The aim of this research project is to investigate the roles and responsibilities of foundation phase heads of departments (HoDs) in the Mpumalanga Province in South Africa. A quantitative research approach was used to assess the perceptions of the foundation phase HoDs. Questionnaires were distributed to 274 foundation phase HoDs in Mpumalanga and SPSS 20 was used to analyse the data. The findings show that HoDs perceive that they are overworked, whereas in reality, the amount of time they spend in school is not as expected in the Personnel Administrative Measures (PAM) document. It emerged that most educators leave school earlier than normal and thus experience a lack of time for supervision and administration, which then becomes a stress factor in the completion of their roles and responsibilities. Twenty two percent of the respondents indicated that they are not familiar with the HoD duties as outlined in the PAM document. Furthermore, the study uncovered issues such as lack of support and training for HoDs, the role of parents as motivators in terms of learner achievement, and the importance of evaluating and developing teachers to provide quality education in the 21st century. This research project utilises instructional leadership as a conceptual framework and maps out the roles and responsibilities of the HoD as outlined in the PAM document. Due to the low Annual National Assessment (ANA) results in literacy and numeracy, the research focuses on the challenges that HoDs in the foundation phase face regarding fulfilling their roles and responsibilities towards ensuring a quality education. On Tuesday 28 June 2011, the Minister of Basic Education, Angie Motshekga, revealed the results of the February 2011 ANA. In excess of 6.5 million learners from Grades 2 to 7 and a sample of G10s wrote tests in literacy/language and numeracy/mathematics. According to the statistics released by the Department of Basic Education (DBE), the average mark for literacy for G3 learners was a mere 35%. Grade 3 learners scored an average of 28% in numeracy. Amongst the Grade 3 learners, the Western Cape performed the best in both literacy and numeracy with 43% for literacy and 36% for numeracy. In Mpumalanga, Grade 3 learners scored 27% in literacy and only managed to score 19% for numeracy (DBE Report 40). If learners can’t read, write, spell and calculate at Grade 3 level, surely there is something wrong. Where are the foundation phase managers and how do they spend their time? Internationally, teachers responsible for supervising Grade R-3 are called middle managers. In South Africa, middle managers are called heads of departments (HoDs). The duties and roles of middle managers (or HoDs) in the foundation phase might be the cause of poor performance of learners in numeracy and literacy, due to insufficient support being provided to educators and learners. The role of HoDs in schools is not widely understood (Turner, 1996; Blandford, 1997; McLendon&Crowther, 1998). As a consequence, the literature relating to their role and functions is sparse. What is apparent, however, is the dual role that HoDs play, namely an administrative role within the school, as well as a teaching responsibility. A great deal of the work in managing the teaching-learning process operates at the middle management level in schools. However, management development often occurs at the senior management level, and HoDs remain the forgotten tier in schools. HoDs co-ordinate all educational activities between the top management of the school and the educators. Gold (1998:1) describes the role of HoDs as the most exciting and probably the most influential position in a well-organised school. Given the dual roles of HoDs, it is evident that they are exposed to a dilemma in executing duties carrying competing demands namely managing a department and being a class teacher at the same time (Blandford, 1997:13). This dual role becomes a particular challenge in the foundation phase, depending on the type of school, e.g. private school, former model C school, township or rural schools (which normally fall under Quintile 1-3), and lastly farm schools. It is challenging, especially in township and farm schools, to manage teaching, supervise educators, ensure learners cooperate positively in a class, and to be responsible for all the classes in a phase, including the own HOD’s class. Educators are experiencing overcrowding in their classrooms and schools are under staffed. A thorough study needed to be conducted to ensure that HoDs in the foundation phase are operating as effectively as those in the intermediate, senior and FET phases. It is critical to formulate strategies to ensure that learners progress positively in the foundation phase, especially in terms of their literacy and numeracy. HoDs must be able to perform their roles and responsibilities to ensure that learners can read and write at Grade 3 level. The PAM document clearly spells out the roles and responsibilities of the HoD; however when an HoD has 90% of their time allocated for teaching, one wonders if it is fair to expect them to carry out their administrative role in the remaining 10% of their time. / Dissertation (MEd)--University of Pretoria, 2012. / Education Management and Policy Studies / unrestricted

Recent advances with the bacterial CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) defense system as genome editing tools have opened a new avenue for targeting disease-causing mutations. The programmability of the Cas9 endonuclease by RNA makes it a potentially powerful therapeutic tool to correct such mutations. The CRISPR-Cas9 system consists of a Cas9 endonuclease that is guided by RNA (sgRNA) to create double-stranded breaks in a target DNA segment complementary to the guide. This process is dependent on a 2-8 nucleotide sequence (called PAM) that is adjacent to the target and functions as a Cas9 binding signal. Each Cas9 ortholog recognizes a unique PAM. However, factors such as the size of Cas9 or the frequency of its PAM sequence in the genome have hindered its clinical use. The Cas9 from Streptococcus pyogenes (SpyCas9) is commonly used in research because its PAM (NGG, where “N” symbolizes any nucleotide) is present every ~8 bp in the genome, providing robust targeting potential. However, it is too large to fit into typical viral vectors used for in vivo delivery, namely adeno-associated vectors (AAV). While several Cas9 orthologs have been characterized, none satisfied the need for a compact, accurate Cas9 with a short PAM. In this thesis, we use two approaches to identify new compact Cas9 orthologs with small PAMs, one using anti-CRISPR proteins and one by searching through closely related Cas9s. First, we use the presence of anti-CRISPRs (naturally occurring, phage-encoded peptides that inhibit CRISPR-Cas9 described in chapter 2) in a genome as indicators of Cas9s that may be highly active. These orthologs come with the added advantage of having inhibitors that can be used as off-switches. We characterize four Cas9s that are targeted by anti-CRISPR proteins and show that they recognize diverse PAMs in vitro. One of the four Cas9’s, namely HpaCas9 from Haemophilus parainfluenzae, induces efficient genome editing in mammalian cells. However, its long N4GATTT PAM does not satisfy the short PAM criterion. For our second approach, we asked whether closely related Cas9 orthologs with drastically different PAM-interacting domains (PIDs, the domain responsible for PAM recognition) recognize different PAMs, and if so, can be used for genome editing. To this end, we exploited natural variation in the PID of closely related Cas9s to identify a compact ortholog from Neisseria meningitidis (Nme2Cas9). Nme2Cas9 recognizes a simple dinucleotide PAM (N4CC) that provides a high target site density. All-in-one AAV delivery of Nme2Cas9 with a guide RNA into adult mouse liver produces efficient genome editing and reduced serum cholesterol with exceptionally high specificity. We further expand our single-AAV platform to pre-implanted zygotes for streamlined generation of genome-edited mice. Finally, we show preliminary data on how CRISPR-Cas9 can be used for therapeutic genome editing for Amytrophic Lateral Sclerosis. Our new findings promise to accelerate the development of genome editing tools for biomedical and therapeutic applications.

<p dir="ltr">Photosynthesis is the basis of primary productivity on Earth. Oxygenic photosynthesis utilizes the nearly inexhaustible energy of radiant solar light to fix atmospheric carbon dioxide into usable forms of chemical energy and produces dioxygen as a product. Central to this process are several large hetero-oligomeric protein complexes that comprise the photosynthetic electron transport chain. Photosystem II (PSII) initiates electron transport through the light-driven oxidation of water, in-turn relinquishing protons and oxygen. Through this reaction, electrons are used to form the reductant NADPH, while protons form a proton-motive gradient that is used to drive synthesis of ATP. As a result of this highly energetic reaction, PSII is often subject to oxidative photodamage due to the production of reactive oxygen species. Inevitably, accumulation of oxidative photodamage disrupts the catalytic activity of PSII, resulting in a loss of photosynthetic activity. To deal with the nearly constant incurred photodamage to PSII, oxygenic photoautotrophs undergo a disassembly and repair cycle that results in the complete turnover of the damaged D1 subunit of PSII. Due to its high tendency for damage, the D1 subunit has a half-life of under one hour in high light intensity. Despite our current understanding of photoinhibition and PSII repair, it is still unclear how D1 is replaced so rapidly in response to damaging conditions. Previous research has indicated a role for phosphorylation of PSII in D1 turnover, however the mechanism has not been totally resolved. In the first chapter of this thesis, our current understanding of PSII phosphorylation and oxidative damage is reviewed in the context of PSII repair. In the second chapter, the role of protein phosphorylation in the PSII repair cycle is investigated in the model organism <i>Arabidopsis</i>. Using several PSII phosphorylation mutants, we demonstrate that phosphorylation seems to mediate disassembly of large PSII supercomplexes and dimers into smaller subcomplexes. In the third chapter, the role of oxidative photodamage is investigated in mediating PSII disassembly. Here, we use several <i>in vitro</i> assays to demonstrate that photodamage is sufficient to induce the disassembly of smaller PSII subcomplexes. In the fourth chapter, a technique for determining the stoichiometry of photosynthetic complexes is examined, with implications for understanding PSII repair. Finally, in the fifth chapter, several conclusions and unanswered questions from this thesis are discussed.</p>

All wireless receivers have some degree of nonlinearity that can negatively impact performance. Two major effects from this nonlinearity are power compression, which leads to amplitude and phase distortions in the received signal, and desensitization caused by a high powered interfering signal at an adjacent channel. As the RF spectrum becomes more crowded, the interference caused by these adjacent signals will become a more significant problem for receiver design. Therefore, having bit and symbol error rate expressions that take the receiver nonlinearity into account will allow for determining the linearity requirements of a receiver. This thesis examines the modeling of the probability density functions of M-PAM and M-QAM signals through an AWGN channel taking into account the impact of receiver nonlinearity. A change of variables technique is used to provide a relationship between the pdf of these signals with a linear receiver and the pdf with a nonlinear receiver. Additionally, theoretical bit and symbol error rates are derived from the pdf expressions. Finally, this approach is extended by deriving pdf and error rate expressions for these signals when nearby blocking signals cause desensitization of the signal of interest. Matlab simulation shows that the derived expressions for a nonlinear receiver have the same accuracy as the accepted expressions for linear receivers. / Master of Science / All wireless receivers have some amount of nonlinearity that can distort a received signal and impact performance. For amplitude modulated signals, the power compression caused by the nonlinear receiver will cause distortions in the amplitude and phase of the received signal. Additionally, a high powered interfering signal at a close frequency can decrease the gain and distort the received signal. This thesis examines how the probability density of an amplitude modulated signal with a nonlinear receiver can be modeled for both of these situations. These theoretical probability density functions are used to derive theoretical error rate expressions for the signals both with and without the adjacent channel interference. Simulations in Matlab show that the accuracy of these derived expressions is similar to the accuracies of the linear receiver expressions. These derived expressions will be able to remove the need for time consuming simulation when designing receivers for wireless systems.

Thesis(MPhil)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: The determination of what the concept ‘sustainable competitive advantage’ means within a service environment and the consequent establishment of key resources within Pam Golding Properties and the role that leadership and the creation of a learning organisation play, formed the core of this study. The case study was therefore undertaken to glean relevant information from reality in order to determine which resources that can be described as intangible assets and competences contribute in a sustainable manner to the organisation’s competitive advantage in a dynamic and changing business environment. Existing and historical resources including leadership and learning within the organisation were identified by means of semi-structured interviews with a range of company executives. These resources were then assessed by means of questionnaires that were distributed to a wide range of stakeholders within the organisation in terms of value for the client, sustainability and transferability. These outcomes, in turn, provided the basis for conclusions and recommendations for future utility in order to maintain competitive advantage that would ultimately lead to sustained superior performance on all fronts. The findings that were made, culminated in a visual representation of leadership and organisational learning that form the core of the organisation and simultaneously illustrating their interdependence with the other key resources, namely organisational culture, the Pam Golding Properties brand, reputation, teamwork, relationships, systems and procedures, managers and agents. These resources form the essence of the organisation. The organisational culture within Pam Golding Properties that is representative of the core values of integrity, honesty, sincerity and service delivery was found to be the overall resource that provides the organisation with sustainable competitive advantage. This was closely followed by the value of the brand and reputation, teamwork and inter-personal relationships, the utilisation of efficient systems and procedures and the recruitment and retention of competent managers and agents. Organisational leadership was found to instil confidence in the organisation. A common, shared vision that is understood and underwritten by all employees is however lacking and change needs to be managed in such a way that the organisation’s core ideology is not compromised, but an envisioned future should be communicated throughout. The brand carries out the promise of the culture and core values, but can be tarnished if the reputation for service excellence is not upheld and it can lose credibility if expectations are not met. The brand thus needs protection from within and this can only happen if the people in the organisation share in the process of and toward an envisioned future. It was established that meaningful change presupposes continual improvement in a dynamic, yet sustainable organisation. It was therefore also recommended that a concerted effort be made to actively promote and strive towards the company becoming a true learning organisation in order to sustain its culture, brand, reputation and other intangible assets and competences. In the event that these and other recommendations in terms of resources are seriously considered and strived for by company leaders, this organisation should be an example to the rest of the world regarding sustainable competitive advantage. / AFRIKAANSE OPSOMMING: Die bepaling van wat die konsep ‘volhoubare mededingende voordeel’ beteken binne ‘n diensomgewing en die daaropvolgende vasstelling van sleutelhulpbronne binne Pam Golding Eiendomme en die rol wat leierskap en die skep van ‘n leerorganisasie speel, het die kern van hierdie studie gevorm. Die gevallestudie is dus onderneem om toepaslike inligting vanuit realiteit te werf, om sodoende vas te stel watter hulpbronne wat as ontasbare bates en bevoegdhede beskryf kan word, op ‘n volhoubare wyse tot die organisasie se mededingende voordeel bydra in ‘n dinamiese en veranderende sake-omgewing. Bestaande en historiese hulpbronne insluitend leierskap en leer binne die organisasie is geïdentifiseer by wyse van semi-gestruktueerde onderhoude wat met ‘n aantal uitvoerende lede van die maatskappy gevoer is. Hierdie hulpbronne is daarna deur middel van vraelyste wat aan ‘n breë reeks insethouers binne die organisasie versprei is, geëvalueer in terme van waarde vir die kliënt, volhoubaarheid en oordraagbaarheid. Hierdie uitkomste het weer die basis verskaf vir afleidings en voorstelle wat gemaak is ten opsigte van toekomsbruikbaarheid om mededingende voordeel te behou wat uiteindelik tot volhoubare superieure verrigting op alle fronte sal lei. Die bevindings wat gemaak is, het in ‘n visuele voorstelling van leierskap en organisasieleer gekulmineer, wat die kern van die organisasie uitmaak en tegelykertyd hul interafhanklikheid illustreer ten opsigte van die ander sleutelhulpbronne, naamlik organisasie-kultuur, die Pam Golding Eiendomme handelsnaam, reputasie, spanwerk, verhoudings, stelsels en prosedures, bestuurders an agente. Hierdie hulpbronne maak die essensie van die organisasie uit. Die organisasie-kultuur binne Pam Golding Eiendomme wat verteenwoordigend is van die kernwaardes van integriteit, eerlikheid, opregtheid en dienslewering het as die oorhoofse hulpbron uitgestaan wat die organisasie van volhoubare mededingende voordeel verseker. Dis gevolg deur die waarde van die handelsnaam en reputasie, spanwerk en inter-persoonlike verhoudings, die benutting van doeltreffende stelsels en prosedures en die werwing en retensie van bekwame bestuurders en agente. Daar is bevind dat organisasie-leierskap vertroue in die organisasie skep. ‘n Gemeenskaplike, gedeelde visie wat deur al die werknemers verstaan en onderskryf word, kom egter kort en verandering behoort op só ‘n wyse bestuur te word, dat die organisasie se kern-ideologie nie onder verdenking gebring word nie, maar ‘n gevisioneerde toekoms behoort deurgaans gekommunikeer te word. Die handelsnaam dra die belofte van die kultuur en kernwaardes uit, maar kan skade opdoen as die reputasie vir diensuitnemendheid nie onderhou word nie en dan kan geloofwaardigheid ingeboet word indien daar nie aan verwagtinge voldoen word nie. Die handelsnaam moet dus van binne uit beskerm word en dit kan slegs gebeur indien die mense in die organisasie aan die proses van ‘n gevisioneerde toekoms deelneem. Dit is bevind dat betekenisvolle verandering aaneenlopende verbetering in ‘n dinamiese, dog volhoubare organisasie veronderstel. Daar is dus ook voorgestel dat ‘n doelbewuste poging aangewend word dat die wording van ‘n ware leerorganisasie aktief gepromoveer en nagestreef behoort te word om sodoende die kultuur, handelsnaam, reputasie en ander ontasbare bates en bevoegdhede vol te kan hou. Indien hierdie en ander voorstelle ten opsigte van hulpbronne ernstig deur die maatskappy se leiers bedink en nagestreef word, behoort hierdie organisasie vir die res van die wêreld ‘n voorbeeld van volhoubare mededingende voordeel te wees.

Baigiamajame darbe pateikta: detergentų paplitimas, jų fizikinės, cheminės savybės, klasifikacija ir daroma žala aplinkai. Analizuojami detergentais užterštų nuotekų valymo metodai. Analizuojami dujų burbuliukų susidarymo detergentų tirpaluose ypatumai, aprašomos dinaminės ir statiškai stabilios putos, pateikiama putų aparatų charakteristika. Pateikiamos suspenduoto sluoksnio charakteristikos ir jo galimybės detergentams iš nuotekų valyti. Darbo tikslas – ištirti suspenduoto sluoksnio įtaką valant detergentus iš nuotekų. Darbą sudaro 7 dalys: įvadas; tyrimo objektas ir problemos aprašymas; detergentais užterštų nuotekų valymas, putų burbuliukų ir putų susidarymo ypatumai, putų aparatai; suspenduoto sluoksnio charakteristikos ir jo galimybės panaudojant detergentams iš nuotekų valyti; eksperimentinė dalis; išvados; literatūros sąrašas. Eksperimentinėje dalyje teoriškai apskaičiuoti suspenduoto sluoksnio parametrai, aprašomas eksperimentinis stendas, jo veikimo principas, naudotos matavimo priemonės, pateikta eksperimento atlikimo metodika, pagal gautus eksperimentinius duomenis apskaičiuoti kintamieji suspenduoto sluoksnio parametrai. Darbo pabaigoje analizuojami gauti rezultatai ir pateikiamos darbo išvados. Darbo apimtis – 67 p. teksto be priedų, 21 iliustracija, 4 lentelės, 24 bibliografiniai šaltiniai. Atskirai pridedami darbo priedai. / Thesis submits the spread of detergents, their physical, chemical properties, classification and environmental damage. There are analyzed various waste water cleaning methods of detergents. Froth formation in detergent leaches, dynamic and static stability of foams and basic information about froth devices are given. The characteristics of the suspended layer and its use in water treatment of detergents are given. The aim of this work – is to explore the suspended layer in cleaning waste water of detergents. Final work consists of seven parts: introduction; the subject matter and the problem description; water purification of synthetic detergents, characteristics of froth bubbles and froth formation, froth machines; suspended layer characteristics and the possibility of using it in waste water cleaning of detergents; experimental part; conclusions and references. Experimental part includes theoretically calculated suspended layer parameters, description of the experimental stand, its operating principle, instruments used during the experimental procedures, calculations of suspended layer variable settings according to the experimental data. In the end the results are analyzed and the conclusions are included. Thesis consists of: 67 p. text without appendixes, 21 picture, 4 tables, 24 bibliographical entries. Appendixes included.

Ultra wide band (UWB) is an extremely promising wireless technology for researchers and industrials. One of the most interesting is its high data rate and fading robustness due to selective frequency fading. However, beside such advantages, UWB system performance is highly affected by existing narrowband interference (NBI), undesired UWB signals and tone/multi-tone noises. For this reason, research about NBI cancellation is still a challenge to improve the system performance vs. receiver complexity, power consumption, linearity, etc. In this work, the two major receiver sections, i.e., analog (radiofrequency or RF) and digital (digital signal processing or DSP), were considered and new techniques proposed to reduce circuit complexity and power consumption, while improving signal parameters. In the RF section, different multiband UWB low-noise amplifier key design parameters were investigated like circuit configuration, input matching and desired/undesired frequency band filtering, highlighting the most suitable filtering package for efficient UWB NBI cancellation. In the DSP section, due to pulse transmitter signals, different issues like modulation type and level, pulse variety, shape and color noise/tone noise assumptions, were addressed for efficient NBI cancelation. A comparison was performed in terms of bit-error rate, signal-to-interference ratio, signal-to-noise ratio, and channel capacity to highlight the most suitable parameters for efficient DSP design. The optimum number of filters that allows the filter bandwidth to be reduced by following the required low sampling rate and thus improving the system bit error rate was also investigated.

<p>This thesis presents the design of a broadband and high speed dc-coupled AGC amplifier for multi-level (4-PAM) signaling with a symbol rate of 1-GS/s ( 2-Gb/s ) . It is a high frequency analog design with several design challenges such as high -3 dB bandwidth ( greater than 500 MHz ) and highly linear gain while accommodating a large input swing range ( 120 mVp-p to 1800 mVp-p diff.) and delivering constant</p><p>differential output swing of 1700 mVp-p to 50-ohm off-chip loads at high speed. Moreover, the gain control circuit has been designed in analog domain. The amplifier incorporates both active and passive feedback in shunt-shunt topology in order to achieve wide bandwidth. This standalone chip has been implemented in AMS 0.35 micron CMOS process. The post layout eye-diagrams seem to be quite satisfactory.</p>

Ultra wide band (UWB) is an extremely promising wireless technology for researchers and industrials. One of the most interesting is its high data rate and fading robustness due to selective frequency fading. However, beside such advantages, UWB system performance is highly affected by existing narrowband interference (NBI), undesired UWB signals and tone/multi-tone noises. For this reason, research about NBI cancellation is still a challenge to improve the system performance vs. receiver complexity, power consumption, linearity, etc. In this work, the two major receiver sections, i.e., analog (radiofrequency or RF) and digital (digital signal processing or DSP), were considered and new techniques proposed to reduce circuit complexity and power consumption, while improving signal parameters. In the RF section, different multiband UWB low-noise amplifier key design parameters were investigated like circuit configuration, input matching and desired/undesired frequency band filtering, highlighting the most suitable filtering package for efficient UWB NBI cancellation. In the DSP section, due to pulse transmitter signals, different issues like modulation type and level, pulse variety, shape and color noise/tone noise assumptions, were addressed for efficient NBI cancelation. A comparison was performed in terms of bit-error rate, signal-to-interference ratio, signal-to-noise ratio, and channel capacity to highlight the most suitable parameters for efficient DSP design. The optimum number of filters that allows the filter bandwidth to be reduced by following the required low sampling rate and thus improving the system bit error rate was also investigated.

Derivat de 3 capítols de la tesi s'han publicat dos articles en revistes científiques i un capítol de llibre: Chapter 3, pg. 61 : Corcoll et al. 2012-HdB Environ Chem-book chapter 4 Chapter 4, pg. 81: Corcoll et al. 2011- Chl-a fluorescence parameters as biomarkers of metal toxicity in fluvial biofilms Chapter 5, pg. 117: Corcoll et al. 2012- The effect of metals on photosynthesis processes and diatom metrics on biofilm from a metal-contaminated river / Metal pollution in rivers is in great concern with human activities in the fluvial watershed. This thesis aims to investigate the potential use of chl-a fluorescence parameters as biomarkers of metal toxicity, and to find cause-effect relationships between metal exposures, other environmental factor (i.e. light), and functional and structural biofilm responses. This thesis demonstrates that the use of chl-a fluorescence parameters allows detect early effects on biofilms caused by zinc toxicity, both in the laboratory as in polluted rivers. In microcosm experiments, the use of chl-a fluorescence parameters allows evaluates structural changes on photosynthetic apparatus and in algal groups’ composition of biofilms long-term exposed to zinc. In order to evaluate the effects of chronic metal pollution in rivers, it is recommended the use of biofilm translocation experiments and the use of a multi-biomarker approach. / La contaminació per metalls en els rius està principalment lligada a l’activitat humana que té lloc a la conca fluvial. Aquesta tesi té per objectiu principal avaluar l'ús potencial dels paràmetres de fluorescència de la chl-a com a biomarcadors de toxicitat per metalls, i trobar relacions causa-efecte entre l’exposició dels metalls, altres factors ambientals (ex. la llum), i les respostes funcionals i estructurals del biofilms. Aquesta tesi demostra que els paràmetres de fluorescència de la chl-a permeten detectar alteracions ràpides del biofilm causades per la toxicitat del zinc, tan al laboratori com en rius contaminats. En microcosmos, els paràmetres de fluorescència de la chl-a permeten avaluar canvis estructurals en l’aparell fotosintètic i en la composició dels grups algals dels biofilms exposats crònicament al zinc. Per avaluar els efectes de la contaminació crònica per metalls en rius es recomana fer experiments de translocació de biofilms i utilitzar una aproximació de multi-biomarcador.