Diffuse Form Research Articles

Migration and Transformation of Greenhouse Gases in Constructed Wetlands: A Bibliometric Analysis and Trend Forecast

Constructed wetlands (CWs), serving as an advanced wastewater treatment system, play a vital role in both the emission and sequestration of diverse GHGs. However, there are few papers reviewing and analyzing developments in the field. In this study, bibliometrics were used as an essential tool for identifying and establishing connections among key elements within a discipline, as well as for analyzing the research status and developmental trends of the research fields. CiteSpace 6.3.1 was utilized to conduct an analysis of the references from the Web of Science Core Collection pertaining to GHG emissions from CWs over the period from 1993 to 2023. This study showed the following conclusions. (1) Organic nitrogen conversion produces N2O, which is eventually transformed into N2 and released from CWs. Anammox represents an attractive route for nitrogen removal. (2) The CO2 is the final product of the oxidation of organic matter in the influent of CWs and can be fixed by plant photosynthesis. Anaerobic fermentation and CO2 reduction produce CH4. The two are emitted through aerenchyma transport, bubble diffusion, and other forms. (3) In the past 30 years, the number of publications and citation frequency shows an increasing trend. China and the United States published more papers. The top ten authors contributed to 20.607% of the total 1019, and the cooperation between different author groups needs to be strengthened. (4) The emerging burst keywords following 2020 are “microbial fuel cell” and “microbial community”, which highlights the current hotspots in research related to GHG emissions from CWs. (5) There is still a lack of long-term and applied discussion on the role of CWs in promoting GHG emission reduction. The relevant reaction conditions and mechanisms need to be explored and the possible research directions can be genetic regulation and information technology.

Assessing left ventricular hemodynamic forces in systemic sclerosis patients: pilot study

Abstract Background Systemic sclerosis (SSc) is a connective tissue disease characterized by sustained inflammation, microvascular pathology changes and fibrosis. Cardiac comorbidities, particularly pulmonary arterial hypertension (PAH), are the leading cause of mortality among SSc patients. Early PAH diagnosis remains difficult. Cardiovascular magnetic resonance imaging (CMR) has emerged as a great noninvasive tool to assess cardiological impact in SSc. Hemodynamic forces (HDF) are a measurement of the global force exchanged between blood volume and myocardium assessed using CMR, based on the Navier-Stokes equation measuring the relationship between pressure gradient and velocity field. Purpose To assess diagnostic value of HDF measurement in SSc compared to healthy controls, as a potential early indicator of subclinical cardiac dysfunction. Methods In a single-center study, all patients with SSc who met the American college of rheumatology, and the European League against Rheumatism classification criteria were included and a CMR exam a 1.5T was performed. HDF were obtained using a post-processing software (Medis Suites, Netherlands). Patients with atrial fibrillation were excluded. To assess HDF, movements from deformation imaging of long axis cine were used for longitudinal (Figure 1) and transversal left ventricle (LV) HDF calculation after initial feature-tracking and measurements of mitral and aortic valve width. To compare different LV sizes, HDF are normalized to LV volume and blood specific weight, thus reported as percentage of gravity acceleration. Then, we performed age matching from an external cohort of healthy controls (1). Results Of the 11 SSc patients (age 46.27±15.2 years, 19% male) recruited, 5 (46%) patients had a diffuse form and 5 (46%) patients had PAH. Two (18%) patients exhibited LV systolic dysfunction with a mean LV ejection fraction (LVEF) of 59%. Regarding the right ventricle (RV), 5 (46%) patients had RV systolic dysfunction (mean RVEF of 50%). Biventricular volumes were normal (mean LV end-diastolic volume [EDV] of 80 ml/m2, respectively mean RV EDV of 77 ml/m2). To assess the diagnostic performance of HDF values we compared HDF in 11 SSc patients and in 11 age-matched healthy controls from an external cohort. SSc patients showed larger LV longitudinal HDF in systole (both RMS and peak, p=0.029, respectively p=0.047) (Figure 2), changes which could be explained by anatomical deformation caused by increased pressure in the RV. During diastole, only one parameter was significantly lower (diastolic deceleration, p=0.040), a finding that might indicate reduced LV compliance in the context of elevated LV filling pressures. Conclusion This pilot study is the first to describe the interest of HDF in SSc patients. HDF analysis has the potential to be a more sensitive marker of cardiac deterioration than traditional volumetric and functional parameters, as patients had higher systolic HDF despite having similar LVEF to controls.

Neuropilin1-dependent paracrine signaling of cancer cells mediated by miRNA exosomal cargo

BackgroundNeuropilin-1 (NRP1) is a transmembrane protein involved in surface receptor complexes for a variety of extracellular signals. NRP1 expression in human cancers is associated with prominent angiogenesis and advanced progression stage. However, the molecular mechanisms underlying NRP1 activity in the tumor microenvironment remain unclear. Notably, diffusible forms of NRP1 in the extracellular space have been reported, but their functional role is poorly understood.MethodsExtracellular vesicles (EV) were isolated from conditioned media of diverse cancer cells. The quality of exosome-enriched preparations was validated by the presence of specific markers in western blotting, as well as by light scattering and nanoparticle tracking analysis. Wound healing, transwell, and digital real-time migration assays were carried out to assess the activity of cancer cell-derived exosomes in the regulation of endothelial cells. RNA interference was applied to obtain NRP1 knock-down, and cDNA transfer to achieve its overexpression, in exosome-releasing cells. The micro-RNA profile carried by exosomes was investigated by Next Generation Sequencing. miRNA-Scope in situ hybridization was used to assess the transfer of miRNA exosome cargo to target cells, and immunofluorescence analysis revealed expression regulation of targeted proteins. miRNA activity was blocked by the use of specific antago-miRs.ResultsIn this study, we show that diverse human cancer cells release NRP1 embedded in exosome-like small extracellular vesicles, which mediate a previously unknown NRP1-dependent paracrine signaling mechanism regulating endothelial cell migration. By transcriptomic analysis of the cargo of NRP1-loaded exosomes, we found a significant enrichment of miR-210-3p, known to promote tumor angiogenesis. Gene knock-down and overexpression experiments demonstrated that the loading of miR-210-3p into exosomes is dependent on NRP1. Data furthermore indicate that the exosomes released through this NRP1-driven mechanism effectively transfer miR-210-3p to human endothelial cells, causing paracrine downregulation of the regulatory cue ephrin-A3 and promotion of cell migration. The mechanistic involvement of miR-210-3p in this pathway was confirmed by applying a specific antago-miR.ConclusionsIn sum, we unveiled a previously unknown NRP1-dependent paracrine signaling mechanism, mediated by the loading of pro-angiogenic miR-210-3p in exosomes released by cancer cells, which underscores the relevance of NRP1 in controlling the tumor microenvironment.

Streaming Torque with Turbulent Diffusion

Abstract Fast type I migration of (proto)planets poses a challenging problem for the core accretion formation scenario. We found that the dust-induced “Streaming Torque” (ST) may slow down or even reverse the planet migration in Q. Hou & C. Yu. But in realistic protoplanetary disks, dust diffusion induced by gas turbulence may have important influences on ST. We perform linear analysis to investigate the effects of dust diffusion on ST. The dependence of ST on dust diffusion may provide better constraints on the turbulence strength and the stopping time τ. We derive the dispersion relation for all the wave modes in the two-fluid system. The dust diffusion will smooth the short-wavelength structure of the the quasi-drift mode and split it into two predominant D-drift modes with opposite directions. The outgoing D-drift mode will contribute to a negative torque on planets, particularly when τ ∼ 0.1, which slightly shifts the zero-torque turning point. We explore how ST depends on the regimes of aerodynamic drag, dust mass fraction, and disk scale height. We compare the radial wavenumbers of D-drift modes under different formulations of dust diffusion and find qualitative agreement. In all cases, τ at the zero-torque turning point, which determines the direction of planetary migration, consistently remains on the order of ∼0.1, corresponding to large pebble-sized dust grains. This suggests that rapid dust coagulation can inhibit the inward migration of planets, implying that weak gas turbulence may enhance the survival of protoplanets.

Need a little love? Go South: patterns of trust across EU member states

ABSTRACT This paper examines the long-term impact of the economic crisis on citizens’ trust towards the EU. Political trust is expected to support the foundation of the institutions and, in this case, it reflects a diffuse form of support. The analysis studies what factors affect trust (additive index, 0 to 10) towards the EU, by using the 2007 and 2018 EB data. Findings demonstrate that the crisis affected lowering levels of trust towards the EU, but not how trust is structured. By applying a similar framework of analysis to examine support for the EU, the analysis finds that trust is explained by both affective and rational utilitarian dimensions, and the comparative research design stresses the distinctiveness of the domestic politics of EU integration. Education and the economy are likely to be critical factors across Eastern Europe; national identity holds a consistent negative relationship across Western Europe; and attachment towards the EU is always the most predominantly significant factor in Southern Europe.

Immunohistochemical expression of TLR1, TLR2, TLR4, and TLR9 in the different types of lesions associated with bovine paratuberculosis

The factors that determine the appearance of the different pathologic forms associated with bovine paratuberculosis are not fully understood, but new research suggests a critical role of innate immunity. Toll-like receptors (TLRs) trigger the recognition of invading pathogens by innate immune cells and the onset of specific immune responses. The aim of this work was to assess, immunohistochemically, the expression of TLR1, TLR2, TLR4, and TLR9 in intestinal samples of 20 cows showing different types of paratuberculous lesions: uninfected controls, focal lesions, paucibacillary, and multibacillary diffuse forms. The majority of labeled cells were morphologically consistent with macrophages. A differential cell count was performed in the intestinal lamina propria, gut-associated lymphoid tissue, and mesenteric lymph node. TLR9 immunolabeling between the different types of lesions was compared using a complete H-score. Focal and diffuse paucibacillary forms contained significantly increased TLR2-expressing macrophages outside of the lesions compared with the controls and diffuse multibacillary forms, and moderate TLR9 immunolabeling within granulomas. In the multibacillary granulomatous lesions, the expression of TLR1 and TLR4 was observed as well as increased TLR9 expression compared with the rest of the groups. Differences in the predominance of one type or another of TLR allows us to elucidate the importance of the innate immune response and its possible role in the development of the different types of paratuberculosis lesions.

Keratodermas in the practice of a family doctor

Keratodermas are a heterogeneous group of dermatological diseases characterized by thickening of the stratum corneum of the epidermis on the palms and soles. This article discusses the main forms of keratodermas, their hereditary characteristics, clinical manifestations, methods of diagnosis and treatment, as well as important aspects of patient monitoring. Keratoderma is divided into diffuse and focal forms, each of which has its own clinical characteristics and types of inheritance (autosomal dominant and autosomal recessive). In particular, diseases such as Unna-Thost keratoderma, Meleda disease, and Papillon — Lefèvre syndrome are mentioned. The main symptoms and morphological changes of the skin in various forms of keratoderma, as well as diagnostic methods, including clinical studies and histology, are described. Treatment of keratoderma is based on the use of retinol preparations and keratolytic agents; the need for an individual approach depending on the form of the disease is emphasized. The criterion for the effectiveness of treatment is a significant reduction in the severity of clinical manifestations. Attention is paid to side effects and complications associated with therapy, as well as the importance of consultation with specialists to prevent secondary diseases such as periodontal disease. Keratoderma is a complex disease that requires an integrated approach to diagnosis and treatment. The prognosis for patients is most often unfavorable, and complete cure is impossible. It is necessary to ensure careful monitoring of the patient's health status and evaluate the efficacy of the treatment used to reduce clinical manifestations. The text provides relevant information for dermatologists and other medical professionals involved in the diagnosis and treatment of skin diseases.

Modelling combined diffusion and surface resistances in adsorbent particles: zero length column for spherical and slab geometries

Mass transport in nanoporous materials is a key property that allows to improve the performance of many gas separation processes and design more efficient heterogeneous catalytic reactors. In many instances a combination of surface resistance and internal diffusion are present. The combined model for surface barrier and diffusion in a ZLC system is discussed in detail and the analytical solutions valid for the traditional and the partial loading experiments have been derived for the spherical and slab geometries. The model reduces to the limiting forms of pure diffusion when 100$$\\end{document}]]>, and pure surface barrier when . This study has shown that most literature studies have analysed ZLC responses incorrectly based on an effective combined dimensionless parameter. Two methods are described to obtain the parameters from the long-time asymptotic behaviour of the response curves. Both approaches have been demonstrated on curves generated from the full model solution and experimental data on an etched sample of Y zeolite. Both the analysis of the model and of the experimental results confirm that to characterize combined surface barriers and diffusion one should perform at least experiments at two different flowrates where the system is kinetically controlled, and crucially a partial loading experiment with a time to the switch which should be at least an order of magnitude smaller than the smallest of the diffusion and surface barrier times.

Magnetic resonance imaging findings of cerebral venous malformations.

Our study aimed to evaluate the incidence and anatomical locations of cerebral venous malformations (CVMs), their alterations over time, and magnetic resonance imaging (MRI) findings of their relationships with each other in patients who underwent magnetic susceptibility-weighted imaging (SWI) and contrast-enhanced MRI. The drainage pattern of developmental venous anomalies (DVAs), the number of collecting veins, DVA thrombosis, signal-intensity abnormalities, and hemosiderin deposits (nodular, diffuse, or both) related to the DVA, were examined. The alterations over time in cavernomas (type and size) were assessed. The study evaluated 7,826 patients who had 8,957 magnetic SWIand contrast-enhanced brain MRIs. A total of 643 CVMs were detected in 520 patients. The frequencies of DVAs, cavernomas, and capillary telangiectasias were 5.26%, 1.28%, and 0.62%, respectively. Isolated DVAs were detected in 430 (71.5%), cavernomas in 77 (12.8%), and capillary telangiectasias in 52 (8.7%) cases of CVMs. The coexistence of DVA with cavernoma and DVA with capillary telangiectasia was found in 38 (6.3%) and 4 (0.7%) cases, respectively. DVA drainage was largely provided by a single collecting vein. Signal-intensity abnormalities associated with the DVA were observed in 7, and two patients had DVA thrombosis. Hemosiderin deposits were nodular in 14 cases, diffuse in three, and both nodular and diffuse in two. In a follow-up of 11 (7.8%) cavernomas, alterations in the type and size were detected. It is not uncommon for cavernomas to become symptomatic owing to alterations in their nature, size, and type over time, while DVAs rarely become symptomatic. Capillary telangiectasias are vascular malformations that tend to remain stable in terms of clinical and imaging features, and those with supratentorial localization are detected more frequently in the frontal lobe. On magnetic susceptibility sequences, hemosiderin deposits can be seen in the GVA region, not rarely but more frequently in nodular form, as well as in diffuse or nodular or diffuse and nodular forms.

Complications of Caroli's Disease: Two Case Reports and a Literature Review

Caroli's disease is a rare congenital disorder of the bile ducts, characterized by intrahepatic segmental dilatation. It can remain asymptomatic for many years. Imaging, especially hepatobiliary MRI, plays a central role in diagnosis, identifying pathognomonic signs (Dot-sign, cyst communication with bile ducts), and monitoring complications. Treatment primarily involves surgery, ranging from partial resection to liver transplantation for diffuse forms. This article presents two cases: one involving an association with cholangiocarcinoma and another complicated by intrahepatic stones and cholangitis. These cases highlight the major complications, diagnostic approaches, and therapeutic strategies for this rare condition.

Giant cell tumor of the tendon sheath: A critical review of current diagnostic and therapeutic approaches with treatment recommendations for hand and foot lesions

Giant cell tumor of the tendon sheath (GCTTS) is a common tumor affecting the hand and foot, often presenting diagnostic and therapeutic challenges due to its variable clinical presentations and biological behaviors. Recent evidence supports a neoplastic origin for this tumor, previously known by various names. GCTTS can be categorized as localized or diffuse, with distinct predilections for specific anatomical locations. While localized GCTTS is typically benign and more common in the hand and wrist, the diffuse form can be aggressive, also affecting the foot and ankle. This critical analysis review aims to provide a comprehensive overview of GCTTS in hand and foot, encompassing its clinical, radiological, histological, and genomic features. In addition, we summarize current management practices, discuss differential diagnoses, analyze recurrence rates following surgical excision, and offer evidence-based treatment recommendations for this diverse group of tumors.

Long-term survival after resection of invasive pancreatic intraductal papillary mucinous neoplasm.

This study aimed to report the long-term outcomes after surgical resection for invasive (I) intraductal papillary mucinous neoplasm (IPMN) and to define prognostic factors for survival. We retrospectively evaluated all consecutive pancreatic resections performed IPMN between January 1, 2007, and December 31, 2022. Multivariate Cox analysis identified risk factors for survival. Surgery for IPMN was performed in 125 patients including 78 I-IPMN (62%). Ninety-day mortality rates was 1.6% (n = 2) with an overall morbidity rate of 44.4%. I-IPMN showed higher serum CA 19 - 9 serum values (p < 0.0001), more frequently jaundice (p = 0.008), more high-risk stigmata (p = 0.002) and diffuse IPMN form (p = 0.005) compared with non-invasive IPMN. The median overall survival for I-IPMN was 178.36 months (95% confidence interval [CI]: 87.01-NR) with overall survival rates at one, three, five, and 10 years of 91%, 75%, 72%, and 62%, respectively. Jaundice (hazard ratio [HR]: 4.23; 95% CI: 1.48-12.07; p = 0.006), T3 lesions (HR: 3.24; 95% CI: 1.65-6.39; p = 0.006), absence of lymph node involvement (HR: 0.15; 95% CI: 0.04-0.60; p = 0.0007), R1 margin status (HR: 2.96;95%CI:1.08-8:15;p = 0.03) and need for venous resection (HR: 4.30; 95% CI: 1.26-14.6; p = 0.006) were identified as independent risk factors for survival. Long-term survival and cure can be observed after surgical resection of pancreatic adenocarcinomas originating from I-IPMN when resected at early stage (Tis, T1, T2). I-IPMN spreading beyond pancreatic ducts (jaundice, T3 lesions, lymph nodes, Veins) have limited long-term survival.

A stabilized parametric finite element method for surface diffusion with an arbitrary surface energy

We proposed a structure-preserving stabilized parametric finite element method (SPFEM) for the evolution of closed curves under anisotropic surface diffusion with an arbitrary surface energy γˆ(θ). By introducing a non-negative stabilizing function k(θ) depending on γˆ(θ), we obtained a novel stabilized conservative weak formulation for the anisotropic surface diffusion. A SPFEM is presented for the discretization of this weak formulation. We construct a comprehensive framework to analyze and prove the unconditional energy stability of the SPFEM under a very mild condition on γˆ(θ), including the critical case where 3γˆ(θ⁎)=γˆ(θ⁎−π). This method can be applied to simulate solid-state dewetting of thin films with arbitrary surface energies, which are characterized by anisotropic surface diffusion and contact line migration. Extensive numerical results are reported to demonstrate the efficiency, accuracy and structure-preserving properties of the proposed SPFEM with anisotropic surface energies γˆ(θ) arising from different applications.

Interplay between a polerovirus and a closterovirus decreases aphid transmission of the polerovirus.

Multi-infection of plants by viruses is very common and can change drastically infection parameters such as virus accumulation, distribution, and vector transmission. Sugar beet is an important crop that is frequently co-infected by the polerovirus beet chlorosis virus (BChV) and the closterovirus beet yellows virus (BYV), both vectored by the green peach aphid (Myzus persicae). These phloem-limited viruses are acquired while aphids ingest phloem sap from infected plants. Here we found that co-infection decreased transmission of BChV by ~50% but had no impact on BYV transmission. The drastic reduction of BChV transmission was due to neither lower accumulation of BChV in co-infected plants nor reduced phloem sap ingestion by aphids from these plants. Using the signal amplification by exchange reaction fluorescent in situ hybridization technique on plants, we observed that 40% of the infected phloem cells were co-infected and that co-infection caused redistribution of BYV in these cells. The BYV accumulation pattern changed from distinct intracellular spherical inclusions in mono-infected cells to a diffuse form in co-infected cells. There, BYV co-localized with BChV throughout the cytoplasm, indicative of virus-virus interactions. We propose that BYV-BChV interactions could restrict BChV access to the sieve tubes and reduce its accessibility for aphids and present a model of how co-infection could alter BChV intracellular movement and/or phloem loading and reduce BChV transmission.IMPORTANCEMixed viral infections in plants are understudied yet can have significant influences on disease dynamics and virus transmission. We investigated how co-infection with two unrelated viruses, BChV and BYV, affects aphid transmission of the viruses in sugar beet plants. We show that co-infection reduced BChV transmission by about 50% without affecting BYV transmission, despite similar virus accumulation rates in co-infected and mono-infected plants. Follow-up experiments examined the localization and intracellular distribution of the viruses, leading to the discovery that co-infection caused a redistribution of BYV in the phloem vessels and altered its repartition pattern within plant cells, suggesting virus-virus interactions. In conclusion, the interplay between BChV and BYV affects the transmission of BChV but not BYV, possibly through direct or indirect virus-virus interactions at the cellular level. Understanding these interactions could be crucial for managing virus propagation in crops and preventing yield losses.

Assessment and Validity of Trichoscopy for Eyebrow Involvement in Lichen Planopilaris and Frontal Fibrosing Alopecia: A Case-Control Study.

Few publications are available on eyebrow trichoscopy in patients with alopecia areata and frontal fibrosing alopecia (FFA). To investigate the validity of using trichoscopy to examine eyebrow involvement in patients with lichen planopilaris (LPP) and FFA. In this case-control study, 109 patients with eyebrow involvement in LPP and FFA (cases) and with acquired hair disorders of the eyebrows (controls) were included. Trichoscopy was highly specific and sensitive for the diagnosis of LPP and FFA. Trichoscopic features significantly associated with LPP were peripilar scaling, peripilar pigmentation, broken hairs, peripilar white halos, diffuse empty follicles, and vellus hair. Localized peripilar erythema and empty follicles were significantly associated with the diffuse form of LPP and the zigzag type of FFA. Yellow dots, dystrophic hairs, hair regrowth in different directions, and diffuse empty follicles were associated with LPP activity and FFA severity. The retrospective nature of the statistical analysis. Trichoscopy is a valid tool for evaluating eyebrow involvement in LPP and FFA. Thus, it could help increase the diagnostic accuracy and predict the prognosis of eyebrow hair loss at an early stage.

Features of Magnetic Resonance Diagnostics of Tenosynovial Giant Cell Tumor (Pigmented Villonodular Synovitis)

Aim. Demonstrate the features of magnetic resonance diagnostics of tenosynovial giant cell tumor.Materials and Methods. Using magnetic resonance imaging, we identified patients with tenosynovial giant cell tumor of the knee joint, describing the diagnostic features and clinical course of diffuse and local forms of the tumor.Results. Specific MRI patterns of tenosynovial giant cell tumor are hemosiderin deposits, villous and nodular growths of the synovium of the knee joint, joint effusion and bone erosion.Conclusion. Тenosynovial giant cell tumor is a rare mesenchymal neoplasm arising from the synovium of joints and tendon sheaths, disabling young able-bodied people. Magnetic resonance imaging, being the “gold” standard for radiological diagnostics, helps to identify specific patterns.

On the Definition of Velocity in Discrete-Time, Stochastic Langevin Simulations

We systematically develop beneficial and practical velocity measures for accurate and efficient statistical simulations of the Langevin equation with direct applications to computational statistical mechanics and molecular dynamics sampling. Recognizing that the existing velocity measures for the most statistically accurate discrete-time Verlet-type algorithms are inconsistent with the simulated configurational coordinate, we seek to create and analyze new velocity companions that both improve existing methods as well as offer practical options for implementation in existing computer codes. The work is based on the set of GJ methods that, of all methods, for any time step within the stability criteria correctly reproduces the most basic statistical features of a Langevin system; namely correct Boltzmann distribution for harmonic potentials and correct transport in the form of drift and diffusion for linear potentials. Several new and improved velocities exhibiting correct drift are identified, and we expand on an earlier conclusion that, generally, only half-step velocities can exhibit correct, time-step independent Maxwell–Boltzmann distributions. Specific practical and efficient algorithms are given in familiar forms, and these are used to numerically validate the analytically derived expectations. One especially simple algorithm is highlighted, and the ability of one of the new on-site velocities to produce statistically correct averages for a particular damping value is specified.

Villo-Nodular Synovitis of the Knee: A Case Report and Review of the Literature

Villonodular synovitis (VNS) is a benign tumor of the joint synovium, tendon sheaths and bursae. It is a rare condition of unknown pathogenesis [1], occurring preferentially in the knees. There are localized, diffuse and mixed forms [2]. Although the clinical manifestations are aspecific, MRI allows a diagnostic approach, even if it can have differential diagnostic problems in case of atypia or with synovial sarcoma. Treatment consists of complete removal of the lesion to avoid recurrence [3].

Diffusion policy: Visuomotor policy learning via action diffusion

This paper introduces Diffusion Policy, a new way of generating robot behavior by representing a robot’s visuomotor policy as a conditional denoising diffusion process. We benchmark Diffusion Policy across 15 different tasks from 4 different robot manipulation benchmarks and find that it consistently outperforms existing state-of-the-art robot learning methods with an average improvement of 46.9%. Diffusion Policy learns the gradient of the action-distribution score function and iteratively optimizes with respect to this gradient field during inference via a series of stochastic Langevin dynamics steps. We find that the diffusion formulation yields powerful advantages when used for robot policies, including gracefully handling multimodal action distributions, being suitable for high-dimensional action spaces, and exhibiting impressive training stability. To fully unlock the potential of diffusion models for visuomotor policy learning on physical robots, this paper presents a set of key technical contributions including the incorporation of receding horizon control, visual conditioning, and the time-series diffusion transformer. We hope this work will help motivate a new generation of policy learning techniques that are able to leverage the powerful generative modeling capabilities of diffusion models. Code, data, and training details are available (diffusion-policy.cs.columbia.edu).

A unified structure-preserving parametric finite element method for anisotropic surface diffusion

We propose and analyze a unified structure-preserving parametric finite element method (SP-PFEM) for the anisotropic surface diffusion of curves in two dimensions ( d = 2 ) (d=2) and surfaces in three dimensions ( d = 3 ) (d=3) with an arbitrary anisotropic surface energy density γ ( n ) \gamma (\boldsymbol {n}) , where n ∈ S d − 1 \boldsymbol {n}\in \mathbb {S}^{d-1} represents the outward unit vector. By introducing a novel unified surface energy matrix G k ( n ) \boldsymbol {G}_k(\boldsymbol {n}) depending on γ ( n ) \gamma (\boldsymbol {n}) , the Cahn-Hoffman ξ \boldsymbol {\xi } -vector and a stabilizing function k ( n ) : S d − 1 → R k(\boldsymbol {n}):\ \mathbb {S}^{d-1}\to {\mathbb R} , we obtain a unified and conservative variational formulation for the anisotropic surface diffusion via different surface differential operators, including the surface gradient operator, the surface divergence operator and the surface Laplace-Beltrami operator. A SP-PFEM discretization is presented for the variational problem. In order to establish the unconditional energy stability of the proposed SP-PFEM under a very mild condition on γ ( n ) \gamma (\boldsymbol {n}) , we propose a new framework via local energy estimate for proving energy stability/structure-preserving properties of the parametric finite element method for the anisotropic surface diffusion. This framework sheds light on how to prove unconditional energy stability of other numerical methods for geometric partial differential equations. Extensive numerical results are reported to demonstrate the efficiency and accuracy as well as structure-preserving properties of the proposed SP-PFEM for the anisotropic surface diffusion with arbitrary anisotropic surface energy density γ ( n ) \gamma (\boldsymbol {n}) arising from different applications.