610 research outputs found
Previsão da procura na indústria do vestuário
Dissertação de mestrado integrado em Engenharia e Gestão IndustrialTradicionalmente, produtos de moda, designadamente na indústria do vestuário, incorrem em grandes
perdas devido a quebras de stock e a stocks obsoletos, devido a dois fatores muito caraterísticos deste
mercado, longos tempos de processamento dos produtos, combinado com a concentração das vendas
em períodos muito curtos. Assim sendo, as previsões de vendas tem tido um papel cada vez maior na
cadeia de abastecimento, e cada vez mais relevantes para a manutenção da competitividade num
mercado cada vez mais globalizado e concorrencial.
Nesse sentido, surge o projeto de investigação apresentado nesta dissertação, que consiste no
desenvolvimento de um modelo de previsão da procura para a empresa Cruz&Areal, detentora da marca
BusUrban Wear.
O atual processo de previsão da procura (indutivo, sem qualquer base matemática), tem conduzido a
elevados custos provenientes de excesso ou quebras de stocks. Neste sentido, o projeto de
desenvolvimento de um modelo de previsão tem como objetivo atingir um valor de erro reduzido (erro
percentual absoluto médio próximo de 10%), que permita a racionalização dos recursos envolvidos e a
maximização da faturação proveniente da redução de stocks conjugada com a minimização das quebras.
Na fase inicial do projeto, foi efetuada a revisão da literatura que incidiu na análise dos conceitos,
técnicas e abordagens no processo de previsão. Esta revisão bibliográfica foi importante para uma melhor
compreensão das dificuldades e desafios associados aos métodos de previsão de novos produtos e a
analisar possíveis abordagens para ultrapassar estas dificuldades.
A fase seguinte consistiu na aplicação das abordagens referidas na literatura no sentido de verificar a
adaptabilidade das mesmas à tipologia do problema, sendo necessário recorrer a uma série de métodos
para a obtenção de resultados enquadrados com o objetivo.
A última fase consistiu num estudo originado pelo tratamento dos dados, que indicava uma grande
oportunidade de optimizar o mostruário (grupo de peças de coleção propostas aos clientes), podendo
levar a poupanças muito significativas e a um eficiente aproveitamento dos recursos.Traditionally, fashion products, particularly in the garment industry have incurred high losses due to stock
outs and inventory obsolete caused by two factors very characteristic of this market, long lead times,
combined with the concentration of sales in very short periods. Therefore, sales forecasts have had a
growing role in the supply chain, and more and more relevant to maintaining competitiveness in an
increasingly globalized and competitive market.
In this regard, arises the research project presented in this dissertation, which is to develop a model for
forecasting demand to the company Cruz&Areal, owner of the brand Bus Urban Wear.
The current process of forecasting demand (inductive, without any mathematical foundation), has led to
high costs from excess stocks or breaks. In this sense, the project of developing a forecasting model aims
to achieve a low error value (mean absolute percentage error around 10%), allowing the rationalization of
resources involved and the maximization of billing from the lower inventories combined with minimization
of stock outs.
In the initial phase of the project was made a literature review that focused on the analysis of concepts,
techniques and approaches in the forecasting process. This literature review was important for a better
understanding of the difficulties and challenges associated with forecasting methods of new products and
analyze possible approaches to overcome these difficulties.
The next step was the application of these approaches referred in the literature in order to verify the
adaptability of them to the typology of the problem, being necessary use a number of methods for
obtaining results framed with the objective.
The final stage consisted of a study caused by the processing of data, which indicated a great opportunity
to optimize the showcase (group of collection pieces offered to customers), that can lead to very
significant savings and an efficient use of resources
Beyond new neurons in the adult hippocampus: imipramine acts as a pro-astrogliogenic factor and rescues cognitive impairments induced by stress exposure
Depression is a prevalent, socially burdensome disease. Different studies have demonstrated the important role of astrocytes in the pathophysiology of depression as modulators of neurotransmission and neurovascular coupling. This is evidenced by astrocyte impairments observed in brains of depressed patients and the appearance of depressive-like behaviors upon astrocytic dysfunctions in animal models. However, little is known about the importance of de novo generated astrocytes in the mammalian brain and in particular its possible involvement in the precipitation of depression and in the therapeutic actions of current antidepressants (ADs). Therefore, we studied the modulation of astrocytes and adult astrogliogenesis in the hippocampal dentate gyrus (DG) of rats exposed to an unpredictable chronic mild stress (uCMS) protocol, untreated and treated for two weeks with antidepressants—fluoxetine and imipramine. Our results show that adult astrogliogenesis in the DG is modulated by stress and imipramine. This study reveals that distinct classes of ADs impact differently in the astrogliogenic process, showing different cellular mechanisms relevant to the recovery from behavioral deficits induced by chronic stress exposure. As such, in addition to those resident, the newborn astrocytes in the hippocampal DG might also be promising therapeutic targets for future therapies in the neuropsychiatric field.ARMS: ELC, NDA, PP, AMP, JSC, MM, AJR, JFO, and L.P. received fellowships from the Portuguese Foundation for Science and Technology (FCT) (IF/00328/2015 to J.F.O.; 2020.02855.CEECIND
to LP). This work was funded by FCT (IF/01079/2014, PTDC/MED-NEU/31417/2017 Grant to JFO),
BIAL Foundation Grants (037/18 to J.F.O. and 427/14 to L.P.), “la Caixa” Foundation Health Research
Grant (LCF/PR/HR21/52410024) and Nature Research Award for Driving Global Impact—2019
Brain Sciences (to L.P.). This was also co-funded by the Life and Health Sciences Research Institute (ICVS), and by FEDER, through the Competitiveness Internationalization Operational Program
(POCI), and by National funds, through the Foundation for Science and Technology (FCT)—project
UIDB/50026/2020 and UIDP/50026/2020. Moreover, this work has been funded by ICVS Scientific
Microscopy Platform, member of the national infrastructure PPBI—Portuguese Platform of Bioimaging (PPBI-POCI-01-0145-FEDER-022122; by National funds, through the Foundation for Science and
Technology (FCT)—project UIDB/50026/2020 and UIDP/50026/2020; “la Caixa” Foundation (ID
100010434 to A.J.R.), under the agreement LCF/PR/HR20/52400020; and the European Research
Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant
agreement No 101003187 to A.J.R.)
Comparative complete scheme and booster effectiveness of COVID‐19 vaccines in preventing SARS‐CoV‐2 infections with SARS‐CoV‐2 Omicron (BA.1) and Delta (B.1.617.2) variants: A case–case study based on electronic health records
Background: Information on vaccine effectiveness in a context of novel variants of
concern (VOC) emergence is of key importance to inform public health policies. This
study aimed to estimate a measure of comparative vaccine effectiveness between
Omicron (BA.1) and Delta (B.1.617.2 and sub-lineages) VOC according to vaccination
exposure (primary or booster).
Methods: We developed a case–case study using data on RT-PCR SARS-CoV2-positive cases notified in Portugal during Weeks 49–51, 2021. To obtain measure
of comparative vaccine effectiveness, we compared the odds of vaccination in Omicron cases versus Delta using logistic regression adjusted for age group, sex, region,
week of diagnosis, and laboratory of origin.
Results: Higher odds of vaccination were observed in cases infected by Omicron
VOC compared with Delta VOC cases for both complete primary vaccination (odds
ratio [OR] = 2.1; 95% confidence interval [CI]: 1.8 to 2.4) and booster dose
(OR = 5.2; 95% CI: 3.1 to 8.8), equivalent to reduction of vaccine effectiveness from 44.7% and 92.8%, observed against infection with Delta, to 6.0% (95% CI: 29.2%
to 12.7%) and 62.7% (95% CI: 35.7% to 77.9%), observed against infection with
Omicron, for complete primary vaccination and booster dose, respectively.
Conclusion: Consistent reduction in vaccine-induced protection against infection
with Omicron was observed. Complete primary vaccination may not be protective
against SARS-CoV-2 infection in regions where Omicron variant is dominant.Grant no. 2021/PHF/23776; POCI-01-0145-FEDER-022184; Project ALG-D2-2021-06info:eu-repo/semantics/publishedVersio
Measurement of the cosmic ray spectrum above eV using inclined events detected with the Pierre Auger Observatory
A measurement of the cosmic-ray spectrum for energies exceeding
eV is presented, which is based on the analysis of showers
with zenith angles greater than detected with the Pierre Auger
Observatory between 1 January 2004 and 31 December 2013. The measured spectrum
confirms a flux suppression at the highest energies. Above
eV, the "ankle", the flux can be described by a power law with
index followed by
a smooth suppression region. For the energy () at which the
spectral flux has fallen to one-half of its extrapolated value in the absence
of suppression, we find
eV.Comment: Replaced with published version. Added journal reference and DO
Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory
The Auger Engineering Radio Array (AERA) is part of the Pierre Auger
Observatory and is used to detect the radio emission of cosmic-ray air showers.
These observations are compared to the data of the surface detector stations of
the Observatory, which provide well-calibrated information on the cosmic-ray
energies and arrival directions. The response of the radio stations in the 30
to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of
the incoming electric field. For the latter, the energy deposit per area is
determined from the radio pulses at each observer position and is interpolated
using a two-dimensional function that takes into account signal asymmetries due
to interference between the geomagnetic and charge-excess emission components.
The spatial integral over the signal distribution gives a direct measurement of
the energy transferred from the primary cosmic ray into radio emission in the
AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air
shower arriving perpendicularly to the geomagnetic field. This radiation energy
-- corrected for geometrical effects -- is used as a cosmic-ray energy
estimator. Performing an absolute energy calibration against the
surface-detector information, we observe that this radio-energy estimator
scales quadratically with the cosmic-ray energy as expected for coherent
emission. We find an energy resolution of the radio reconstruction of 22% for
the data set and 17% for a high-quality subset containing only events with at
least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy
We measure the energy emitted by extensive air showers in the form of radio
emission in the frequency range from 30 to 80 MHz. Exploiting the accurate
energy scale of the Pierre Auger Observatory, we obtain a radiation energy of
15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV
arriving perpendicularly to a geomagnetic field of 0.24 G, scaling
quadratically with the cosmic-ray energy. A comparison with predictions from
state-of-the-art first-principle calculations shows agreement with our
measurement. The radiation energy provides direct access to the calorimetric
energy in the electromagnetic cascade of extensive air showers. Comparison with
our result thus allows the direct calibration of any cosmic-ray radio detector
against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI.
Supplemental material in the ancillary file
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4
While the increasing availability of global databases on ecological communities has advanced our knowledge
of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In
the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of
Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus
crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced
environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian
Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by
2050. This means that unless we take immediate action, we will not be able to establish their current status,
much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio
Mapping density, diversity and species-richness of the Amazon tree flora
Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution
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