No description available.

<p>The  Pakistan  poultry  industry  has  developed  into  the  11thlargest  poultry  industry  in  the world  and  poultry  products  provide  high-quality  and  affordable  protein  sources  to  communities throughout the country. However, <em>Salmonella </em>Gallinarum, the etiological agent for fowl typhoid, is  endemic  in  Pakistan  with  infections  leading  to  high  mortality  and  substantial  economic  loss. Currently, <em>Salmonella </em>Gallinarum  infectionsin  Pakistan  poultry  are  controlled  with  antibiotics. The continued emergence of antibiotic resistance, however, has led to global initiatives to reduce the  use  of  antibiotics  in  both  human  and  veterinary  medicine.  Concurrently,  the  Pakistan government  recently  introduced  new  national  policies  that  limit  the  use  of  antibiotics  for performance  in  livestock  and  poultry  production.  As  such,  controlling  bacterial  infections  in poultry  without  increasing  the  likelihood  of  antibiotic use could  ensure  the  sustainability  of Pakistan  poultry  production  without  posing  risks  to  public  health.  Toward  this  end,  we hypothesized that <em>Salmonella</em> Gallinarum infections inchickens could be prevented or otherwise controlled through the use of phages. To test this hypothesis, wastewater samples were collected from Lahore, Pakistan and different cities of Indiana, US and processed to isolate bacteriophages. The  phages  were  characterized  in  terms  of  morphology,  host  spectra,  lytic  capacity,  genomic sequencing,  and  survivability  in  different  environments. Transmission  electron  microscopy showed these phages belonged to myoviridae (n = 5) and podoviridae (n = 1) families. Spectrum analysis  revealed  that  each  phage  lysed  at  least  8  out  of  10  different  strains  of <em>Salmonella </em>Gallinarum and significantly reduced (P < 0.05) <em>Salmonella </em>Gallinarum when co-cultured in liquid medium with the bacterium. Stability of the phages was tested insimulated gastric fluid (SGF; pH= 2.5) andsimulated intestinal fluid (SIF; pH~6.8). Results showed that phage concentrationswere reduced to undetectable levels when exposed to SGF for more than 5 minutes. However, exposure to SIF did not result in appreciable reductions in phage concentrations. To mitigate potential effects of  gastric  environments,  phages  were  encapsulated  using  a  sodium  alginate-based  method.  In contrast  to  unprotected  phages,  encapsulated  phages  remained  viable  (~100%)  after  30  minutes exposure to SGF. Additionally, encapsulation efficiencies ranged between 90-99%. Encapsulated phages were sequentially incubated in SGF (30 minutes) and SIF(120 minutes) to determine the rate  of  release  of  the  phages  from  capsules. All  phages  were  released from  capsules after  60 minutes  of  exposureto  SIF. To  determine  if  the  phages  effectively  controlled <em>Salmonella </em>Gallinarum infections in chickens, 100, day-old Jumbo Cornish Rock Cross birds were randomly assigned  to  one  of  four  treatments:  1)  Control 1  (bacterial  challenge,  no  phage  treatment);  2) Control 2 (no phage or bacterial challenge); 3) challenged with SalmonellaGallinarum and treated with  unprotected  phages;  and  4)  challenged  with <em>Salmonella</em> Gallinarum  and  treated  with encapsulated phages. At7 d of age, chicks receiving the bacterial challenge were administered 5 X106CFU (500 μL) of <em>Salmonella</em> Gallinarum. For birds in phage treatment groups, the phages were administered (500 uL; 5 X108 PFU/mL or g) at 0, 12, and 24 hours post-challenge. Six birds from each group were euthanized at 1, 2, and 4 days post-challenge (dpc) and cecal SalmonellaGallinarum  concentrations  were  quantified.  At 1  dpc, birds  treated  with  unprotected  and encapsulated  phages  had significantly lower (P  <  0.05) SalmonellaGallinarum concentrations(4.36 ± 0.20and 5.05 ± 0.22 logCFU/g, respectively) than those found in untreated birds (5.71 ± 0.13). Likewise,  at4  dpc, <em>Salmonella </em>Gallinarum concentrationsin  ceca  of  birds  treated  with encapsulated and unprotected phages were significantly lower (P < 0.05; 3.26 ± 0.62 and 4.02 ± 0.15 log  CFU/g,  respectively)  than  those  found  in untreated  birds(4.65  ±  0.08log  CFU/g). A second trial was conducted with higher challenge doses (1 mL at 1× 109CFU) and an additional treatment including a mixture (1:1) of unprotected and encapsulated phages. At1dpc, <em>Salmonella</em> Gallinarum concentrations  in the ceca  of  birds  treated  with unprotected  phages,  encapsulated phages, and a mixture of unprotected  and encapsulated phages  were significantly lower(4.28 ± 0.11, 3.72 ± 0.40, and 3.81 ± 0.36log CFU/g, respectively) than found in those of untreated birds (5.26 ± 0.19log CFU/g). At 2 dpc, concentrations of<em> Salmonella </em>Gallinarumin the ceca of birds treated  with  unprotected,  encapsulated,  and  a mixture  of  unprotected  and  encapsulated  phages were significantly  lower  (P  <  0.05; 4.31  ±0.53, 3.96  ±0.61,  and 4.38  ±  0.44logCFU/g, respectively) than those found in the ceca of untreated birds (5.72 ± 0.27logCFU/g).However, no significant differences were found in concentrations of <em>Salmonella</em> Gallinarum in the ceca of birds treated with encapsulated phages versus those treated with unprotected phagesor a mixture of   encapsulated   and   unprotected   phages.   Similarly,   at   4   dpc, <em>Salmonella </em>Gallinarum concentrations in the ceca  of  birds  treated  with unprotected  phages, encapsulated  phages,  and  a mixture of unprotected and encapsulated phages were significantly lower (3.17 ± 0.45, 3.56 ± 0.51, and 3.81 ± 0.54log CFU/g, respectively) than found in those of untreated birds (5.79 ± 0.08log CFU/g). At  7  d  post-challenge,  concentrations of <em>Salmonella</em> Gallinarum in  the  ceca  of  birds treated  with mixture  of  unprotected  and  encapsulated phages(2.40  ±  0.55log  CFU/g)  were significantly lower (P  <  0.05) than  those  found  in the ceca  of  untreated  birds(7.08  ±  0.19log CFU/g). Similarly,  concentrations of<em> Salmonella</em> Gallinarum  in the  ceca of  birds  treated  with encapsulated and unprotected phages were significantly lower (P < 0.05; 4.29 ± 0.39and 4.60 ± 0.37 log  CFU/g,  respectively)  than  those  found  in  untreated  birds.  Taken  together,  these  data indicate that <em>Salmonella </em>Gallinarum infections could be controlled with phage-based treatments. Additionally, the use of a mixture of unprotected and encapsulated phages may be more effective, presumably  by  allowing  unprotected  phages  to  act  immediately  in  the  proximal  gastrointestinal tract  (GIT;  e.g.,  crop)  with  encapsulated  phages  having  greater  activity  once  released  from capsules in the distal small intestine. While no deleterious effects of the phages were observed on the chickens themselves, continuing studies should more comprehensively assess host-response to phage treatment including potential impact on microbial communities throughout the chicken GIT.</p>

A study of European households found that Food and drink causes a fourth of the total various environmental impacts. Globally does the food sector account for 22 % of all the greenhouse gas emissions. The climate impact from different foods do however vary significantly, and meat products does generally cause higher greenhouse gas emissions than plant-based foods. A reduction of the meat consumption is suggested by many researchers as one of the most important measures in order to move towards a more sustainable food consumption and production. The grocery retailers have an important role as gatekeepers between the consumer and the products, and the aim of this thesis is to study a transition towards a larger range and increased sales of plant-based protein alternatives to meat from the retailers’ perspective. It does so by attempting to identify drivers and barriers from their point of view. Data was collected through interviews with representatives for the largest retailer groups (n=3) and interviews with store managers (n=8) as well as by examining the product range in the stores (n=10). Grocery stores were located in two different cities; the district Södermalm in central Stockholm and Östersund, a mid-sized town in the Northern parts of Sweden. The results from the interviews showed an increase in the range as well as the sales of vegetarian products at all the participating retailers and stores, and all the interviewees believed that this will continue to increase even further in the future. Flexitarians and young people stands out as the main groups of consumers who buy these products and thus lies behind this increase. What drives the consumers has been identified as an increased awareness, an improved product range and media attention. From the retailers’ perspective it is also now considered a competitive advantage to offer an attractive range of these products. Price has been identified as one of the main barriers for a future expansion of the sales these vegetarian alternatives, but several of the participants also believed that a lot of people are not at all interested in lowering their meat consumption which would be a central obstacle to overcome to get a wide spread in society as a whole. Even if the products have improved recently they may still not be attractive enough to be considered as an alternative for all consumers. The findings also indicate that there is a relatively small difference between the two participating cities, with the main exception that the stores at Södermalm in general offers more perishable vegetarian alternatives than the stores in Östersund does. The most significant differences, regarding product range, was found within ICA (Sweden’s largest food retailer) where the stores are privately owned and the store managers can choose assortment which differs from the other two large retailers Axfood and Coop where it is centrally controlled. The representatives from the retailer groups had rather different views on their ownrole in the development of the vegetarian alternatives but also on what future measures they believed are needed for a future development and impact. This has consequences for the consumers as the range differs to a large degree, to some extent between the different retailer groups, but mainly within the largest one (ICA). The results from this study cannot be generalised, but may provide new insights to a perspective that seems to not have been studied before and might constitute a point of departure for future research. / Mat och dryck står för ungefär en fjärdedel av vår miljö- och klimatpåverkan och globalt står livsmedelssektorn för 22 % av alla växthusgasutsläpp. Klimatpåverkan varierar dock kraftigt mellan olika typer av livsmedel och generellt sett är utsläppen från kött flera gånger större än för vegetabiliska livsmedel. Att minska köttkonsumtionen och övergå till mer vegetabiliska proteiner anses vara en av de viktigaste åtgärderna för att nå en mer hållbar matkonsumtion. Som länken mellan varan och konsumenten har dagligvaruhandeln en viktig roll för att förutsättningarna ska finnas på plats. Den här studien syftar till att undersöka handelns syn på utvecklingen av en ökad´andel vegetariska alternativ till kött, genom att belysa drivkrafter, hinder samt hur utbudet ser ut. Data samlades in genom intervjuer med centrala representanter för ICA, Coop och Axfood (n=3) samt genom intervjuer med butikschefer (n=8) och sortimentsundersökningar i butik (n=10) i en stor respektive mellanstor svensk stad (på Södermalm i Stockholm samt i Östersund). Resultaten visar att försäljningen och utbudet av vegetariska produkter har de senaste åren ökat kraftigt hos alla medverkande butiker och bolag, och utvecklingen tros även fortsätta i framtiden. Det är främst flexitarianer och unga som är drivande för utvecklingen, och en ökad medvetenhet (miljö, hälsa och djurvälfärd) samt att utbudet blivit bättre pekas ut som bidragande orsaker. För butikerna och bolagen själva är det även en konkurrensfördel att ha ett bra vegetariskt utbud. Ett av de främsta hindren som kommit fram för den fortsatta utvecklingen är att det är många som inte är intresserade av att minska sin köttkonsumtion, att produkterna inte är tillräckligt attraktiva och att de kan vara dyra. Resultaten visar också att skillnaden i utbud mellan städerna är relativt liten, med undantaget att det är en mindre andel färska alternativ i Östersund än på Södermalm. De största skillnaderna i hur många vegetariska alternativ som kunden har att välja på (oberoende av stad) finns inom ICA som drivs av privata handlare och där butikerna i större grad kan påverka sitt sortiment, tillskillnad från Axfood och Coop där sortimenten centralstyrs. De centrala representanter som medverkat har olika syn på sin egen roll i utvecklingen samt vilka åtgärder som behövs för en fortsatt utveckling. För konsumenten finns det en relativt stor skillnad i bredden på det vegetariska utbudet beroende på vilken butik de väljer att gå till, vilket verkar vara en konsekvens av vilken nivå sortimentet bestäms på. Resultaten från studien går inte attgeneraliseras, men de kan ge nya insikter i ett perspektiv som inte verkar studerats tidigare och vara en utgångspunkt för framtida studier.

This thesis project is a contribution to addressing the pressing need for sustainable alternatives to fossil fuels and traditional plastics. The work focuses on enzymatic saccharification of microalgae biomass to generate a sugar-rich stream as raw material for biofuels and bioplastics production. Microalgae and cyanobacteria are highlighted for their ability to convert CO2 into valuable biomass components in the presence of light.  To enhance biomass conversion efficiency, the enzymatic hydrolysis of microalgae and cyanobacteria is explored by utilizing various enzymes to break down complex polymers into valuable sugars. Additionally, the cultivation of cyanobacteria is studied to optimize the overall process. Results indicate challenges, such as measurement uncertainty and the need for biomass pretreatment, suggesting areas for further research.  The primary objective of this thesis work is to optimize enzymatic hydrolysis processes by determining the optimal combinations of enzymes, to enhance biomass conversion efficiency. It also underscores the importance of microorganisms in transitioning to a more environmentally friendly future by offering sustainable alternatives to conventional products.

Titre de l'écran-titre (visionné le 11 décembre 2023) / Ce mémoire porte sur le cheminement scolaire et professionnel des enseignant.e.s débutant.e.s, en contexte d'insertion professionnelle, dans les écoles alternatives primaires publiques au Québec. Cette recherche s'intéresse au parcours de ces enseignant.e.s afin de comprendre les effets de leurs expériences personnelles et professionnelles sur leur insertion. En outre, cette recherche permettra de mettre en lumière le processus de création de l'identité professionnelle des enseignant.e.s débutant.e.s (Goyette, 2014). Dans le cadre de cette étude qualitative, 10 participant.e.s ont répondu à un questionnaire sous forme d'une entretien semi-dirigé. Nous avons pu qualifier leurs expériences d'insertion professionnelle et leurs expériences d'apprentissage dans les écoles alternatives primaires publiques du Québec. L'analyse des 10 entretiens semi-dirigés démontre que les nouveaux.elles enseignant.e.s vivent dans les écoles alternatives une expérience d'insertion qui comporte plusieurs singularités, notamment en ce qui concerne la collaboration avec les parents, le rythme des élèves et la planification. L'analyse révèle, entre autres, les avantages et les inconvénients de la collaboration entre les enseignant.e.s et les parents. L'étude révèle également des habiletés nouvelles chez les jeunes enseignant.e.s dans les écoles alternatives. Appuyée par la théorie sociale cognitive des cheminements scolaires et professionnels, l'étude permet de conclure que si les objectifs et les choix personnels de l'individu sont bien déterminés, cela augmente le sentiment de bien-être d'un.e enseignant.e et favorise son insertion (Bandura 1986 ; Croteau et Bouffard, 2019). Finalement, à partir des résultats obtenus et dans une perspective de développement des écoles alternatives, nous avons suggéré des pistes de solutions pour améliorer l'insertion professionnelle des enseignant.e.s dans les écoles alternatives primaires publiques au Québec. / This thesis focuses on the educational and professional path of beginning teachers, in the context of professional integration, in public primary alternative schools in Quebec. This research focuses on the career path of these teachers in order to understand the effects of their personal and professional experiences on their integration. In addition, this research will highlight the process of creating the professional identity of beginning teachers (Goyette, 2014). In this qualitative study, 10 participants responded to a questionnaire during a semi-structured interview. We were able to qualify their experiences of professional integration and their learning experiences in alternative public primary schools in Quebec. The analysis of the 10 semi-structured interviews shows that the new teachers live in alternative schools an integration experience that includes several singularities, especially with regard to collaboration with parents, student pace and planning. The analysis reveals the advantages and disadvantages of collaboration between teachers and parents. The study also reveals new skills among young teachers in alternative schools. Supported by the cognitive social theory of educational and professional pathways, the study concludes that if the individual's goals and personal choices are well determined, it increases the sense of well-being of one. e teacher and promotes its integration (Bandura 1986; Croteau and Bouffard, 2019). Finally, based on the results obtained, with a view to developing alternative schools, we suggested possible solutions to improve the professional integration of teachers in alternative public primary schools in Quebec.

Penology / (M.A. (Penology)

Quantified decision-making refers to the scaling of factors such as crime seriousness, risk assessment, violation severity, and punitive responses or intensity of surveillance. As such, it is largely based on the justice principle, according to which the punitive response should be commensurate with the crime committed. This study consequently looks at the applicability of a retributive stance towards probation, and suggests a quantified, or structured, approach to decision-making in probation with special reference to the South African situation. Referring to historical and ideological precedents, it is maintained that the current crisis in corrections - referring to the congestion of prison facilities and the negative spin-offs related to it - can, to a large extent, be ascribed to an over reliance on imprisonment as a sentencing option. It is argued that imprisonment can be seen as a failure in terms of both its basic motives, and more importantly, with regard to its unintended consequences, necessitating a search for viable sentencing alternatives. With regard to probation, and Intensive Supervision Probation (ISP) in particular, this study recognizes its limitations, but maintains that probation still holds the greatest potential as a workable alternative to incarceration. In view of South African corrections, that is plagued by prison overcrowding, on the one hand, and certain structural shortcomings, on the other, a structured probation system is proposed that will evade the weaknesses of subjective decisionmaking, which often act to intensify the crisis. It is proposed that quantified decision-making tools be developed that will replace both sentencing and revocation decisions. It is further suggested that an effective risk prediction instrument be developed to guide the probation process. / Penology / D. Litt. et Phil.

This qualitative study aimed to explore how to handle aggression in therapy from a Gestalt perspective. In order to reach the aim of this study a conceptual framework was done exploring terms central to this project including aggression and Gestalt Play therapy. Unstructured, telephonic interviews were then conducted with seven Gestalt Play therapists working with children in the Western Cape exploring ways to handle and treat aggression in therapy. The data collected during these interviews were then analyzed and several themes were identified and explored by conducting a literature control. Guidelines were then formulated and written on how to handle aggression in therapy from a Gestalt perspective as part of the concluding chapter of this research report. / Social Work / M. Diac (Play Therapy)

La chimie est un sujet difficile étant donné ses concepts nombreux et souvent peu intuitifs. Mais au-delà de ces difficultés d’ordre épistémologique, l’apprentissage de la chimie peut être en péril lorsqu’il s’appuie sur des fondations instables, mêlées de conceptions alternatives. Les conceptions alternatives sont les représentations internes, tacites, des étudiants, qui sont en désaccord avec la théorie scientifiquement acceptée. Leur présence dans leur esprit peut nuire à la compréhension conceptuelle, et elle peut mener les étudiants à expliquer le comportement de la matière incorrectement et à faire des prédictions inexactes en chimie. Les conceptions alternatives sont réputées répandues et difficiles à repérer dans un cadre traditionnel d’enseignement. De nombreuses conceptions alternatives en chimie ont été mises en lumière par différents groupes de chercheurs internationaux, sans toutefois qu’une telle opération n’ait jamais été réalisée avec des étudiants collégiaux québécois. Le système d’éducation postsecondaire québécois représentant un contexte unique, une étude des difficultés particulières de ces étudiants était nécessaire pour tracer un portrait juste de la situation. De plus, des chercheurs proposent aujourd’hui de ne pas faire uniquement l’inventaire des conceptions, mais de s’attarder aussi à étudier comment, par quel processus, elles mènent à de mauvaises prédictions ou explications. En effet, ils soutiennent que les catalogues de conceptions ne peuvent pas être facilement utilisés par les enseignants, ce qui devrait pourtant être la raison pour les mettre en lumière : qu’elles soient prises en compte dans l’enseignement. Toutefois, aucune typologie satisfaisante des raisonnements et des conceptions alternatives en chimie, qui serait appuyée sur des résultats expérimentaux, n’existe actuellement dans les écrits de recherche. Plusieurs chercheurs en didactique de la chimie suggèrent qu’une telle typologie est nécessaire et devrait rendre explicites les modes de raisonnement qui mettent en jeu ces conceptions alternatives. L’explicitation du raisonnement employé par les étudiants serait ainsi la voie permettant de repérer la conception alternative sur laquelle ce raisonnement s’appuie. Le raisonnement est le passage des idées tacites aux réponses manifestes. Ce ne sont pas toutes les mauvaises réponses en chimie qui proviennent de conceptions alternatives : certaines proviennent d’un manque de connaissances, d’autres d’un agencement incorrect de concepts pourtant corrects. Comme toutes les sortes de mauvaises réponses d’étudiants sont problématiques lors de l’enseignement, il est pertinent de toutes les considérer. Ainsi, ces préoccupations ont inspiré la question de recherche suivante : Quelles conceptions alternatives et quels processus de raisonnement mènent les étudiants à faire de mauvaises prédictions en chimie ou à donner de mauvaises explications du comportement de la matière? C’est pour fournir une réponse à cette question que cette recherche doctorale a été menée. Au total, 2413 étudiants ont participé à la recherche, qui était divisée en trois phases : la phase préliminaire, la phase pilote et la phase principale. Des entrevues cliniques ont été menées à la phase préliminaire, pour explorer les conceptions alternatives des étudiants en chimie. Lors de la phase pilote, des questionnaires à choix multiples avec justification ouverte des réponses ont été utilisés pour délimiter le sujet, notamment à propos des notions de chimie les plus pertinentes sur lesquelles concentrer la recherche et pour mettre en lumière les façons de raisonner des étudiants à propos de ces notions. La phase principale, quant à elle, a utilisé le questionnaire à deux paliers à choix multiples « Molécules, polarité et phénomènes » (MPP) développé spécifiquement pour cette recherche. Ce questionnaire a été distribué aux étudiants via une adaptation de la plateforme Web ConSOL, développée durant la recherche par le groupe de recherche dont fait partie la chercheuse principale. Les résultats montrent que les étudiants de sciences de la nature ont de nombreuses conceptions alternatives et autres difficultés conceptuelles, certaines étant très répandues parmi leur population. En particulier, une forte proportion d’étudiants croient que l’évaporation d’un composé entraîne le bris des liaisons covalentes de ses molécules (61,1 %), que tout regroupement d’atomes est une molécule (78,9 %) et que les atomes ont des propriétés macroscopiques pareilles à celles de l’élément qu’ils constituent (66,0 %). D’un autre côté, ce ne sont pas toutes les mauvaises réponses au MPP qui montrent des conceptions alternatives. Certaines d’entre elles s’expliquent plutôt par une carence dans les connaissances antérieures (par exemple, lorsque les étudiants montrent une méconnaissance d’éléments chimiques communs, à 21,8 %) ou par un raisonnement logique incomplet (lorsqu’ils croient que le seul fait de posséder des liaisons polaires rend nécessairement une molécule polaire, ce qu’on observe chez 24,1 % d’entre eux). Les conceptions alternatives et les raisonnements qui mènent à des réponses incorrectes s’observent chez les étudiants de première année et chez ceux de deuxième année du programme de sciences, dans certains cas avec une fréquence diminuant entre les deux années, et dans d’autres, à la même fréquence chez les deux sous-populations. Ces résultats permettent de mitiger l’affirmation, généralement reconnue dans les écrits de recherche, selon laquelle les conceptions alternatives sont résistantes à l’enseignement traditionnel : selon les résultats de la présente recherche, certaines d’entre elles semblent en effet se résoudre à travers un tel contexte d’enseignement. Il demeure que plusieurs conceptions alternatives, carences dans les connaissances antérieures de base et erreurs de raisonnement ont été mises en lumière par cette recherche. Ces problèmes dans l’apprentissage mènent les étudiants collégiaux à faire des prédictions incorrectes du comportement de la matière, ou à expliquer ce comportement de façon incorrecte. Au regard de ces résultats, une réflexion sur l’enseignement de la chimie au niveau collégial, qui pourrait faire une plus grande place à la réflexion conceptuelle et à l’utilisation du raisonnement pour la prédiction et l’explication des phénomènes étudiés, serait pertinente à tenir. / The difficulties found in learning Chemistry are mostly ascribed to the fact that it comprises many complex and counter-intuitive concepts. But beyond these epistemological challenges, learning chemistry can be in jeopardy when it relies on learners’ unstable foundations mixed with alternative conceptions. Alternative conceptions are tacit internal representations that students hold in disagreement with scientifically accepted theories. The presence of alternative conceptions in students’ minds might harm their conceptual understanding leading them to wrongly explain the behaviour of matter and to make incorrect predictions in chemistry. Alternative conceptions are recognised as widespread and difficult to identify in a traditional educational setting. Many alternative conceptions in chemistry have been identified by different groups of researchers in international settings, but such an operation has never been carried out with Quebec college students. As Quebec’s post-secondary education system represents a unique context, a study of the particular difficulties of students in this system was necessary to draw an accurate picture of the situation. Furthermore, researchers presently suggest not only to list such alternative conceptions, but also to explore by what processes they lead to wrong predictions or explanations. Researchers indeed argue that mere lists of alternative conceptions cannot be easily used by teachers, who should be the target audience for these results if they are to take into account alternative conceptions in their teaching. However, no satisfactory typology of reasoning processes and alternative conceptions in chemistry exists today in the research literature. Several researchers in chemistry education suggest that such a typology is needed and should render explicit the reasoning processes involving these alternative conceptions. Explicitation of the reasoning used by the students while performing a task in chemistry would be the way to identify the alternative conception on which this reasoning is based. Reasoning is viewed as the process that proceeds from implicit ideas to explicit answers. Not all wrong answers in chemistry come from alternative conceptions: some come from a lack of knowledge, other from logical errors. Since all types of wrong answers from students are problematic during teaching, it is relevant to consider them all. Thus, these concerns have inspired the following research question: What alternative conceptions and modes of reasoning lead students to make poor predictions in chemistry or to give wrong explanations of the behavior of matter? This doctoral research was conducted to provide an answer to this question. In total, 2,413 students enrolled in Science programmes in Québec’s college (postsecondary pre-university) system were involved in this research, which was divided into three phases: preliminary phase, pilot phase and main phase. Clinical interviews were conducted in the preliminary phase to explore chemistry students’ alternative conceptions. During the pilot phase, multiple-choice questions with open-ended justification were used to delimit the chemistry topics to be studied and to highlight ways of reasoning that students use. The main phase, for its part, used the two-tier “Molecules, Polarity and Phenomena” questionnaire (MPP) developed specifically for this research. The questionnaire was distributed to students via an adaptation of the Consol Web platform, developed by the research group of the principal investigator of this doctoral study. The results show that Science students hold several alternative designs, some of which are quite widespread among the population. In particular, a high proportion of students believe that evaporation causes the breaking of covalent bonds of the molecules (61.1 %), that all atom groups are molecules (78.9 %) and that atoms have similar macroscopic properties as the element (66.0 %). On the other hand, not all bad answers in the MPP show alternative conceptions. Some of them are rather explained by a deficiency in prior knowledge (for example, when students show a lack of knowledge of common chemical elements, 21.8 %) or an incomplete logical reasoning (when they believe the mere possession of polar bonds necessarily makes a molecule polar, which is observed in 24.1% of them). Alternative conceptions and reasoning that lead to incorrect answers are found among first-year and second-year students in the Science program, in some cases with decreasing frequency between the two years, and in others, at the same frequency in both subpopulations. These results mitigate the statement generally found in the research literature, that alternative conceptions are resistant to traditional teaching: according to the results of this research, some of them seem to actually be resolved through such a teaching context. The fact remains, however, that several alternative conceptions, deficiencies in basic prior knowledge and reasoning errors have been highlighted by this research. These learning problems lead college students to make incorrect predictions about the behaviour of matter, or to explain this behaviour incorrectly. In view of these results, a reflection on the teaching of chemistry at the college level, placing a greater emphasis on conceptual thinking and the use of reasoning for the prediction and explanation of the studied phenomena, should be considered.

Les objectifs de ce travail étaient d’évaluer la prévalence vie entière des traitements à visée psychotrope et les caractéristiques associées à cet usage dont l’adéquation avec l’existence de troubles psychiatriques. Les travaux ont été réalisés à partir des données issues de l’enquête Santé Mentale en Population Générale sur un échantillon de 36 785 adultes représentatifs de la population générale française. Un tiers des sujets a rapporté avoir fait usage d’au moins un traitement psychotrope au cours de la vie. L’inadéquation diagnostic-traitement est retrouvée dans le sens « usage en l’absence de trouble psychiatrique » aussi bien que dans le sens « absence d’usage en présence de trouble identifié ». Ainsi, seul un tiers des sujets avec un diagnostic de trouble dépressif récurrent a fait usage d’un traitement antidépresseur ou thymorégulateur. Concernant l’utilisation de traitements alternatifs, seuls 1,3 % des personnes rapportent un usage de traitement homéopathique à visée psychotrope. Ces traitements sont principalement utilisés par des personnes présentant un trouble anxieux en association avec un traitement psychotrope conventionnel. Des études ultérieures documentant l’ensemble des traitements à visée psychotrope utilisé dans le traitement des symptômes psychiques permettraient d’affiner les résultats sur l’adéquation diagnostic-traitement et d’estimer le nombre de sujets évitant le recours aux traitements conventionnels par l’utilisation d’alternatives thérapeutiques. / The aims of this work were to assess the lifetime prevalence of psychotropic drug use and the characteristics associated with use, particularly the congruence with psychiatric diagnoses. The studies were performed using the database from the survey Mental Health in the General Population including 36 785 persons representative of the French general population. One out of three subjects reported a lifetime use of psychotropic treatment. The non-congruence between diagnosis and psychotropic drug was observed in the pattern “use without psychiatric disorders” as well as in the pattern “no use with psychiatric disorders”. So, only one out of three persons with recurrent major depressive disorder reported having used an antidepressant or a mood stabilizer. Regarding complementary and alternative medicine use, only 1,3% of persons reported use of homeopathic treatment for psychiatric symptoms. These treatments were mainly used by persons with anxiety symptoms in association with conventional psychotropic drugs. Further studies assessing the all the treatments used for psychiatric symptoms would allow to refine the results on the congruence between diagnosis and psychotropic drug and to estimate the number of persons avoiding use of conventional psychotropic drugs by using complementary and alternative medicine.