Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 271
Filtrar
1.
J Phys Condens Matter ; 36(21)2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38354419

RESUMO

We present a comprehensive investigation of the crystal and magnetic structures of the van der Waals antiferromagnetα-RuCl3using single crystal x-ray and neutron diffraction. The crystal structure at room temperature is a monoclinic (C2/m). However, with decreasing temperature, a remarkable first-order structural phase transition is observed, leading to the emergence of a rhombohedral (R3-) structure characterized by three-fold rotational symmetry forming an isotropic honeycomb lattice. On further cooling, a zigzag-type antiferromagnetic order develops belowTN=6∼6.6K. The critical exponent of the magnetic order parameter was determined to beß=0.11(1), which is close to the two-dimensional Ising model. Additionally, the angular dependence of the magnetic critical field of the zigzag antiferromagnetic order for the polarized ferromagnetic phase reveals a six-fold rotational symmetry within theab-plane. These findingsreflect the symmetry associated with the Ising-like bond-dependent Kitaev spin interactions and underscore the universality of the Kitaev interaction-dominated antiferromagnetic system.

2.
Opt Express ; 32(2): 2356-2363, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38297768

RESUMO

Terahertz scattering-type scanning near-field optical microscopy (THz-sSNOM) provides a noninvasive way to probe the low frequency conductivity of materials and to characterize material compositions at the nanoscale. However, the potential capability of atomic compositional analysis with THz nanoscopy remains largely unexplored. Here, we perform THz near-field imaging and spectroscopy on a model rare-earth alloy of lanthanum silicide (La-Si) which is known to exhibit diverse compositional and structural phases. We identify subwavelength spatial variations in conductivity that is manifested as alloy microstructures down to much less than 1 µm in size and is remarkably distinct from the surface topography of the material. Signal contrasts from the near-field scattering responses enable mapping the local silicon/lanthanum content differences. These observations demonstrate that THz-sSNOM offers a new avenue to investigate the compositional heterogeneity of material phases and their related nanoscale electrical as well as optical properties.

3.
Rev Sci Instrum ; 94(4)2023 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38081286

RESUMO

We have developed a versatile near-field microscopy platform that can operate at high magnetic fields and below liquid-helium temperatures. We use this platform to demonstrate an extreme terahertz (THz) nanoscope operation and to obtain the first cryogenic magneto-THz time-domain nano-spectroscopy/imaging at temperatures as low as 1.8 K, magnetic fields of up to 5 T, and with operation of 0-2 THz. Our Cryogenic Magneto-Terahertz Scattering-type Scanning Near-field Optical Microscope (or cm-THz-sSNOM) instrument is comprised of three main equipment: (i) a 5 T split pair magnetic cryostat with a custom made insert, (ii) a custom sSNOM instrument capable of accepting ultrafast THz excitation, and (iii) a MHz repetition rate, femtosecond laser amplifier for broadband THz pulse generation and sensitive detection. We apply the cm-THz-sSNOM to obtain proof of principle measurements of superconductors and topological semimetals. The new capabilities demonstrated break grounds for studying quantum materials that require an extreme environment of cryogenic operation and/or applied magnetic fields in nanometer space, femtosecond time, and THz energy scales.

4.
J Pediatr Urol ; 19(5): 642.e1-642.e6, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37481429

RESUMO

INTRODUCTION: Circumcision is a common procedure that can evoke caregiver anxiety in the postoperative period due to unfamiliarity with the healing process. To mitigate unnecessary healthcare utilization such as phone calls and unanticipated clinic or emergency department (ED) visits, photographic atlases have been developed to better prepare caregivers for the recovery process. The objective of our study is to further investigate the efficacy of a photographic atlas in its ability to decrease postoperative healthcare utilization using an increased sample size and extended study period compared to previous studies. MATERIALS AND METHODS: In this study, we compared a prospective intervention cohort of patients undergoing circumcision at our institution who received a photographic atlas during postoperative teaching to a retrospective cohort of patients who had not received it. Our primary outcome was unanticipated healthcare utilization, defined as postoperative telephone calls and unanticipated presentations to the urology clinic or ED. RESULTS: The retrospective no-atlas cohort included 105 patients, and the prospective intervention atlas cohort included 80 patients. Both groups were similar with respect to age (p = 0.47) and other demographics. There was no statistically significant difference in healthcare utilization between the no-atlas and atlas cohort. Specifically, we identified no difference in the number of phone calls to clinic staff (12 [11.4%] vs. 11 [13.8%], p = 0.64) or unanticipated postoperative clinic or ED visits (2 [1.9%] vs. 4 [5.0%], p = 0.41). DISCUSSION: The use of a photographic atlas as part of caregiver support for circumcision patients did not demonstrate a statistically significant reduction in either postoperative phone calls or clinic/ED visits. The decrease in absolute number of caregiver phone calls was minimal (12-11), with a small increase in follow-up presentations (2-4). The lack of significant change may be due to the already infrequent occurrence of these events following circumcision, as demonstrated by the no-atlas cohort. Other potential advantages of the atlas, such as improved caregiver confidence and satisfaction, may have been present, but were not measured in this study. CONCLUSIONS: Adding to the mixed results of previous studies, these findings do not support that photographic atlases decrease unanticipated healthcare utilization in children undergoing a circumcision. However, utilization was found to be low. Additionally, further studies are needed to determine other significant benefits of this form of education, such as improved caregiver confidence and satisfaction.


Assuntos
Circuncisão Masculina , Masculino , Criança , Humanos , Estudos Prospectivos , Estudos Retrospectivos , Aceitação pelo Paciente de Cuidados de Saúde , Instituições de Assistência Ambulatorial
5.
Acad Radiol ; 30(7): 1472-1480, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36323613

RESUMO

RATIONALE AND OBJECTIVES: To evaluate the effectiveness of an artificial intelligence (AI) in radiology literacy course on participants from nine radiology residency programs in the Southeast and Mid-Atlantic United States. MATERIALS AND METHODS: A week-long AI in radiology course was developed and included participants from nine radiology residency programs in the Southeast and Mid-Atlantic United States. Ten 30 minutes lectures utilizing a remote learning format covered basic AI terms and methods, clinical applications of AI in radiology by four different subspecialties, and special topics lectures on the economics of AI, ethics of AI, algorithm bias, and medicolegal implications of AI in medicine. A proctored hands-on clinical AI session allowed participants to directly use an FDA cleared AI-assisted viewer and reporting system for advanced cancer. Pre- and post-course electronic surveys were distributed to assess participants' knowledge of AI terminology and applications and interest in AI education. RESULTS: There were an average of 75 participants each day of the course (range: 50-120). Nearly all participants reported a lack of sufficient exposure to AI in their radiology training (96.7%, 90/93). Mean participant score on the pre-course AI knowledge evaluation was 8.3/15, with a statistically significant increase to 10.1/15 on the post-course evaluation (p= 0.04). A majority of participants reported an interest in continued AI in radiology education in the future (78.6%, 22/28). CONCLUSION: A multi-institutional AI in radiology literacy course successfully improved AI education of participants, with the majority of participants reporting a continued interest in AI in radiology education in the future.


Assuntos
Inteligência Artificial , Radiologia , Humanos , Alfabetização , Radiologia/educação , Algoritmos , Escolaridade
6.
Int J Prosthodont ; 34(4): 365­372, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33616560

RESUMO

PURPOSE: To test whether internal accuracy affects the load-bearing capacity of 0.5-mm-thick occlusal veneers made out of milled or heat-pressed lithium disilicate (LS2). MATERIALS AND METHODS: Extracted human molars (N = 80) were divided into four groups (n = 20 each) depending on the bonding substrate (enamel [E] or dentin [D]) and the fabrication method (milling [CAD] or heat pressing [PRE]) for the occlusal LS2 veneers: (1) E-CAD, (2) D-CAD, (3) E-PRE, or (4) D-PRE. After restoration fabrication, the abutment teeth and the corresponding restorations were scanned and superimposed in order to measure the marginal and internal accuracy. After adhesive cementation, the specimens were thermomechanically aged and thereafter loaded until fracture. The load-bearing capacities (Fmax) were measured. Fmax and the marginal and internal accuracy between the groups were compared using Kruskal-Wallis test (P < .05) and pairwise group comparisons. In addition, the relationship between Fmax and the internal accuracy was analyzed using Spearman rank correlation. RESULTS: Median Fmax values (and first and third quartiles) per group were as follows: 1,495 N (Q1: 932; Q3: 2'318) for E-CAD; 1,575 N (Q1: 1,314; Q3: 1,668) for E-PRE; 1,856 N (Q1: 1,555; Q3: 2,013) for D-CAD; and 1,877 N (Q1: 1,566; Q3: 2,131) for D-PRE. No statistical difference was found between the groups (P = .0981). Overall, the internal accuracy in the areas of the cusp (P < .0007) and fossa (P < .0001) showed significant differences. While no significant differences were detected in the marginal area (P = .3518), a significant correlation with a negative linear relationship was found between the 3D internal accuracy and the Fmax values (P = .0007). CONCLUSION: An increase in the internal accuracy raised the load-bearing capacity of minimally invasive LS2 occlusal veneers. In general, the restorations bonded to dentin in the occlusal regions showed a better accuracy compared to those bonded to enamel.


Assuntos
Cerâmica , Facetas Dentárias , Idoso , Desenho Assistido por Computador , Porcelana Dentária , Análise do Estresse Dentário , Humanos , Teste de Materiais , Suporte de Carga
7.
Phys Rev Lett ; 124(15): 157401, 2020 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-32357060

RESUMO

We discover hidden Rashba fine structure in CH_{3}NH_{3}PbI_{3} and demonstrate its quantum control by vibrational coherence through symmetry-selective vibronic (electron-phonon) coupling. Above a critical threshold of a single-cycle terahertz pump field, a Raman phonon mode distinctly modulates the middle excitonic states with persistent coherence for more than ten times longer than the ones on two sides that predominately couple to infrared phonons. These vibronic quantum beats, together with first-principles modeling of phonon periodically modulated Rashba parameters, identify a threefold excitonic fine structure splitting, i.e., optically forbidden, degenerate dark states in between two bright ones with a narrow, ∼3 nm splitting. Harnessing of vibronic quantum coherence and symmetry inspires light-perovskite quantum control and sub-THz-cycle "Rashba engineering" of spin-split bands for ultimate multifunction device.

8.
Eur J Neurol ; 27(2): 343-351, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31535427

RESUMO

BACKGROUND AND PURPOSE: The rate at which the chance of a good outcome of endovascular stroke therapy (EVT) decays with time when eligible patients are selected by baseline diffusion-weighted magnetic resonance imaging (DWI-MRI) and whether ischaemic core size affects this rate remain to be investigated. METHODS: This study analyses a prospective multicentre registry of stroke patients treated with EVT based on pretreatment DWI-MRI that was categorized into three groups: small [Diffusion-Weighted Imaging Alberta Stroke Program Early Computed Tomography Score (DWI-ASPECTS)] (8-10), moderate (5-7) and large (<5) cores. The main outcome was a good outcome at 90 days (modified Rankin Scale 0-2). The interaction between onset-to-groin puncture time (OTP) and DWI-ASPECTS categories regarding functional outcomes was investigated. RESULTS: Ultimately, 985 patients (age 69 ± 11 years; male 55%) were analysed. Potential interaction effects between the DWI-ASPECTS categories and OTP on a good outcome at 90 days were observed (Pinteraction  = 0.06). Every 60-min delay in OTP was associated with a 16% reduced likelihood of a good outcome at 90 days amongst patients with large cores, although no associations were observed amongst patients with small to moderate cores. Interestingly, the adjusted rates of a good outcome at 90 days steeply declined between 65 and 213 min of OTP and then remained smooth throughout 24 h of OTP (Pnonlinearity  = 0.15). CONCLUSIONS: Our study showed that the probability of a good outcome after EVT nonlinearly decreased, with a steeper decline at earlier OTP than at later OTP. Discrepant effects of OTP on functional outcomes by baseline DWI-ASPECTS categories were observed. Thus, different strategies for EVT based on time and ischaemic core size are warranted.


Assuntos
Acidente Vascular Cerebral , Idoso , Idoso de 80 Anos ou mais , Alberta , Isquemia Encefálica/diagnóstico por imagem , Isquemia Encefálica/terapia , Imagem de Difusão por Ressonância Magnética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/terapia , Tempo para o Tratamento , Resultado do Tratamento
9.
J Nutr Health Aging ; 23(10): 930-936, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31781721

RESUMO

This study aimed to clarify the association between calorie intake and cognitive function in community-dwelling older adults. A cross-sectional analysis was performed on the first-year baseline data of 1559 adults aged 70-84 years using population data from the Korean Frailty and Aging Cohort Study. We included 543 participants who participated in nutritional surveys and accurately responded regarding their daily calorie intake. Daily ingestion was measured using the 24-hour dietary recall method, and neuropsychological tests evaluated cognitive characteristics. Logistic regression models were utilized to calculate odds ratios (ORs) with 95% confidence intervals (CIs). The prevalence rate of cognitive impairment was 8%. Subjects with cognitive impairment mainly showed memory loss. After adjusting the confounding factors, participants who had less than the recommended intake were susceptible to cognitive impairment compared to those who that had the proposed intake (adjusted OR: 7.70, 95% CI: 1.01-58.45). We showed that lesser calorie intake than the recommended intake increases the ORs of cognitive impairment. We suggest that an adequate calorie intake protects against cognitive decline, and further studies are essential to investigate the influence of calorie intake reduction on the elderly before widespread application.


Assuntos
Cognição/fisiologia , Ingestão de Energia/fisiologia , Testes Neuropsicológicos/normas , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/psicologia , Estudos de Coortes , Estudos Transversais , Feminino , Fragilidade , Humanos , Masculino , República da Coreia/epidemiologia
10.
J Chem Phys ; 151(24): 244706, 2019 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-31893879

RESUMO

We report the discovery of helicity-dependent ultrafast photocurrent generation in organic-inorganic perovskite by measuring terahertz (THz) electric field emissions in the time-domain. We find signatures of the circular photogalvanic effect (CPGE) where right circularly polarized light and left circularly polarized light lead to different photocurrent generation. The direction of photocurrent is also resolved by measuring the polarization of the emitted THz pulses. Furthermore, we observe distinct wavelength-dependent, coherent phonon dynamics using THz pump-induced differential reflectivity, indicative of multiple exciton resonances. Both the CPGE and exciton fine structure, together with theoretical simulations, provide compelling and complementary evidence for the existence of Rashba-type bands in perovskite.

11.
J Physiol Pharmacol ; 69(3)2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30149369

RESUMO

Repeated bouts of ulcerative colitis featured troublesome course of inflammatory bowel disease leading to fatal colitis-associated cancer, which is strongly associated with oxidative stress and sustained inflammation. Since oligonol, low molecular weighted polyphenol extracted from fruit lychee, showed antioxidative and anti-inflammatory actions, we hypothesized that oligonolcan prevent relapse of colitis. We compared oligonol with current gold standard therapeutics, sulfasalazine in preventive efficacy of relapse. First, dextran sulfate sodium (DSS)-induced colitis were made following pretreatment with oligonol, 10, 50, and 100 mg/kg for 7 days to measure therapeutic effect of oligonol and relapse model via repeated DSS administration was made following with either 50 mg/kg oligonol or 30 mg/kg sulfasalazine to explore relapse preventing action of oligonol in C57BL/6 mice. Detailed changes in colon were measured to explain molecular mechanisms. Pretreatment of 10, 50, 100 mg/kg oligonol (p.o.), significantly reduced DSS-induced colitis; total pathologic scores, colon length, and clinical symptom scores (P < 0.05). Oligonol pretreatment significantly decreased the levels of interleukin (IL)-1, IL-6, and tumor necrosis factor-α (TNF-α) as well as nuclear factor-κB (NF-κB), c-Fos, and c-Jun in affected colon tissues, but the expression of heme oxygenase-1 (HO-1) and NADH: quinone oxidoreductase-1(NQO-1) as well as total antioxidant concentration (P < 0.005) was significantly increased with oligonol. A relapse model established with repeated DSS administration led to high mortality. However, oligonol significantly ameliorated exacerbations of colitis, while sulfasalazine did not (P < 0.01). Significantly decreased expressions of cyclooxygenase-2 (COX-2), TNF-α, and macrophages inhibition were relapse preventing actions of oligonal, but significant action of oligonol relevant to relapse prevention was either significantly increased expressions of NQO-1 or significantly preserved mucin (P < 0.05). Concerted anti-inflammatory, antioxidative, and host defense enhancing actions of oligonol can be applied during maintenance therapy of IBD to prevent relapse of IBD.


Assuntos
Anti-Inflamatórios/uso terapêutico , Antioxidantes/uso terapêutico , Catequina/análogos & derivados , Colite Ulcerativa/tratamento farmacológico , Fenóis/uso terapêutico , Animais , Anti-Inflamatórios/farmacologia , Antioxidantes/farmacologia , Catequina/farmacologia , Catequina/uso terapêutico , Colite Ulcerativa/induzido quimicamente , Colite Ulcerativa/metabolismo , Colite Ulcerativa/patologia , Colo/efeitos dos fármacos , Colo/metabolismo , Colo/patologia , Citocinas/sangue , Sulfato de Dextrana , Heme Oxigenase-1/metabolismo , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Masculino , Proteínas de Membrana/metabolismo , Camundongos Endogâmicos C57BL , NAD(P)H Desidrogenase (Quinona)/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , NF-kappa B/metabolismo , Fenóis/farmacologia , Proteínas Proto-Oncogênicas c-fos/metabolismo , Prevenção Secundária
12.
Aliment Pharmacol Ther ; 48(2): 196-205, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29869804

RESUMO

BACKGROUND: There are increasing reports of paradoxical psoriasiform diseases secondary to anti-tumour necrosis factor (TNF) agents. AIMS: To determine the risks of paradoxical psoriasiform diseases secondary to anti-TNF agents in patients with inflammatory bowel disease (IBD). METHODS: A nationwide population study was performed using the Korea National Health Insurance Claim Data. A total of 50 502 patients with IBD were identified between 2007 and 2016. We compared 5428 patients who were treated with any anti-TNF agent for more than 6 months (anti-TNF group) and 10 856 matched controls who had never taken anti-TNF agents (control group). RESULTS: Incidence of psoriasis was significantly higher in the anti-TNF group (36.8 per 10 000 person-years) compared to the control group (14.5 per 10 000 person-years) (hazard ratio [HR] 2.357, 95% confidence interval [CI] 1.668-3.331). Palmoplantar pustulosis (HR 9.355, 95% CI 2.754-31.780) and psoriatic arthritis (HR 2.926, 95% CI 1.640-5.218) also showed higher risks in the anti-TNF group. In subgroup analyses, HRs for psoriasis by IBD subtype were 2.549 (95% CI 1.658-3.920) in Crohn's disease and 2.105 (95% CI 1.155-3.836) in ulcerative colitis. Interestingly, men and younger (10-39 years) patients have significantly higher risks of palmoplantar pustulosis (HR 19.682 [95% CI 3.867-100.169] and HR 14.318 [95% CI 2.915-70.315], respectively), whereas women and older (≥40 years) patients showed similar rates between the two groups. CONCLUSIONS: The risks of psoriasiform diseases are increased by anti-TNF agents in patients with IBD. Among psoriasiform diseases, the risk of palmoplantar pustulosis shows the biggest increase particularly in male and younger patients.


Assuntos
Anti-Inflamatórios/efeitos adversos , Doenças Inflamatórias Intestinais/tratamento farmacológico , Doenças Inflamatórias Intestinais/epidemiologia , Psoríase/induzido quimicamente , Psoríase/epidemiologia , Fator de Necrose Tumoral alfa/antagonistas & inibidores , Adalimumab/efeitos adversos , Adalimumab/uso terapêutico , Adolescente , Adulto , Idoso , Anti-Inflamatórios/uso terapêutico , Estudos de Casos e Controles , Criança , Estudos de Coortes , Colite Ulcerativa/tratamento farmacológico , Colite Ulcerativa/epidemiologia , Doença de Crohn/tratamento farmacológico , Doença de Crohn/epidemiologia , Feminino , Humanos , Incidência , Infliximab/efeitos adversos , Infliximab/uso terapêutico , Masculino , Pessoa de Meia-Idade , República da Coreia/epidemiologia , Estudos Retrospectivos , Adulto Jovem
13.
Rev Sci Instrum ; 89(4): 043504, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29716340

RESUMO

A visible bremsstrahlung detector array diagnostic system has been developed on the Korea Superconducting Tokamak Advanced Research (KSTAR) to view the whole minor radius in a narrow region of the continuum free of spectral lines. The interference filters coupled with photomultiplier tubes have been employed to determine the effective charge Zeff by using visible bremsstrahlung data during neutral beam injection in the KSTAR plasma. The Zeff profiles are typically flat for L-mode plasmas and evolve to hollow profiles during the H mode in the KSTAR. A comparison of the visible bremsstrahlung emission based on the calculated Zeff profiles is consistent with measured values of Zeff from a visible spectrometer in the core plasma. The electron temperature is measured by X-ray imaging crystal spectrometry, and electron density needed for the analysis is taken by the assumption of parabolic profiles of these parameters. The line of sight averaged local bremsstrahlung emissivity is determined with low uncertainty, and the radial emissivity is obtained by using the Abel inversion technique. In addition, a dependence of effective charge Zeff on the line-averaged electron density is evaluated, and Zeff is also determined to observe the effect of boronization.

14.
Sci Rep ; 8(1): 4661, 2018 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-29549304

RESUMO

Two dimensional layered organic-inorganic halide perovskites offer a wide variety of novel functionality such as solar cell and optoelectronics and magnetism. Self-assembly of these materials using solution process (ex. spin coating) makes crystalline thin films synthesized at ambient environment. However, flexibility of organic layer also poses a structure stability issue in perovskite thin films against environment factors (ex. moisture). In this study, we investigate the effect of solvents and moisture on structure and property in the (C6H5(CH2)2NH3)2(Cu, Mn)Cl4 (Cu-PEA, Mn-PEA) perovskite thin films spin-coated on Si wafer using three solvents (H2O, MeOH, MeOH + H2O). A combination of x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS) show that relative humidity (RH) has a profound effect on perovskite thin films during sample synthesis and storage, depending on the kind of solvent used. The ones prepared using water (Cu-PEA:H2O, Mn-PEA:H2O) show quite different behavior from the other cases. According to time-dependent XRD, reversible crystalline-amorphous transition takes place depending on RH in the former cases, whereas the latter cases relatively remain stable. It also turns out from XAS that Mn-PEA thin films prepared with solvents such as MeOH and MeOH + H2O are disordered to the depth of about 4 nm from surface.

15.
Lett Appl Microbiol ; 66(4): 300-305, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29315769

RESUMO

Klebsiella oxytoca naturally produces a large amount of 2,3-butanediol (2,3-BD), a promising chemical with wide industrial applications, along with various by-products. Previously, we have developed a metabolically engineered K. oxytoca ΔldhA ΔpflB strain to reduce the formation of by-products. To improve 2,3-BD productivity and examine the stability of K. oxytoca ΔldhA ΔpflB strain for industrial application, a semi-continuous two-stage simultaneous saccharification and fermentation (STSSF) process was developed. The STSSF with the K. oxytoca ΔldhA ΔpflB mutant using cassava as a carbon source could produce 108 ± 3·73 g(2,3-BD)  l-1 with a yield of 0·45 g(2,3-BD)  g(glucose)-1 and a productivity of 3·00 g(2,3-BD) l-1  h-1 . No apparent changes in the final titre, yield and productivity of 2,3-BD were observed for up to 20 cycles of STSSF. Also, microbial contamination and spontaneous mutation of the host strain with potential detrimental effects on fermentation efficiency did not occur during the whole fermentation period. These results strongly underpin that the K. oxytoca ΔldhA ΔpflB mutant is stable and that the STSSF process is commercially exploitable. SIGNIFICANCE AND IMPACT OF THE STUDY: There is growing interest in the production of 2,3-butanediol (2,3-BD) from renewable resources by microbial fermentation because of its wide applications to specialty and commodity chemical industries. Klebsiella oxytoca usually produces 2,3-BD as a major end product during the fermentation of carbohydrates. This is the first study to provide a high-efficiency simultaneous saccharification and 2,3-BD fermentation process. Also, this study proves the stability of a metabolically engineered 2,3-BD overproducing K. oxytoca strain for industrial application.


Assuntos
Reatores Biológicos/microbiologia , Butileno Glicóis/metabolismo , Klebsiella oxytoca/metabolismo , Engenharia Metabólica/métodos , Fermentação/genética , Fermentação/fisiologia , Glucose/metabolismo
16.
Clin Otolaryngol ; 43(1): 137-143, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28605121

RESUMO

OBJECTIVE: To analyse the association between 24-hour multichannel intraluminal impedance-pH (24-h MII-pH) parameters and each item of the reflux finding score (RFS) to determine whether the laryngoscopic findings of the RFS could reflect the characteristics of reflux in patients with laryngopharyngeal reflux (LPR). STUDY DESIGN: Prospective cohort study. SETTINGS: Tertiary care referral medical centre. PARTICIPANTS: Patients complaining of LPR symptoms were evaluated via a 24-hour MII-pH. Among them, 99 patients whose LPR was confirmed via 24-hour MII-pH were enrolled in this study. MAIN OUTCOME MEASURES: Correlations between RFS ratings and 24-hour MII-pH parameters were evaluated and compared between patients with or without each laryngoscopic finding used in the RFS. RESULTS: Subglottic oedema had a statistically significant positive correlation with number of non-acid LPR and non-acid full column reflux events. Ventricular obliteration and posterior commissure hypertrophy showed a significant correlation with non-acid exposure time and total reflux exposure time. We also found a significant correlation between granuloma/granulation score and number of acid LPR events. The numbers of non-acid LPR and full column reflux events in patients with subglottic oedema were significantly higher than those without subglottic oedema. CONCLUSION: Among the laryngoscopic findings used in the RFS, subglottic oedema is specific for non-acid reflux episodes, and granuloma/granulation is specific for acid reflux episodes.


Assuntos
Refluxo Laringofaríngeo/diagnóstico , Laringoscopia/métodos , Inquéritos e Questionários , Monitoramento do pH Esofágico , Feminino , Seguimentos , Humanos , Refluxo Laringofaríngeo/fisiopatologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Índice de Gravidade de Doença , Fatores de Tempo
17.
Annu Int Conf IEEE Eng Med Biol Soc ; 2017: 572-575, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29059937

RESUMO

Dual high and low energy images of Dual Energy X-ray Absorptiometry (DEXA) suffer from noises due to the use of weak amount of X-rays. Denoising these DEXA images could be a key process to enhance and improve a Bone Mineral Density (BMD) map which is derived from a pair of high and low energy images. This could further improve the accuracy of diagnosis of bone fractures, osteoporosis, and etc. In this paper, we present a denoising technique for dual high and low energy images of DEXA via non-local means filter (NLMF). The noise of dual DEXA images is modeled based on both source and detector noises of a DEXA system. Then, the parameters of the proposed NLMF are optimized for denoising utilizing the experimental data from uniform phantoms. The optimized NLMF is tested and verified with the DEXA images of the uniform phantoms and real human spine. The quantitative evaluation shows the improvement of Signal-to-Noise Ratio (SNR) for the high and low phantom images on the order of 30.36% and 27.02% and for the high and low real spine images on the order of 22.28% and 33.43%, respectively. Our work suggests that denoising via NLMF could be a key preprocessing process for clinical DEXA imaging.


Assuntos
Absorciometria de Fóton , Imagens de Fantasmas , Razão Sinal-Ruído
18.
Annu Int Conf IEEE Eng Med Biol Soc ; 2017: 1230-1233, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29060098

RESUMO

Automatic detection and classification of the masses in mammograms are still a big challenge and play a crucial role to assist radiologists for accurate diagnosis. In this paper, we propose a novel computer-aided diagnose (CAD) system based on one of the regional deep learning techniques: a ROI-based Convolutional Neural Network (CNN) which is called You Only Look Once (YOLO). Our proposed YOLO-based CAD system contains four main stages: mammograms preprocessing, feature extraction utilizing multi convolutional deep layers, mass detection with confidence model, and finally mass classification using fully connected neural network (FC-NN). A set of training mammograms with the information of ROI masses and their types are used to train YOLO. The trained YOLO-based CAD system detects the masses and classifies their types into benign or malignant. Our results show that the proposed YOLO-based CAD system detects the mass location with an overall accuracy of 96.33%. The system also distinguishes between benign and malignant lesions with an overall accuracy of 85.52%. Our proposed system seems to be feasible as a CAD system capable of detection and classification at the same time. It also overcomes some challenging breast cancer cases such as the mass existing in the pectoral muscles or dense regions.


Assuntos
Mamografia , Neoplasias da Mama , Humanos , Redes Neurais de Computação
19.
J Fish Biol ; 91(6): 1582-1602, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29034467

RESUMO

Potential roles of the rostrum of sawsharks (Pristiophoridae), including predation and self-defence, were assessed through a variety of inferential methods. Comparison of microwear on the surface of the rostral teeth of sawsharks and sawfishes (Pristidae) show that microwear patterns are alike and suggest that the elongate rostra in these two elasmobranch families are used for a similar purpose (predation). Raman spectroscopy indicates that the rostral teeth of both sawsharks and sawfishes are composed of hydroxyapatite, but differ in their collagen content. Sawfishes possess collagen throughout their rostral teeth whereas collagen is present only in the centre of the rostral teeth of sawsharks, which may relate to differences in ecological use. The ratio of rostrum length to total length in the common sawshark Pristiophorus cirratus was found to be similar to the largetooth sawfish Pristis pristis but not the knifetooth sawfish Anoxypristis cuspidata. Analysis of the stomach contents of P. cirratus indicates that the diet consists of demersal fishes and crustaceans, with shrimp from the family Pandalidae being the most important dietary component. No prey item showed evidence of wounds inflicted by the rostral teeth. In light of the similarities in microwear patterns, rostral tooth chemistry and diet with sawfishes, it is hypothesised that sawsharks use their rostrum in a similar manner for predation (sensing and capturing prey) and possibly for self-defence.


Assuntos
Elasmobrânquios/fisiologia , Dente/anatomia & histologia , Animais , Dieta , Elasmobrânquios/anatomia & histologia , Comportamento Predatório , Rajidae , Análise Espectral Raman , Dente/química , Dente/fisiologia
20.
Nutr Metab Cardiovasc Dis ; 27(5): 456-461, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28428029

RESUMO

BACKGROUND AND AIMS: Increasing evidence has indicated that insulin resistance is associated with inflammation. However, few studies have investigated the association between white blood cell (WBC) count and insulin resistance, as measured by a homeostasis model assessment of insulin resistance (HOMA-IR) in a general pediatric population. This study aimed to examine the association between WBC count and insulin resistance as measured by HOMA-IR in a nationally representative sample of children and adolescents. METHODS AND RESULTS: In total, 2761 participants (1479 boys and 1282 girls) aged 10-18 years were selected from the 2008-2010 Korean National Health and Nutrition Examination Survey. Insulin resistance was defined as a HOMA-IR value greater than the 90th percentile. The odds ratios and 95% confidence intervals for insulin resistance were determined using multiple logistic regression analysis. The mean values of most cardiometabolic variables tended to increase proportionally with WBC count quartiles. The prevalence of insulin resistance significantly increased in accordance with WBC count quartiles in both boys and girls. Compared to individuals in the lowest WBC count quartile, the odds ratio for insulin resistance for individuals in the highest quartile was 2.84 in boys and 3.20 in girls, after adjusting for age, systolic blood pressure, body mass index, and waist circumference. CONCLUSION: A higher WBC count was positively associated with an increased risk of insulin resistance in Korean children and adolescents. This study suggests that WBC count could facilitate the identification of children and adolescents with insulin resistance.


Assuntos
Inflamação/sangue , Resistência à Insulina , Contagem de Leucócitos , Síndrome Metabólica/sangue , Adolescente , Fatores Etários , Biomarcadores/sangue , Glicemia/análise , Criança , Estudos Transversais , Feminino , Humanos , Inflamação/diagnóstico , Inflamação/epidemiologia , Insulina/sangue , Modelos Logísticos , Masculino , Síndrome Metabólica/diagnóstico , Síndrome Metabólica/epidemiologia , Análise Multivariada , Inquéritos Nutricionais , Razão de Chances , Valor Preditivo dos Testes , Prevalência , República da Coreia/epidemiologia , Medição de Risco , Fatores de Risco
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA