Search

In comets and in the cold phase of the interstellar medium (ISM), ammonium salts are key molecular species due to their role in the retention of volatile compounds on cold surfaces. In the case of sulphur, the H |$_2$| S/OCS ratio observed in protostars could be explained by the presence of ammonium hydrosulphide (NH |$_4$| SH) salts. However, laboratory data on the properties of NH4SH in ISM cold relevant conditions are rather scarce, as they usually focus on the atmosphere of Jupiter. We propose to consolidate the laboratory data regarding NH |$_4$| SH on grains, by performing temperature programmed desorption experiments and Fourier transform infrared reflection spectroscopy. The salt was also exposed to H atoms to mimic the ISM conditions. NH |$_4$| SH was found to form in situ at 10 K, from a mixture of ammonia (NH |$_3$|⁠) and hydrogen sulphide (H |$_2$| S). The NH |$_4^+$| infrared feature (1485 cm |$^{-1}$|⁠) is the most prominent one at 80 K. As pure species, H |$_2$| S and NH |$_3$| desorb at 76 and 90 K, respectively, whereas they are released into the gas phase at 153 K when adsorbed in the form of salt. The presence of water delays the desorption of the salt until the very end of the water desorption, but does not affect the desorption kinetics. During H-exposure, the salt is dissociated and no new product was detected. As a comparative study, salts have been included in the Nautilus gas–grain model. The results show a good correlation with the observations of IRAS 16293−2422B, as opposed to when NH |$_4$| SH is not included in the model. [ABSTRACT FROM AUTHOR]

Context. Nitrogen-bearing molecules (such as N2H+ and NH3) are excellent tracers of high-density and low-temperature regions, such as dense cloud cores. Notably, they could help advance the understanding of snow lines in protoplanetary discs and the chemical evolution of comets. However, much remains unknown about the chemistry of N-bearing molecules on grain surfaces, which could play an important role in their formation and evolution. Aims. In this work, we experimentally study the behaviour of NH3 on surfaces that mimic grain surfaces under interstellar conditions in the presence of some other major components of interstellar ices (i.e. H2O, CO2, CO). We measure the binding energy distributions of NH3 from different H2O ice substrates and also investigate how it could affect the NH3 snow line in protoplanetary discs. Methods. We performed laboratory experiments using the ultra-high vacuum (UHV) set-up VENUS (VErs des NoUvelles Syntheses). We co-deposited NH3 along with other adsorbates (H2O, 13CO, and CO2) and performed temperature programmed desorption (TPD) and temperature programmed-during exposure desorption (TP-DED) experiments. The experiments were monitored using a quadrupole mass spectrometer and a Fourier transform reflection absorption infrared spectrometer (FT-RAIRS). We obtained the binding energy distribution of NH3 on crystalline ice (CI) and compact amorphous solid water ice by analysing the TPD profiles of NH3 obtained after depositions on these substrates. Results. In the co-deposition experiments, we observed a significant delay in the desorption and a decrease of the desorption rate of NH3 when H2O is introduced into the co-deposited mixture of NH3–13CO or NH3–CO2, which is not the case in the absence of H2O. Secondly, we noticed that H2O traps roughly 5–9% of the co-deposited NH3, which is released during the phase change of water from amorphous to crystalline. Thirdly, we obtained a distribution of binding energy values of NH3 on both ice substrates instead of an individual value, as assumed in previous works. For CI, we obtained an energy distribution between 3780 K and 4080 K, and in the case of amorphous ice, the binding energy values were distributed between 3630 K and 5280 K; in both cases we used a pre-exponential factor of A = 1.94 × 1015 s−1. Conclusions. From our experiments, we conclude that the behaviour of NH3 is significantly influenced by the presence of water, owing to the formation of hydrogen bonds with water, in line with quantum calculations. This interaction, in turn, preserves NH3 on the grain surfaces longer and up to higher temperatures, making it available closer to the central protostar in protoplanetary discs than previously thought. It explains well why the NH3 freeze-out in pre-stellar cores is efficient. When present along with H2O, CO2 also appears to impact the behaviour of NH3, retaining it at temperatures similar to those of water. This may impact the overall composition of comets, particularly the desorption of molecules from their surface as they approach the Sun. [ABSTRACT FROM AUTHOR]

A gestão de territórios fronteiriços é um desafio para os governos subnacionais por conta da descontinuidade territorial. As zonas de fronteiras são formadas por, pelo menos, duas áreas geográficas pertencentes a países distintos. Muitos dos problemas e dificuldades da gestão são compartilhados pelos vizinhos, mas não suas soluções, que esbarram nos limites jurisdicionais. Cada vez mais são observadas as necessidades de municípios fronteiriços serem protagonistas no enfrentamento de dificuldades que excedem seus limites geográficos. Este artigo discute as possibilidades de governança territorial entre territórios localizados em regiões de fronteira. Para tanto, recorreu-se a pesquisa bibliográfica e vivências em consulados brasileiros no exterior de um dos autores. Constatou-se já existir uma literatura que acena para a importância da participação dos governos subnacionais nos rumos da política internacional, em especial. Os municípios fronteiriços podem e devem estimular iniciativas de cooperação e aproveitar instrumentos já existentes, como os comitês de fronteira, para que se tornem porta-vozes dos clamores locais juntos aos governos nacionais.

Accurate and early yield estimation (from pea size) allows 1.- Make decisions at field level: green harvesting, irrigation management. 2.- Advance or organise the purchase of grapes from suppliers. 3.- Forecast the volume of wine produced in the campaign that has not yet begun. 4.- Define the quality of the vintage: regular and detailed monitoring of whether, or not, the heterogeneity of the leaf surface, photosynthetic activity or soil moisture observed in the vineyards is as expected at this time, compared with historical values. 5.- Precise control of each vine in production, knowing which vines are no longer productive or should be grubbed up. The Sentinel-2 satellite has generated a time series of images spanning more than six years, which is a great help in analysing the state of permanent crops such as vineyards, where grapes are produced every year. The weekly comparison of what is happening in the current season with what has happened in the previous six seasons is information that is in line with agricultural practices: Winegrowers make the mental exercise of comparing how the vines are developing today with how they developed in previous seasons, with the aim of repeating the years of good yields. In addition, several commercial satellites can now capture images of 50 centimetres pixel resolution or even better, making it possible to check the health of each vine every year. Since 2020, GMV and Pago de Carraovejas have been working together to develop a yield estimation service based on field information and satellite images that feed machine learning algorithms. This paper describes the path followed from the beginning and the steps taken, summarising as follows: 1. - Machine learning algorithm trained with cluster counting and satellite data. 2. - Adjustment of the number of vines in production in each vineyard using very high-resolution imagery. 3. - Machine learning algorithm trained on real production from past campaigns and historical Sentinel-2 time series. The results obtained by comparing the actual grape intake in the winery with the yield estimation range from 91% accuracy in 2020 to 95% accuracy in 2022.

Comprehending the significance of legacy in end-of-life (EoL) situations helps palliative care professionals enhance person-centered outcomes for those with a life-threatening illness and their families. Our purpose was to conduct a concept analysis of legacy in EoL care. By employing Walker and Avant's approach, we identified the concept's defining characteristics. Subsequently, we established the antecedents, consequences, and empirical referents. After conducting a thorough review of titles and abstracts, a total of 30 publications were analyzed. These articles were sourced from three databases (CINAHL, Medline via PubMed, and Scopus) from 2002 to 2023. Our analysis identified several core attributes of legacy: (a) leave behind something of value that transcends death; (b) determine how people want to be remembered; (c) build and bestow across generations; (d) integrate advance care planning through EoL conversations and shared decision-making; and (e) develop strategies of dignity-conserving care. The consequences are related to improvements in spiritual and subjective well-being; coping with inevitable EoL existential issues; decreases in EoL suffering; engendering self-awareness, hope, gratitude, and peace; achieving and maintaining dignity; creating good memories; promoting mutually constructive and transformative relationships; and fostering the adjustment of bereaved people. Nevertheless, further effort is required to implement the key attributes of legacy that form the basis for creating legacy-oriented interventions near the EoL.

Experimental and computational chemistry are two disciplines used to conduct research in astrochemistry, providing essential reference data for both astronomical observations and modeling. These approaches not only mutually support each other, but also serve as complementary tools to overcome their respective limitations. Leveraging on such synergy, we characterized the binding energies (BEs) of ethanol (CH 3 CH 2 OH) and ethylamine (CH 3 CH 2 NH 2 ), two interstellar complex organic molecules (iCOMs), on crystalline and amorphous water ices through density functional theory (DFT) calculations and temperature-programmed desorption (TPD) experiments. Experimentally, CH 3 CH 2 OH and CH 3 CH 2 NH 2 behave similarly, in which desorption temperatures are higher on the water ices than on a bare gold surface. Computed cohesive energies of pure ethanol and ethylamine bulk structures allow describing of the BEs of the pure species deposited on the gold surface, as extracted from the TPD curve analyses. The BEs of submonolayer coverages of CH 3 CH 2 OH and CH 3 CH 2 NH 2 on the water ices cannot be directly extracted from TPD due to their co-desorption with water, but they are computed through DFT calculations, and found to be greater than the cohesive energy of water. The behaviour of CH 3 CH 2 OH and CH 3 CH 2 NH 2 is different when depositing adsorbate multilayers on the amorphous ice, in that, according to their computed cohesive energies, ethylamine layers present weaker interactions compared to ethanol and water. Finally, from the computed BEs of ethanol, ethylamine and water, we can infer that the snow-lines of these three species in protoplanetary disks will be situated at different distances from the central star. It appears that a fraction of ethanol and ethylamine is already frozen on the grains in the water snow-lines, causing their incorporation in water-rich planetesimals.

The COVID-19 pandemic imposed changes upon the capacity of healthcare systems, with significant repercussions on healthcare provision, particularly at end-of-life. This study aims to analyze the concept map of death unpreparedness due to the COVID-19 pandemic, capturing the relationships among the attributes, antecedents, consequences, and empirical indicators. Walker and Avant's method was used to guide an analysis of this concept. A literature search was performed systematically, between May 2022 and August 2023, using the following electronic databases on the Elton Bryson Stephens Company (EBSCO) host platform: Medical Literature Analysis and Retrieval System Online (Medline), Psychological Information Database (PsycINFO), Cumulative Index to Nursing and Allied Health Literature (CINAHL) Complete, Cochrane Library, and Nursing and Allied Health Collection. Thirty-four articles were retrieved. The unexpected and unpredictable impositions associated with inexperience and unskillfulness in dealing with COVID-19 configured challenges for healthcare professionals, family/caregivers, and even the dying person. Nine key attributes emerged in three main domains: (1) Individual: (a) disease-related conditions, (b) separation distress, and (c) scarcity of death and grief literacy; (2) Relational: (a) Dying alone, (b) poor communication, and (c) existential issues; and (3) Contextual: (a) disrupted collective mourning and grieving, (b) disrupted compassionate care and, (c) pandemic social stigma. This study contributed a full definition of death unpreparedness in a global pandemic scenario such as COVID-19. In this sense, feeling unprepared or unready for death brought new challenges to the bioecological resources of those affected. It is essential to embrace strategies capable of providing emotional and spiritual support in the dying process and to respect patient wishes. The lessons learned from COVID-19 should be applied to events with a comparable impact to minimize their consequences.

Keystroke dynamics can valuably contribute to the development of intelligent authentication systems by enabling a single and continuous authentication process in a passive and non-intrusive manner by continuously verifying a user's identity. This work describes the KeyRecs dataset, which contains fixed-text and free-text samples of user typing behavior and demographic information of the participants age, gender, handedness, and nationality. The keystroke data was obtained from 99 participants of various nationalities who completed password retype and transcription exercises. The recorded samples consist of inter-key latencies computed in a digraph fashion measuring the time between each key press and release during an exercise. KeyRecs can be leveraged to improve the recognition of authorized users and prevent unauthorized access in biometric authentication software., (© 2023 The Author(s).)

Palliative care nurses experience huge pressures, which only increased with coronavirus disease 2019 (COVID-19). A reflection on the new demands for nursing care should include an evaluation of which evidence-based practices should be implemented in clinical settings. This paper discusses the impacts and challenges of incorporating coaching strategies into palliative care nursing. Evidence suggests that coaching strategies can foster emotional self-management and self-adjustment to daily life among nurses. The current challenge is incorporating this expanded knowledge into nurses' coping strategies. Coaching strategies can contribute to nurses' well-being, empower them, and consequently bring clinical benefits to patients, through humanized care focused on the particularities of end-of-life patients and their families., Competing Interests: Declaration of Conflicting Interests: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2022.)

For the production of healthier fruit snacks, vacuum frying is a promising alternative for atmospheric frying, to reduce the oil content, while maintaining a high nutritional quality. This paper evaluates the effect of ripening stages, frying temperature, and time on the quality of vacuum-fried mango. Unripe mango was dehydrated faster than ripe mango and had a higher hardness after frying at 110 and 120°C. Fat content in fried ripe mango was higher. Total ascorbic acid and β-carotene in both ripening stages were not different, but after frying total ascorbic acid in unripe mango remains higher. A novel image analysis was applied to quantify the color distribution of fried mango. Color changes in unripe mango were more susceptible to temperature and time. Considering all quality parameters, vacuum frying of unripe mango at the optimal condition of 100°C for 20 min is preferred for producing high-quality healthier fruit snacks., (Copyright © 2020 Ayustaningwarno, van Ginkel, Vitorino, Dekker, Fogliano and Verkerk.)

Ethnopharmacological Relevance: Piper cernuum Vell (Piperaceae) is a native species from Atlantic rain forest, popularly known as pariparoba. Its leaves have been commonly used by rural and urban communities from State of São Paulo, Brazil, to treat pain (orally and topically), and hepatic and renal complications., Aim of the Study: In this study we evaluated the acute and sub-acute toxicity, genotoxicity and mutagenicity of hydroalcoholic extract obtained from P. cernuum leaf using in vivo and in vitro methods., Material and Methods: In the acute toxicity study, mice were orally treated with P. cernuum extract (2000 mg/kg, p.o.). General behavior and mortality were observed for up to 14 days. In the sub-acute toxicity study, P. cernuum extract was given orally as a single administration to the rats at doses of 50 or 250 mg/kg/day, for 28 days. General behavior, body weight, biochemical and hematological parameters, organ coefficients and pathological morphology were analyzed. The P. cernuum mutagenicity was evaluated using mammalian cell micronucleus assay. Additionally, in vitro toxicity profile of the extract was assessed through cytotoxicity, hemolytic activity, and genotoxicity assay., Results: Data from comet assay demonstrates that high concentrations of P. cernuum extract induce genotoxicity. However, no evidence of hemolytic, cytotoxic or mutagenicity activity was found. In addition, the acute and sub-acute toxicity studies did not show significant changes in body weight, general behavior, hematology and biochemical parameters, organ weight and liver and kidney histopathological analysis., Conclusions: Together, the results herein obtained indicate that P. cernuum leaves extract did not present significant toxicity when administered to male or female rats. Additionally, no significant alteration in hematological, biochemical and morphological parameters were observed. Data obtained in vitro shows that extract did not present cytotoxicity and mutagenicity. However, the extract induces in vitro genotoxicity, but in high concentration. Further studies are necessary to evaluate the safety of long-term exposure to P. cernuum leaves extract added to in vivo genotoxicity., (Copyright © 2018 Elsevier B.V. All rights reserved.)

We document chigger mite (Acari: Trombiculidae) ectoparasitic infestation (prevalence and intensity) on a population of Catharus ustulatus (Turdidae) wintering at a site (PAD A) in southeastern Peru undergoing development for natural gas exploration. We compare prevalence (i.e., the proportion of individuals infested by chigger mites) and intensity (i.e., the average number of larvae and larvae clusters in infested individuals) at forest edge (<100 m) and interior (>100 m) from PAD A because variations in biotic (e.g., vegetation cover) and abiotic (e.g., relative humidity and temperature) factors are expected to influence chigger mite abundance. Chigger mite prevalence was 100%; all C. ustulatus captured were infested regardless of distance. The range of variation in larvae (2-72 larvae/individual) and cluster intensity (1-4 clusters/individual) did not differ between edge and interior ( P > 0.05), despite differences in herbaceous vegetation cover (U M-W = 180, n = 30, 31; P < 0.01). Ectoparasitic prevalence and intensity in long-distance migratory birds might add risks to an already hazardous journey; because ectoparasitic variation and other selective pressures experienced by individuals at each locality not only may be a cause of within-site mortality, but, by affecting the physical condition of birds, may be carried over to subsequent sites and affect reproductive success and survival. Documenting ectoparasitism at any phase of the life cycle of migrants could improve understanding of population declines of migratory birds.

Gas-phase affinity studies based on cations and anions commonly present in ionic liquid structures, give quantitative information about the magnitude of the interactions holding the two species together when ILs are formed. They also provide clues on how these interactions depend on the nature of the cationic and anionic moieties. In the present work, mass spectrometric experiments, performed using electrospray ionization quadrupole ion-trap and Fourier transform ion cyclotron resonance mass spectrometry, were used to obtain two affinity scales by Cooks' kinetic method: one scale for the various cations for the bis(trifluoromethylsulfonyl)imide anion, [NTf2 ](-) , and another for the different anions for the 1-butyl-3-methylimidazolium cation, [C4 mim](+) . The obtained results are compared with previously reported data and discussed in terms of the structural characteristics of the different cationic and anionic species., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A general strategy to determine enthalpies of formation of protic ionic liquids, based solely on enthalpy of solution measurements, was conceived and tested for 1-methylimidazolium ethanoate, leading to Δ(f)H°(m){[Hmim][O(2)CCH(3)], 1} = -(425.7 ± 1.2) kJ mol(-1). This result in conjunction with the enthalpy of formation of gaseous 1-methylimidazole (mim) proposed in this work, Δ(f)H°(m)(mim, g) = 126.5 ± 1.1 kJ mol(-1), and Δ(f)H°(m)(CH(3)COOH, g) taken from the literature, allowed the calculation of the enthalpy of the vaporisation process [Hmim][O(2)CCH(3)](l) → mim(g) + CH(3)COOH(g) as Δ(vap)H°(m){[Hmim][O(2)CCH(3)]} = 119.4 ± 3.0 kJ mol(-1). The agreement between this value and Δ(vap)H°(m){[Hmim][O(2)CCH(3)]} = 117.3 ± 0.5 kJ mol(-1), obtained for the direct vaporisation of [Hmim][O(2)CCH(3)], by Calvet-drop microcalorimetry, gives a good indication that, as previously suggested by Fourier transform ion cyclotron resonance mass spectrometry, Raman spectroscopy, and GC-MS experiments, the vaporisation of [Hmim][O(2)CCH(3)] essentially involves a proton transfer mechanism with formation of the two volatile neutral precursor molecules (mim and CH(3)COOH). Although being a low ionicity protic ionic liquid, [Hmim][O(2)CCH(3)] was chosen to validate the methodology proposed here, since its vaporisation mechanism has been unequivocally demonstrated by different methods and for different pressure ranges.

The vaporization of a dicationic ionic liquid at moderate temperatures and under reduced pressures--recently studied by line-of-sight mass spectrometry--was further analyzed using an ion-cyclotron resonance mass spectroscopy technique that allows the monitoring of the different species present in the gas phase through the implementation of controlled ion-molecule reactions. The results support the view that the vapour phase of an aprotic dicationic ionic liquid is composed of neutral ion triplets (one dication attached to two anions). Molecular dynamics simulations were also performed in order to explain the magnitude of the vaporization enthalpies of dicationic ionic liquids vis-à-vis their monocationic counterparts.

The sublimation/vaporization of the protic ionic liquid 1,1,3,3-tetramethylguanidinium chloride, [Htmg]Cl, was studied by Fourier transform ion cyclotron resonance mass spectrometry in the temperature range 298-488 K and under a reduced pressure of 3.2 x 10(-6) to 1.5 x 10(-5) Pa. The results show that no charged species are present in the vapor over the condensed phase. Furthermore, ion-molecule reaction studies found no evidence of neutral ion pairs in the gas phase. This indicates that the sublimation/vaporization of [Htmg]Cl conforms to the general mechanism postulated for the distillation of protic ionic liquids, which involves a proton transfer leading to the formation of the neutral acid and base precursors, in this case hydrogen chloride and 1,1,3,3-tetramethylguanidine.

The urinary tract is one of the more common sites of bacterial infections, especially in women. Urinary infection can be defined as an infection of urinary tract structures which occurs, generally, as a consequence of the presence or colonization by urine bacteria. The aim of this study was to determine the etiology of urinary tract infections and their susceptibility to antimicrobial agents in the region of Vale do Sousa and Tâmega. From February 2008 to January 2009, 18653 urine cultures were analyzed. From these cultures 1037 were positive. From this total of positive cultures, 18,3% were from males and 81.7% were from females. In bacteriological positive tests, 23 different strains of microorganisms were found. It was verified that the most frequent microorganism was Escherichia coli, followed by Proteus mirabilis, Klebsiella pneumoniae, Enterococcus faecalis and Pseudomonas aeruginosa. For antimicrobial susceptibility it was verified that Escherichia coli showed low susceptibility to amoxicillin and cotrimoxazole. Proteus mirabilis showed good susceptibility to cefotaxime and low to cotrimoxazole, amoxicillin and ciprofloxacin. For Klebsiella pneumoniae was found only a reasonable susceptibility to gentamicin and Enterococcus faecalis showed amoxicillin susceptibility. Pseudomonas aeruginosa showed low susceptibility to all antibiotics analyzed with the exception of the combination piperacillin/tazobactam. In conclusion, this study shows that Escherichia coli, Proteus mirabilis and Klebsiella pneumoniae are the three main microorganisms that causes urinary infections in the region of Vale do Sousa and Tâmega. Therefore, the antimicrobial empirically used must have a spectrum against enterobacteria, because they are the most likely to be present in urinary tract infections acquired in the community. A periodic analysis of the susceptibility profile should be performed over time for each region in order to help in the beginning of the empirical antimicrobial treatment.

In order to diagnose abnormality in tongue strength and endurance and to obtain more precise rehabilitation planning, the aims of this study were to examine typical tongue strength and endurance of 75 healthy Portuguese speakers. The tongue strength and endurance scores were obtained using the Iowa Oral Performance Instrument (IOPI Model 2.0). The participants ranged in age from 20 to 77 years of age. To assess whether there were differences across age and gender, the participants were divided into three age categories (20-40; 41-60; 61-80) and both genders to establish a total of 6 groups. The results revealed that there were no significant differences across age and gender and that the healthy speakers of Portuguese were able to maintain 50% maximum pressure for a shorter period of time than those documented in English speakers. The data collected will provide an important database for speech-language pathologists with the purpose of diagnosis of tongue dysfunction.

Objective: To evaluate laryngeal function and speech disorders in children and adults with traumatic brain injury (TBI) by applying both perceptual and instrumental analysis., Participants: 15 children and 15 adults with moderate to severe acquired TBI and 2 control groups (19 adults and 16 children)., Main Measures: A battery of perceptual analyses (the Frenchay Dysarthria Assessment (FDA) and speech sample assessment) and instrumental techniques (electrolaryngographic and computerized airflow/air pressure analysis systems-Aerophone II)., Results: While children with TBI exhibited fewer speech disorders (based on the deviant laryngeal features) than did the adult group with TBI during the perceptual assessments, the significant differences found between both groups using electroglottography (EGG) analysis for the laryngeal function investigation could be explained by the anatomical and physiological differences between adults and children. Consistent with the findings based on electroglottography, the aerodynamic analysis carried out in the present study failed to demonstrate significant changes in laryngeal function following TBI in either adults or children., Conclusions: Four reasons may explain the differences between children and adults: (1) the different types of injury can vary the degree of neurologic impairment, (2) potential differences during recovery, (3) the developmental changes in, or level of maturation of, laryngeal function in the pediatric group and, (4) time postinjury. Because of these variations, children may be better able to compensate for any impairment.

Objective: The primary aim of the present investigation was to obtain the nasalance score in Portuguese speakers with multiple sclerosis (MS) in order to identify velopharyngeal impairments and to enhance clinicians' ability to employ appropriate therapy strategies for speech disorders in MS., Design: Perceptual assessments (speech sample analysis) and instrumental technique (Nasometer) were performed. Two passages were constructed in the Portuguese Language: one similar to the Grandfather Passage for perceptual assessments and the other similar to the Zoo Passage for the nasalance score., Participants: Seventy (70) adult Portuguese speakers with MS and seventy five (75) nonneurologically disordered Portuguese speakers were involved in this study., Results/conclusion: The mean nasalance score of the MS participants was found to be significantly higher than of the control group, confirming velopharyngeal dysfunction in the Portuguese speakers group with MS. The results in this study contrast with a low incidence of velopharyngeal impairment present in English speakers with MS. These findings are discussed with respect to the degree of hypernasality and the potential influence of these impairments on the verbal output of the speakers of Portuguese.

Three Azospirillum brasilense mutants constitutive for nitrogen fixation (Nif(C)) in the presence of NH4(+) and deficient in nitrate-dependent growth were used as tools to define the roles of the glnB and ntrYX genes in this organism. Mutant HM14 was complemented for nitrate-dependent growth and NH4(+) regulation of nitrogenase by plasmid pL46 which contains the ntrYX genes of A. brasilense. Mutant HM26 was restored for NH4(+) regulation and nitrate-dependent growth by plasmid pJC1, carrying the A. brasilense glnB gene expressed from a constitutive promoter. Mutant HM053, on the other hand, was not complemented for NH4(+) regulation of nitrogenase and nitrate-dependent growth by both plasmids pJCI and pL46. The levels and control of glutamine synthetase activity of all mutants were not affected by both plasmids pL46 (ntrYX) and pJC1 (glnB). These results support the characterization of strains HM14 as an ntrYX mutant and strain HM26 as a glnB mutant and the involvement of ntrYX and glnB in the regulation of the general nitrogen metabolism in A. brasilense.