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1.
J Orthop Trauma ; 2024 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-39137060

RESUMEN

OBJECTIVES: To determine the difference in mortality and reoperation rate between femoral neck fractures (FNFx) treated with cannulated screw fixation (CS) or hemiarthroplasty (HA). METHODS: Design: Retrospective study. SETTING: Institutional registry data from a single Level I trauma center. PATIENT SELECTION CRITERIA: Inclusion criteria were patients ≥60 years old with a FNFx (AO/OTA 31-B) who underwent primary operative treatment with a HA or CS. OUTCOME MEASURES AND COMPARISONS: Mortality and reoperation rates following primary operative treatment between patients treated with either hemiarthroplasty or cannulated screws. Kaplan-Meier survival curves were generated. Comparisons in the primary outcomes were made between the hemiarthroplasty or cannulated screw cohorts using univariate and multivariate analysis where appropriate. RESULTS: A total of 2,211 patients were included in the study (1,721 HA and 490 CS) and followed for an average of 34.5 months. The average age was 82.3 years (60-106 years) and predominantly female (66.3%). 1-year mortality was higher for the HA group compared to CS with a HR of 1.37 (p=0.03), however over the lifetime of patient or to final follow up, survival was not statistically significant with a RR of 0.95 95% CI, 0.83-1.1, p=0.97) The rate of reoperation at one year was lower for HA (5.0%) than for CS (10.1%), (HR 3.0, 95% CI, 2.1-4.34, p<0.0001). CONCLUSIONS: Patients with FNFx treated with hemiarthroplasty had the same risk of mortality as those patients treated with cannulated screws across lifetime of patients or until final follow up. There is no difference in mortality at the 30- and 90-day timepoint, but a significant difference in mortality at 1 year. Hemiarthroplasty treatment was associated with a significantly lower reoperation risk when compared to cannulated screws across the lifetime of the patient or until final follow up. LEVEL OF EVIDENCE: Level III. See Instructions for Authors for a complete description of levels of evidence.

2.
Obes Res Clin Pract ; 18(3): 195-200, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38955573

RESUMEN

INTRODUCTION: Revisional bariatric surgery (RBS) for insufficient weight loss/weight regain or metabolic relapse is increasing worldwide. There is currently no large multinational, prospective data on 30-day morbidity and mortality of RBS. In this study, we aimed to evaluate the 30-day morbidity and mortality of RBS at participating centres. METHODS: An international steering group was formed to oversee the study. The steering group members invited bariatric surgeons worldwide to participate in this study. Ethical approval was obtained at the lead centre. Data were collected prospectively on all consecutive RBS patients operated between 15th May 2021 to 31st December 2021. Revisions for complications were excluded. RESULTS: A total of 65 global centres submitted data on 750 patients. Sleeve gastrectomy (n = 369, 49.2 %) was the most common primary surgery for which revision was performed. Revisional procedures performed included Roux-en-Y gastric bypass (RYGB) in 41.1 % (n = 308) patients, One anastomosis gastric bypass (OAGB) in 19.3 % (n = 145), Sleeve Gastrectomy (SG) in 16.7 % (n = 125) and other procedures in 22.9 % (n = 172) patients. Indications for revision included weight regain in 615(81.8 %) patients, inadequate weight loss in 127(16.9 %), inadequate diabetes control in 47(6.3 %) and diabetes relapse in 27(3.6 %). 30-day complications were seen in 80(10.7 %) patients. Forty-nine (6.5 %) complications were Clavien Dindo grade 3 or higher. Two patients (0.3 %) died within 30 days of RBS. CONCLUSION: RBS for insufficient weight loss/weight regain or metabolic relapse is associated with 10.7 % morbidity and 0.3 % mortality. Sleeve gastrectomy is the most common primary procedure to undergo revisional bariatric surgery, while Roux-en-Y gastric bypass is the most commonly performed revision.


Asunto(s)
Cirugía Bariátrica , Reoperación , Pérdida de Peso , Humanos , Femenino , Masculino , Reoperación/estadística & datos numéricos , Cirugía Bariátrica/métodos , Cirugía Bariátrica/mortalidad , Cirugía Bariátrica/efectos adversos , Persona de Mediana Edad , Adulto , Estudios Prospectivos , Complicaciones Posoperatorias/mortalidad , Complicaciones Posoperatorias/etiología , Complicaciones Posoperatorias/epidemiología , Obesidad Mórbida/cirugía , Obesidad Mórbida/mortalidad , Derivación Gástrica/métodos , Derivación Gástrica/mortalidad , Derivación Gástrica/efectos adversos , Gastrectomía/métodos , Gastrectomía/efectos adversos , Aumento de Peso , Morbilidad
3.
Nat Rev Cardiol ; 2024 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-39030270

RESUMEN

For more than 60 years, humans have travelled into space. Until now, the majority of astronauts have been professional, government agency astronauts selected, in part, for their superlative physical fitness and the absence of disease. Commercial spaceflight is now becoming accessible to members of the public, many of whom would previously have been excluded owing to unsatisfactory fitness or the presence of cardiorespiratory diseases. While data exist on the effects of gravitational and acceleration (G) forces on human physiology, data on the effects of the aerospace environment in unselected members of the public, and particularly in those with clinically significant pathology, are limited. Although short in duration, these high acceleration forces can potentially either impair the experience or, more seriously, pose a risk to health in some individuals. Rather than expose individuals with existing pathology to G forces to collect data, computational modelling might be useful to predict the nature and severity of cardiovascular diseases that are of sufficient risk to restrict access, require modification, or suggest further investigation or training before flight. In this Review, we explore state-of-the-art, zero-dimensional, compartmentalized models of human cardiovascular pathophysiology that can be used to simulate the effects of acceleration forces, homeostatic regulation and ventilation-perfusion matching, using data generated by long-arm centrifuge facilities of the US National Aeronautics and Space Administration and the European Space Agency to risk stratify individuals and help to improve safety in commercial suborbital spaceflight.

4.
Materials (Basel) ; 17(14)2024 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-39063726

RESUMEN

Combinative methodologies have the potential to address the drawbacks of unimodal non-destructive testing and evaluation (NDT & E) when inspecting multilayer structures. The aim of this study is to investigate the integration of information gathered via phased-array ultrasonic testing (PAUT) and pulsed thermography (PT), addressing the challenges posed by surface-level anomalies in PAUT and the limited deep penetration in PT. A center-of-mass-based registration method was proposed to align shapeless inspection results in consecutive insertions. Subsequently, the aligned inspection images were merged using complementary techniques, including maximum, weighted-averaging, depth-driven combination (DDC), and wavelet decomposition. The results indicated that although individual inspections may have lower mean absolute error (MAE) ratings than fused images, the use of complementary fusion improved defect identification in the total number of detections across numerous layers of the structure. Detection errors are analyzed, and a tendency to overestimate defect sizes is revealed with individual inspection methods. This study concludes that complementary fusion provides a more comprehensive understanding of overall defect detection throughout the thickness, highlighting the importance of leveraging multiple modalities for improved inspection outcomes in structural analysis.

5.
Pediatr Pulmonol ; 2024 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-38958238

RESUMEN

OBJECTIVES: To quantify the association of ambient air pollution (particulate matter, PM2.5) exposure with medically attended acute respiratory illness among infants with bronchopulmonary dysplasia (BPD). STUDY DESIGN: Single center, retrospective cohort study of preterm infants with BPD in Metropolitan Philadelphia. Multivariable logistic regression quantified associations of annual mean PM2.5 exposure (per µg/m3) at the census block group level with medically attended acute respiratory illness, defined as emergency department (ED) visits or hospital readmissions within a year after first hospital discharge adjusting for age at neonatal intensive care unit (NICU) discharge, year, sex, race, insurance, BPD severity, and census tract deprivation. As a secondary analysis, we examined whether BPD severity modified the associations. RESULTS: Of the 378 infants included in the analysis, 189 were non-Hispanic Black and 235 were publicly insured. Census block PM2.5 level was not significantly associated with medically attended acute respiratory illnesses, ED visits, or hospital readmissions in the full study cohort. We observed significant effect modification by BPD grade; each 1 µg/m3 higher annual PM2.5 exposure was medically attended acute respiratory illness (adjusted odds ratio [aOR] 1.65, 95% CI: 1.06-2.63) among infants with Grade 1 BPD but not among infants with grade 3 BPD (aOR 0.83, 95% CI: 0.47-1.48) (interaction p = .024). CONCLUSIONS: Cumulative PM2.5 exposure in the year after NICU discharge was not significantly associated with medically attended acute respiratory illness among infants with BPD. However, infants with Grade 1 BPD had significantly higher odds with higher exposures. If replicated, these findings could inform anticipatory guidance for families of these infants to avoid outdoor activities during high pollution days after NICU discharge.

6.
J Am Dent Assoc ; 2024 Jul 27.
Artículo en Inglés | MEDLINE | ID: mdl-39078361

RESUMEN

BACKGROUND: Over the past decade, orthodontics has advanced markedly with digital methods, cutting-edge biomechanics, and 3-dimensional diagnostics. However, the rapid adoption of these innovations without rigorous evaluation of their evidential support has led to new unsubstantiated orthodontic-surgical indications. METHODS: This article explores emerging orthodontic practices, focusing on the interpretation of orthodontic principles and the reliance on imaging-based diagnoses. RESULTS: Strict adherence to mechanistic orthodontic principles and reliance on imaging findings can result in overzealous treatment protocols. It also emphasizes the state of knowledge regarding temporomandibular disorders (TMDs) and the lack of consensus and evidence-based guidelines. CONCLUSIONS: There is an urgent need for the profession to integrate TMD knowledge, adopt evidence-based practices, and critically evaluate new methods before implementation. PRACTICAL IMPLICATIONS: Orthodontists should move away from outdated mechanistic beliefs and integrate clinical knowledge from TMD research into their practices. Increased awareness and potential legal repercussions may drive a necessary reevaluation and stronger adherence to evidence-based methods.

7.
Biomed Opt Express ; 15(5): 3265-3284, 2024 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-38855664

RESUMEN

It has been known for more than 220 years that the image quality of the human eye is significantly degraded by chromatic aberrations. Recently, it was shown experimentally that correcting chromatic aberrations results in a 0.2- to 0.8-line improvement in visual acuity. Here we ask, is this expected? We developed tools that enable simulations of the optical impact of physiologically relevant amounts of chromatic aberration in real human eyes and combined these with tools that compute the visual acuity of an ideal observer. This allows us to characterize the theoretical impact of chromatic aberration correction on visual acuity. Results indicate a substantive improvement of 0.4- to 2-lines in ideal observer visual acuity with chromatic aberration correction. Ideal observer thresholds benefit significantly more from correction of longitudinal than correction of transverse chromatic aberration. Finally, improvements in ideal observer visual acuity are greater for subjects with less monochromatic aberration, such that subjects with better baseline optical quality benefit most from correction of chromatic aberrations.

8.
Nanoscale ; 16(31): 14722-14729, 2024 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-38922329

RESUMEN

Electron-assisted oxidation of Co-Si-based focused electron beam induced deposition (FEBID) materials is shown to form a 2-4 nm metal oxide surface layer on top of an electrically insulating silicon oxide layer less than 10 nm thick. Differences between thermal and electron-induced oxidation on the resulting microstructure are illustrated.

9.
Artículo en Inglés | MEDLINE | ID: mdl-38791862

RESUMEN

OBJECTIVE: To analyze the association of components of the Centers for Disease Control and Prevention (CDC) Environmental Justice Index (EJI) with respiratory health outcomes among infants with bronchopulmonary dysplasia (BPD) within one year after discharge from the neonatal intensive care unit. METHODS: This was a retrospective cohort study of a cohort of preterm infants with BPD. Multivariable logistic regression models estimated associations of EJI and its components with medically attended acute respiratory illness, defined as an ED visit or inpatient readmission, within one year of discharge from the neonatal intensive care unit. A mediation analysis was conducted to evaluate how environmental injustice may contribute to racial disparities in acute respiratory illness. RESULTS: Greater EJI was associated with an increased risk of medically attended respiratory illness (per EJI standard deviation increment, aOR 1.38, 95% CI: 1.12-1.69). Of the index's components, the Environmental Burden Module's Air pollution domain had the greatest association (aOR 1.44, 95% CI: 1.44-2.61). With respect to individual indicators within the EJI, Diesel Particulate Matter (DSLPM) and Air Toxic Cancer Risk (ATCR) demonstrated the strongest relationship (aOR 2.06, 95% CI: 1.57-2.71 and aOR 2.10, 95% CI: 1.59-2.78, respectively). Among non-Hispanic Black infants, 63% experienced a medically attended acute respiratory illness as compared to 18% of non-Hispanic White infants. DSLPM mediated 39% of the Black-White disparity in medically attended acute respiratory illness (p = 0.004). CONCLUSIONS: Environmental exposures, particularly air pollution, are associated with post-discharge respiratory health outcomes among preterm infants with BPD after adjusting for clinical, demographic, and social vulnerability risk factors. Certain types of air pollutants, namely, DSLPM, are more greatly associated with acute respiratory illness. Environmental exposures may contribute to racial disparities in medically attended acute respiratory illness among infants with BPD.


Asunto(s)
Displasia Broncopulmonar , Recien Nacido Prematuro , Humanos , Displasia Broncopulmonar/epidemiología , Estudios Retrospectivos , Recién Nacido , Masculino , Femenino , Exposición a Riesgos Ambientales/efectos adversos , Alta del Paciente/estadística & datos numéricos , Enfermedades Respiratorias/epidemiología , Contaminación del Aire/efectos adversos , Estados Unidos/epidemiología , Lactante
10.
Nat Commun ; 15(1): 4235, 2024 May 18.
Artículo en Inglés | MEDLINE | ID: mdl-38762489

RESUMEN

Inflammation induced by lung infection is a double-edged sword, moderating both anti-viral and immune pathogenesis effects; the mechanism of the latter is not fully understood. Previous studies suggest the vasculature is involved in tissue injury. Here, we report that expression of Sparcl1, a secreted matricellular protein, is upregulated in pulmonary capillary endothelial cells (EC) during influenza-induced lung injury. Endothelial overexpression of SPARCL1 promotes detrimental lung inflammation, with SPARCL1 inducing 'M1-like' macrophages and related pro-inflammatory cytokines, while SPARCL1 deletion alleviates these effects. Mechanistically, SPARCL1 functions through TLR4 on macrophages in vitro, while TLR4 inhibition in vivo ameliorates excessive inflammation caused by endothelial Sparcl1 overexpression. Finally, SPARCL1 expression is increased in lung ECs from COVID-19 patients when compared with healthy donors, while fatal COVID-19 correlates with higher circulating SPARCL1 protein levels in the plasma. Our results thus implicate SPARCL1 as a potential prognosis biomarker for deadly COVID-19 pneumonia and as a therapeutic target for taming hyperinflammation in pneumonia.


Asunto(s)
COVID-19 , Células Endoteliales , Pulmón , Activación de Macrófagos , SARS-CoV-2 , Animales , Humanos , COVID-19/inmunología , COVID-19/virología , COVID-19/metabolismo , COVID-19/patología , Ratones , Células Endoteliales/metabolismo , Células Endoteliales/virología , Células Endoteliales/inmunología , SARS-CoV-2/fisiología , Pulmón/virología , Pulmón/patología , Pulmón/inmunología , Receptor Toll-Like 4/metabolismo , Receptor Toll-Like 4/genética , Proteínas de Unión al Calcio/metabolismo , Proteínas de Unión al Calcio/genética , Ratones Endogámicos C57BL , Neumonía Viral/inmunología , Neumonía Viral/patología , Neumonía Viral/virología , Neumonía Viral/metabolismo , Masculino , Macrófagos/metabolismo , Macrófagos/inmunología , Femenino , Ratones Noqueados , Proteínas de la Matriz Extracelular
11.
Inorg Chem ; 63(18): 8131-8141, 2024 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-38639743

RESUMEN

Mixed metal oxyhalides are an exciting class of photocatalysts, capable of the sustainable generation of fuels and remediation of pollutants with solar energy. Bismuth oxyhalides of the types Bi4MO8X (M = Nb and Ta; X = Cl and Br) and Bi2AO4X (A = most lanthanides; X = Cl, Br, and I) have an electronic structure that imparts photostability, as their valence band maxima (VBM) are composed of O 2p orbitals rather than X np orbitals that typify many other bismuth oxyhalides. Here, flux-based synthesis of intergrowth Bi4NbO8Cl-Bi2GdO4Cl is reported, testing the hypothesis that both intergrowth stoichiometry and M identity serve as levers toward tunable optoelectronic properties. X-ray scattering and atomically resolved electron microscopy verify intergrowth formation. Facile manipulation of the Bi4NbO8Cl-to-Bi2GdO4Cl ratio is achieved with the specific ratio influencing both the crystal and electronic structures of the intergrowths. This compositional flexibility and crystal structure engineering can be leveraged for photocatalytic applications, with comparisons to the previously reported Bi4TaO8Cl-Bi2GdO4Cl intergrowth revealing how subtle structural and compositional features can impact photocatalytic materials.

12.
Sensors (Basel) ; 24(7)2024 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-38610473

RESUMEN

The integration of machine learning and robotics brings promising potential to tackle the application challenges of mobile robot navigation in industries. The real-world environment is highly dynamic and unpredictable, with increasing necessities for efficiency and safety. This demands a multi-faceted approach that combines advanced sensing, robust obstacle detection, and avoidance mechanisms for an effective robot navigation experience. While hybrid methods with default robot operating system (ROS) navigation stack have demonstrated significant results, their performance in real time and highly dynamic environments remains a challenge. These environments are characterized by continuously changing conditions, which can impact the precision of obstacle detection systems and efficient avoidance control decision-making processes. In response to these challenges, this paper presents a novel solution that combines a rapidly exploring random tree (RRT)-integrated ROS navigation stack and a pre-trained YOLOv7 object detection model to enhance the capability of the developed work on the NAV-YOLO system. The proposed approach leveraged the high accuracy of YOLOv7 obstacle detection and the efficient path-planning capabilities of RRT and dynamic windows approach (DWA) to improve the navigation performance of mobile robots in real-world complex and dynamically changing settings. Extensive simulation and real-world robot platform experiments were conducted to evaluate the efficiency of the proposed solution. The result demonstrated a high-level obstacle avoidance capability, ensuring the safety and efficiency of mobile robot navigation operations in aviation environments.

13.
J Phys Chem C Nanomater Interfaces ; 128(7): 2967-2977, 2024 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-38444783

RESUMEN

The investigation of precursor classes for the fabrication of nanostructures is of specific interest for maskless fabrication and direct nanoprinting. In this study, the differences in material composition depending on the employed process are illustrated for focused-ion-beam- and focused-electron-beam-induced deposition (FIBID/FEBID) and compared to the thermal decomposition in chemical vapor deposition (CVD). This article reports on specific differences in the deposit composition and microstructure when the (H3Si)2Fe(CO)4 precursor is converted into an inorganic material. Maximum metal/metalloid contents of up to 90 at. % are obtained in FIBID deposits and higher than 90 at. % in CVD films, while FEBID with the same precursor provides material containing less than 45 at. % total metal/metalloid content. Moreover, the Fe:Si ratio is retained well in FEBID and CVD processes, but FIBID using Ga+ ions liberates more than 50% of the initial Si provided by the precursor. This suggests that precursors for FIBID processes targeting binary materials should include multiple bonding such as bridging positions for nonmetals. In addition, an in situ method for investigations of supporting thermal effects of precursor fragmentation during the direct-writing processes is presented, and the applicability of the precursor for nanoscale 3D FEBID writing is demonstrated.

14.
J Oral Rehabil ; 51(7): 1109-1112, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38475861

RESUMEN

OBJECTIVE: The objective of this commentary is to advocate for a holistic, ontology-based definition of bruxism. The intention is to synthesise the best aspects of current definitions into a structured ontological model, thereby refining and enhancing a comprehensive understanding of the full spectrum of bruxism. MATERIALS AND METHODS: The commentary elaborates on the process of integrating these insights into a hierarchical ontology that aligns with ontological principles. SETTINGS AND SAMPLE POPULATION: Not directly applicable as this is a commentary. RESULTS/CONCLUSION: The proposed ontology-based definition of bruxism aims to clarify communication within the medical community and advance research by enabling a comprehensive ontology-based classification of bruxism. By aligning with ontological principles, this approach aspires to act as a catalyst for further research, discussion and consensus in the field.


Asunto(s)
Bruxismo , Semántica , Terminología como Asunto , Humanos , Ontologías Biológicas , Salud Holística
15.
Nanoscale Adv ; 6(7): 1837-1846, 2024 Mar 26.
Artículo en Inglés | MEDLINE | ID: mdl-38545290

RESUMEN

The 16e square-planar bis-thiolato-Au(iii) complexes [AuIII(1,2-dicarba-closo-dodecarborane-1,2-dithiolato)2][NBu4] (Au-1) and [AuIII(4-methyl-1,2-benzenedithiolato)2][NBu4] (Au-2) have been synthesized and fully characterized. Au-1 and Au-2 were encapsulated in the symmetrical triblock copolymer poloxamer (Pluronic®) P123 containing blocks of poly(ethylene oxide) and poly(propylene oxide), giving micelles AuMs-1 and AuMs-2. High electron flux in scanning transmission electron microscopy (STEM) was used to generate single gold atoms and gold nanocrystals on B/S-doped graphitic surfaces, or S-doped amorphous carbon surfaces from AuMs-1 and AuMs-2, respectively. Electron energy loss spectroscopy (EELS) data suggested strong interactions of gold atoms/nanocrystals with boron in the B/S-doped graphitic matrix. Density-functional theory (DFT) calculations, also supported the experimental findings, pointing towards strong Au-B bonds, depending on the charge on the Au-(B-graphene) fragment and the presence of further defects in the graphene lattice.

16.
Sensors (Basel) ; 24(5)2024 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-38474913

RESUMEN

The field of learning-based navigation for mobile robots is experiencing a surge of interest from research and industry sectors. The application of this technology for visual aircraft inspection tasks within a maintenance, repair, and overhaul (MRO) hangar necessitates efficient perception and obstacle avoidance capabilities to ensure a reliable navigation experience. The present reliance on manual labour, static processes, and outdated technologies limits operation efficiency in the inherently dynamic and increasingly complex nature of the real-world hangar environment. The challenging environment limits the practical application of conventional methods and real-time adaptability to changes. In response to these challenges, recent years research efforts have witnessed advancement with machine learning integration aimed at enhancing navigational capability in both static and dynamic scenarios. However, most of these studies have not been specific to the MRO hangar environment, but related challenges have been addressed, and applicable solutions have been developed. This paper provides a comprehensive review of learning-based strategies with an emphasis on advancements in deep learning, object detection, and the integration of multiple approaches to create hybrid systems. The review delineates the application of learning-based methodologies to real-time navigational tasks, encompassing environment perception, obstacle detection, avoidance, and path planning through the use of vision-based sensors. The concluding section addresses the prevailing challenges and prospective development directions in this domain.

17.
Phys Rev Lett ; 132(9): 094002, 2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38489623

RESUMEN

We study the statistics of velocity circulation in two-dimensional classical and quantum turbulence. We perform numerical simulations of the incompressible Navier-Stokes and the Gross-Pitaevskii (GP) equations for the direct and inverse cascades. Our GP simulations display clear energy spectra compatible with the double cascade theory of two-dimensional classical turbulence. In the inverse cascade, we found that circulation intermittency in quantum turbulence is the same as in classical turbulence. We compare GP data to Navier-Stokes simulations and experimental data from Zhu et al. [Phys. Rev. Lett. 130, 214001 (2023)PRLTAO0031-900710.1103/PhysRevLett.130.214001]. In the direct cascade, for nearly incompressible GP flows, classical and quantum turbulence circulation displays the same self-similar scaling. When compressibility becomes important, quasishocks generate quantum vortices and the equivalence of quantum and classical turbulence only holds for low-order moments. Our results establish the boundaries of the equivalence between two-dimensional classical and quantum turbulence.

18.
Phys Rev Lett ; 132(9): 093801, 2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38489636

RESUMEN

We report the first experimental demonstration of the replica symmetry breaking (RSB) phenomenon in a fiber laser system supporting standard mode-locking (SML) regime. Though theoretically predicted, this photonic glassy phase remained experimentally undisclosed so far. We employ an ytterbium-based mode-locked fiber laser with a very rich phase diagram. Two phase transitions are observed separating three different regimes: cw, quasi-mode-locking (QML), and SML. The regimes are intrinsically related to the distinct dynamics of intensity fluctuations in the laser spectra. We set the connection between the RSB glassy phase with frustrated modes and onset of L-shaped intensity distributions in the QML regime, which impact directly the replica overlap measure.

19.
Elife ; 122024 Feb 14.
Artículo en Inglés | MEDLINE | ID: mdl-38354040

RESUMEN

Neurostimulation of the hippocampal formation has shown promising results for modulating memory but the underlying mechanisms remain unclear. In particular, the effects on hippocampal theta-nested gamma oscillations and theta phase reset, which are both crucial for memory processes, are unknown. Moreover, these effects cannot be investigated using current computational models, which consider theta oscillations with a fixed amplitude and phase velocity. Here, we developed a novel computational model that includes the medial septum, represented as a set of abstract Kuramoto oscillators producing a dynamical theta rhythm with phase reset, and the hippocampal formation, composed of biophysically realistic neurons and able to generate theta-nested gamma oscillations under theta drive. We showed that, for theta inputs just below the threshold to induce self-sustained theta-nested gamma oscillations, a single stimulation pulse could switch the network behavior from non-oscillatory to a state producing sustained oscillations. Next, we demonstrated that, for a weaker theta input, pulse train stimulation at the theta frequency could transiently restore seemingly physiological oscillations. Importantly, the presence of phase reset influenced whether these two effects depended on the phase at which stimulation onset was delivered, which has practical implications for designing neurostimulation protocols that are triggered by the phase of ongoing theta oscillations. This novel model opens new avenues for studying the effects of neurostimulation on the hippocampal formation. Furthermore, our hybrid approach that combines different levels of abstraction could be extended in future work to other neural circuits that produce dynamical brain rhythms.


Asunto(s)
Encéfalo , Gastrópodos , Animales , Frecuencia Cardíaca , Hipocampo , Simulación por Computador
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