Once-yearly zoledronic acid and days of disability, bed rest, and back pain: randomized, controlled HORIZON Pivotal Fracture Trial.

The objective of this study was to determine the effect of once-yearly zoledronic acid on the number of days of back pain and the number of days of disability (ie, limited activity and bed rest) owing to back pain or fracture in postmenopausal women with osteoporosis. This was a multicenter, randomized, double-blind, placebo-controlled trial in 240 clinical centers in 27 countries. Participants included 7736 postmenopausal women with osteoporosis. Patients were randomized to receive either a single 15-minute intravenous infusion of zoledronic acid (5 mg) or placebo at baseline, 12 months, and 24 months. The main outcome measures were self-reported number of days with back pain and the number of days of limited activity and bed rest owing to back pain or a fracture, and this was assessed every 3 months over a 3-year period. Our results show that although the incidence of back pain was high in both randomized groups, women randomized to zoledronic acid experienced, on average, 18 fewer days of back pain compared with placebo over the course of the trial (p = .0092). The back pain among women randomized to zoledronic acid versus placebo resulted in 11 fewer days of limited activity (p = .0017). In Cox proportional-hazards models, women randomized to zoledronic acid were about 6% less likely to experience 7 or more days of back pain [relative risk (RR) = 0.94, 95% confidence interval (CI) 0.90-0.99] or limited activity owing to back pain (RR = 0.94, 95% CI 0.87-1.00). Women randomized to zoledronic acid were significantly less likely to experience 7 or more bed-rest days owing to a fracture (RR = 0.58, 95% CI 0.47-0.72) and 7 or more limited-activity days owing to a fracture (RR = 0.67, 95% CI 0.58-0.78). Reductions in back pain with zoledronic acid were independent of incident fracture. Our conclusion is that in women with postmenopausal osteoporosis, a once-yearly infusion with zoledronic acid over a 3-year period significantly reduced the number of days that patients reported back pain, limited activity owing to back pain, and limited activity and bed rest owing to a fracture.

State of Iowa HIV and AIDS Surveillance Report, December 2004

After taking a dip in 2003, HIV diagnoses were back up in 2004. There were 103 persons diagnosed in 2004, very close to our ten-year average of 100 cases per year. In 2003, there were 91 diagnoses. The increase in 2004 was limited to one demographic group: white, U.S.-born males. Most of these were men who have sex with men, but there were also small increases among injection-drug-using men and those without a known risk. Their median age was 41, slightly older than the overall median age of 38 years. Eighty percent were residents of the 10 most populous counties in Iowa, particularly the counties of Polk, Pottawattamie, Johnson, Linn, Scott, Story, and Woodbury.

Policy Making in Divided Government. A Pivotal Actors Model with Party Discipline.

This article presents a formal model of policy decision-making in an institutional framework of separation of powers in which the main actors are pivotal political parties with voting discipline. The basic model previously developed from pivotal politics theory for the analysis of the United States lawmaking is here modified to account for policy outcomes and institutional performances in other presidential regimes, especially in Latin America. Legislators' party indiscipline at voting and multi-partism appear as favorable conditions to reduce the size of the equilibrium set containing collectively inefficient outcomes, while a two-party system with strong party discipline is most prone to produce 'gridlock', that is, stability of socially inefficient policies. The article provides a framework for analysis which can induce significant revisions of empirical data, especially regarding the effects of situations of (newly defined) unified and divided government, different decision rules, the number of parties and their discipline. These implications should be testable and may inspire future analytical and empirical work.

Policy making in divided government. A pivotal actors model with party discipline

This article presents a formal model of policy decision-making in an institutional framework of separation of powers in which the main actors are pivotal political parties with voting discipline. The basic model previously developed from pivotal politics theory for the analysis of the United States lawmaking is here modified to account for policy outcomes and institutional performances in other presidential regimes, especially in Latin America. Legislators' party indiscipline at voting and multi-partism appear as favorable conditions to reduce the size of the equilibrium set containing collectively inefficient outcomes, while a two-party system with strong party discipline is most prone to produce 'gridlock', that is, stability of socially inefficient policies. The article provides a framework for analysis which can induce significant revisions of empirical data, especially regarding the effects of situations of (newly defined) unified and divided government, different decision rules, the number of parties and their discipline. These implications should be testable and may inspire future analytical and empirical work.

Gestão do Desempenho como ferramenta para o alcance dos objectivos estratégicos

The current context of a strong competition and the ongoing search for competitive advantages requires more than processes modernization, technological and financial resources. It requires a competent workforce, strongly committed and engaged with Organization’s challenges. Under this scenario, it seems crucial to synchronize their performance with Organization’s strategy, aimed at pursuing its effective achievement. If well used, the Performance Evaluation as a strategy for Human Resource Management presents itself as an instrument to foster high levels of performance. A more recent approach of this policy refers to Performance Management representing a dynamic and participative evaluation system, which combines the development of consensual goals, support and follow-up for further execution of respective assessment. This research was based on the ENAPOR, S.A (Porto da Praia) case, with the intention of checking the alignment of its Performance Evaluation System with the Company's strategic goals and what the process features.

Heterotrimeric Go protein links Wnt-Frizzled signaling with ankyrins to regulate the neuronal microtubule cytoskeleton.

Drosophila neuromuscular junctions (NMJs) represent a powerful model system with which to study glutamatergic synapse formation and remodeling. Several proteins have been implicated in these processes, including components of canonical Wingless (Drosophila Wnt1) signaling and the giant isoforms of the membrane-cytoskeleton linker Ankyrin 2, but possible interconnections and cooperation between these proteins were unknown. Here, we demonstrate that the heterotrimeric G protein Go functions as a transducer of Wingless-Frizzled 2 signaling in the synapse. We identify Ankyrin 2 as a target of Go signaling required for NMJ formation. Moreover, the Go-ankyrin interaction is conserved in the mammalian neurite outgrowth pathway. Without ankyrins, a major switch in the Go-induced neuronal cytoskeleton program is observed, from microtubule-dependent neurite outgrowth to actin-dependent lamellopodial induction. These findings describe a novel mechanism regulating the microtubule cytoskeleton in the nervous system. Our work in Drosophila and mammalian cells suggests that this mechanism might be generally applicable in nervous system development and function.

Effect of ganglion blockade with pentolinium on circulating neuropeptide Y levels in conscious rats.

The vasoconstrictor peptide, neuropeptide Y (NPY), is present in perivascular noradrenergic neurons of all mammals studied and may be important in the regulation of blood pressure. High plasma levels of NPY have been measured in the rat. To investigate partially the source and factors controlling the release of the circulating peptide, the effect of pentolinium tartrate administration has been studied in conscious rats. Pentolinium given as a bolus (5 mg/kg) followed by an infusion of a further 5 mg/kg/30 min produced a highly significant reduction in blood pressure of more than 40 mm Hg, when compared to either basal values or control animals treated with saline. Pentolinium treatment resulted in significantly lower plasma neuropeptide Y levels (31.0 +/- 6.7 fmol/ml) compared with those of control animals (78.6 +/- 8.2 fmol/ml). Circulating catecholamines were also significantly reduced in those animals receiving pentolinium. These results are compatible with circulating NPY arising from the sympathetic nervous system, with release being controlled by the mechanisms already established for catecholamines.

Study Regarding Implementation of a Uniform Statewide System to Allow for Electronic Transactions for the Registration and Titling of Motor Vehicles

LEGISLATIVE STUDY – The 83rd General Assembly of the Iowa Legislature, in Senate File 2273, directed the Iowa Department of Transportation (DOT) to conduct a study of how to implement a uniform statewide system to allow for electronic transactions for the registration and titling of motor vehicles. PARTICIPANTS IN STUDY – As directed by Senate File 2273, the DOT formed a working group to conduct the study that included representatives from the Consumer Protection Division of the Office of the Attorney General, the Department of Public Safety, the Department of Revenue, the Iowa State County Treasurer’s Association, the Iowa Automobile Dealers Association, and the Iowa Independent Automobile Dealers Association. CONDUCT OF THE STUDY – The working group met eight times between June 17, 2010, and October 1, 2010. The group discussed the costs and benefits of electronic titling from the perspectives of new and used motor vehicle dealers, county treasurers, the DOT, lending institutions, consumers and consumer protection, and law enforcement. Security concerns, legislative implications, and implementation timelines were also considered. In the course of the meetings the group: 1. Reviewed the specific goals of S.F. 2273, and viewed a demonstration of Iowa’s current vehicle registration and titling system so participants that were not users of the system could gain an understanding of its current functionality and capabilities. 2. Reviewed the results of a survey of county treasurers conducted by the DOT to determine the extent to which county treasurers had processing backlogs and the extent to which county treasurers limited the number of dealer registration and titling transactions that they would process in a single day and while the dealer waited. Only eight reported placing a limit on the number of dealer transactions that would be processed while the dealer waited (with the number ranging from one to four), and only 11 reported a backlog in processing registration and titling transactions as of June 11, 2010, with most backlogs being reported in the range of one to three days. 3. Conducted conference calls with representatives of the American Association of Motor Vehicle Administrators (AAMVA) and representatives of three states -- Kansas, which has an electronic lien and titling (ELT) program, and Wisconsin and Florida, each of which have both an ELT program and an electronic registration and titling (ERT) program – to assess current and best practices for electronic transactions. In addition, the DOT (through AAMVA) submitted a survey to all U.S. jurisdictions to determine how, if at all, other states implemented electronic transactions for the registration and titling of motor vehicles. Twenty-eight states responded to the survey; of the 28 states that responded, only 13 allowed liens to be added or released electronically, and only five indicated allowing applications for registration and titling to be submitted electronically. DOT staff also heard a presentation from South Dakota on its ERT system at an AAMVA regional meeting. ELT information that emerged suggests a multi-vendor approach, in which vendors that meet state specifications for participation are authorized to interface with the state’s system to serve as a portal between lenders and the state system, will facilitate electronic lien releases and additions by offering lenders more choices and the opportunity to use the same vendor in multiple states. The ERT information that emerged indicates a multi-interface approach that offers an interface with existing dealer management software (DMS) systems and through a separate internet site will facilitate ERT by offering access that meets a variety of business needs and models. In both instances, information that emerged indicates that, in the long-term, adoption rates are positively affected by making participation above a certain minimum threshold mandatory. 4. To assess and compare functions or services that might be offered by or through a vendor, the group heard presentations from vendors that offer products or services that facilitate some aspect of ELT or ERT. 5. To assess the concerns, needs and interest of Iowa motor vehicle dealers, the group surveyed dealers to assess registration and titling difficulties experienced by dealers, the types of DMS systems (if any) used by dealers, and the dealers’ interest and preference in using an electronic interface to submit applications for registration and titling. Overall, 40% of the dealers that responded indicated interest and 57% indicated no interest, but interest was pronounced among new car dealers (75% were interested) and dealers with a high number of monthly transactions (85% of dealers averaging more than 50 sales per month were interested). The majority of dealers responding to the dealer survey ranked delays in processing and problems with daily limits on transaction as ―minor difficulty or ―no difficulty. RECOMMENDATIONS -- At the conclusion of the meetings, the working group discussed possible approaches for implementation of electronic transactions in Iowa and reached a consensus that a phased implementation of electronic titling that addressed first electronic lien and title transactions (ELT) and electronic fund transfers (EFT), and then electronic applications for registration and titling (ERT) is recommended. The recommendation of a phased implementation is based upon recognition that aspects of ELT and EFT are foundational to ERT, and that ELT and EFT solutions are more readily and easily attained than the ERT solution, which will take longer and be somewhat more difficult to develop and will require federal approval of an electronic odometer statement to fully implement. ELT – A multi-vendor approach is proposed for ELT. No direct costs to the state, counties, consumers, or dealers are anticipated under this approach. The vendor charges participating lenders user or transaction fees for the service, and it appears the lenders typically absorb those costs due to the savings offered by ELT. Existing staff can complete the programming necessary to interface the state system with vendors’ systems. The estimated time to implement ELT is six to nine months. Mandatory participation is not recommended initially, but should be considered after ELT has been implemented and a suitable number of vendors have enrolled to provide a fair assessment of participation rates and opportunities. EFT – A previous attempt to implement ELT and EFT was terminated due to concern that it would negatively impact county revenues by reducing interest income earned on state funds collected by the county and held until the monthly transfer to the state. To avoid that problem in this implementation, the EFT solution should remain revenue neutral to the counties, by allowing fees submitted by EFT to be immediately directed to the proper county account. Because ARTS was designed and has the capacity to accommodate EFT, a vendor is not needed to implement EFT. The estimated time to implement EFT is six to nine months. It is expected that EFT development will overlap ELT development. ERT – ERT itself must be developed in phases. It will not be possible to quickly implement a fully functioning, paperless ERT system, because federal law requires that transfer of title be accompanied by a written odometer statement unless approval for an alternate electronic statement is granted by the National Highway Traffic Safety Administration (NHTSA). It is expected that it will take as much as a year or more to obtain NHTSA approval, and that NHTSA approval will require design of a system that requires the seller to electronically confirm the seller’s identity, make the required disclosure to the buyer, and then transfer the disclosure to the buyer, who must also electronically confirm the buyer’s identity and electronically review and accept the disclosure to complete and submit the transaction. Given the time that it will take to develop and gain approval for this solution, initial ERT implementation will focus on completing and submitting applications and issuing registration applied for cards electronically, with the understanding that this process will still require submission of paper documents until an electronic odometer solution is developed. Because continued submission of paper documents undermines the efficiencies sought, ―full‖ ERT – that is, all documents necessary for registration and titling should be capable of approval and/or acceptance by all parties, and should be capable of submission without transmittal or delivery of duplicate paper documents .– should remain the ultimate goal. ERT is not recommended as a means to eliminate review and approval of registration and titling transactions by the county treasurers, or to place registration and titling approval in the hands of the dealers, as county treasurers perform an important role in deterring fraud and promoting accuracy by determining the genuineness and regularity of each application. Authorizing dealers to act as registration agents that approve registration and title applications, issue registration receipts, and maintain and deliver permanent metal license plates is not recommended. Although distribution of permanent plates by dealers is not recommended, it is recommended that dealers participating in ERT generate and print registration applied for cards electronically. Unlike the manually-issued cards currently in use, cards issued in this fashion may be queried by law enforcement and are less susceptible to misuse by customers and dealers. The estimated time to implement the electronic application and registration applied for cards is 12 to 18 months, to begin after ELT and EFT have been implemented. It is recommended that focus during this time be on facilitating transfers through motor vehicle dealers, with initial deployment focused on higher-volume dealers that use DMS systems. In the long term an internet option for access to ERT must also be developed and maintained to allow participation for lower-volume dealers that do not use a DMS system. This option will also lay the ground work for an ERT option for sales between private individuals. Mandatory participation in Iowa is not recommended initially. As with ELT, it is recommended that mandatory participation be considered after at least an initial phase of ERT has been implemented and a suitable number of dealers have enrolled to provide a fair assessment of participation rates and opportunities. The use of vendors to facilitate ERT is not initially proposed because 1) DOT IT support staff is capable of developing a system that will interact with DMS systems and will still have to develop a dealer and public interface regardless of whether a vendor acts as intermediary between the DMS systems, and 2) there is concern that the cost of the vendor-based system, which is funded by transaction-based payments from the dealer to the vendor, will be passed to the consumer in the form of additional documentation or conveyance fees. However, the DOT recommends flexibility on this point, as development and pilot of the system may indicate that a multi-vendor approach similar to that recommended for ELT may increase the adoption rate by larger dealers and may ultimately decrease the user management to be exercised by DOT staff. If vendors are used in the process, additional legislation or administrative rules may be needed to control the fees that may be passed to the consumer. No direct cost to the DOT or county treasurers is expected, as the DOT expects that it may complete necessary programming with existing staff. Use of vendors to facilitate ERT transactions by dealers using DMS systems would result in transaction fees that may ultimately be passed to consumers. LEGISLATION – As a result of the changes implemented in 2004 under Senate File 2070, the only changes to Iowa statutes proposed are to section 321.69 of the Iowa Code, ―Damage disclosure statement,and section 321.71, ―Odometer requirements.‖ In each instance, authority to execute these statements by electronic means would be clarified by authorizing language similar to that used in section 321.20, subsections ―2‖ and ―3,‖ which allows for electronic applications and directs the department to ―adopt rules on the method for providing signatures for applications made by electronic means.‖ In these sections, the authorizing language might read as follows: Notwithstanding contrary provisions of this section, the department may develop and implement a program to allow for any statement required by this section to be made electronically. The department shall adopt rules on the method for providing signatures for statements made by electronic means. Some changes to DOT administrative rules will be useful but only to enable changes to work processes that would be desirable in the long term. Examples of long term work processes that would be enabled by rule changes include allowing for signatures created through electronic means and electronic odometer certifications. The DOT rules, as currently written, do not hinder the ability to proceed with ELT, EFT, and ERT.

Physical quality of an Oxisol cultivated with maize submited to cover crops in the pre-cropping period

The intensive use of land alters the distribution of the pore size which imparts consequences on the soil physical quality. The Least Limiting Water Range (LLWR) allows for the visualization of the effects of management systems upon either the improvement or the degradation of the soil physical quality. The objective of this study was to evaluate the physical quality of a Red Latosol (Oxisol) submited to cover crops in the period prior to the maize crop in a no-tillage and conventional tillage system, using porosity, soil bulk density and the LLWR as attributes. The treatments were: conventional tillage (CT) and a no-tillage system with the following cover crops: sunn hemp (Crotalaria juncea L.) (NS), pearl millet (Pennisetum americanum (L.) Leeke) (NP) and lablab (Dolichos lablab L.) (NL). The experimental design was randomized blocks in subdivided plots with six replications, with the plots being constituted by the treatments and the subplots by the layers analyzed. The no-tillage systems showed higher total porosity and soil organic matter at the 0-0.5 m layer for the CT. The CT did not differ from the NL or NS in relation to macroporosity. The NP showed the greater porosity, while CT and NS presented lower soil bulk density. No < 10 % airing porosity was found for the treatments evaluated, and value for water content where soil aeration is critical (θPA) was found above estimated water content at field capacity (θFC) for all densities. Critical soil bulk density was of 1.36 and 1.43 Mg m-3 for NP and CT, respectively. The LLWR in the no-tillage systems was limited in the upper part by the θFC, and in the bottom part, by the water content from which soil resistance to penetration is limiting (θPR). By means of LLWR it was observed that the soil presented good physical quality.

Physical quality of a yellow latossol under integrated crop-livestock system

Soil physical quality is essential to global sustainability of agroecosystems, once it is related to processes that are essential to agricultural crop development. This study aimed to evaluate physical attributes of a Yellow Latossol under different management systems in the savanna area in the state of Piaui. This study was developed in Uruçuí southwest of the state of Piauí. Three systems of soil management were studied: an area under conventional tillage (CT) with disk plowi and heavy harrow and soybean crop; an area under no-tillage with soybean-maize rotation and millet as cover crop (NT + M); two areas under Integrated Crop-Livestock System, with five-month pasture grazing and soybean cultivation and then continuous pasture grazing (ICL + S and ICL + P, respectively). Also, an area under Native Forest (NF) was studied. The soil depths studied were 0.00-0.05, 0.05-0.10 and 0.10-0.20 m. Soil bulk density, as well as porosity and stability of soil aggregates were analyzed as physical attributes. Anthropic action has changed the soil physical attributes, in depth, in most systems studied, in comparison to NF. In the 0.00 to 0.05 m depth, ICL + P showed higher soil bulk density value. As to macroporosity, there was no difference between the management systems studied and NF. The management systems studied changed the soil structure, having, as a result, a small proportion of soil in great aggregate classes (MWD). Converting native forest into agricultural production systems changes the soil physical quality. The Integrated Crop-Livestock System did not promote the improvement in soil physical quality.

Urea coated with oxidized charcoal reduces ammonia volatilization

Urea is the most consumed nitrogen fertilizer in the world. However, its agronomic and economic efficiency is reduced by the volatilization of NH3, which can reach 78 % of the applied nitrogen. The coating of urea granules with acidic compounds obtained by charcoal oxidation has the potential to reduce the volatilization, due to the acidic character, the high buffering capacity and CEC. This work aimed to evaluate the effect of HNO3-oxidized carbon on the control of NH3 volatilization. These compounds were obtained by oxidation of Eucalyptus grandis charcoal, produced at charring temperatures of 350 and 450 ºC, with 4.5 mol L-1 HNO3. The charcoal was oxidized by solubilization in acidic or alkaline medium, similar to the procedure of soil organic matter fractionation (CHox350 and CHox450). CHox was characterized by C, H, O, N contents and their respective atomic relations, by the ratio E4 (absorbance 465 nm) by E6 (absorbance 665 nm), and by active acidity and total acidity (CEC). The inhibitory effect of CHox on the urease activity of Canavalia ensiformis was assessed in vitro. The NH3 volatilization from urea was evaluated with and without coating of oxidized charcoal (U-CHox350 or U-CHox450) in a closed system with continuous air flow. The pH of both CHox was near 2.0, but the total acidity of CHox350 was higher, 72 % of which was attributed to carboxylic groups. The variation in the ionization constants of CHox350 was also greater. The low E4/E6 ratios characterize the high stability of the compounds in CHox. CHox did not inhibit the urease activity in vitro, although the maximum volatilization peak from U-CHox450 and U-CHox350 occurred 24 h after that observed for uncoated urea. The lowest volatilization rate was observed for U-CHox350 as well as a 43 % lower total amount of NH3 volatilized than from uncoated urea.

Carbon balance and crop residue management in dynamic equilibrium under a no-till system in Campos Gerais

The adoption of no-tillage systems (NT) and the maintenance of crop residues on the soil surface result in the long-term increase of carbon (C) in the system, promoting C sequestration and reducing C-CO2 emissions to the atmosphere. The purpose of this study was to evaluate the C sequestration rate and the minimum amount of crop residues required to maintain the dynamic C equilibrium (dC/dt = 0) of two soils (Typic Hapludox) with different textural classes. The experiment was arranged in a 2 x 2 x 2 randomized block factorial design. The following factors were analyzed: (a) two soil types: Typic Hapludox (Oxisol) with medium texture (LVTM) and Oxisol with clay texture (LVTA), (b) two sampling layers (0-5 and 5-20 cm), and (c) two sampling periods (P1 - October 2007; P2 - September 2008). Samples were collected from fields under a long-term (20 years) NT system with the following crop rotations: wheat/soybean/black oat + vetch/maize (LVTM) and wheat/maize/black oat + vetch/soybean (LVTA). The annual C sequestration rates were 0.83 and 0.76 Mg ha-1 for LVTM and LVTA, respectively. The estimates of the minimum amount of crop residues required to maintain a dynamic equilibrium (dC/dt = 0) were 7.13 and 6.53 Mg ha-1 year-1 for LVTM and LVTA, respectively. The C conversion rate in both studied soils was lower than that reported in other studies in the region, resulting in a greater amount of crop residues left on the soil surface.

Solvable dynamics in a system of interacting random tops

A new solvable model of synchronization dynamics is introduced. It consists of a system of long range interacting tops or magnetic moments with random precession frequencies. The model allows for an explicit study of orientational effects in synchronization phenomena as well as nonlinear processes in resonance phenomena in strongly coupled magnetic systems. A stability analysis of the incoherent solution is performed for different types of orientational disorder. A system with orientational disorder always synchronizes in the absence of noise.

Magnetic microstructures from magnetic force microscopy and Monte Carlo simulation in CoFe-Ag-Cu granular films

CoFe-Ag-Cu granular films, prepared by rf sputtering, displayed magnetic domain microstructures for ferromagnetic concentrations above about 32% at, and below the percolation threshold. All samples have a fcc structure with an (111) texture perpendicular to the film plane. Magnetic force microscopy (MFM) showed a variety of magnetic domain microstructures, extremely sensitive to the magnetic history of the sample, which arise from the balance of the ferromagnetic exchange, the dipolar interactions and perpendicular magnetocrystalline anisotropy, MFM images indicate that in virgin samples, magnetic bubble domains with an out-of-plane component of the magnetization are surrounded by a quasicontinuous background of opposite magnetization domains. The application of a magnetic field in different geometries drastically modifies the microstructure of the system in the remanent state: i) for an in-plane field, the MFM images show that most of the magnetic moments are aligned along the film plane, ii) for an out-of-plane field, the MFM signal increases about one order of magnitude, and out-of-plane striped domains with alternating up and down magnetization are stabilized. Numerical simulations show that a variety of metastable domain structures (similar to those observed experimentally) can be reached, depending on magnetic history, in systems with competing perpendicular anisotropy, exchange and dipolar interactions.

Temporal and spatial dynamics of benthic invertebrate communities in an alpine glacier-fed alluvial system

Summary The present thesis work focused on the ecology of benthic invertebrates in the proglacial floodplain of the Rhone in the Swiss Alps. The main glacial Rhone River and a smaller glacial tributary, the Mutt River, joined and entered a braiding multi-thread area. A first part concentrated on the disruption of the longitudinal patterns of environmental conditions and benthic invertebrate fauna in the Rhone by its tributary the Mutt. The Mutt had less harsh environmental conditions, higher taxonomic richness and more abundant zoobenthos compared to the Rhone upstream of the confluence. Although the habitat conditions in the main stream were little modified by the tributary, the fauna was richer and more diverse below the confluence. Colonisation from the Mutt induced the occurrence of faunal elements uncommon of glacial streams in the upper Rhone, where water temperature remains below 4°C. Although the glacial Rhone dominated the system with regard to hydrology and certain environmental conditions, the Mutt tributary has to be seen as the faunal driver of the system. The second part of the study concerned the spatio-temporal differentiation of the habitats and the benthic communities along and across the flood plain. No longitudinal differentiation was found. The spatial transversal differentiation of three habitat types with different environmental characteristics was successfully reflected in the spatial variability of benthic assemblages. This typology separated marginal sites of the flood plain, left bank sites under the influence of the Mutt, and the right bank sites under the influence of the Rh6ne. Faunistic spatial differences were emphasized by the quantitative structure of the fauna, richness, abundances and Simpson index of diversity. Seasonal environmental variability was positively related with Simpson index of diversity and the total richness per site. Low flow conditions were the most favourable season for the fauna and November was characterized by low spatial environmental heterogeneity, high spatial heterogeneity of faunal assemblage, maximum taxonomic richness, a particular taxonomic composition, highest abundances, as well as the highest primary food resources. The third part studied the egg development of three species of Ephemeroptera in the laboratory at 1.5 to 7°C and the ecological implications in the field. Species revealed very contrasting development strategies. Baetis alpinus has a synchronous and efficient egg development, which is faster in warmer habitats, enabling it to exploit short periods of favourable conditions in the floodplain. Ecdyonurus picteti has a very long development time slightly decreasing in warmer conditions. The high degree of individual variation suggests a genetic determination of the degree-days demand. Combined with the glacial local conditions, this strategy leads to an extreme delay of hatching and allows it to develop in very unpredictable habitats. Rhithrogena nivata is the second cold adapted species in Ephemeroptera. The incubation duration is long and success largely depends on the timing of hatching and the discharge conditions. This species is able to exploit extremely unstable and cold habitats where other species are limited by low water temperatures. The fourth part dealt with larval development in different habitats of the floodplain. Addition of data on egg development allowed the description of the life histories of the species from oviposition until emergence. Rhithrogena nivata and loyolaea generally have a two-year development, with the first winter passed as eggs and the second one as larvae. Development of Ecdyonurus picteti is difficult to document but appears to be efficient in a harsh and unpredictable environment. Baetis alpinus was studied separately in four habitats of the floodplain system with contrasting thermal regimes. Differences in success and duration of larval development and in growth rates are emphasised. Subvention mechanisms between habitats by migration of young or grown larvae were demonstrated. Development success and persistence of the populations in the system were thus increased. Emergence was synchronised to the detriment of the optimisation of the adult's size and fecundity. These very different development strategies induce a spatial and temporal distribution in the use of food resources and ecological niches. The last part of this work aimed at the synthesis of the characteristics and the ecological features of three distinct compartments of the system that are the upper Rhone, the Mutt and the floodplain. Their particular role as well as their inter-dependence concerning the structure and the dynamics of the benthic communities was emphasised. Résumé Ce travail de thèse est consacré à l'écologie des invertébrés benthiques dans la zone alluviale proglaciaire du Rhône dans les Alpes suisses. Le Rhône, torrent glaciaire principal, reçoit les eaux de la Mutt, affluent glaciaire secondaire, puis pénètre dans une zone de tressage formée de plusieurs bras. La première partie de l'étude se concentre sur la disruption par la Mutt des processus longitudinaux, tant environnementaux que faunistiques, existants dans le Rhône. Les conditions environnementales régnant dans la Mutt sont moins rudes, la richesse taxonomique plus élevée et le zoobenthos plus abondant que dans le Rhône en amont de la confluence. Bien que les conditions environnementales dans le torrent principal soient peu modifiées par l'affluent, la faune s'avère être plus riche et plus diversifiée en aval de la confluence. La colonisation depuis la Mutt permet l'occurrence de taxons inhabituels dans le Rhône en amont de la confluence, où la température de l'eau se maintient en dessous de 4°C. Bien que le Rhône, torrent glaciaire principal, domine le système du point de vu de l'hydrologie et de certains paramètres environnementaux, l'affluent Mutt doit être considéré comme l'élément structurant la faune dans le système. La deuxième partie concerne la différentiation spatiale et temporelle des habitats et des communautés benthiques à travers la plaine alluviale. Aucune différentiation longitudinale n'a été mise en évidence. La différentiation transversale de trois types d'habitats sur la base des caractéristiques environnementales a été confirmée par la variabilité spatiale de la faune. Cette typologie sépare les sites marginaux de la plaine alluviale, ceux sous l'influence de la Mutt (en rive gauche) et ceux sous l'influence du Rhône amont (en rive droite). Les différences spatiales de la faune sont mises en évidence par la structure quantitative de la faune, la richesse, les abondances et l'indice de diversité de Simpson. La variabilité saisonnière du milieu est positivement liée avec l'indice de diversité de Simpson et la richesse totale par site. L'étiage correspond à la période la plus favorable pour la faune et novembre réunit des conditions de faible hétérogénéité spatiale du milieu, de forte hétérogénéité spatiale de la faune, une richesse taxonomique maximale, une composition faunistique particulière, les abondances ainsi que les ressources primaires les plus élevées. La troisième partie est consacrée à l'étude du développement des oeufs de trois espèces d'Ephémères au laboratoire à des températures de 1.5 à 7°C, ainsi qu'aux implications écologiques sur le terrain. Ces espèces présentent des stratégies de développement très contrastées. Baetis alpinus a un développement synchrone et efficace, plus rapide en milieu plus chaud et lui permettant d'exploiter les courtes périodes de conditions favorables. Ecdyonurus picteti présente une durée de développement très longue, diminuant légèrement dans des conditions plus chaudes. L'importante variation interindividuelle suggère un déterminisme génétique de la durée de développement. Cette stratégie, associée aux conditions locales, conduit à un décalage extrême des éclosions et permet à l'espèce de se développer dans des habitats imprévisibles. Rhithrogena nivata est la seconde espèce d'Ephémères présentant une adaptation au froid. L'incubation des oeufs est longue et son succès dépend de la période des éclosions et des conditions hydrologiques. Cette espèce est capable d'exploiter des habitats extrêmement instables et froids, où la température est facteur limitant pour d'autres espèces. La quatrième partie traite du développement larvaire dans différents habitats de la plaine alluviale. Le développement complet est décrit pour les espèces étudiées de la ponte jusqu'à l'émergence. Rhithrogena nivata et loyolaea atteignent généralement le stade adulte en deux ans, le premier hiver étant passé sous forme d'oeuf et le second sous forme de larve. Le développement de Ecdyonurus picteti est difficile à documenter, mais s'avère cependant efficace dans un environnement rude et imprévisible. Baetis alpinus a été étudié séparément dans quatre habitats de la plaine ayant des régimes thermiques contrastés. La réussite et la durée du développement embryonnaire ainsi que les taux de croissance y sont variables. Des mécanismes de subvention entre habitats sont possibles par la migration de larves juvéniles ou plus développées, augmentant ainsi la réussite du développement et le maintien des populations dans le système. L'émergence devient synchrone, au détriment de l'optimisation de la taille et de la fécondité des adultes. Ces stratégies très différentes induisent une distribution spatiale et temporelle dans l'usage des ressources et des niches écologiques. La dernière partie synthétise les caractéristiques écologiques des trois compartiments du système que sont le Rhône amont, la Mutt et la zone alluviale. Leurs rôles particuliers et leurs interdépendances du point de vue de la structure et de la dynamique des communautés benthiques sont mis en avant.