1,169 research outputs found
Order processing improvement in military logistics by Value Stream Analysis lean methodology
Military logistics is a complex process where response times, demand uncertainty, high variety of material references and cost effectiveness turn decisive for combat capability. Considered as the bridge between the deployed forces and the industrial base that provides materials and services that the forces needed to accomplish their mission, capacity and efficiency of delivery are required for its processes. The required flexibility could only be achieved by improving the Supply Chain Management (SCM) in order to optimize delivery lead times. To cope with these requirements, lean thinking can be extended to military organizations. This research justifies and proposes the use of Lean Six Sigma (LSS) methodologies from manufacturing to optimize logistics processes in the defense sector. In particular, the article presents the benefits and results obtained using Value Stream Analysis and DMAIC (Define, Measure, Analyze, Improve, Control) problem-solving methodology to improve the order processing lead-time as key performance indicator of a military unit delivery fulfilment
Value stream analysis in military logistics: The improvement in order processing procedure
Military logistics is a complex process where response times, demand uncertainty, wide variety of material references, and cost-effectiveness are decisive for combat capability. The demanding flexibility can only be achieved by improving supply chain management (SCM) to minimize lead times. To cope with these requirements, lean thinking can be extended to military organizations. This research justifies and proposes the use of lean methodologies to improve logistics processes with the case study of a military unit. In particular, the article presents the results obtained using value stream mapping (VSM) and value stream design (VSD) tools to improve the order processing lead time of spare items. The procedure starts with an order generation from a military unit that requests the material and ends before transportation to the final destination. The whole project was structured, considering the define-measure-analyze-improve-control (DMAIC) problem-solving methodology. The results show that the future state map might increase added-value activities from 44% to 70%. After implementation, it was demonstrated that the methodology applied reduced the lead-time average and deviation up to 69.6% and 61.9%, respectively
A comprehensive asteroseismic modelling of the high-amplitude delta Scuti star RV Arietis
We present a comprehensive asteroseismic study of the double-mode
high-amplitude delta Scuti star HD 187642 (RV Arietis). The modelling includes
some of the most recent techniques: 1) effects of rotation on both equilibrium
models and adiabatic oscillation spectrum, 2) non-adiabatic study of radial and
non-radial modes, 3) relationship between the fundamental radial mode and the
first overtone in the framework of Petersen diagrams. The analysis reveals that
two of the observed frequencies are very probably identified as the fundamental
and first overtone radial modes. Analysis of the colour index variations,
together with theoretical non-adiabatic calculations, points to models in the
range of [7065,7245] K in effective temperature and of [1190, 1270] Myr in
stellar age. These values were found to be compatible with those obtained using
the three other asteroseismic techniques.Comment: accepted for publication in A&
Seismology of beta Cephei stars: differentially-rotating models for interpreting the oscillation spectrum of nu-Eridani
A method for the asteroseismic analysis of beta Cephei stars is presented and
applied to the star nu Eridani. The method is based on the analysis of
rotational splittings, and their asymmetries using differentially-rotating
asteroseismic models. Models with masses around 7.13 M_sun, and ages around
14.9 Myr, were found to fit better 10 of the 14 observed frequencies, which
were identified as the fundamental radial mode and the three L=1 triplets g, p,
and p. The splittings and aymmetries found for these modes recover those
provided in the literature, except for p. For this last mode, all its
non-axysimmetric components are predicted by the models. Moreover, opposite
signs of the observed and predicted splitting asymmetries are found. If
identification is confirmed, this can be a very interesting source of
information about the internal rotation profile, in particular in the outer
regions of the star.
In general, the seismic models which include a description for shellular
rotation yield slightly better results as compared with those given by
uniformly-rotating models. Furthermore, we show that asymmetries are quite
dependent on the overshooting of the convective core, which make the present
technique suitable for testing the theories describing the angular momentum
redistribution and chemical mixing due to rotationally-induced turbulence.Comment: 11 pages, 9 figures, 8 tables. ApJ (in press
The pulsating hot subdwarf Balloon 090100001: results of the 2005 multisite campaign
We present the results of a multisite photometric campaign on the pulsating
sdB star Balloon 090100001. The star is one of the two known hybrid hot
subdwarfs with both long- and short-period oscillations. The campaign involved
eight telescopes with three obtaining UBVR data, four B-band data, and one
Stromgren uvby photometry. The campaign covered 48 nights, providing a temporal
resolution of 0.36microHz with a detection threshold of about 0.2mmag in
B-filter data.
Balloon 090100001 has the richest pulsation spectrum of any known pulsating
subdwarf B star and our analysis detected 114 frequencies including 97
independent and 17 combination ones. The strongest mode (f_1) in the 2.8mHz
region is most likely radial while the remaining ones in this region form two
nearly symmetric multiplets: a triplet and quintuplet, attributed to
rotationally split \ell=1 and 2 modes, respectively. We find clear increases of
splitting in both multiplets between the 2004 and 2005 observing campaigns,
amounting to 15% on average. The observed splittings imply that the rotational
rate in Bal09 depends on stellar latitude and is the fastest on the equator. We
use a small grid of models to constrain the main mode (f_1), which most likely
represents the radial fundamental pulsation. The groups of p-mode frequencies
appear to lie in the vicinity of consecutive radial overtones, up to the third
one. Despite the large number of g-mode frequencies observed, we failed to
identify them, most likely because of the disruption of asymptotic behaviour by
mode trapping. The observed frequencies were not, however, fully exploited in
terms of seismic analysis which should be done in the future with a larger grid
of reliable evolutionary models of hot subdwarfs.Comment: accepted for publication in MNRA
Hydrological response of a dryland ephemeral river to southern African climatic variability during the last millennium
12 pĂĄginas, 6 figuras, 2 tablas.-- El PDF del artĂculo esta en su versiĂłn post print.A long-term flood record from the Buffels River, the largest ephemeral river of NW South Africa (9250 km2), was reconstructed based on interpretation of palaeoflood, documentary and instrumental rainfall data. Palaeoflood data were obtained at three study reaches, with preserved sedimentary evidence indicating at least 25 large floods during the last 700 yr. Geochronological control for the palaeoflood record was provided by radiocarbon and optically stimulated luminescence (OSL) dating. Annual resolution was obtained since the 19th century using the overlapping documentary and instrumental records. Large floods coincided in the past within three main hydroclimatic settings: (1) periods of regular large flood occurrence (1 large flood/~30 yr) under wetter and cooler prevailing climatic conditions (AD 1600â1800), (2) decreasing occurrence of large floods (1 large flood/~100 yr) during warmer conditions (e.g., AD 1425â1600 and after 1925), and (3) periods of high frequency of large floods (~ 4â5 large floods in 20â30 yr) coinciding with wetter conditions of decadal duration, namely at AD 1390â1425, 1800â1825 and 1915â1925. These decadal-scale periods of the highest flood frequency seem to correspond in time with changes in atmospheric circulation patterns, as inferred when comparing their onset and distribution with temperature proxies in southern Africa.The study was funded by the 6th Framework Programme of the
European Commission through the project âFloodWater recharge of
alluvial Aquifers in Dryland Environmentsâ, WADE Project (contract
no. GOCE-CT-2003-506680).Peer reviewe
The Frequency Ratio Method for the seismic modelling of gamma Doradus stars. II The role of rotation
The effect of rotation on the Frequency Ratio Method (Moya et al. 2005) is
examined. Its applicability to observed frequencies of rotating gamma Doradus
stars is discussed taking into account the following aspects: the use of a
perturbative approach to compute adiabatic oscillation frequencies; the effect
of rotation on the observational Brunt-Vaisala integral determination and
finally, the problem of disentangling multiplet-like structures from frequency
patterns due to the period spacing expected for high-order gravity modes in
asymptotic regime. This analysis reveals that the FRM produces reliable results
for objects with rotational velocities up to 70 kms/s, for which the FRM
intrinsic error increases one order of magnitude with respect to the typical
FRM errors given in Moya et al. (2005). Our computations suggest that, given
the spherical degree "l" identification, the FRM may be discriminating for m =
0 modes, in the sense that the method avoids any misinterpretation induced by
the presence of rotationally split multiplet-like structures, which reinforces
the robustness of the method. However, if "l" is unknown, such discrimination
is not ensured. In order to check the FRM in presence of slow-moderate
rotation, we have applied it to the three observed frequencies of the slowly
rotating (vsini = 29 km/s) gamma Doradus star HD48501.Comment: A&A, in pres
Variation in assignment of the COPD patients into a GOLD group according to symptoms severity
Introduction: The Global Organization of Lung Disease (GOLD) classifies patients with chronic obstructive pulmonary disease (COPD) taking into account the symptoms. The modified Medical Research Councilâs dyspnea scale (mMRC) and the COPD assessment test (CAT) are used to assess these symptoms. In this study, we analyze the concordance of GOLD classification using mMRC and CAT. Patients and Methods: This is an observational study of a cohort of 169 patients with COPD, who were classified following the GOLD 2017 recommendations, using both mMRC and CAT. A concordance analysis was applied, and a ROC curve was generated to identify the CAT score that best concorded with the mMRC scale. Results: The concordance for the GOLD groups classified by CAT and mMRC was moderate (kappa 0.492). For mMRC score of 1 and 2, a CAT score of =9 and =16 showed the maximum value of the Youden index, respectively. By reclassifying the patients with the new cut-off points obtained, the best concordance was obtained between the cut-off point for CAT of 16 and for mMRC of 2, followed by CAT of 9 and mMRC of 1. Conclusion: Because of the deficient concordance between CAT and mMRC, we propose the use of new cut-off points in future updates of the GOLD strategy
Protein kinase B (AKT) upregulation and Thy-1-α<sub>v</sub>ÎČ<sub>3</sub> integrin-induced phosphorylation of Connexin43 by activated AKT in astrogliosis.
In response to brain injury or inflammation, astrocytes undergo hypertrophy, proliferate, and migrate to the damaged zone. These changes, collectively known as "astrogliosis", initially protect the brain; however, astrogliosis can also cause neuronal dysfunction. Additionally, these astrocytes undergo intracellular changes involving alterations in the expression and localization of many proteins, including α <sub>v</sub> ÎČ <sub>3</sub> integrin. Our previous reports indicate that Thy-1, a neuronal glycoprotein, binds to this integrin inducing Connexin43 (Cx43) hemichannel (HC) opening, ATP release, and astrocyte migration. Despite such insight, important links and molecular events leading to astrogliosis remain to be defined.
Using bioinformatics approaches, we analyzed different Gene Expression Omnibus datasets to identify changes occurring in reactive astrocytes as compared to astrocytes from the normal mouse brain. In silico analysis was validated by both qRT-PCR and immunoblotting using reactive astrocyte cultures from the normal rat brain treated with TNF and from the brain of a hSOD1 <sup>G93A</sup> transgenic mouse model. We evaluated the phosphorylation of Cx43 serine residue 373 (S373) by AKT and ATP release as a functional assay for HC opening. In vivo experiments were also performed with an AKT inhibitor (AKTi).
The bioinformatics analysis revealed that genes of the PI3K/AKT signaling pathway were among the most significantly altered in reactive astrocytes. mRNA and protein levels of PI3K, AKT, as well as Cx43, were elevated in reactive astrocytes from normal rats and from hSOD1 <sup>G93A</sup> transgenic mice, as compared to controls. In vitro, reactive astrocytes stimulated with Thy-1 responded by activating AKT, which phosphorylated S373Cx43. Increased pS373Cx43 augmented the release of ATP to the extracellular medium and AKTi inhibited these Thy-1-induced responses. Furthermore, in an in vivo model of inflammation (brain damage), AKTi decreased the levels of astrocyte reactivity markers and S373Cx43 phosphorylation.
Here, we identify changes in the PI3K/AKT molecular signaling network and show how they participate in astrogliosis by regulating the HC protein Cx43. Moreover, because HC opening and ATP release are important in astrocyte reactivity, the phosphorylation of Cx43 by AKT and the associated increase in ATP release identify a potential therapeutic window of opportunity to limit the adverse effects of astrogliosis
- âŠ