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1.
Tech Coloproctol ; 27(10): 867-872, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-36856913

RESUMO

BACKGROUND: Rubber band ligation (RBL) is a widely accepted intervention for the treatment of haemorrhoids. However, post procedure pain is a common complaint. The aim of this study was to determine whether the addition of local anaesthetic (LA) to the haemorrhoid pedicle base, post RBL, aids in reducing early post-procedure pain. Additionally, to compare perceived perianal numbness, oral analgesia usage and total consumption, and adverse events. METHODS: This study was a prospective, single-blinded randomised controlled trial. Patients were recruited from colorectal clinics in two Australian hospitals between 2018-2019. Patients randomised to the intervention (LA) group received 2mls bupivacaine 0.5% with adrenaline 1:200,000 to each haemorrhoid base. Patients in the control group were not administered LA. Pain scores were recorded over 48 h using visual analogue scales. Analgesia consumption was documented and other secondary objectives were recorded dichotomously (yes/no). RESULTS: At 1 h post-procedure, patient reported pain scores were significantly lower in the LA group compared to the control group (p = 0.04). There were no significant differences in pain scores between the groups at 4, 24 or 48 h. Additionally, there were no significant differences between groups with respect to oral analgesia usage, perianal numbness or adverse events. CONCLUSIONS: LA to the haemorrhoid pedicle post RBL may significantly reduce early post procedure pain without any increased risk of adverse effects.


Assuntos
Hemorroidas , Dor Processual , Humanos , Anestésicos Locais , Hemorroidas/cirurgia , Hemorroidas/etiologia , Estudos Prospectivos , Hipestesia/etiologia , Austrália , Ligadura/efeitos adversos , Ligadura/métodos , Dor Processual/etiologia , Dor Pós-Operatória/tratamento farmacológico , Dor Pós-Operatória/etiologia
2.
Colorectal Dis ; 23(1): 274-282, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32750730

RESUMO

AIM: The aim of this work was to examine the efficacy of oral metronidazole in reducing posthaemorrhoidectomy pain versus placebo. METHOD: Forty patients were randomized to either metronidazole and standard care or placebo and standard care (21 metronidazole, 19 placebo) in a double-blinded, randomized controlled trial. The main outcome measure was posthaemorrhoidectomy pain scores over 21 days, measured on a 10-point Likert scale. RESULTS: There were no significant differences between groups with regards to age, gender, smoking status, self-reported general health or quality of life, haemorrhoid-related pain, haemorrhoid-related impact on quality of life, reported satisfaction with surgery, experience of surgery, median overall pain score or likelihood of recommending surgery to others. For reported median worst pain scores and defaecation-related pain, a trend to significance was identified between groups on days 16 and 18-21, with the metronidazole group reporting less pain. However, these differences were not significant when prespecified Bonferroni correction criteria were used. Using multilevel mixed effects modelling, the impact of time on median worst pain score was identified to be highly significant (P < 0.0001) whereas treatment allocation (placebo versus metronidazole) did not significantly affect the improvement in patients' reported pain (P = 0.8837). CONCLUSION: Our data do not support the hypothesis that postoperative metronidazole has a clinically meaningful effect on posthaemorrhoidectomy pain. This study adds to the previous literature, and implies that it should not be routinely used as an adjunct to analgesia.


Assuntos
Hemorroidectomia , Hemorroidas , Método Duplo-Cego , Hemorroidectomia/efeitos adversos , Hemorroidas/complicações , Hemorroidas/cirurgia , Humanos , Metronidazol/uso terapêutico , Dor Pós-Operatória/tratamento farmacológico , Dor Pós-Operatória/etiologia , Qualidade de Vida
3.
Angiol Sosud Khir ; 27(3): 54-65, 2021.
Artigo em Inglês, Russo | MEDLINE | ID: mdl-34528589

RESUMO

Described in the article is a clinical case report regarding complete endovascular arterialization of deep crural and pedal veins in a male patient with accompanying pathology and impossibility of intraluminal restoration of the arterial bed. Peculiarities of the presented case report consisted in creation of an arteriovenous anastomosis in the upper third of the crus using an endovascular technique. During treatment, a repeat intervention was required, i. e., balloon angioplasty of veins and implantation of an additional stent graft due to reocclusion of veins because of long-term local treatment of wounds and cytostatic therapy for background diseases (chronic myeloleukaemia and rheumatoid arthritis). The performed treatment resulted in a clear trend towards healing of the wounds on the foot and limb salvage.


Assuntos
Procedimentos Endovasculares , Isquemia , Amputação Cirúrgica , , Humanos , Isquemia/diagnóstico , Isquemia/etiologia , Isquemia/cirurgia , Perna (Membro) , Salvamento de Membro , Masculino , Resultado do Tratamento , Veias/cirurgia
4.
PLoS Genet ; 11(4): e1004953, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25874869

RESUMO

Shade from neighboring plants limits light for photosynthesis; as a consequence, plants have a variety of strategies to avoid canopy shade and compete with their neighbors for light. Collectively the response to foliar shade is called the shade avoidance syndrome (SAS). The SAS includes elongation of a variety of organs, acceleration of flowering time, and additional physiological responses, which are seen throughout the plant life cycle. However, current mechanistic knowledge is mainly limited to shade-induced elongation of seedlings. Here we use phenotypic profiling of seedling, leaf, and flowering time traits to untangle complex SAS networks. We used over-representation analysis (ORA) of shade-responsive genes, combined with previous annotation, to logically select 59 known and candidate novel mutants for phenotyping. Our analysis reveals shared and separate pathways for each shade avoidance response. In particular, auxin pathway components were required for shade avoidance responses in hypocotyl, petiole, and flowering time, whereas jasmonic acid pathway components were only required for petiole and flowering time responses. Our phenotypic profiling allowed discovery of seventeen novel shade avoidance mutants. Our results demonstrate that logical selection of mutants increased success of phenotypic profiling to dissect complex traits and discover novel components.


Assuntos
Magnoliopsida/genética , Redes e Vias Metabólicas , Fenótipo , Fototropismo/genética , Ciclopentanos/metabolismo , Flores/fisiologia , Genes de Plantas , Ácidos Indolacéticos/metabolismo , Magnoliopsida/metabolismo , Magnoliopsida/fisiologia , Mutação , Oxilipinas/metabolismo , Folhas de Planta/fisiologia , Sementes/fisiologia , Luz Solar
5.
Proc Natl Acad Sci U S A ; 110(28): E2655-62, 2013 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-23803858

RESUMO

Although applied over extremely short timescales, artificial selection has dramatically altered the form, physiology, and life history of cultivated plants. We have used RNAseq to define both gene sequence and expression divergence between cultivated tomato and five related wild species. Based on sequence differences, we detect footprints of positive selection in over 50 genes. We also document thousands of shifts in gene-expression level, many of which resulted from changes in selection pressure. These rapidly evolving genes are commonly associated with environmental response and stress tolerance. The importance of environmental inputs during evolution of gene expression is further highlighted by large-scale alteration of the light response coexpression network between wild and cultivated accessions. Human manipulation of the genome has heavily impacted the tomato transcriptome through directed admixture and by indirectly favoring nonsynonymous over synonymous substitutions. Taken together, our results shed light on the pervasive effects artificial and natural selection have had on the transcriptomes of tomato and its wild relatives.


Assuntos
Seleção Genética , Solanum lycopersicum/genética , Transcriptoma , Regulação da Expressão Gênica de Plantas , Genes de Plantas
6.
Surgeon ; 14(4): 184-9, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25630375

RESUMO

BACKGROUND: Many patients who undergo a Hartmann's procedure do not have their stoma reversed. We analysed parameters and co-morbidity scales to assess their accuracy in predicting likelihood of undergoing reversal. MATERIAL AND METHODS: Retrospective analysis of 165 patients from a prospective colorectal database who were discharged home following a Hartmann's procedure at Barwon Health (Geelong, Australia), a regional centre, between 2002 and 2010. Parameters measured included age, sex, time to reversal, ICU admission and pathology results were recorded. Patients' ASA, POSSUM and Elixhauser co-morbidity scales were retrospectively analysed. RESULTS: Reversal of Hartmann's was performed in 74/165 (45%) patients after a median of 294 days (range 70-902). Age (mean 58.5 vs 72.9 years, p < 0.001), ICU stay (34/74 vs 66/91, p < 0.001), ASA (p < 0.002), Elixhauser co-morbidity count (mean 1.14 vs 1.92, p < 0.002) and a malignant diagnosis (9/74 vs 31/91, p < 0.002) were all associated with a decreased reversal rate on univariate analysis. Age was the only parameter found to be significant on multivariate analysis. The complication rate was 23/74, with 7/74 noted to have major complications (Clavian-Dindo III-IV). Reasons for not reversing patients included age and co-morbidities, patient refusal, and malignant disease progression. CONCLUSIONS: More than half the patients undergoing a Hartmann's procedure did not proceed to a closure of their stoma. Age was the only parameter significant in predicting those patients undergoing reversal.


Assuntos
Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/cirurgia , Colostomia/efeitos adversos , Colostomia/métodos , Comorbidade , Fatores Etários , Idoso , Estudos de Coortes , Colectomia/métodos , Neoplasias Colorretais/patologia , Bases de Dados Factuais , Feminino , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Invasividade Neoplásica/patologia , Estadiamento de Neoplasias , Complicações Pós-Operatórias/fisiopatologia , Complicações Pós-Operatórias/cirurgia , Prognóstico , Estudos Prospectivos , Reoperação/métodos , Reoperação/estatística & dados numéricos , Estudos Retrospectivos , Medição de Risco , Taxa de Sobrevida , Resultado do Tratamento
7.
Am J Orthod Dentofacial Orthop ; 150(6): 950-957, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27894544

RESUMO

INTRODUCTION: The purpose of this study was to evaluate the effects of longitudinal flutes on miniscrew implant (MSI) stability and bone healing. METHODS: Using 11 skeletally mature New Zealand white rabbits, we placed 31 longitudinally fluted and 31 nonfluted, 3-mm-long MSIs in standardized positions in their calvaria and immediately loaded them with 100 g using nickel-titanium coil springs. Insertion torque values were obtained for each MSI placed; removal torque values were obtained for 28 MSIs that had been in place for 6 weeks and 20 MSIs that had been in place for 2 weeks. The bone volume fractions at 6 to 24, 24 to 42, and 42 to 60 µm from the MSI surfaces were evaluated using microcomputed tomography with an isotropic resolution of 6 µm. RESULTS: The success rate was 97% for both the fluted and nonfluted MSIs. The difference in insertion torque between the fluted and nonfluted MSIs was not statistically significant (P = 0.930). After 2 weeks, there was no statistically significant (P = 0.702) difference in removal torque between the fluted and nonfluted MSIs. After 6 weeks, removal torque values were significantly (P = 0.008) higher for the fluted (3.42 ± 0.26 N.cm) than the nonfluted (2.49 ± 0.20 N.cm) MSIs. Bone volume fractions of the 6-to-24-, 24-to-42-, and 42-to-60-µm layers were significantly (P <0.05) greater for the nonfluted than the fluted MSIs. CONCLUSIONS: Loaded 3-mm-long MSIs with and without flutes have high success rates. Longitudinal flutes placed in 3-mm MSIs increased their removal torque by 37% and decreased the amount of bone immediately surrounding them.


Assuntos
Parafusos Ósseos , Osteogênese , Animais , Feminino , Coelhos , Crânio/cirurgia , Torque
8.
Artigo em Russo | MEDLINE | ID: mdl-26470430

RESUMO

AIM: Selection of optimal dosage regimen, length of treatment course (frequency of administration), safety, tolerance and clinical effectiveness evaluation of the medical preparation fortepren in patients with chronical recurrent herpes virus infection of genital localization. MATERIALS AND METHODS: The medical product of antiviral and immune modulating effect--fortepren (sodium polyprenyl phosphate) as a 4 mg/ml solution for injections combined with the base course of acyclic nucleoside acyclovir, 400 mg tablets, held studies. 40 male and female patients participated in the study. After a 10-day acyclovir course (400 mg x 3 times a day) for removing the acute phase, 4 groups of 10 individuals were formed: 1--5 ml (20 mg) of fortepren i/m once at day 13 ± 2 after the start of the study after the completion of the treatment of the acute phase of the disease; 2--5 ml (20 mg) fortepren i/m 3 times at an interval of 21 days; 3--2 ml (8 mg) fortepren i/m 3 times at an interval of 21 days; 4 (control)--5 ml of placebo i/m at remission stage 3 times at an interval of 21 days. Increase of the duration of inter-recurrence period, decrease of the severity of the recurrences, state of skin and mucous damage elements, improvements of immunologic parameters were considered during effectiveness evaluation. RESULTS: Significant differences in the frequency of recurrences of genital herpes were shown for 3 months of observation in experimental and control groups. A significant reduction of genital herpes recurrence frequency from 3.52 ± 0.09 (before treatment) to 2.89 ± 0.08 (after treatment) was noted in patients of group 3 (p < 0.001). The frequency of recurrences in the control group was 3.84 ± 0.10, that was higher than the parameters in all the experimental groups. A significant reduction of the rash area was noted in group 3, moreover, a redution of frequency of detection of clinical manifestations of genital herpes in the form of vesicle elements after treatment in groups 2 (p = 0.02) and 3 (p = 0.005) was found. Evaluation of local symptoms has established that burning have caused minimal discomfort for patients of groups 3 and 4 and itch and soreness--of groups 1 and 3. The least pronounced exacerbations were noted in patients of group 3. Intramuscular administration of fortepren preparation was established to result in the increase of titers of leukocyte virus-induced interferon for the whole duration of treatment. CONCLUSION: An intramuscular dose of 2 ml (8 mg) at recurrence stage 3 times at an interval of 21 days after the completion of the 10-day base course of treatment of the acute phase of chronical recurrent herpes virus infection of genital localization using acyclovir was accepted as an optimal dosage regimen. Analysis of the obtained results has shown an acceptable safety profile and a good level of tolerance for fortepren preparation.


Assuntos
Aciclovir/administração & dosagem , Antivirais/administração & dosagem , Herpes Genital/tratamento farmacológico , Fosfatos de Poli-Isoprenil/administração & dosagem , Adolescente , Adulto , Doença Crônica , Quimioterapia Combinada , Feminino , Herpes Genital/imunologia , Humanos , Fatores Imunológicos , Masculino , Pessoa de Meia-Idade
9.
Angiol Sosud Khir ; 20(3): 81-6, 2014.
Artigo em Russo | MEDLINE | ID: mdl-25267227

RESUMO

Surgical interventions are used more often for treatment of patients with lesions of arteries of the femoropopliteal segment. Considerable role in widening indications for using an endovascular method of treatment is played by improvement of roentgenosurgical tools and equipment. Implantation of stents into arteries of this segment has become a standard intervention whose results are the starting point for comparing with the results of other methods of roentgenendovascular revascularization. The SUPERA Veritas system is the first nitinol interwoven stent that is fracture-resistant due to special manufacturing technology. The results of multicenter randomized studies are suggestive of its good clinical effect in restoration of the lumen of arteries of the femoral-popliteal segment. According to the findings of European and American researchers, the stent's primary patency lies within the range from 79.2 to 87.7% which is comparable to primary patency of nitinol stents with antiproliferative drug coating. The authors share the first experience with this stent in Russia, reflecting peculiarities of its implantation, as well as describing clinical case reports of using this stent in arteries of the femoropopliteal segment in patients with atherosclerosis of lower limb arteries and diabetes mellitus, also providing the data on stent's patency one year after implantation according to the findings of noninvasive studies.

10.
Sci Rep ; 14(1): 32, 2024 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-38168502

RESUMO

The epidemiology of vertebral fractures (VF) in underrepresented populations is not well-documented. This cohort study was part of a longitudinal osteoporosis research project with the aim of determining the prevalence, incidence, and risk factors for VF. 401 individuals (155 men) aged 50 years and older without a clinical diagnosis of VF were took radiographs at baseline and 2 years later. VF were ascertained using the Genant's semi-quantitative method. Bone mineral density (BMD) of femoral neck and lumbar spine were measured by dual-energy X-ray absorptiometry (Hologic Inc). The association between VF and risk factors was analyzed by the multiple logistic regression. The 95% confidence interval for prevalence and incidence was estimated by exact Poisson test. At baseline, the prevalence of VF was 12.2% (n = 49, 95% CI 9.0-16.2%) and increased with advancing age with one-fifth of those aged 70 and older having a VF. During the follow-up period, we observed 6 new VF, making the incidence of 6.6/1000 person-years (n = 6, 95% CI 2.4-14.3). The risk of prevalent VF was associated with male gender (OR: 2.67; 95% CI 1.28-5.87) and T-score at the femoral neck (OR per one SD decrease: 1.1; 1.03-1.17). These data indicate that VF is common among adults, and that lower femoral neck BMD was a risk factor for VF.


Assuntos
Osteoporose , Fraturas da Coluna Vertebral , Adulto , Masculino , Humanos , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Fraturas da Coluna Vertebral/diagnóstico por imagem , Fraturas da Coluna Vertebral/epidemiologia , Fraturas da Coluna Vertebral/etiologia , Estudos de Coortes , Prevalência , Incidência , Vietnã , Osteoporose/diagnóstico por imagem , Osteoporose/epidemiologia , Osteoporose/complicações , Densidade Óssea , Absorciometria de Fóton/métodos , Fatores de Risco , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/lesões
11.
Opt Express ; 21(22): 25788-95, 2013 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-24216805

RESUMO

A Stokes vector based non-data-aided (NDA) differential group delay (DGD) estimation scheme with flexible bandwidth requirements is investigated. The scheme is demonstrated in both experiments and simulations for 40-Gb/s polarization-multiplexed coherent optical OFDM systems with up to 1000-km long haul transmission with an estimation error of less than 2.5 ps after 1000-km standard single-mode fiber transmissions.

12.
Opt Express ; 21(17): 20187-96, 2013 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-24105564

RESUMO

We report the use of implicit training-aided channel estimation (ITA-CE) for polarization-division-multiplexed (PDM) single-carrier coherent optical systems. With the concept of ITA-CE, where the training sequence (TS) is arithmetically added onto the information symbols rather than appearing in separate time slots, overhead-free transmission can be achieved with minor optical signal to noise ratio (OSNR) penalty. ITA-CE system enables simple digital pilot-tone based frequency-offset compensation, and inherits the benefits from typical training-aided channel acquisition and data recovery. Furthermore, we address the issue of self-interference to channel estimation (CE) of ITA-CE system in this paper. The data-induced interference can be eliminated by removing the cyclic mean of the transmitted signal, which can accelerate the convergence of the CE and allows smaller power to be allocated to the TS, leading to enhanced system performance. Numerical simulations and experiments for both PDM-QPSK and PDM-16-QAM systems have been conducted to verify the proposed scheme. Comparable performance to the conventional blind equalization system can be achieved when employing the transmitter side pre-distortion approach to the ITA-CE system.

13.
Pediatr Emerg Care ; 29(3): 305-13, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23426254

RESUMO

OBJECTIVES: Infrared thermal detection systems (ITDSs) have been used with limited success outside the United States to screen for fever during recent outbreaks of novel infectious diseases. Although ITDSs are fairly accurate in detecting fever in adults, there is little information about their utility in children. METHODS: In a pediatric emergency department, we compared temperatures of children (<18 years old) measured using 3 ITDSs (OptoTherm Thermoscreen, FLIR ThermoVision 360, and Thermofocus 0800H3) to standard, age-appropriate temperature measurements (confirmed fever defined as ≥38.0°C [oral or rectal], ≥37.0°C [axillary]). Measured temperatures were compared with parental reports of fever using descriptive, multivariate, and receiver operating characteristic analyses. RESULTS: Of 855 patients, 400 (46.8%) had parent-reported fever, and 306 (35.8%) had confirmed fever. At optimal fever thresholds, OptoTherm and FLIR had sensitivity (83.0% and 83.7%, respectively) approximately equal to parental report (83.9%) and greater than Thermofocus (76.8%), and specificity (86.3% and 85.7%) greater than parental report (70.8%) and Thermofocus (79.4%). Correlation coefficients between traditional thermometry and ITDSs were 0.78 (OptoTherm), 0.75 (FLIR), and 0.66 (Thermofocus). CONCLUSIONS: Compared with traditional thermometry, FLIR and OptoTherm were reasonably accurate in detecting fever in children and better predictors of fever than parental report. These findings suggest that ITDSs could be a useful noninvasive screening tool for fever in the pediatric age group.


Assuntos
Febre/diagnóstico , Raios Infravermelhos , Programas de Rastreamento/instrumentação , Termografia/instrumentação , Adolescente , Criança , Pré-Escolar , Serviço Hospitalar de Emergência , Feminino , Humanos , Lactente , Masculino , Curva ROC , Sensibilidade e Especificidade
14.
Adv Orthop ; 2023: 3270372, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36643872

RESUMO

Background: Simple bone cysts are benign bony lesions. Treatment strategies are varied for this particular pathology. It remains controversial as to what the ideal treatment strategy is. Recently, bony substitute injections have emerged as a potential option for treatment. This paper aimed to describe our institution's experience in using bony substitute injections to treat unicameral bone cysts. Methods: A retrospective review of consecutive patients over an 84-month period at a tertiary paediatric hospital was performed. Information regarding patients' presentation, diagnosis, and management was recorded and summarised. Results: A total of 15 patients were included in our study, with a mean follow-up of 118 weeks. 86.7% of patients demonstrated clinical resolution (absence of pain at the latest follow-up) and 80% of patients demonstrated radiographic resolution. Only one patient sustained a subtrochanteric fracture post-index operation, whilst two others demonstrated redevelopment of cystic architecture on follow-up. Conclusion: This study demonstrates that bone substitute injection is potentially a minimally invasive and seemingly successful technique in the treatment of unicameral bone cysts and other simple bone lesions. Further randomised and comparative studies are required to confirm and validate our findings.

15.
Zh Nevrol Psikhiatr Im S S Korsakova ; 123(10): 106-112, 2023.
Artigo em Russo | MEDLINE | ID: mdl-37966448

RESUMO

OBJECTIVE: To analyze spontaneous behavior in 36 male rhesus macaques during formation of alcoholic motivation under free choice. MATERIAL AND METHODS: The model composed the initiation stage with the provision of an aqueous ethanol solution of increasing concentration from 1 to 4% with a sweetener and restricted access to the tap water supply and the subsequent stage of the formation of alcoholic motivation with a free choice between 4% ethanol solution without sweetener and water. The behavior was recorded by the «One-Zero¼ method with ethogram compiled in accordance with the behavioral peculiarities of rhesus monkeys when housed individually. Three subgroups of high, medium and low-level ethanol consumption were distinguished. RESULTS: In the subgroup of high ethanol consumption median consumption was 1.70 g/kg/day at initiation (p<0.05, compared to other subgroups) and 1.79 g/kg/day (p<0.05) at free choice stage. Animals of high consumption subgroup had significantly higher frequency being at the cage bottom and in a sitting posture. We observed significant changes in a number of indicators of spontaneous behavior depending on the level of ethanol consumption, which included displacement behavior, stereotypic behavior and posture of animals. In the high consumption subgroup, there was a significant increase in the frequency of stereotypic behavior, atypical behavior, being on four legs, as well as a decrease in the frequency of being at the back side of the cage and of displacement behavior. At the same time, the inhibitory effect of ethanol on the hypothalamic-pituitary-adrenal system was revealed. CONCLUSION: In the model of free choice alcohol self-administration rhesus monkeys demonstrate a significant change in a number of indicators of spontaneous behavior depending on the level of ethanol consumption, which includes displacement, stereotypic behaviors and animal posture.


Assuntos
Consumo de Bebidas Alcoólicas , Etanol , Animais , Masculino , Macaca mulatta , Motivação , Edulcorantes
16.
Opt Express ; 20(26): B452-61, 2012 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-23262888

RESUMO

This paper presents a novel technique capable of Rayleigh backscattering (RB) mitigation and chromatic dispersion (CD) compensation for wavelength-division-multiplexed passive optical network (WDM-PON). The reduction of the interference caused by RB and CD in the uplink based on reflective electro-absorption modulator (REAM) is realized by the proposed correlative level (CL) coding. We investigate the RB-induced interferometric crosstalk for different fiber lengths. 10 Gb/s and 20 Gb/s transmissions over 70 km and 35 km fiber are demonstrated using the CL codes of dicode and modified duobinary (MD), respectively. Significant improvement in system resilience to backscattered seed light is verified for both dicode and MD coding. MD-coded signal also exhibits considerable robustness against the effects of CD.

17.
Opt Express ; 20(27): 27981-91, 2012 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-23263032

RESUMO

In this paper, we investigate the transmission impairments in a high-speed single-feeder wavelength-division-multiplexed passive optical network (WDM-PON) employing low-bandwidth upstream transmitter. A 1-GHz reflective semiconductor optical amplifier (RSOA) is operated at the rates of 10 Gb/s and 20 Gb/s in the proposed WDM-PON. Since the system performance is seriously limited by its uplink in both capacity and reach owing to inter-symbol interference and reflection noise, we present a novel technique with simultaneous capability of spectral efficiency enhancement and transmission distance extension in the uplink via coding and equalization that exploit the principles of partial-response (PR) signal. It is experimentally demonstrated that the proposed system supports the delivery of 10 Gb/s and 20 Gb/s upstream signals over 75-km and 25-km bidirectional fiber, respectively. The configuration of PR equalizer is optimized for its best performance-complexity trade-off. The reflection tolerance of 10 Gb/s and 20 Gb/s channels is improved by 8 dB and 6 dB, respectively, with PR coding. The proposed cost-effective signal processing scheme has great potential for the next-generation access networks.


Assuntos
Redes de Comunicação de Computadores/instrumentação , Compressão de Dados/métodos , Tecnologia de Fibra Óptica/instrumentação , Dispositivos Ópticos , Telecomunicações/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento
18.
Opt Express ; 20(26): B141-50, 2012 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-23262844

RESUMO

We report a two-stage blind frequency domain equalization method for long-haul coherent polarization-multiplexed (pol-mux) systems using quadrature phase shift keying (QPSK) and 16-quadrature amplitude modulation (16-QAM). In the first stage, blind CD parameter prediction is conducted prior to a CD equalizer. This supports flexible path switching in optical networks. In the second stage, a frequency-domain multi-modulus algorithm (MMA) equalizer is used to cope with the residual fiber impairments and perform polarization de-multiplexing. Compared with the conventional constant modulus algorithm (CMA), MMA shows advantages including better steady state performance and a faster convergence rate. Furthermore, all the estimation and equalization algorithms are implemented in the frequency domain which potentially provides the least complexity for the pol-mux optical coherent systems. The proposed algorithm is experimentally demonstrated with an 800-km 10 Gbaud coherent optical pol-mux system. For QPSK signal, the proposed method achieves error-free transmission and shows superior convergence speed against CMA, and for 16-QAM signals, the proposed MMA outperforms CMA with more than 1-dB improvement in Q-value.

19.
Opt Express ; 20(27): 28724-33, 2012 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-23263110

RESUMO

We propose using low bandwidth coherent receivers for distributed optical performance monitoring. We demonstrate optical signal-to-noise ratio (OSNR) monitoring of both 20-Gb/s single-polarization and 40-Gb/s polarization-multiplexed coherent optical orthogonal frequency-division multiplexing (CO-OFDM) signals with a 0.8-GHz receiver using both data-aided (DA) and non-data-aided (NDA) approaches. The sampling rate of the performance monitor is much lower than the signal baud rate, so provides a cost-effective solution for distributed optical performance monitoring. The proposed method is demonstrated experimentally and through simulation. The results show that after calibration the OSNR monitoring error is less than 1 dB and the two approaches are not affected by fiber dispersion after 800-km transmission and 30-ps differential group delay (DGD).


Assuntos
Tecnologia de Fibra Óptica/instrumentação , Modelos Teóricos , Dispositivos Ópticos , Telecomunicações/instrumentação , Simulação por Computador , Desenho Assistido por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Luz , Espalhamento de Radiação
20.
Opt Express ; 20(16): 17711-21, 2012 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-23038323

RESUMO

We present a novel statistical moments-based method for optical signal-to-noise ratio (OSNR) monitoring in polarization-multiplexed (pol-mux) coherent optical systems. This technique only requires the knowledge of the envelope of the equalized signal before phase correction, which can be achieved by using any two arbitrary statistical moments, and it is suitable for both constant and non-constant modulus modulation formats. The proposed estimation method is experimentally demonstrated for 10-Gbaud pol-mux coherent systems using QPSK and 16-QAM. Additionally, numerical simulations are carried out to demonstrate 20-Gbaud systems using 16-QAM and 64-QAM. The results show that the OSNR can be estimated accurately over a wide range of values for QPSK, 16-QAM or 64-QAM systems up to 1920-km long and with up to 50-ps all-order polarization mode dispersion. By setting a proper reference value for calibration, the proposed algorithm also shows good tolerance when the received signal is not well compensated.

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