to
small volumes is a matter of increasing scientific and technological
importance. Here, we demonstrate a pulse protocol using individual paramagnetic
nitrogen vacancy (NV) centers in diamond to observe the time evolution of 1H
spins from organic molecules located a few nanometers from the diamond surface.
The protocol records temporal correlations among the interacting 1H spins, and
thus is sensitive to the local system dynamics via its impact on the nuclear
spin relaxation and interaction with the NV. We are able to gather information
on the nanoscale rotational and translational diffusion dynamics by carefully
analyzing the time dependence of the NMR signal. Applying this technique to
various liquid and solid samples, we find evidence that liquid samples form a
semi-solid layer of 1.5 nm thickness on the surface of diamond, where
translational diffusion is suppressed while rotational diffusion remains
present. Extensions of the present technique could be adapted to highlight the
chemical composition of molecules tethered to the diamond surface or to
investigate thermally or chemically activated dynamical processes such as
molecular folding
Apparent diffusion coefficient by diffusion-weighted magnetic resonance imaging as a sole biomarker for staging and prognosis of gastric cancer
Objective: To investigate the role of apparent diffusion coefficient (ADC) from diffusion-weighted magnetic
resonance imaging (DW-MRI) when applied to the 7th TNM classification in the staging and prognosis of gastric
cancer (GC).
Methods: Between October 2009 and May 2014, a total of 89 patients with non-metastatic, biopsy proven GC
underwent 1.5T DW-MRI, and then treated with radical surgery. Tumor ADC was measured retrospectively and
compared with final histology following the 7th TNM staging (local invasion, nodal involvement and according to
the different groups — stage I, II and III). Kaplan-Meier curves were also generated. The follow-up period is
updated to May 2016.
Results: Median follow-up period was 33 months and 45/89 (51%) deaths from GC were observed. ADC was
significantly different both for local invasion and nodal involvement (P<0.001). Considering final histology as the
reference standard, a preoperative ADC cut-off of 1.80×10–3 mm2
/s could distinguish between stages I and II and an
ADC value of ≤1.36×10–3 mm2
/s was associated with stage III (P<0.001). Kaplan-Meier curves demonstrated that
the survival rates for the three prognostic groups were significantly different according to final histology and ADC
cut-offs (P<0.001).
Conclusions: ADC is different according to local invasion, nodal involvement and the 7th TNM stage groups
for GC, representing a potential, additional prognostic biomarker. The addition of DW-MRI could aid in the
staging and risk stratification of GC
On the Maximum Crossing Number
Research about crossings is typically about minimization. In this paper, we
consider \emph{maximizing} the number of crossings over all possible ways to
draw a given graph in the plane. Alpert et al. [Electron. J. Combin., 2009]
conjectured that any graph has a \emph{convex} straight-line drawing, e.g., a
drawing with vertices in convex position, that maximizes the number of edge
crossings. We disprove this conjecture by constructing a planar graph on twelve
vertices that allows a non-convex drawing with more crossings than any convex
one. Bald et al. [Proc. COCOON, 2016] showed that it is NP-hard to compute the
maximum number of crossings of a geometric graph and that the weighted
geometric case is NP-hard to approximate. We strengthen these results by
showing hardness of approximation even for the unweighted geometric case and
prove that the unweighted topological case is NP-hard.Comment: 16 pages, 5 figure
A Classical Sequential Growth Dynamics for Causal Sets
Starting from certain causality conditions and a discrete form of general
covariance, we derive a very general family of classically stochastic,
sequential growth dynamics for causal sets. The resulting theories provide a
relatively accessible ``half way house'' to full quantum gravity that possibly
contains the latter's classical limit (general relativity). Because they can be
expressed in terms of state models for an assembly of Ising spins living on the
relations of the causal set, these theories also illustrate how
non-gravitational matter can arise dynamically from the causal set without
having to be built in at the fundamental level. Additionally, our results bring
into focus some interpretive issues of importance for causal set dynamics, and
for quantum gravity more generally.Comment: 28 pages, 9 figures, LaTeX, added references and a footnote, minor
correction
T-Duality Transformation and Universal Structure of Non-Critical String Field Theory
We discuss a T-duality transformation for the c=1/2 matrix model for the
purpose of studying duality transformations in a possible toy example of
nonperturbative frameworks of string theory. Our approach is to first
investigate the scaling limit of the Schwinger-Dyson equations and the
stochastic Hamiltonian in terms of the dual variables and then compare the
results with those using the original spin variables. It is shown that the
c=1/2 model in the scaling limit is T-duality symmetric in the sphere
approximation. The duality symmetry is however violated when the higher-genus
effects are taken into account, owing to the existence of global Z_2 vector
fields corresponding to nontrivial homology cycles. Some universal properties
of the stochastic Hamiltonians which play an important role in discussing the
scaling limit and have been discussed in a previous work by the last two
authors are refined in both the original and dual formulations. We also report
a number of new explicit results for various amplitudes containing macroscopic
loop operators.Comment: RevTex, 46 pages, 5 eps figure
Generalized Penner models to all genera
We give a complete description of the genus expansion of the one-cut solution
to the generalized Penner model. The solution is presented in a form which
allows us in a very straightforward manner to localize critical points and to
investigate the scaling behaviour of the model in the vicinity of these points.
We carry out an analysis of the critical behaviour to all genera addressing all
types of multi-critical points. In certain regions of the coupling constant
space the model must be defined via analytical continuation. We show in detail
how this works for the Penner model. Using analytical continuation it is
possible to reach the fermionic 1-matrix model. We show that the critical
points of the fermionic 1-matrix model can be indexed by an integer, , as it
was the case for the ordinary hermitian 1-matrix model. Furthermore the 'th
multi-critical fermionic model has to all genera the same value of
as the 'th multi-critical hermitian model. However, the
coefficients of the topological expansion need not be the same in the two
cases. We show explicitly how it is possible with a fermionic matrix model to
reach a multi-critical point for which the topological expansion has
alternating signs, but otherwise coincides with the usual Painlev\'{e}
expansion.Comment: 27 pages, PostScrip
- …