Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 49
Filtrar
1.
Genomics ; 116(1): 110777, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38163572

RESUMO

Genomic studies with Salmonella enterica serovar Typhimurium reveal a crucial role of horizontal gene transfer (HGT) in the acquisition of accessory cellular functions involved in host-interaction. Many virulence genes are located in genomic islands, plasmids and prophages. GreA and GreB proteins, Gre factors, interact transiently with the RNA polymerase alleviating backtracked complexes during transcription elongation. The overall effect of Gre factors depletion in Salmonella expression profile was studied. Both proteins are functionally redundant since only when both Gre factors were depleted a major effect in gene expression was detected. Remarkably, the accessory gene pool is particularly sensitive to the lack of Gre factors, with 18.6% of accessory genes stimulated by the Gre factors versus 4.4% of core genome genes. Gre factors involvement is particularly relevant for the expression of genes located in genomic islands. Our data reveal that Gre factors are required for the expression of accessory genes.


Assuntos
Proteínas de Bactérias , Salmonella typhimurium , Salmonella typhimurium/genética , Salmonella typhimurium/metabolismo , Plasmídeos , Virulência/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo
3.
Sensors (Basel) ; 23(15)2023 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-37571449

RESUMO

Experiences of virtual reality (VR) can easily break if the method of evaluating subjective user states is intrusive. Behavioral measures are increasingly used to avoid this problem. One such measure is eye tracking, which recently became more standard in VR and is often used for content-dependent analyses. This research is an endeavor to utilize content-independent eye metrics, such as pupil size and blinks, for identifying mental load in VR users. We generated mental load independently from visuals through auditory stimuli. We also defined and measured a new eye metric, focus offset, which seeks to measure the phenomenon of "staring into the distance" without focusing on a specific surface. In the experiment, VR-experienced participants listened to two native and two foreign language stimuli inside a virtual phone booth. The results show that with increasing mental load, relative pupil size on average increased 0.512 SDs (0.118 mm), with 57% reduced variance. To a lesser extent, mental load led to fewer fixations, less voluntary gazing at distracting content, and a larger focus offset as if looking through surfaces (about 0.343 SDs, 5.10 cm). These results are in agreement with previous studies. Overall, we encourage further research on content-independent eye metrics, and we hope that hardware and algorithms will be developed in the future to further increase tracking stability.


Assuntos
Realidade Virtual , Humanos , Percepção Auditiva , Idioma , Interface Usuário-Computador , Inquéritos e Questionários
4.
Anthropol Anz ; 80(1): 23-29, 2023 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-36155612

RESUMO

The existence of a third root in the mandibular first molars may have implications for certain dental treatments; however, its greatest relevance could be in anthropological and forensic sciences, because its prevalence varies significantly according to ethnic groups. The purpose of this research was to determine the prevalence of radix entomolaris (RE) in a sample of Chilean people. A random sample of 1330 digital periapical radiographs of endodontically treated mandibular first molars (551 males and 779 females, aged between 18 and 87 years) were evaluated. The prevalence of RE, its distribution by sex and root canal lengths were determined. Evidence demonstrated that the formation of RE is associated with ancestry and its frequency is variable according to populations studied, being more frequent in Asians and Native Americans. The prevalence of RE in the studied people was 3.16%, similar to frequencies reported in European individuals (3.4%-4.2%). The 61.90% of RE were located at the right side of the mandible and 38.10% at the left side. The average working length of RE was 19.52 mm. No statistically significant differences in frequencies were observed by sex (p = 0.19). The prevalence of RE varies among continental population groups. However, due to human migration, the frequency of this physical trait could be modified in specific geographic regions. The observed prevalence of RE in the study group was similar to the prevalence ranges observed for European ancestry populations and it was considerably lower than the data reported for non-Europeans. The absence of sexual dimorphism is consistent with results of previous studies performed worldwide.


Assuntos
Dentição , Raiz Dentária , Masculino , Feminino , Humanos , Adolescente , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Chile/epidemiologia , Raiz Dentária/diagnóstico por imagem , Dente Molar , Etnicidade , Mandíbula
5.
Rep Pract Oncol Radiother ; 28(6): 720-727, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38515815

RESUMO

Background: Several measurements defining the expected 30-day mortality (30-DM) to use in audit of radiation oncology departments have been proposed. However, its external validity is limited because of the lack of data from non-English speaking countries. This study assessed 30-DM in patients treated with palliative radiotherapy (PRT) in a Chilean-reference radiotherapy centre and explored if there had been tailored treatment at the end of life. Materials and methods: Retrospective data collection was carried out for all patients treated at our institution between 1st January 2018 and 31st December 2021. Individual factors were modelled first to check for univariate association with 30-DM, those variables with a significance level of < 0.05 were considered for the final multivariable model. Results: 3,357 patients were included. The most common primary malignancies were breast (22%) and lung (16.1%). The most common treatment sites were bone (47.7%) and brain (12.2%). Overall, 30-DM was 14.7%, this rate was higher in patients treated for brain metastases (25.7%) and thoracic palliation (22.1%). 30-DM was associated with poor performance status (p < 0.01), lung and esophageal-gastric cancer (p = 0.04 and p = 0.02, respectively), metastases other than bone (p < 0.01), brain metastases (p < 0.01) and private health insurance (p <0.01). Conclusions: In patients treated for brain metastasis and thoracic palliation 30-DM was higher than suggested benchmarks. Moreover, in these groups long courses of PRT were often performed. Audit data should be useful for planning interventions that improve selection of patients and prompting review of policies for indication and fractionation schedules of PRT.

6.
Microorganisms ; 10(10)2022 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-36296197

RESUMO

Rdar biofilm formation of Salmonella typhimurium and Escherichia coli is a common ancient multicellular behavior relevant in cell-cell and inter-organism interactions equally, as in interaction with biotic and abiotic surfaces. With the expression of the characteristic extracellular matrix components amyloid curli fimbriae and the exopolysaccharide cellulose, the central hub for the delicate regulation of rdar morphotype expression is the orphan transcriptional regulator CsgD. Gre factors are ubiquitously interacting with RNA polymerase to selectively overcome transcriptional pausing. In this work, we found that GreA/GreB are required for expression of the csgD operon and consequently the rdar morphotype. The ability of the Gre factors to suppress transcriptional pausing and the 147 bp 5'-UTR of csgD are required for the stimulatory effect of the Gre factors on csgD expression. These novel mechanism(s) of regulation for the csgD operon might be relevant under specific stress conditions.

7.
PLoS One ; 17(8): e0271172, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35930546

RESUMO

It is an increasingly accepted idea that biological diversity stabilizes ecosystem processes and the services they provide to society. By reducing biomass fluctuation, biodiversity could mitigate the impact of changing environmental conditions on rural incomes as long as people exploits a diverse set of natural assets. This effect is analogous to the risk-spreading function of financial portfolios. This paper presents evidence of the portfolio effect for an open-access artisanal fishery in an estuarine ecosystem, located in a Colombian Biosphere Reserve. Using catch statistics from 2002 to 2018, we evaluate the contribution of catch diversity to the stabilization of fishing income. We find that changes in catch composition are related to seasonal and interannual variations in salinity conditions. The portfolio effect arises from asynchronous fluctuations of fish species due to fluctuating environmental conditions. Catch diversification, instead of specialization, help achieve resilient fisheries.


Assuntos
Ecossistema , Pesqueiros , Animais , Biodiversidade , Conservação dos Recursos Naturais , Peixes , Humanos , Caça , Renda
8.
Clin Transl Oncol ; 24(9): 1800-1808, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35474170

RESUMO

BACKGROUND: Breast cancer (BC) prevalence steadily increases in older patients but their treatment is based on the geriatric evaluations of comorbidities and potential benefits proved in clinical trials with younger patients. The lack of better decision-making tools urges to promote the search for new prognostic markers. The association between inflammation, aging and cancer may be crucial for better treatment selection. We sought to analyze its impact on the survival of older BC patients, evaluating the interaction with age and comorbidities. METHODS: We evaluated the relationship between inflammatory biomarkers at BC diagnosis (circulating blood cell counts and inflammatory indexes) and BC-related and not related mortality rate, evaluating the influence of comorbidities and age through the competitive risks assessment. RESULTS: We analyzed 148 consecutive BC patients aged ≥ 70 years old, diagnosed with BC and regional lymph node metastases. After the median follow-up of 51.5 months, 59 patients died (28 due to breast cancer progression and 31 because of other causes). Increased levels of circulating monocytes, neutrophils and neutrophil-to-lymphocytes ratio and decreased level of eosinophils and eosinophil multiple by neutrophils-to-lymphocytes ratio were associated with higher probability of BC-related death but not with death related to other causes. CONCLUSION: Our data suggest a role of inflammatory parameters as a possible prognostic tool in therapeutic decision-making process in older patients with BC, as increased level of inflammation was associated with cancer-specific mortality. Prospective studies may give the possibility of refining the geriatric evaluation for BC treatment in elderly.


Assuntos
Neoplasias da Mama , Idoso , Mama/patologia , Neoplasias da Mama/patologia , Feminino , Humanos , Inflamação/patologia , Prognóstico , Estudos Prospectivos
9.
Surg Neurol Int ; 13: 45, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35242411

RESUMO

BACKGROUND: Cerebellar liponeurocytoma is rare intracranial tumor appearing mostly in the posterior fossa. CASE DESCRIPTION: We hereby report a long follow-up of a case of cerebellar liponeurocytoma in a 60-year-old female. At first, she presented in March of 2010 with the symptoms of hydrocephalus and was found to have a lesion located in the fourth ventricle. The tumor was resected with a small remnant around the brainstem which grew on serial imaging. Due to slow tumor growth, the patient was treated with conformal radiotherapy and was kept under follow-up with both outpatient visits and serial brain imaging. In 2018, due to low back pain and lumbar radicular pain, a new set of images of the spine was obtained which revealed multilevel intradural tumor spinal dissemination. The patient further underwent an open spinal biopsy at the level of L5 which revealed the same pathology of the intracranial tumor. The patient went on to receive total spine irradiation. CONCLUSION: This case report describes a rare metastatic phenomenon to the spinal cord of the exact same pathology and grade of an intracranial cerebellar liponeurocytoma tumor.

10.
Breast Cancer Res Treat ; 191(1): 219-220, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34609641

RESUMO

We retrospectively reviewed the data from patients ≥ 70 years old treated between January 2012 and January 2017. Axillary staging was scarcely used in the therapeutic algorithm but arm lymphedema was significantly associated to axillar dissection (p=0.04) and regional nodal irradiation (p = 0.02). Aggressive management of axilla did not provide relevant information for deciding chemotherapy but added morbidity.


Assuntos
Neoplasias da Mama , Idoso , Axila/patologia , Neoplasias da Mama/patologia , Dissecação , Feminino , Humanos , Excisão de Linfonodo , Linfonodos/patologia , Estadiamento de Neoplasias , Estudos Retrospectivos , Biópsia de Linfonodo Sentinela
11.
Obstet Gynecol ; 138(4): 616-621, 2021 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-34623073

RESUMO

OBJECTIVE: To characterize respiratory emissions produced during labor and vaginal delivery vis-à-vis the potential for transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: Observational study of three women who tested negative for SARS-CoV-2 and had uncomplicated vaginal deliveries. Using background-oriented schlieren imaging, we evaluated the propagation of respiratory emissions produced during the labor course and delivery. The primary outcome was the speed and propagation of breath over time, calculated through processed images collected throughout labor and delivery. RESULTS: In early labor with regular breathing, the speed of the breath was 1.37 meters/s (range 1.20-1.55 meters/s). The breath appeared to propagate faster with a cough during early labor at a speed of 1.69 meters/s (range 1.22-2.27 meters/s). During the second stage of labor with Valsalva and forced expiration, the propagation speed was 1.79 meters/s (range 1.71-1.86 meters/s). CONCLUSION: Labor and vaginal delivery increase the propagation of respiratory emissions that may increase risk of respiratory transmission of SARS-CoV-2.


Assuntos
Microbiologia do Ar , COVID-19/transmissão , Exposição por Inalação/análise , Trabalho de Parto/fisiologia , Respiração , Adulto , Parto Obstétrico/métodos , Transmissão de Doença Infecciosa , Feminino , Humanos , Gravidez , SARS-CoV-2 , Vagina , Adulto Jovem
12.
Clin Pathol ; 14: 2632010X211051741, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34661104

RESUMO

Lambert-Eaton syndrome is a rare paraneoplastic disorder of the neuromuscular junction, characterized by impaired release of acetylcholine, which causes proximal muscle weakness, depressed tendon reflexes, and autonomic changes. Most cases of Lambert-Eaton syndrome present in small-cell lung carcinoma, and only a few cases have been reported in other lung subtypes. Herein, we report a case of 69 years old male patient with Lambert-Eaton syndrome as a rare association with a pulmonary large-cell neuroendocrine carcinoma, which presented 5 months before neoplasm diagnosis. A lobectomy was auspiciously performed. A review of the literature is also presented.

13.
Artigo em Inglês | MEDLINE | ID: mdl-34682375

RESUMO

Delivering metaphors experientially has been emphasized in several psychotherapies, such as acceptance and commitment therapy. However, few research has analyzed the variables involved in the efficacy of metaphors. This experimental analog study aims to advance in this topic by analyzing the effect of two components involved in the experiential delivery of metaphors in psychotherapy. The first component is presenting the metaphor by asking the individual to imagine herself as the protagonist of the story versus presenting the metaphor in the third person (Self vs. Other). The second component is the inclusion of verbal cues prompting the relational elaboration of the rules derived from the metaphor content versus not including these prompts (Elaboration vs. No Elaboration). The effect of these components was tested in a double-blind, randomized, 2 × 2 factorial experiment that used the cold pressor task (CPT). Eighty-four participants were exposed to the CPT at the pretest. Afterward, participants were randomly assigned to four experimental protocols. The protocols were audiotaped and consisted of the same metaphor presented in four slightly different ways. Specifically, the protocol of Condition A involved a metaphor with Self and Elaboration, Condition B involved Self and No Elaboration, Condition C involved Other and Elaboration, and Condition D involved Other and No Elaboration. Then, participants were re-exposed to the CPT in the posttest. We hypothesized that Condition A (Self and Elaboration) would show a higher mean increase in pain tolerance than the remaining conditions, which would show similar results. The results were consistent with this hypothesis because Condition A showed a higher percentual increase in pain tolerance (Condition A: M = 268.21, SD = 167.47; Condition B: M = 180.86, SD = 73.01; Condition C: M = 204.81, SD = 100.19; Condition D: M = 175.41, SD = 76.00). A Bayesian informative hypothesis evaluation showed that this hypothesis obtained the highest posterior model probability. Thus, the results indicate that introducing metaphors by asking the individual to imagine herself as the protagonist of the story and providing prompts for relational elaboration might increase the therapeutic effect of the metaphor.


Assuntos
Terapia de Aceitação e Compromisso , Metáfora , Teorema de Bayes , Sinais (Psicologia) , Humanos , Idioma
15.
J Med Eng Technol ; 45(8): 606-613, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34225554

RESUMO

This study hypothesised that benign and tumour-bearing uterine tissue could be differentiated by their unique electrical bioimpedance patterns, with the aid of artificial intelligence. Twenty whole, ex-vivo uterine specimens were obtained at the time of hysterectomy. A total of 11 benign and 9 malignant specimens were studied. A uterine bioimpedance probe was designed to measure the tissue between the endometrial and serosal layers of the uterus. The impedance data was then analysed with multiple instance learning and principal component analysis, forms of artificial intelligence. Final pathology results for the specimens included uterine sarcoma, adenocarcinoma, carcinosarcoma, and high-grade serous carcinoma. The analysis correctly identified 78% (7/9) of the malignant specimens and 82% (9/11) of the benign specimens. The overall accuracy of our analysis was 80%. Our results demonstrate distinction between electrical impedance properties of malignant and benign uterine specimens. Bioimpedance and artificial intelligence may have potential implications in risk assessment of patients and may subsequently guide surgical decision-making regarding route of organ removal.


Assuntos
Leiomioma , Neoplasias Uterinas , Inteligência Artificial , Feminino , Humanos , Estudos Retrospectivos , Neoplasias Uterinas/diagnóstico
16.
Molecules ; 26(9)2021 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-33925792

RESUMO

Low-density polyethylene (LDPE) sheets (3.0 ± 0.1 cm) received sequential treatment, first by the action of direct-current low-pressure plasma (DC-LPP) with a 100% oxygen partial pressure, 3.0 × 10-2 mbar pressure, 600 V DC tension, 5.6 cm distance, 6-min treatment. Then, sheets were submitted to TiO2 photocatalysis at UV radiation at 254 nm (TiO2/UV) with a pH value of 4.5 ± 0.2 and a TiO2 concentration of 1 gL-1. We achieved a complementary effect on the transformation of LDPE films. With the first treatment, ablation was generated, which increased hydrophilicity. With the second treatment, the cavities appeared. The changes in the LDPE sheets' hydrophobicity were measured using the static contact angle (SCA) technique. The photocatalytic degradation curve at 400 h revealed that the DC-LPP photocatalysis sequential process decreased SCA by 82°. This was achieved by the incorporation of polar groups, which increased hydrophilicity, roughness, and rigidity by 12 and 38%, respectively. These sequential processes could be employed for LDPE and other material biodegradation pretreatment.

18.
Span J Psychol ; 24: e19, 2021 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-33745479

RESUMO

Previous research has shown that individuals suffering from depression and generalized anxiety disorder (GAD) seem to have inhibitory control deficits compared with healthy controls. However, few studies have been conducted in Spanish-speaking countries. Thus, this study aims to analyze the performance on the Stroop Color and Word Test (SCWT) between groups of Colombian participants with clinical levels of depression and GAD symptoms and a nonclinical control group. According to previous research, we expected to find significant differences in inhibitory control among groups. An ex post facto design was implemented. The SCWT was administered to a total sample of 105 individuals (64.8% women, M = 22.94 years, SD = 4.62), including 27 depressed and 15 anxious participants according to their scores on the Personal Health Questionnaire-9 and the Generalized Anxiety Disorder-7, respectively. Bayesian t-tests showed that depressed participants showed the same processing speed but lower scores on inhibitory control than healthy controls, BF = 13.70, δ = 0.50, 95% CI [0.08, 0.94]. Conversely, anxious participants showed deficits in processing speed, SCWT-Word: BF = 16.19, δ = 0.68, 95% CI [0.15, 1.24]; SCWT-Color: BF = 5.98, δ = 0.50, 95% CI [-0.01, 1.04], but not in inhibitory control compared with the nonanxious counterparts. This study provides preliminary evidence concerning the inhibitory control deficits in Colombian depressed individuals and processing speed deficits in those experiencing clinical levels of GAD symptoms.


Assuntos
Ansiedade , Depressão , Transtornos de Ansiedade , Teorema de Bayes , Cognição , Feminino , Humanos , Masculino
19.
Rev. colomb. gastroenterol ; 35(4): 447-454, dic. 2020. tab
Artigo em Espanhol | LILACS | ID: biblio-1156327

RESUMO

Resumen Introducción: la obstrucción intestinal por bridas es responsable del 25 % de las consultas a urgencias por dolor abdominal agudo, generando un alto riesgo de lesión iatrogénica por reintervenciones de urgencia. Una alternativa para determinar la necesidad de manejo quirúrgico sería el manejo médico conservador inicial y evaluar su respuesta en un período de 12-72 horas. Objetivo: describir los desenlaces clínicos de los pacientes adultos con obstrucción intestinal por bridas en un hospital de tercer nivel y que recibieron manejo médico no quirúrgico al ingreso. Metodología: estudio observacional tipo cohorte, prospectivo, de los pacientes atendidos con tratamiento conservador durante el período 2012-2013 por obstrucción intestinal. Se recogió información sociodemográfica y clínica de los pacientes, así como seguimiento hasta el alta hospitalaria. Para el análisis se empleó estadística descriptiva y se analizó con SPSS V.15. Resultados: el 58,9 % de los casos eran masculinos con edad media de 55,2 años, el 57,1 % tenía comorbilidades en las que predominaron las enfermedades cardiovasculares y 91,1 % tenía antecedentes quirúrgicos, la mitad de ellos por procesos inflamatorios. Los principales síntomas fueron emesis y distención abdominal. La respuesta al tratamiento conservador fue de 80,4 %; del 19,6 % que requirió manejo quirúrgico, en el 81,8 % de los casos el hallazgo intraoperatorio fue de obstrucción intestinal por bridas. El tiempo medio de hospitalización fue de 5,5 días y durante el estudio solo un paciente falleció. Conclusión: el manejo médico conservador debe ser considerado como el tratamiento inicial de esta entidad por su alta tasa de respuesta, disminución de complicaciones posoperatorias y estancia hospitalaria.


Abstract Introduction: Intestinal obstruction by adhesions accounts for 25% of consultations to the emergency department associated with acute abdominal pain, generating a high risk of iatrogenic injury by emergency reinterventions. An alternative to determine the need for surgical treatment is providing conservative medical management first and then assessing patients' response within 12-72 hours. Objective: To describe the clinical outcomes of adult patients with bowel obstruction caused by adhesions treated at a tertiary care hospital who received non-surgical medical treatment on admission. Methodology: Observational, prospective cohort study on patients treated conservatively during the period 2012-2013 for intestinal obstruction. Socio-demographic and clinical information was collected from patients, and follow-up was done until discharge. The analysis was carried out using descriptive statistics in SPSS v15. Results: 58.9% of the cases occurred in men, and the average age was 55.2 years. 57.1% of the patients had comorbidities predominantly associated with cardiovascular diseases, and 91.1% had previously undergone a surgical procedure, half of them due to inflammatory processes. The most common symptoms were emesis and abdominal distention. The response to conservative treatment was 80.4% of the 19.6% that required surgical management. In 81.8% of the cases, intestinal obstruction caused by adhesions was the main intraoperative finding. The average time of hospitalization was 5.5 days, and during the study only one patient died. Conclusion: Conservative medical management should be considered as the initial treatment for this entity due to its high response rate, reduction of postoperative complications, and shorter hospital stay.


Assuntos
Humanos , Masculino , Feminino , Complicações Pós-Operatórias , Tratamento Conservador , Obstrução Intestinal , Sinais e Sintomas , Tempo , Doenças Cardiovasculares , Dor Abdominal , Hospitalização
20.
Biosci. j. (Online) ; 36(6): 2007-2019, 01-11-2020. tab, graf, ilus
Artigo em Inglês | LILACS | ID: biblio-1148024

RESUMO

Levels of weed infestation can be inferred from climate information since every species requires specific conditions for its germination process. This study aimed to evaluate weed species and their emergence flow in hilly areas, when subjected to different environmental conditions of temperature and luminosity. Two experiments were carried out in a completely randomized design with four replications. In the first experiment, treatments used plastic films (no film; film just on top; partially closed film; and fully closed film), whereas the second experiment used black polyethylene covers (0; 35; 50; and 80%). Weed emergence in the area was monitored daily, until the establishment of the emergence flow. Soil temperature, solar radiation interception and soil moisture were also monitored. For the analysis of species subjected to every type and level of covers, phytosociological parameters and the emergence speed index were calculated. Data were submitted to analysis of covariance and, when they were significant, the Tukey test (p ≤ 0.05) was applied. A hierarchical cluster analysis was performed to relate factors and experimental levels to distribution intervals of climate covariates. Increase of 8.5°C in soil temperature favors the emergence of crabgrass, while reducing the emergence of alexander grass, morning glory, beggartick and sida. The main species that adapted to decrease in temperature and solar radiation are sida, alexander grass and crab grass. Besides, decrease in radiation increases the number of magnoliopsida species and enables all species to establish faster.


As informações climáticas permitem inferir qual será o nível de infestação de plantas daninhas, sendo que cada espécie exige requisitos específicos para ocorrência do processo germinativo. Objetivou-se avaliar as espécies infestantes e o fluxo de emergência de plantas daninhas em área de coxilha, quando submetidas a diferentes condições ambientais de temperatura e luz. Realizaram-se dois experimentos em delineamento inteiramente casualizado, com quatro repetições. No primeiro experimento os tratamentos foram definidos por cobertura com filme plástico (sem filme, filme somente em cima, parcialmente fechado e totalmente fechado) e, no segundo, por coberturas de polietileno preto (0; 35; 50; e 80%). A emergência de plantas daninhas na área foi monitorada diariamente, até estabelecimento do fluxo de emergência. Realizou-se também o monitoramento da temperatura do solo, interceptação da radiação solar e umidade do solo. Para a análise das espécies em cada tipo e nível de cobertura foram calculados os parâmetros fitossociológicos e o índice de velocidade de emergência. Os dados obtidos foram submetidos à análise de covariância e quando significativo procedeu-se o teste de Tukey (p≤0,05). Foi realizada análise de grupamento hierárquico para relacionar os fatores e os níveis experimentais aos intervalos da distribuição das covariáveis climáticas. O aumento em 8,5°C na temperatura do solo favorece a emergência de milhã, enquanto que reduz a emergência de papuã, corriola, picão-preto e guanxuma. As principais espécies a se adaptar as condições de redução da temperatura e radiação solar são guanxuma, papuã e milhã, sendo que a redução da radiação aumenta a frequência das espécies magnoliopsidas e proporciona o estabelecimento mais rápido de todas as espécies.


Assuntos
Mudança Climática , Germinação , Plantas Daninhas
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA