The spread of Covid-19 led to social restrictions of various kinds, of which closing schools was one. This paper studies the effect of school closures on parental labor supply. To this end, I use repeated cross-sectional data on households at the monthly level from the US Current Population Survey (CPS), and employ a difference-in-differences methodology where I compare the labor market outcomes for parents to school-aged children that require supervision with parents to slightly older children, before and after March 2020. The results show that there is a significant reduction in the labor supply of parents to younger children as a result of school closures, and that the effects are larger for mothers than for fathers.

This paper studies how the school closures in Kenya as a result of the corona pandemic have affected students in Kenya depending on different socio-economic classes. In addition, the study examines how access to the internet, the gender of the student, access to education during the school closures and location of residence affected the return to school after the school closures in Kenya. In order to obtain results, the work is based on data from Covid-19 Rapid Response Phone survey made by The World Bank in collaboration with the Kenya National Bureau of Statistics and the University of California. Furthermore, have pooled cross section regressions and cross section regressions been used. In addition, fixed effects for households have been included to measure how the children are affected differently excluding the social circumstances. The results that this paper presents are that factors influencing the returning rate in Kenya during the school closure were internet access, gender, availability of distance learning and place of residence. Surprisingly, girls were more likely to return to school, contrary to gender norms. Initially, access to education and the internet correlated positively with not returning to school, but later it had a negative impact, which may indicate that students with access to this delayed their return. In conclusion, socio-economic factors and access to the internet and distance learning played a significant role in influencing dropout rates in Kenya.

<div>The integral closure $\overline{I}$ of an ideal $I$ in a ring $R$ consists of all elements $x \in R$ that are integral over $I$. If $R$ is an algebra over an infinite field $k$, one can define general elements of $I=\left( x_{1},\ldots,x_{n}\right)$ as $x_{\alpha}=\sum_{i=1}^{n}\alpha_{i}x_{i}$ with $(\alpha_{1},\ldots,\alpha_{n})$ belonging to a Zariski-open subset of $k^{n}$. </div><div><br></div><div>We prove that for any ideal $I$ of height at least $2$ in a local, equidimensional excellent algebra over a field of characteristic zero, the integral closure specializes with respect to a general element of $I$. That is, we show that $\overline{I}/(x)=\overline{I/(x)}$. </div><div><br></div><div>In a Noetherian local ring $(R,m)$ of dimension $d$, one has a sequence of ideals approximating the integral closure of $I$ for $I$ an $m$-primary ideal. The ideals </div><div>\[ I \subseteq I_{\{d\}} \subseteq \cdots \subseteq I_{\{1\}} \subseteq I_{\{0\}}=\overline{I}\]</div><div>are the coefficient ideals of $I$. The $i^{\text{th}}$ coefficient ideal $I_{\{i\}}$ of $I$ is the largest ideal containing $I$ and integral over $I$ for which the first $i+1$ Hilbert coefficients of $I$ and $I_{\{i\}}$ coincide. </div><div><br></div><div>With a goal of understanding how coefficient ideals behave under specialization by general elements, we turn to the case of monomial ideals in polynomial rings over a field. A consequence of the specialization of the integral closure is that the $i^{\text{th}}$ coefficient ideal specializes when the $i^{\text{th}}$ coefficient ideal coincides with the integral closure. To this end, we give a formula for first coefficient ideals of $m$-primary monomial ideals generated in one degree in $2$ variables in order to describe when $I_{\{1\}}=\overline{I}$. In the $2$-dimensional case, we characterize the behavior of all coefficient ideals with respect to specialization by general elements. </div><div><br></div><div>In the $d$-dimensional case for $d \geq 3$, we give a characterization of when $I_{\{1\}}=\overline{I}$ for $m$-primary monomial ideals generated in one degree. In the final chapter, we give an application to the core, by characterizing when $\core(I)=\adj(I^{d})$ for such ideals.</div><div><br></div>

No description available.

Thesis (MBA)--Stellenbosch University, 2000. / During the last five years, successful mine closure has become one of Iscor Coal Business primary strategic focus areas. Three Iscor Coalmines are currently in different stages of closure, i.e. North Field, Hlobane and Dumacol and the demand on management time spent on this issue is increasing. The changing legal environment, especially issues concerning rehabilitation and mine closure, demands that every company must take full responsibility for any detrimental effect that their operations may have on the environment. This study concerns itself with establishing a generic procedure for mine closure. The interface with all stakeholders, external and internal, is considered. The primary focus areas are determined and the most important issues within each area are discussed in such a way that operational managers and strategists could use it as base knowledge for future closures. Applying the model to an actual closure process, i.e. the closure of Durnacol Coalmine, tested the validity of the model and it was verified that the process could be used as a base for future reference.

L’évolution des vins lors de la conservation en bouteille est un processus lent et complexe où les obturateurs jouent un rôle fondamental, conséquence directe de leur perméabilité à l’oxygène mais aussi des interactions physico-chimiques avec les constituants du vin.Dans un premier temps nous avons étudié l’effet de la conservation en bouteille des vins de Sauvignon blanc après 24 mois d’embouteillage. Dans cette étude, la combinaison des conditions de mise en bouteille et des taux de transfert d'oxygène à travers les bouchons ont eu un effet significatif sur le développement du Sauvignon après l'embouteillage. Les vins fermés hermétiquement en bouteille « ampoule » ou avec des obturateurs à très faible taux de transfert d'oxygène comme les capsules à vis, présentent les plus fortes concentrations en dioxyde de soufre, en acide ascorbique, et en thiols variétaux, mais aussi des niveaux élevés de sulfure d’hydrogène (H2S), qui ont complètement masqué le fruité des vins, par rapport au caractère réduit dominant. Les plus fortes concentrations en 3-sulfanyl-hexanol (3SH) ont été trouvées pour les vins présents dans les bouteilles « ampoules » suivi des bouteilles scellées avec des bouchons à vis saran et des bouchons agglomérés. Les teneurs les plus faibles en 3SH ont été trouvées pour les bouteilles scellées avec des bouchons synthétiques (Nomacorc classic). Le développement du vin à partir de deux mois semble être plutôt lié aux propriétés de perméabilité des différents obturateurs utilisés.Dans un deuxième temps nous avons voulu étudier l’incidence de sept types d’obturateurs (bouchon en liège : naturel, naturel colmaté, microaggloméré, ciré, bouchons synthétiques, capsules à vis : saran et saranex) sur des marqueurs chimiques d’oxydation et de réduction, sur les teneurs en oxygène du vin, ainsi que sur la composition phénolique et aromatique des vins issus de cinq cépages (Merlot, Cabernet Sauvignon, Syrah, Sauvignon blanc et Riesling). Nous avons vérifié que la concentration d’oxygène dans l’espace de tête après embouteillage varie selon le type d’obturateurs, celle-ci peut être jusqu’à trois fois plus importante dans le cas des capsules à vis. Les teneurs en oxygène apportées lors de la mise en bouteille pourraient être responsables de l’absence de discriminations des paramètres chimiques entre les différentes modalités d’obturateurs, après 24 mois de conservation en bouteille. Nous avons mis en évidence une évolution de la composition des vins, avec une diminution importante des concentrations de certains composés (certaines anthocyanes telles que la malvidine et la cyanidine-3-O-glucoside ont diminuées de 60%, des flavanols monomères et dimères présentent des diminutions de l’ordre de 20%) pour les cépages rouges et une augmentation pour d’autres composés, comme l’H2S ou la 3-méthyl-2,4-nonanedione (MND, augmentation de 10%) ou le 1,1,6-triméthyl-1,2-dihydronaphtalène (TDN), dans le cas du Riesling; il est intéressant de remarquer que l’évolution de ce dernier semble être dépendante du type de bouchon, alors que les taux d’autres composés comme le sulfure de diméthyl (DMS) ne semblent pas être affectés par l’obturateur.L’étude des interactions entre les différents obturateurs et les composés soufrés du vin, tel que le sulfure d’hydrogène, responsables des odeurs désagréables couramment appelés « odeurs de réduction » a été réalisée. Nous constatons pour la première fois l’existence d’une sorption/ « scalping » de 75% d’ H2S ou de DMS en solution, après 25 jours de macération par les bouchons en liège. Nous montrons que certains des obturateurs étudiés peuvent sorber/scalper ces molécules, en milieu modèle hydroalcoolique, ouvrant ainsi les portes à des futures expérimentations portant sur l’obturateur en tant que constituant actif d’un emballage jouant un rôle dans la composition, l’évolution et la perception sensorielle du vin. / Wine post-bottling evolution is a slow and complex process where the closures play a fundamental role as a consequence of their permeability to oxygen and of physicochemical interactions with the constituents of wine.Initially we studied the effect of conservation in bottle of Sauvignon Blanc wines after 24 months of bottling. In this study, the combination of the bottling conditions and rates of oxygen transfer through closures have had a significant effect on the development of Sauvignon after bottling. Wine stored in an airtight bottle or under closures allowing very low oxygen transfer, such as screw caps, had the highest concentrations of sulfur dioxide, ascorbic acid, and varietal thiols; these wines also had the highest levels of hydrogen sulfide (H2S) with dominant reduced off-flavours masking their fruity character. The highest concentrations of 3-sulfanyl-hexanol (3SH) were found in wines contained in the airtight bottles followed by those sealed with screw caps saran and agglomerated corks. The lowest levels were found in bottles sealed with synthetic corks (Nomacorc classic). The development of wine after two months seems to be related to the permeability properties of the different plugs used.Secondly, we studied the impact of seven types of closures (natural cork, colmated cork, microagglomerated cork, natural cork with wax, synthetic, screw caps: saran and saranex) on oxidation and reduction chemical markers, on oxygen contents, as well as phenolic and aromatic composition of wines from five grape varieties (Merlot, Cabernet Sauvignon, Shiraz, Sauvignon Blanc and Riesling). We observed that the oxygen concentration in the headspace after bottling varies with the type of closure, being up to three times higher in the case of screw caps. The oxygen introduced during bottling may be responsible for the lack of overall discrimination between chemical parameters of the different modalities of closures after 24 months of storage. We have demonstrated a change in the composition of wines, with a significant decrease in concentrations of certain compounds (anthocyanins like malvidin and cyanidin-3-O-glucoside were reduced by 60%, flavanol monomers and dimers decreased about 20%) for red grape varieties and an increase of other compounds such as H2S or 3-methyl-2,4-nonanedione (MND), with an increase of 10% or 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN), in the case of Riesling. The evolution of the latter appears to be dependent on the type of closure, while rates of other compounds such as dimethyl sulfide (DMS) remain unaffected.The interactions between different closures and sulfur compounds, such as hydrogen sulfide, responsible for the “reduction” off-flavours in wine were studied. We see for the first time the existence of a sorption/scalping, by cork stoppers, of 75% of H2S or DMS in solution, after 25 days of maceration. We show that some of the closures studied can sorb/scalp these molecules in wine-like media. This may have an impact on the composition, the development and sensory perception of wine, opening the door to future experiments regarding closures as active packaging constituents

Natural corks have long been used as wine closures. However, they are associated with causing multiple adverse effects to the wine they are attempting to preserve. Alternative closures such as synthetic corks and screw caps were developed in order to reduce and/or eliminate these problems. However, the major cause of concern regarding these closures is of consumers' acceptance. The effect of how three types of closures (Natural Cork, Synthetic Cork and Screw Cap) affected wine consumers' perceptions of the quality of wine was examined in this study. This project was divided into two experiments. The first experiment determined if frequent wine consumers could detect sensorial differences between the three closure types. The second experiment ascertained if and how regular wine consumers' perceptions were altered based on the type of closure with which the wine samples were bottled. It was determined that the wine consumers could not significantly detect a difference between any of the three closure type samples based only on sensory stimuli. The results from the second experiment found for the Chardonnay samples, the knowledge that the wine samples came from a natural cork or a synthetic cork did not significantly affect the liking, quality or purchase intent scores. However, when the panelists knew that the sample was bottled with a screw cap, they thought it was of lower quality, were less willing to buy a wine like the sample and they lowered the price they were willing to pay. For the Merlot samples, knowledge that the sample came from a natural cork caused the wine consumers to significantly increase both their opinions of the quality of the wine and the amount they were willing to pay for the wine. When they knew that the sample was bottled with a screw cap, they reduced the price they would pay for the wine. / Graduation date: 2005

Des données de Statistique Canada montrent que le Québec a perdu 86 700 emplois manufacturiers nets entre 2004 et 2008, ce qui représente un recul de 13,8% (Bernard, 2009). Un dollar canadien fort, la concurrence internationale, les délocalisations de la production et les consolidations globales d'opérations sont souvent mentionnés comme étant les causes des difficultés du secteur manufacturier canadien - principalement concentré au Québec et en Ontario. La crise financière amorcée à l’été 2007, a contribué à aggraver la crise propre au secteur manufacturier dont les origines remontent au début des années 2000 (Weir, 2007; AgirE, 2008; Pilat et al., 2006). Cette recherche examine le processus de restructuration du secteur manufacturier québécois de manière détaillée au niveau des établissements afin d’en évaluer l’ampleur et la nature entre 2003 et 2008. Les données colligées permettent de poser un regard unique et original sur les restructurations ayant impliqué des licenciements collectifs au Québec. Ces données sont issues de deux sources. D'abord, nous avons utilisé une liste d‘entreprises qui ont envoyé un avis de licenciement collectif au Ministère de l’Emploi et de la Solidarité sociale du Québec entre 2003 et 2008. En second lieu, nous avons eu recours aux archives en ligne des médias pour trouver d’autres évènements de restructuration non rapportés par le ministère ainsi que pour obtenir des informations complémentaires sur les évènements déjà compilés dans la liste du ministère. Notre méthodologie de recherche et notre typologie analytique des types de restructuration sont basées sur celles développées par l’European Monitoring Center on Change (EMCC) et reprises dans certaines études comme celles de Bronfenbrenner et Luce (2004) et Hickey et Schenk (soumis). Les résultats, présentés en termes d’événements de restructuration et d’emplois perdus, sont ventilés en fonction de quelques variables (année d’occurrence, taille de l’établissement, sous-secteur d’activité, intensité technologique, région administrative, types de restructuration). Les raisons données par l’entreprise afin de justifier la restructuration ont aussi été colligées. Au cours de la période étudiée, nous avons identifié au total 1 631 évènements de restructurations dans le secteur manufacturier à travers toutes les régions du Québec, qui ont entraîné la perte de 129 383 emplois. Ainsi, 78 246 emplois ont été perdus suite à la réduction des activités de l‘établissement et 51 137 emplois l’ont été suite à la fermeture de leur établissement. La forme la plus fréquente de restructuration est la restructuration interne, suivi par la faillite/fermeture. Les types de restructuration qui ont engendré le plus de pertes d’emplois en moyenne par évènement sont dans l’ordre, la délocalisation, la sous-traitance, la consolidation d’activités ainsi que la fusion-acquisition. L’année 2008 fut celle où il y a eu le plus grand nombre de restructurations. Montréal et la Montérégie sont les régions qui ont le plus été touchées par la restructuration, les pertes d’emplois et les fermetures d’établissements. Les industries à faible intensité technologique ont davantage été frappées par la crise manufacturière. C’est le sous-secteur du papier et du bois qui connu le plus grand nombre d’événements de restructurations. Ce sous-secteur a aussi subi les pertes d’emplois les plus importantes, suivi par le sous-secteur du textile et du vêtement. Ces deux industries se partagent plus de la moitié des fermetures d’établissements. L’insuffisance de la demande (22,1%), la concurrence internationale (14,3%), la hausse de la valeur du dollar canadien (11,2%), la réorganisation interne de l’entreprise (11,1%), la rationalisation des coûts visant une augmentation de la profitabilité (10,1%) ainsi que les difficultés financières (9,9%) sont les motifs principaux donnés par les employeurs. Nos résultats montrent qu’il y a eu deux temps dans l’évolution de la restructuration du secteur manufacturier au Québec. Un premier temps au début de la période où des changements structurels profonds ont été observés dans certaines industries (p.ex. le bois-papier et le textile-vêtement) et un second temps, en fin de période caractérisé par des changements davantage liés à la conjoncture en raison de la crise économique dont les effets commençaient à se faire sentir à ce moment (Institut de la statistique du Québec, 2009a). / Data from Statistics Canada show that Quebec lost 86.700 manufacturing jobs between 2004 and 2008, which represents a withdraw of -13,8% (Bernard, 2009). A high value Canadian dollar, international competition, production shifts and global operations consolidations are often mentioned as causes of the difficulties in Canadian manufacturing — mainly concentrated in Quebec and Ontario, which have both been severely hit. The financial crisis that broke out in the summer 2007, contributed to worsen the crisis, specific to the manufacturing sector whose origins go up at the beginning of the years 2000 (Weir, 2007; AgirE, 2008; Pilat and al., 2006). This paper examines these aspects in some detail at the establishment level, in order to assess its extent and nature between 2003 and 2008. The data set featured provides a unique overview of the specific aspects of the restructuring processes that involve job losses in Quebec. Two original sources contributed to our study. First, we consulted the list of companies that sent a notification of mass termination to the Quebec Ministry of Labour between 2003 and 2008. Second, we searched electronic media archives to find new cases of plant closures not reported by the Ministry and additional information on the cases found with the Ministry database. Our tracking methodology and analytical typology of restructuring processes are based on those developed by the European Monitoring Center on Change (EMCC) and used in other studies by Bronfenbrenner and Luce (2004) and by Hickey and Schenk (submitted). The results, presented in terms of restructuring events and job losses, are broken down into a few variables (year of occurrence, facility size, sub-sector, technological intensity, administrative region, restructuring type). In total for the study period, we have identified 1,631 restructuring events within Quebec’s regions, which resulted in the loss of 129,383 jobs. Thus, 78,246 workers lost their jobs due to downsizing and 51,137 workers lost their jobs due to closures. Internal restructuring is the most frequent form of restructuring, followed by bankruptcy/closure. Offshoring, outsourcing, relocation and merger/acquisition are the types of restructuring that have resulted on average, in more job losses per event in Quebec's manufacturing sector during the study period. The year 2008 was one that generated the most restructuring events. Montreal and Monteregie are the regions that were the most affected by restructuring events, job losses and plant closures. Overall, it’s the low-technology industries that were the most impacted by the manufacturing crisis. The paper and wood industry had the greatest amount of restructuring events. This sub-sector also had the most job losses, followed by the textiles and clothing industry. These two industries share more than half of the closures. Demand shortage (22.1%), global competition (14.3%), the rise of Canadian dollar (11.2%), internal corporate reorganization (11.1%), cost rationalization to increase profitability (10.1%) and financial difficulties (9.9%) were the main reasons given by employers. Our results show that there were two stages in the evolution of the restructuring events within Quebec’s manufacturing sector. First, structural changes were observed in some industries (e.g. wood and paper and textile-garment) at the beginning of the period and a second phase characterized by economic related changes , due to the economic crisis, whose effects began to be felt at that time (Quebec Institute of Statistics, 2009a).

A 3-D numerical model of the Head of Passes and Bird’s Foot Delta of the Mississippi River- was developed. The model was based on Delft3D and simulates the hydrodynamics and salinity transport for Head of Passes area from RM 6.5 to Gulf of Mexico. The model was calibrated, validated, and used to predict the response of the river to certain stimuli, such as - channel closures, channel modifications and diversions. The model includes West Bay, Southwest Pass, South Pass, Pass-A-Loutre and Main Pass. Three basic cases were developed: existing conditions, closure of Southwest Pass with a levee of 1.5m with dredging of Pass-A-Loutre to 13.7 meter depth, and closure of Southwest Pass and South Pass with dredging of Pass-A-Loutre to 13.7 meter (45 ft) depth. Salinity has been added to the model. It has been proved that salinity intrusion has a significant impact on the model instantaneous discharge. For all passes except Southwest Pass instantaneous discharge decreases almost in half. Closure of Southwest Pass and dredging of Pass-A-Loutre leads to changes in flow speed and distribution. As a result Pass-A-Loutre becomes a main River channel.

The Gulf of Mexico commercial reef fish fishery has experienced significant management changes and disturbance in recent years, including transitioning two major fisheries from a traditional open access system into a limited entry individual fishing quota (IFQ) system in 2007 and 2010. Also in 2010, the Deepwater Horizon oil spill (DWH) released an estimated 4.9 million barrels of oil into the Gulf (~206 million U.S. gallons), and is still the largest U.S. environmental disaster to date. Emergency fishing closures initiated shortly after the oil spill began were successful in keeping tainted seafood from reaching markets. However, effects of DWH closures on fisher decision making, fishery productivity, and distribution of fishing effort all remain poorly understood. Understanding the range and magnitude of fishers’ responses to perturbations — including regulatory change and human-induced environmental disasters — is critical for designing effective management and disaster response policies that can meet biological, ecological, economic, social, and sustainability objectives. This work characterized the spatial and temporal patterns of productivity and fishing effort for the Gulf of Mexico (GoM) commercial reef fish fishery. Patterns of productivity and effort distribution were used to examine the response of fishers to management change and large-scale disturbance, namely the DWH fishing closures. Fisheries-dependent logbook trip reports were used to quantify revenue and catch-per-unit-effort (CPUE) patterns from 2000-2014. Novel to fisheries work in the GoM, complementary vessel monitoring systems (VMS) satellite tracking data were used to quantify high-resolution spatial distribution patterns over time, relative to the DWH fishing closures. A general linear modeling (GLM) approach was also used to examine which variables may have contributed to resilience of fishers after DWH closures. Results suggested that this fishery was largely resilient to the DWH fishing closures in 2010, although exact outcomes varied by region. Overall fleet-level productivity steadily increased over time, but regional patterns were based on major species in catch. Productivity in the western GoM was consistently highest over time, and trips in the west and central GoM were dominated by Red snapper (Lutjanus campechanus) and Vermilion snapper (Rhomboplites aurorubens). Trips in the east were dominated by Red grouper (Epinephelus morio) and Gag grouper (Mycteroperca microlepis). Shifts in spatial distribution to new productive fishing grounds or reduced competition via fewer vessels or trips may explain the increases in productivity observed over the study period. Consolidation in the fleet was apparent, with fewer individual vessels and fewer total trips over time. However, the rate of vessel drop out after DWH (5%) was far below the annual background attrition rate of ~14-20%. Relative productivity patterns inside vs. outside the boundaries of fishing closures did not change over time, and there were even some increases in productivity observed during and after DWH in the eastern GoM. Yet, vessels that dropped out after DWH were concentrated in the north-central and eastern GoM. Distribution of fishing grounds before and after DWH were highly similar, and there were increases in effort along the outer West Florida Shelf. Variability in revenue and CPUE, CPUE magnitude, and magnitude of grouper landings were significant predictors of dropping out of the fishery in the GLMs. Synergies with the Red snapper or Grouper-Tilefish IFQs may have “primed” the fishery for resilience by eliminating inconsistent or marginal fishers before the oil spill, and may further explain some of the spatially varying patterns of productivity and attrition after 2010. Resilience was likely also enhanced by the more than $2 billion in emergency compensation payments made to captains, crew, and vessel owners for lost fishing income and assistance with oil remediation efforts. This work stands to make a significant contribution to our understanding of how the DWH oil spill impacted fisheries and communities in the GoM. The results add to a growing body of literature suggesting that the acute population- and ecosystem-level impacts of the DWH oil spill were not as strong or severe as initially anticipated. This work also stands to make contributions to the broader understanding of how this fishery has performed in the wake of recent management change and major environmental disturbance.