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1.
Rev Med Interne ; 44(10): 539-545, 2023 Oct.
Artigo em Francês | MEDLINE | ID: mdl-37558601

RESUMO

Celiac disease is a frequent auto-immune disease characterized by villous atrophy related to gluten intake in patients with genetic susceptiblity. Patients do not present symptoms in the majority of cases. Presence of the disease must be investigated in case of digestive symptoms or presence of auto-immune disease. Diagnosis is based on anti-transglutaminase antibody and dudodenal biospies. The only available treatment is gluten-free diet. Associated auto-immune diseases must be investigated, especially thyroiditis. Complications related to nutritional deficiency must be accounted for also.

2.
Dig Liver Dis ; 55(9): 1194-1200, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37244790

RESUMO

BACKGROUND: Increased C-reactive protein (CRP) is used to diagnose and predict response to treatment in acute severe ulcerative colitis (UC). AIMS: To investigate the connection between CRP elevation and deep ulcers in UC. METHODS: Patients with active UC were enrolled in a multicenter prospective cohort and a retrospective cohort of consecutive patients undergoing colectomy from 2012 to 2019. RESULTS: Forty-one (9 (22%) with deep ulcers) patients were included in the prospective cohort: 4/5 (80%) patients with CRP > 100 mg/L, 2/10 (20%) patients with CRP between 30 and 100 mg/L and 3/26 (12%) patients with CRP < 30 mg/L had deep ulcers (p = 0.006). In the retrospective cohort [46 patients (31 (67%) with deep ulcers)], 14/14 (100%) patients with CRP > 100 mg/L, 11/17 (65%) patients with CRP between 30 and 100 mg/l and 6/15 (40%) patients with CRP < 30 mg/L had deep ulcers (p = 0.001). Positive predictive value of CRP > 100 mg/l for presence of deep ulcers was 80% and 100% in both cohorts, respectively. CONCLUSIONS: CRP elevation is a robust surrogate marker for presence of deep ulcers in UC. Elevated CRP or presence of deep ulcers could influence the choice of medical therapy in acute severe UC.


Assuntos
Colite Ulcerativa , Humanos , Biomarcadores , Proteína C-Reativa/metabolismo , Colite Ulcerativa/complicações , Colite Ulcerativa/cirurgia , Colite Ulcerativa/diagnóstico , Estudos Prospectivos , Estudos Retrospectivos , Índice de Gravidade de Doença , Úlcera
3.
J Crohns Colitis ; 16(10): 1523-1530, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-35512337

RESUMO

INTRODUCTION: Knowledge about the cancer risk when initiating a biologic in inflammatory bowel disease [IBD] patients with prior malignancy remains scarce, especially for vedolizumab. Our aim was to evaluate the rate of incident cancer in a cohort of IBD patients with prior non-digestive malignancy, according to the subsequent treatment given. METHODS: A multicentre retrospective study included consecutive IBD patients with prior non-digestive malignancy. Inclusion date corresponded to the diagnosis of index malignancy. Patients were categorized into different cohorts according to the first treatment [none, conventional immunosuppressant, anti-TNF, or vedolizumab] to which they were exposed after inclusion and before incident cancer [recurrent or new cancer]. RESULTS: Among the 538 patients {58% female; mean (standard deviation [SD]) age inclusion: 52 [15] years} analyzed, the most frequent malignancy was breast cancer [25%]. The first immunomodulator given after inclusion was a conventional immunosuppressant in 27% of patients, anti-TNF in 21%, or vedolizumab in 9%. With a median (interquartile range [IQR]) follow-up duration of 55 [23-100] months, 100 incident cancers were observed. Crude cancer incidence rates per 1000 person-years were 47.0 for patients receiving no immunomodulator, 36.6 in the anti-TNF cohort, and 33.6 in the vedolizumab cohort [p = 0.23]. Incident-cancer free survival rates were not different between patients receiving anti-TNF and those receiving vedolizumab [p = 0.56]. After adjustment, incidence rates were not different between patients receiving no immunomodulator, anti-TNF, or vedolizumab. CONCLUSIONS: In this large multicentre cohort study, there was no difference of cancer incidence in those IBD patients with prior non-digestive malignancy, treated with vedolizumab or anti-TNF.


Assuntos
Doenças Inflamatórias Intestinais , Neoplasias , Humanos , Feminino , Adolescente , Masculino , Estudos de Coortes , Estudos Retrospectivos , Inibidores do Fator de Necrose Tumoral , Doenças Inflamatórias Intestinais/tratamento farmacológico , Imunossupressores/uso terapêutico , Neoplasias/induzido quimicamente , Fármacos Gastrointestinais/uso terapêutico
4.
J Crohns Colitis ; 16(8): 1202-1210, 2022 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-35218189

RESUMO

BACKGROUND AND AIMS: Optimal management of patients with inflammatory bowel disease [IBD] after anti-tumour necrosis factor [TNF] discontinuation due to severe induced skin lesions is unclear. Our study aimed to describe dermatological and IBD evolution after anti-TNF discontinuation for this side effect. METHODS: We conducted a multicentre retrospective study including consecutive IBD patients who discontinued anti-TNF due to severe induced skin lesions. Our objectives were to determine factors associated with dermatological remission [complete disappearance of skin lesions] and with IBD relapse in patients with inactive disease at inclusion, notably the impact of an early switch to another biological agent within 3 months of anti-TNF discontinuation. RESULTS: Among the 181 patients [134 women, 160 Crohn's disease] included in the 13 participating centres, dermatological remission occurred in 110 [62%] patients with a median [interquartile range, IQR] interval of 8.0 [6.8-11.0] months. Scalp location was independently associated with less remission of skin lesions (hazard ratio [HR] = 0.64 [95% CI 0.43-0.94], p = 0.02) while early switch was independently associated with a higher probability of remission of skin lesions (HR = 1.64 [95% CI 1.1-2.5], p = 0.02). Among the 148 patients with inactive IBD at inclusion, disease relapse occurred in 75 [51%] patients with a median [IQR] interval of 26.0 [23.0-39.1] months. Survival rates without IBD relapse at 1 year were 85.8% [95% CI 77.5-94.9] in the early switch group and 59.3% [95% CI 48.9-71.9] in the other group [p < 0.01]. CONCLUSIONS: Early switch to a new biological is associated with a higher probability of healing of anti-TNF-induced skin lesions and significantly reduces the risk of IBD relapse.


Assuntos
Doença de Crohn , Doenças Inflamatórias Intestinais , Dermatopatias , Adalimumab/efeitos adversos , Estudos de Coortes , Doença de Crohn/induzido quimicamente , Doença de Crohn/tratamento farmacológico , Feminino , Humanos , Doenças Inflamatórias Intestinais/induzido quimicamente , Doenças Inflamatórias Intestinais/tratamento farmacológico , Infliximab/efeitos adversos , Necrose/induzido quimicamente , Necrose/tratamento farmacológico , Recidiva , Estudos Retrospectivos , Dermatopatias/tratamento farmacológico , Inibidores do Fator de Necrose Tumoral/efeitos adversos , Fator de Necrose Tumoral alfa
5.
Artigo em Inglês | MEDLINE | ID: mdl-34690392

RESUMO

We propose PET scanners using low atomic number media that undergo a persistent local change of state along the paths of the Compton recoil electrons. Measurement of the individual scattering locations and angles, deposited energies, and recoil electron directions allows using the kinematical constraints of the 2-body Compton scattering process to perform a statistical time-ordering of the scatterings, with a high probability of precisely identifying where the gamma first interacted in the detector. In these cases the Line-of-Response is measured with high resolution, determined by the underlying physics processes and not the detector segmentation. There are multiple such media that act through different mechanisms. As an example in which the change of state is quantum-mechanical through a change in molecular configuration, rather than thermodynamic, as in a bubble chamber, we present simulations of a two-state photoswitchable organic dye, a 'Switchillator', that is activated to a fluorescent-capable state by the ionization of the recoil electrons. The activated state is persistent, and can be optically excited multiple times to image individual activated molecules. Energy resolution is provided by counting the activated molecules. Location along the LOR is implemented by large-area time-of-flight MCP-PMT photodetectors with single photon time resolution in the tens of ps and sub-mm spatial resolution. Simulations indicate a large reduction of dose.

6.
Colorectal Dis ; 23(1): 114-122, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32961618

RESUMO

AIM: Over the past 10 years, several studies have focused on sexuality in patients with Crohn's disease. Very few of them specifically focused on perianal disease (PD). This study aimed to compare the prevalence of sexual dysfunction (SD) in Crohn's disease patients with active PD versus controls without active PD. METHOD: Patients from 14 French centres with active PD, defined by the presence of symptomatic ulceration, fistula or stenosis, were arbitrarily included. They were compared with controls from the existing SEXIA cohort. Men completed the International Index of Erectile Function (IIEF) and women the Female Sexual Function Index (FSFI). The primary end-point was SD defined by FSFI < 26.55 in women and IIEF < 42.9 in men. RESULTS: Ninety-seven patients (64 women, 33 men) and 238 controls (131 women, 107 men) were included. SD was found in 66% of the female patients versus 50% of the controls (P = 0.04). In the male population, SD was found in 30% of the cases versus 16% of the controls (P = 0.06). Erectile dysfunction affected 46% of the male patients and 43% of the controls (P = 0.8). On multivariate analysis, the predictive factor most strongly associated with SD in women was severely active anal PD defined by a perineal disease activity index > 4 [OR = 13.05 (2.32-73.44)]. CONCLUSION: Women with active PD had an increased prevalence of SD compared with controls without active PD. In the male population, the study was unable to determine whether there was a difference as it was underpowered.


Assuntos
Doença de Crohn , Disfunção Erétil , Disfunções Sexuais Fisiológicas , Doença de Crohn/complicações , Doença de Crohn/epidemiologia , Disfunção Erétil/epidemiologia , Disfunção Erétil/etiologia , Feminino , Humanos , Masculino , Prevalência , Comportamento Sexual , Disfunções Sexuais Fisiológicas/epidemiologia , Disfunções Sexuais Fisiológicas/etiologia
7.
Rev Med Interne ; 41(8): 523-528, 2020 Aug.
Artigo em Francês | MEDLINE | ID: mdl-32674898

RESUMO

Microscopic colitis is frequently found as a cause of chronic watery diarrhea in women after menopause. The disease can be associated with a medication side effect in half of the patients (non-steroidal anti-inflammatory drugs or proton pump inhibitors for instance). Colonic biopsies are mandatory for the diagnosis of microscopic colitis and should be performed in several locations of the colon. Management of microscopic colitis is first based on avoiding iatrogenic factors and smoking together with symptomatic treatment of diarrhea (loperamide, cholestyramine). In case of failure or severe symptoms, budesonide is the key treatment. The aim of the treatment is to achieve clinical remission, defined as less than 3 liquid stools per day, to improve quality of life. After a first course of budesonide, recurrence of diarrhea is frequent and a maintenance therapy can be prescribed for several months. In case of intolerance or refractoriness, second-line therapy (immunosuppressants, biological therapy, surgery) should be discussed in multidisciplinary team meeting.


Assuntos
Colite Microscópica , Colite Microscópica/diagnóstico , Colite Microscópica/epidemiologia , Colite Microscópica/etiologia , Colite Microscópica/terapia , Diagnóstico Diferencial , Técnicas de Diagnóstico do Sistema Digestório , Humanos , Prevalência , Fatores de Risco
9.
IDCases ; 17: e00563, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31193456

RESUMO

Pseudomonas aeruginosa is an uncommon cause of necrotizing acute community-acquired pneumonia (CAP). Only thirteen cases have been previously reported in the literature. In this article, we describe a case of previously healthy 80-year-old male patient, who presented in septic shock caused by necrotizing CAP. Despite inadequate empiric antimicrobial treatment, the patient survived and was able to return to his home after three weeks of hospitalization. To the best of our knowledge, this is the second case of septic shock secondary to P. aeruginosa necrotizing CAP and bacteremia, with optimal clinical outcome. We highlight the evolution of this pathology remains unpredictable, despite the factors related to the host and the bacterium.

10.
Prog Urol ; 28(6): 329-335, 2018 May.
Artigo em Francês | MEDLINE | ID: mdl-29705059

RESUMO

INTRODUCTION: Military people are inapt for presence of urinary stones. In this specific population, the treatment of stones is even more aggressive than for the general population without recommendation. The final decision about aptitude is the responsibility of the military doctor. Whereas, ureteroscopy has its place there and must done by any urologist. METHODS: The purpose of this study was to estimate the results of treatments by ureteroscopy in this population. Success was defined by the complete absence of fragment visualized in the imaging of control operating comment and so the end of the inaptitude time. RESULTS: Between 2009 and 2016, forty-two were treated for ureteral or renal calculi. The population comprises of 93% men, 35 years old on average. The stones were mainly multiple (more 2) and the medium size is 5mm; sixteen (42.9%) was at the left and eight (19%) was bilateral. In 78.8% (78) of the cases there was a stone in renal position whose 50% (39) still at the lower calyx. In total, 5% of the patients were stone-free in 2 sessions on average. The average deadline of inaptitude of the initial consultation in the resumption of work was of 6 months. In 4% of the cases there was a complication operating rank 4. CONCLUSION: This study confirms the feasibility, the weak harmlessness of ureteroscopy and the lesser deadline of inaptitude. Every urologist can treat this specific population. The patient must be informed and accept the treatment because of excluding referential. LEVEL OF EVIDENCE: 4.


Assuntos
Aptidão , Competência Clínica , Medicina Militar , Ureteroscopia , Urolitíase/cirurgia , Adulto , Testes de Aptidão , Competência Clínica/normas , Avaliação Educacional , Feminino , Humanos , Cálculos Renais/cirurgia , Masculino , Pessoa de Meia-Idade , Medicina Militar/educação , Medicina Militar/normas , Militares , Estudos Retrospectivos , Resultado do Tratamento , Ureteroscopia/educação , Ureteroscopia/métodos , Ureteroscopia/normas , Cálculos Urinários/cirurgia , Adulto Jovem
12.
J Crohns Colitis ; 11(11): 1347-1352, 2017 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-28981625

RESUMO

BACKGROUND: Improvement of quality of life is a main objective in inflammatory bowel disease [IBD] management. Data on sexual dysfunction [SD] in IBD are scarce. This study compared rates of SD between IBD patients and healthy controls [HC], and searched for predictors of SD. METHODS: All consecutive IBD patients seen in two tertiary centres during 2 months were invited to fill an anonymous validated questionnaire on their sexual function [Female Sexual Index Function and International Index of Erectile Function]. The same questionnaires were filled by HC and by patients with irritable bowel syndrome [IBS] enrolled as a second comparative group. RESULTS: In all, 358 IBD patients filled the questionnaire [192 women]-including 238 with Crohn's disease and 120 with ulcerative colitis-and 110 HC [54 women] and 107 IBS patients [54 women]. In women, SD rates were 53.6% in IBD vs 28% in HC [p < 0.01] and 77.5% in IBS [p = 0.10] patients; in men, figures were 16.9% in IBD, 7.4% in HC [p = 0.64], and 26.4% in IBS [p = 0.60]. An erectile dysfunction [ED] was reported by 43% of IBD patients, 13% of HC [p < 0.01] and 55% of IBS patients [p = 0.60 vs IBD]. Predictors of SD and ED were social and emotional functioning, anxiety in women and depression in men. IBD activity was not associated with SD. CONCLUSIONS: In IBD, 54% of women have an SD and 43% of men an ED. These rates are significantly higher than in HC, mostly driven by psychological factors, and independent from disease severity.


Assuntos
Doenças Inflamatórias Intestinais/complicações , Disfunções Sexuais Fisiológicas/etiologia , Adulto , Estudos de Casos e Controles , Colite Ulcerativa/complicações , Doença de Crohn/complicações , Estudos Transversais , Disfunção Erétil/epidemiologia , Disfunção Erétil/etiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Disfunções Sexuais Fisiológicas/epidemiologia , Inquéritos e Questionários
13.
Sci Rep ; 6: 32653, 2016 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-27596609

RESUMO

Isotropic gases irradiated by long pulses of intense IR light can generate very high harmonics of the incident field. It is generally accepted that, due to the symmetry of the generating medium, be it an atomic or an isotropic molecular gas, only odd harmonics of the driving field can be produced. Here we show how the interplay of electronic and nuclear dynamics can lead to a marked breakdown of this standard picture: a substantial part of the harmonic spectrum can consist of even rather than odd harmonics. We demonstrate the effect using ab-initio solutions of the time-dependent Schrödinger equation for and its isotopes in full dimensionality. By means of a simple analytical model, we identify its physical origin, which is the appearance of a permanent dipole moment in dissociating homonuclear molecules, caused by light-induced localization of the electric charge during dissociation. The effect arises for sufficiently long laser pulses and the region of the spectrum where even harmonics are produced is controlled by pulse duration. Our results (i) show how the interplay of femtosecond nuclear and attosecond electronic dynamics, which affects the charge flow inside the dissociating molecule, is reflected in the nonlinear response, and (ii) force one to augment standard selection rules found in nonlinear optics textbooks by considering light-induced modifications of the medium during the generation process.

14.
Phys Rev Lett ; 117(9): 093003, 2016 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-27610851

RESUMO

One of the current challenges in high-harmonic generation is to extend the harmonic cutoff to increasingly high energies while maintaining or even increasing the efficiency of the high-harmonic emission. Here we show that the combined effect of down-chirped pulses and nuclear dynamics in light molecules allows one to achieve this goal, provided that long enough IR pulses are used to allow the nuclei to move well outside the Franck-Condon region. We also show that, by varying the duration of the chirped pulse or by performing isotopic substitution while keeping the pulse duration constant, one can control the extension of the harmonic plateau.

15.
Phys Med Biol ; 61(12): 4599-622, 2016 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-27227430

RESUMO

In this work, we propose a framework for optimizing spectral CT imaging parameters and hardware design with regard to material classification tasks. Compared with conventional CT, many more parameters must be considered when designing spectral CT systems and protocols. These choices will impact material classification performance in a non-obvious, task-dependent way with direct implications for radiation dose reduction. In light of this, we adapt Hotelling Observer formalisms typically applied to signal detection tasks to the spectral CT, material-classification problem. The result is a rapidly computable metric that makes it possible to sweep out many system configurations, generating parameter optimization curves (POC's) that can be used to select optimal settings. The proposed model avoids restrictive assumptions about the basis-material decomposition (e.g. linearity) and incorporates signal uncertainty with a stochastic object model. This technique is demonstrated on dual-kVp and photon-counting systems for two different, clinically motivated material classification tasks (kidney stone classification and plaque removal). We show that the POC's predicted with the proposed analytic model agree well with those derived from computationally intensive numerical simulation studies.


Assuntos
Doses de Radiação , Tomografia Computadorizada por Raios X/métodos , Simulação por Computador , Teste de Materiais/métodos , Teste de Materiais/normas , Imagens de Fantasmas , Fótons , Tomografia Computadorizada por Raios X/normas
16.
IEEE Trans Nucl Sci ; 62(5): 2310-2317, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26705368

RESUMO

X-ray fluorescence computed tomography (XFCT) is an emerging imaging modality that maps the three-dimensional distribution of elements, generally metals, in ex vivo specimens and potentially in living animals and humans. Building on our previous synchrotron-based work, we experimentally explored the use of a benchtop X-ray fluorescence computed tomography system for mapping trace-metal ions in biological samples. This system utilizes a scanning pencil-beam to stimulate the object and then relies on a detection system, with single or multiple slit apertures placed in front of position-sensitive X-ray detectors, to collect the fluorescence X-rays and to form 3-D elemental map without the need for tomographic imaging reconstruction. The technique was used to generate images of the elemental distributions of a triple-tube phantom and an osmium-stained zebrafish.

17.
Rev Med Interne ; 36(9): 626-30, 2015 Sep.
Artigo em Francês | MEDLINE | ID: mdl-25467298

RESUMO

INTRODUCTION: Intravesical therapy with bacillus Calmette-Guérin (BCG) has proved to be effective in the treatment of superficial bladder tumors. Side-effects include local infections and rarely disseminated BCG infection with multiple end organ complications such as granulomatous hepatitis, pneumonitis, aortitis and bone marrow involvement. CASE REPORT: We report an 83-year-old man who presented with chronic granulomatous hepatitis. This was related to intravesical BCG therapy received two years earlier for superficial bladder cancer. Aortitis, splenic infarction and hematopoietic involvement were also diagnosed. Outcome was favorable following adapted antibiotic course. CONCLUSION: This case report highlights the possibility of widespread BCG infection following intravesical treatment, and the need for vigilance in patients with a history of such a therapy even several years later.


Assuntos
Antineoplásicos/efeitos adversos , Vacina BCG/efeitos adversos , Granuloma/microbiologia , Hepatite/microbiologia , Infecções por Mycobacterium/etiologia , Mycobacterium bovis/isolamento & purificação , Neoplasias da Bexiga Urinária/tratamento farmacológico , Administração Intravesical , Idoso de 80 Anos ou mais , Antineoplásicos/administração & dosagem , Vacina BCG/administração & dosagem , Vacinas Anticâncer/administração & dosagem , Vacinas Anticâncer/efeitos adversos , Humanos , Masculino , Neoplasias da Bexiga Urinária/microbiologia
18.
Phytopathology ; 104(6): 586-96, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24283538

RESUMO

Although bacterial wilt remains a major plant disease throughout South America and the Caribbean, the diversity of prevalent Ralstonia solanacearum populations is largely unknown. The genetic and phenotypic diversity of R. solanacearum strains in French Guiana was assessed using diagnostic polymerase chain reactions and sequence-based (egl and mutS) genotyping on a 239-strain collection sampled on the families Solanaceae and Cucurbitaceae, revealing an unexpectedly high diversity. Strains were distributed within phylotypes I (46.9%), IIA (26.8%), and IIB (26.3%), with one new endoglucanase sequence type (egl ST) found within each group. Phylotype IIB strains consisted mostly (97%) of strains with the emerging ecotype (IIB/sequevar 4NPB). Host range of IIB/4NPB strains from French Guiana matched the original emerging reference strain from Martinique. They were virulent on cucumber; virulent and highly aggressive on tomato, including the resistant reference Hawaii 7996; and only controlled by eggplant SM6 and Surya accessions. The emerging ecotype IIB/4NPB is fully established in French Guiana in both cultivated fields and uncultivated forest, rendering the hypothesis of introduction via ornamental or banana cuttings unlikely. Thus, this ecotype may have originated from the Amazonian region and spread throughout the Caribbean region.


Assuntos
Cucurbitaceae/microbiologia , Variação Genética , Genoma Bacteriano/genética , Doenças das Plantas/microbiologia , Ralstonia solanacearum/genética , Solanaceae/microbiologia , Proteínas de Bactérias/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Ecótipo , Guiana Francesa , Genótipo , Geografia , Especificidade de Hospedeiro , Tipagem Molecular , Fenótipo , Filogenia , Reação em Cadeia da Polimerase , Ralstonia solanacearum/classificação , Ralstonia solanacearum/isolamento & purificação , Ralstonia solanacearum/patogenicidade , Análise de Sequência de DNA , Virulência
19.
Phys Rev Lett ; 110(11): 113001, 2013 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-25166527

RESUMO

We present a theoretical study of H(2)(+) ionization under strong IR femtosecond pulses by using a method designed to extract correlated (2D) photoelectron and proton kinetic energy spectra. The results show two distinct ionization mechanisms-tunnel and multiphoton ionization-in which electrons and nuclei do not share the energy from the field in the same way. Electrons produced in multiphoton ionization share part of their energy with the nuclei, an effect that shows up in the 2D spectra in the form of energy-conservation fringes similar to those observed in weak-field ionization of diatomic molecules. In contrast, tunneling electrons lead to fringes whose position does not depend on the proton kinetic energy. At high intensity, the two processes coexist and the 2D plots show a very rich behavior, suggesting that the correlation between electron and nuclear dynamics in strong field ionization is more complex than one would have anticipated.

20.
J Phys Chem A ; 116(46): 11304-10, 2012 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-22853717

RESUMO

A pump-probe scheme is proposed to investigate the autoionization dynamics of the optically forbidden Q(1)(1)Σ(g)(+) doubly excited states of the H(2) molecule. The scheme consists of a pump that contains an attosecond pulse train (APT) and an infrared (IR) pulse, which is phase-locked with the APT, and an IR probe identical to the former IR pulse. The dynamical information is obtained by analyzing the electron kinetic energy spectra (EKE) and proton kinetic energy spectra (PKE) as a function of the time delay between the pump and the probe. The essential requirement for an efficient population of the Q(1)(1)Σ(g)(+) states is that they are resonantly coupled to both the dipole-allowed Q(1)(1)Σ(u)(+) doubly excited states and the ground state of H(2) by the combined effect of the APT + IR fields.

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