Human centred manufacturing: methodology for ergonomic previsional evaluation of manual assembly operations

The challenge of flexibility and productivity for manufacturing operations needs a new concept based on “human-centered manufacturing process”. This concept must consider basically the ergonomics of workplaces and workload balancing. The application of this concept is achievable through the detailed knowledge of the interaction between human and workplace, in particular as far as the mechanical load (or work load) arising from product design and from manufacturing process definition (included tools and equipment). The measurement of workload then is a fundamental for new (and existing) workplaces. In this paper is described the methodology that considers the procedure and instruments for measuring ergonomic parameters and the use of EAWS method to assess the ergonomic risk level of the workplace summarized by a score. EAWS considers postural aspects and dynamics of work activity. Design or modification of the workplace can be defined on base of the results obtained by the methodology application

Self-Dualities and Renormalization Dependence of the Phase Diagram in 3d O(N)O(N) Vector Models

In the classically unbroken phase, 3d $O(N)$ symmetric $\phi^4$ vector models admit two equivalent descriptions connected by a strong-weak duality closely related to the one found by Chang and Magruder long ago. We determine the exact analytic renormalization dependence of the critical couplings in the weak and strong branches as a function of the renormalization scheme (parametrized by $\kappa$) and for any $N$. It is shown that for $\kappa=\kappa_*$ the two fixed points merge and then, for $\kappa<\kappa_*$, they move into the complex plane in complex conjugate pairs, making the phase transition no longer visible from the classically unbroken phase. Similar considerations apply in 2d for the $N=1$ $\phi^4$ theory, where the role of classically broken and unbroken phases is inverted. We verify all these considerations by computing the perturbative series of the 3d $O(N)$ models for the vacuum energy and for the mass gap up to order eight, and Borel resumming the series. In particular, we provide numerical evidence for the self-duality and verify that in renormalization schemes where the critical couplings are complex the theory is gapped. As a by-product of our analysis, we show how the non-perturbative mass gap at large $N$ in 2d can be seen as the analytic continuation of the perturbative one in the classically unbroken phase.Comment: 38 pages, 12 figures; v3: version to appear in JHE

Stone-Gelfand duality for metrically complete lattice-ordered groups

We extend Yosida's 1941 version of Stone-Gelfand duality to metrically complete unital lattice-ordered groups that are no longer required to be real vector spaces. This calls for a generalised notion of compact Hausdorff space whose points carry an arithmetic character to be preserved by continuous maps. The arithmetic character of a point is (the complete isomorphism invariant of) a metrically complete additive subgroup of the real numbers containing $1$, namely, either $\frac{1}{n}\mathbb{Z}$ for an integer $n = 1, 2, \dots$, or the whole of $\mathbb{R}$. The main result needed to establish the extended duality theorem is a substantial generalisation of Urysohn's Lemma to such "arithmetic" compact Hausdorff spaces. The original duality is obtained by considering the full subcategory of spaces whose each point is assigned the entire group of real numbers. In the introduction we indicate motivations from and connections with the theory of dimension groups.Comment: 24 pages, 2 figure

Self-Dualities and Renormalization Dependence of the Phase Diagram in 3d O(N)O(N) Vector Models

In the classically unbroken phase, 3d O(N) symmetric phi (4) vector models admit two equivalent descriptions connected by a strong-weak duality closely related to the one found by Chang and Magruder long ago. We determine the exact analytic renormalization dependence of the critical couplings in the weak and strong branches as a function of the renormalization scheme (parametrized by kappa) and for any N. It is shown that for kappa = kappa the two fixed points merge and then, for kappa &lt; , they move into the complex plane in complex conjugate pairs, making the phase transition no longer visible from the classically unbroken phase. Similar considerations apply in 2d for the N = 1 phi (4) theory, where the role of classically broken and unbroken phases is inverted. We verify all these considerations by computing the perturbative series of the 3d O(N) models for the vacuum energy and for the mass gap up to order eight, and Borel resumming the series. In particular, we provide numerical evidence for the self-duality and verify that in renormalization schemes where the critical couplings are complex the theory is gapped. As a by-product of our analysis, we show how the non-perturbative mass gap at large N in 2d can be seen as the analytic continuation of the perturbative one in the classically unbroken phase

Renormalization scheme dependence, RG flow, and Borel summability in phi^4 Theories in d<4

Renormalization group (RG) and resummation techniques have been used in N-component.4 theories at fixed dimensions below four to determine the presence of nontrivial IR fixed points and to compute the associated critical properties. Since the coupling constant is relevant in d &lt; 4 dimensions, the RG is entirely governed by renormalization scheme-dependent terms. We show that the known proofs of the Borel summability of observables depend on the renormalization scheme and apply only in "minimal" ones, equivalent in d = 2 to an operatorial normal ordering prescription, where the beta-function is trivial to all orders in perturbation theory. The presence of a nontrivial fixed point can be unambiguously established by considering a physical observable, like the mass gap, with no need of RG techniques. Focusing on the N = 1, d = 2.4 theory, we define a one-parameter family of renormalization schemes where Borel summability is guaranteed and study the accuracy on the determination of the critical exponent. as the scheme is varied. While the critical coupling shows a significant sensitivity on the scheme, the accuracy in. is essentially constant. As a by-product of our analysis, we improve the determination of. obtained with RG methods by computing three more orders in perturbation theory

Metabolic progression to clinical phenotype in classic Fabry disease

BACKGROUND: Fabry disease is an X-linked lysosomal storage disorder due to α-galactosidase A (α-Gal A) deficiency. Clinical onset of Fabry disease is preceded by significant storage of globotriaosylceramide (Gb3) and related glycosphingolipids, but the extent of the metabolic progression before symptoms is unknown. Using a newly recognized effector and marker of Fabry disease, globotriaosylsphingosine (LysoGb3), we aimed to provide a metabolic picture of classic Fabry disease from the neonatal period to childhood. METHODS: LysoGb3 was assessed at different times in two brothers with classic Fabry disease (genotype c. 370–2 A > G). The firstborn was diagnosed after clinical onset at 11 years of age, whereas the second-born was diagnosed in the neonatal period. LysoGb3 was measured in dried blood spots by high-sensitive electrospray ionization liquid chromatography tandem mass spectrometry. RESULTS: Blood LysoGb3 concentrations were consistent with patients’ age and clinical picture, with lower levels in the asymptomatic neonate (19.1 ng/ml) and higher levels in the symptomatic child (94.3 ng/ml). In the second-born, LysoGb3 doubled during the first 5 months of life (37.4 ng/ml), reaching ~40% concentration observed in the symptomatic period. The neonatal LysoGb3 concentration in classic Fabry disease exceeded that observed in normal subjects by over 15 times. CONCLUSIONS: A substantial increase of LysoGb3 was documented during the first months of life in classic Fabry disease, suggesting an early plateau during the pre-symptomatic period. Such a progressive metabolic trend during the pre-symptomatic period implies the potential definition of a metabolic threshold useful for a preventive therapeutic approach of classic Fabry disease. Additionally, the consistent increase of LysoGb3 in the neonatal period in classic Fabry disease suggests LysoGb3 as a useful marker for improving the specificity of newborn screening for Fabry disease