Distant Surfaces Research Articles

Cleaning performance of electric toothbrushes around brackets applying different brushing forces: an in-vitro study

Throughout treatment with fixed orthodontic appliances, effective plaque control is crucial to maintaining dental health. This in-vitro study evaluated the cleaning performance of eleven different brush heads of seven electric toothbrushes (oscillating-rotating and sonic motions) and varying brushing forces around orthodontic brackets. Six Mini Diamond® Twin brackets were placed on black-stained front teeth. Teeth were coated with white titanium oxide and brushed in a machine six times for one minute with two different brushing forces (1 N and 1.5 N). Eleven different brush heads were evaluated (either oscillating-rotating or sonic movements). The teeth were scanned and planimetrically evaluated after brushing. Three detailed plaque areas (DPAs) were created: proximal (< 1 mm to bracket), mid-tier (1–2 mm to bracket), and distant (> 2 mm to bracket). The proportion of contaminated proximal, mid-tier, and distant surfaces (white regions) in relation to the respective DPA was calculated. Independent of brushing forces, places with a higher distance (> 2 mm) to the orthodontic bracket had the least amount of residual contamination, followed by areas with a minor (1–2 mm) and proximal distance (< 1 mm). In all of the brushes tested and for both estimated brushing forces, the region with the highest residual contamination was the proximal area. The brush heads of the Paro® Sonic toothbrush left the least amount of residual contamination. The cleaning performance of electric toothbrushes around brackets on upper incisors varied across the brushes examined. The proximal area has the most residual contamination. Furthermore, 9 out of 11 toothbrushes cleaned more successfully with 1.5 N than with 1 N brushing force.

Rapid SARS-CoV-2 disinfection on distant surfaces with UV-C: The inactivation is affected by the type of material

SARS-CoV-2 is responsible for the COVID-19 pandemic, which has caused almost 570 million infections and over six million deaths worldwide. To help curb its spread, solutions using ultraviolet light (UV) for quick virus inactivation inside buildings without human intervention could be very useful to reduce chances of contagion. The UV dose must be sufficient to inactivate the virus considering the different materials in the room, but it should not be too high, not to degrade the environment. In the present study, we have analyzed the ability of a 254 nm wavelength UV-C lamp to inactivate dried samples of SARS-CoV-2 exposed at a distance of two meters, simulating a full-scale scenario. Our results showed that virus inactivation was extremely efficient in most tested materials, which included plastic, metal, wood, and textile, with a UV-C exposure of only 42 s (equivalent to 10 mJ/cm2). However, porous materials like medium density fibreboard, were hard to decontaminate, indicating that they should be avoided in hospital rooms and public places.

A robust end-to-end deep learning framework for detecting Martian landforms with arbitrary orientations

With increasingly massive amounts of high-resolution images of Mars, automated detection of geological landforms on Mars has received widespread interest. It is significant for acquiring knowledge of distant planetary surfaces and processes, or manifold onboard applications such as spacecraft motion estimation and obstacle avoidance. This is a challenging task, not only because of the multiple sizes of targets and complex image backgrounds, but also the various orientations of some bar-shaped landforms in satellite images captured from the top view. The existing methods for directed landform detection require several pre or post-processing operations to extract possible regions of interest and final detection results with orientation, which are very time consuming. In this paper, a new end-to-end deep learning framework is developed for detecting arbitrarily-directed landforms. This framework, named Rotated-SSD (Single Shot MultiBox Detector, SSD), can locate and identify different landforms on Mars in one pass, by using rotatable anchor-box based mechanism. To enhance its robustness against angle variation of the targets and complex backgrounds, a new efficient match strategy is proposed for anchoring default boxes to ground truth boxes in the model training process and an autoencoder-based unsupervised pre-training operation is introduced to improve both the model training and inference performance. The proposed framework is tested for detection of bar-shaped buttes and dark slope streaks on satellite images. The detection results show that our framework can significantly contribute to onboard motion estimation systems. The comparative results demonstrate that the proposed match strategy outperforms other state-of-the-art match strategies with regard to model training efficiency and prediction accuracy. The pre-training strategy can facilitate the training of deep architectures in case of limited available training data.

Volumetric Occupancy Mapping With Probabilistic Depth Completion for Robotic Navigation

In robotic applications, a key requirement for safe and efficient motion planning is the ability to map obstacle-free space in unknown, cluttered 3D environments. However, commodity-grade RGB-D cameras commonly used for sensing fail to register valid depth values on shiny, glossy, bright, or distant surfaces, leading to missing data in the map. To address this issue, we propose a framework leveraging probabilistic depth completion as an additional input for spatial mapping. We introduce a deep learning architecture providing uncertainty estimates for the depth completion of RGB-D images. Our pipeline exploits the inferred missing depth values and depth uncertainty to complement raw depth images and improve the speed and quality of free space mapping. Evaluations on synthetic data show that our approach maps significantly more correct free space with relatively low error when compared against using raw data alone in different indoor environments; thereby producing more complete maps that can be directly used for robotic navigation tasks. The performance of our framework is validated using real-world data.

Mechanisms of Atomization from Rotary Dental Instruments and Its Mitigation

Since the onset of coronavirus disease 2019, the potential risk of dental procedural generated spray emissions (including aerosols and splatters), for severe acute respiratory syndrome coronavirus 2 transmission, has challenged care providers and policy makers alike. New studies have described the production and dissemination of sprays during simulated dental procedures, but findings lack generalizability beyond their measurements setting. This study aims to describe the fundamental mechanisms associated with spray production from rotary dental instrumentation with particular focus on what are currently considered high-risk components—namely, the production of small droplets that may remain suspended in the room environment for extended periods and the dispersal of high-velocity droplets resulting in formites at distant surfaces. Procedural sprays were parametrically studied with variables including rotation speed, burr-to-tooth contact, and coolant premisting modified and visualized using high-speed imaging and broadband or monochromatic laser light–sheet illumination. Droplet velocities were estimated and probability density maps for all laser illuminated sprays generated. The impact of varying the coolant parameters on heating during instrumentation was considered. Complex structured sprays were produced by water-cooled rotary instruments, which, in the worst case of an air turbine, included droplet projection speeds in excess of 12 m/s and the formation of millions of small droplets that may remain suspended. Elimination of premisting (mixing of coolant water and air prior to burr contact) resulted in a significant reduction in small droplets, but radial atomization may still occur and is modified by burr-to-tooth contact. Spatial probability distribution mapping identified a threshold for rotation speeds for radial atomization between 80,000 and 100,000 rpm. In this operatory mode, cutting efficiency is reduced but sufficient coolant effectiveness appears to be maintained. Multiple mechanisms for atomization of fluids from rotatory instrumentation exist, but parameters can be controlled to modify key spray characteristics during the current crisis.

Clear sky blinks.

Ice blinks and water skies are brightness variations on the undersides of overcasts that allow ground-based observers to judge the nature of distant surfaces such as water (dark) or ice (bright). The clear sky should also scatter light from distant surfaces that might be visually detectable. We demonstrate that clear sky blinks do occur, can be visually discerned, and can be successfully photographed. We also model them theoretically using Monte Carlo simulations. The presence of atmospheric aerosols significantly enhances clear sky blinks.

Comparison and evaluation of a high volume air sampling system for the collection of Clostridioides difficile endospore aerosol in health care environments

Environmental contamination of patient rooms and adjacent areas with C. difficile spores is a recognized transmission risk. Previous studies have shown that spores are aerosolized during patient care. These spores can remain airborne for extended periods and may contaminate distant surfaces. High-volume air sampling equipment allows for the collection of a large volume of air and was evaluated in the collection of C. difficile aerosol. Air samplers evaluated in this research included the DFU-1000, XMX/2L-MIL, Biocapture-650, and a MB2. Aerosols of C. difficile were generated in a 5-m3 chamber and each air sampler sampled in the aerosol test chamber simultaneously with referee air samplers. The DFU-1000 achieved the highest efficiency of the 4 air samplers (P = .0145) with a mean efficiency of 38.60%. The relative efficiencies of the Biocapture-650, XMX/2L-MIL, and MB2 were 28.16%, 10.51%, and 3.05%, respectively. This study demonstrated high variation based on the sampling method employed. Based on the results of these studies, high-volume air samplers may be effectively applied to sample for airborne C. difficile in health care environments. The high sampling flow rate of the DFU-1000 would allow for the complete sampling of a patient room-sized volume in less than 1 hour.

Molecular mechanism of GPCR-mediated arrestin activation.

Despite intense interest in discovering drugs that cause G-protein-coupled receptors (GPCRs) to selectively stimulate or block arrestin signalling, the structural mechanism of receptor-mediated arrestin activation remains unclear1,2. Here we reveal this mechanism through extensive atomic-level simulations of arrestin. We find that the receptor's transmembrane core and cytoplasmic tail-which bind distinct surfaces on arrestin-can each independently stimulate arrestin activation. We confirm this unanticipated role of the receptor core, and the allosteric coupling between these distant surfaces of arrestin, using site-directed fluorescence spectroscopy. The effect of the receptor core on arrestin conformation is mediated primarily by interactions of the intracellular loops of the receptor with the arrestin body, rather than the marked finger-loop rearrangement that is observed upon receptor binding. In the absence of a receptor, arrestin frequently adopts active conformations when its own C-terminal tail is disengaged, which may explain why certain arrestins remain active long after receptor dissociation. Our results, which suggest that diverse receptor binding modes can activate arrestin, provide a structural foundation for the design of functionally selective ('biased') GPCR-targeted ligands with desired effects on arrestin signalling.

NAD+ analog reveals PARP-1 substrate-blocking mechanism and allosteric communication from catalytic center to DNA-binding domains

PARP-1 cleaves NAD+ and transfers the resulting ADP-ribose moiety onto target proteins and onto subsequent polymers of ADP-ribose. An allosteric network connects PARP-1 multi-domain detection of DNA damage to catalytic domain structural changes that relieve catalytic autoinhibition; however, the mechanism of autoinhibition is undefined. Here, we show using the non-hydrolyzable NAD+ analog benzamide adenine dinucleotide (BAD) that PARP-1 autoinhibition results from a selective block on NAD+ binding. Following DNA damage detection, BAD binding to the catalytic domain leads to changes in PARP-1 dynamics at distant DNA-binding surfaces, resulting in increased affinity for DNA damage, and providing direct evidence of reverse allostery. Our findings reveal a two-step mechanism to activate and to then stabilize PARP-1 on a DNA break, indicate that PARP-1 allostery influences persistence on DNA damage, and have important implications for PARP inhibitors that engage the NAD+ binding site.

Long Distance Modulation of Disorder-to-Order Transitions in Protein Allostery.

Elucidation of the molecular details of allosteric communication between distant sites in a protein is key to understanding and manipulating many biological regulatory processes. Although protein disorder is acknowledged to play an important thermodynamic role in allostery, the molecular mechanisms by which this disorder is harnessed for long distance communication are known for a limited number of systems. Transcription repression by the Escherichia coli biotin repressor, BirA, is allosterically activated by binding of the small molecule effector biotinoyl-5'-AMP. The effector acts by promoting BirA dimerization, which is a prerequisite for sequence-specific binding to the biotin biosynthetic operon operator sequence. A 30 Å distance separates the effector binding and dimerization surfaces in BirA, and previous studies indicate that allostery is mediated, in part, by disorder-to-order transitions on the two coupled sites. In this work, combined experimental and computational methods have been applied to investigate the molecular basis of allosteric communication in BirA. Double-mutant cycle analysis coupled with thermodynamic measurements indicates functional coupling between residues in disordered loops on the two distant surfaces. All atom molecular dynamics simulations reveal that this coupling occurs through long distance reciprocal modulation of the structure and dynamics of disorder-to-order transitions on the two surfaces.

3D saliency detection based on background detection

Unlike 2D saliency detection, 3D saliency detection can consider the effects of depth and binocular parallax. In this paper, we propose a 3D saliency detection approach based on background detection via depth information. With the aid of the synergism between a color image and the corresponding depth map, our approach can detect the distant background and surfaces with gradual changes in depth. We then use the detected background to predict the potential characteristics of the background regions that are occluded by foreground objects through polynomial fitting; this step imitates the human imagination/envisioning process. Finally, a saliency map is obtained based on the contrast between the foreground objects and the potential background. We compare our approach with 14 state-of-the-art saliency detection methods on three publicly available databases. The proposed model demonstrates good performance and succeeds in detecting and removing backgrounds and surfaces of gradually varying depth on all tested databases.

Structural cartilage damage attracts circulating rheumatoid arthritis synovial fibroblasts into affected joints

BackgroundRheumatoid arthritis synovial fibroblasts (RASFs) are known to travel via the bloodstream from sites of cartilage destruction to new locations where they reinitiate the destructive processes at distant articular cartilage surfaces. In this study, we examined the role of interleukin (IL)-1-induced cartilage changes and their chemotactic effect on RASF transmigratory capacity.MethodsTo investigate synovial fibroblast (SF) transmigration through endothelial layers, we used a modified Boyden chamber with an endothelioma cell layer (bEnd.5) as a barrier and IL-1-treated murine cartilage explants as a chemotactic stimulus for SFs from human tumor necrosis factor–transgenic (hTNFtg) mice. We injected recombinant IL-1 or collagenase into knee joints of wild-type mice, followed by tail vein injection of fluorescence-labeled hTNFtg SFs. The distribution and intensity of transmigrating hTNFtg SFs were measured by fluorescence reflectance imaging with X-ray coregistration. Toluidine blue staining was performed to evaluate the amount of cartilage destruction.ResultsHistomorphometric analyses and in vivo imaging revealed a high degree of cartilage proteoglycan loss after intra-articular IL-1 and collagenase injection, accompanied by an enhanced in vivo extravasation of hTNFtg SFs into the respective knee joints, suggesting that structural cartilage damage contributes significantly to the attraction of hTNFtg SFs into these joints. In vitro results showed that degraded cartilage was directly responsible for the enhanced transmigratory capacity because stimulation with IL-1-treated cartilage, but not with IL-1 or cartilage alone, was required to increase hTNFtg SF migration.ConclusionsThe present data indicate that structural cartilage damage facilitates the migration of arthritic SF into affected joints. The prevention of early inflammatory cartilage damage may therefore help prevent the progression of rheumatoid arthritis and its spread to previously unaffected joints.

Strategies to improve local control of resected pancreas adenocarcinoma

BackgroundOnly approximately one in ten pancreas cancer patients is a candidate for potentially curative resection of this disease. Even this small fraction of patients has a poor prognosis following pancreatico-duodenectomy. The disease has an anatomic location that makes it difficult for the surgeon to maintain adequate margins of resection and prevent tumor spillage at the time of resection. Also, the disease is biologically aggressive and even with a complete visible resection of the disease, micrometastases are likely to remain behind. MethodsA survey of the sites for surgical treatment failure of resected pancreas cancer was performed. Also, the multiple modalities used in an attempt to improve the results of cancer resection are scrutinized. ResultsThe surgical treatment failures are regional in nature and occur at the resection site and on peritoneal surfaces, within the liver, and within the regional lymph nodes. These anatomic sites account for nearly 100% of the initial sites of disease progression. Current hypothesis suggests that micrometastases released from the cancer specimen by the trauma of surgery account for the high incidence of resection site progression and peritoneal metastases. Although surgical trauma may contribute to micrometastases within the liver and lymph nodes, these are most likely present though not detected by preoperative radiologic studies. Adjuvant treatments such as neoadjuvant chemotherapy or combination systemic chemotherapy have not been associated with improved survival. Extended resections such as total pancreatectomy or extended lymphadenectomy have not been associated with benefit. However, resection with a negative margin of excision along with the removal of at least 12 lymph nodes in and around the pancreaticoduodenectomy specimen is associated with superior outcomes. A regional chemotherapy treatment that consists of hyperthermic intraperitoneal chemotherapy (HIPEC) with gemcitabine and long-term normothermic intraperitoneal chemotherapy (NIPEC-LT) gemcitabine for 6 months postoperatively is suggested as a new treatment that has demonstrated decreases in local-regional failure and promises to more adequately target micrometastases in the peritoneal space, in the liver and lymph nodes. ConclusionsPancreas cancer surgery should attempt to achieve negative margins of resection with the removal of at least 12 lymph nodes. Hyperthermic intraperitoneal gemcitabine can adequately eradicate malignant cells dislodged from the cancer specimen into the bed of the resection at high density and on distant peritoneal surfaces as peritoneal metastases. Long-term intraperitoneal gemcitabine may act on micrometastases in the liver through absorption into the portal vein blood and the lymph nodes as a result of gemcitabine absorption by subperitoneal lymphatic channels. The use of HIPEC and NIPEC-LT gemcitabine may improve local control of resected pancreas cancer.

Does shallow dike intrusion and widening remain a possible mechanism for graben formation on Mars?

Shallow dike intrusion and widening was proposed several decades ago as a cause of surface faulting and graben formation on Earth. This hypothesis was subsequently applied to the spectacular linear and/or radial graben systems visible on Mars. However, a recent study has suggested that shallow dike intrusion on Mars results in contractional folding and uplift adjacent to dike walls rather than extensional faulting and subsidence above the dike tip, even in the presence of concurrent regional extension. Here, discrete element numerical modeling is used to re-examine the typical style of deformation above the shallow tips of widening dikes on Mars. The dikes are embedded in a frictional, cohesive material representing the Martian crust. In the experiments presented here, subsidence and extensional faulting (graben formation) are produced above the dike tips, even with modest amounts of widening. For suggested depths to dike tips on Mars, an overlying graben is produced in all cases; no upright detachment-style folds are produced. Results indicate that dike widening does indeed remain a possible mechanism for graben formation on Mars. Implications for the interpretation of deformation associated with shallow dike intrusion on Earth and distant planetary surfaces are discussed.

P10.22 Engineering human rhinovirus serotype-a1 as a vaccine vector

Introduction Vaccination is the optimal long-term solution to the human immuno-defficiency virus (HIV) pandemic. A majority of new HIV infections result from mucosal transmission, highlighting the need for novel vaccines that primarily generate mucosal immunity. Like HIV, human rhinovirus serotype-A1 (HRV-A1, the common cold virus) is primarily transmitted via mucosal surfaces. This makes HRV-A1 a potential vector for mucosally targeted vaccines to generate robust protection against HIV at the vaginal and other distant mucosal surfaces, and systemically. Methods Using recombinant technology, we inserted discrete overlapping fragments of HIV gag and full-length tat into the junction between genes that encode HRV-A1 structural and non-structural proteins to generate recombinant HRV-A1s (rHRV-A1s) encoding HIV Gag and Tat proteins. Results Transfection of H1-HeLa cells with rHRV-A1s transcripts yielded infectious and replication-competent rHRV-A1s with similar growth characteristics as wildtype HRV-A1. We also confirmed that cells infected with rHRV-A1s stably expressed Gag and Tat (beyond 5 passages), of the correct sizes and mainly localised in the cytoplasm as revealed by western blot assay, reverse-transcription polymerase chain reaction and immunofluorescence. These results have been recently accepted for publication in Virus Research Journal (reference number: VIRUS96578, April 2015). Conclusion To the best of our knowledge, this is the first time replication-competent and stable HRV-A1 vectors have been generated. The individual rHRV-A1gag/tat generated in this study have been mixed into a cocktail vaccine and administered intranasally to female Balb/C mice to evaluate its immunogenicity (animal experiments currently on-going). The protective efficacy of the resultant HIV-Gag-specific cell-mediated and Tat humoral responses will be documented in mice challenged intravaginally with chimeric rodent ecotropic murine leukaemia virus (EcoHIV). EcoHIV was developed by replacing the coding region of glycoprotein-120 (gp-120) of HIV strain NL4–3 with gp80 of EcoHIV to ensure that the chimeric virus infected murine cells only. Disclosure of interest statement This work was supported by a grant from The Hospital Research Foundation (THRF), Woodville, South Australia and grant number APP1026293 from the National Health and Medical Research Council (NHMRC) of Australia. TK is a post-graduate Fellow supported by THRF while SA and GE are Senior Research Fellows of the NHMRC. The authors declare no financial or commercial conflict of interest.

Allosteric Coupling via Distant Disorder-to-Order Transitions

Intrinsic disorder provides a means of maximizing allosteric coupling in proteins. However, the mechanisms by which the disorder functions in allostery remain to be elucidated. Small ligand, bio-5′-AMP, binding and dimerization of the Escherichia coli biotin repressor are allosterically coupled. Folding of a disordered loop in the allosteric effector binding site is required to realize the full coupling free energy of −4.0±0.3kcal/mol observed in the wild-type protein. Alanine substitution of a glycine residue on the dimerization surface that does not directly contribute to the dimerization interface completely abolishes this coupling. In this work, the structure of this variant, solved by X-ray crystallography, reveals a monomeric corepressor-bound protein. In the structure loops, neither of which contains the alanine substitution, on both the dimerization and effector binding surfaces that are folded in the corepressor-bound wild-type protein are disordered. The structural data combined with functional measurements indicate that allosteric coupling between ligand binding and dimerization in BirA (E. coli biotin repressor/biotin protein ligase) is achieved via reciprocal communication of disorder-to-order transitions on two distant functional surfaces.

A8.15 The Focal Contact Protein Lasp-1 Modulates the Migration Capacity of Synovial Fibroblasts

Background and ObjectivesRA synovial fibroblasts (SF) have been suggested to contribute to the spreading of disease through their ability to leave cartilage destruction sites, migrate via the bloodstream and re-initiate...

Structural Topology and Activation of an Initial Adenylate Kinase–Substrate Complex

Enzymatic activity is ultimately defined by the structure, chemistry, and dynamics of the Michaelis complex. A large number of experimentally determined structures between enzymes and substrates, substrate analogues, or inhibitors exist. However, transient, short-lived encounter and equilibrium structures also play fundamental roles during enzymatic reaction cycles. Such structures are inherently difficult to study with conventional experimental techniques. The enzyme adenylate kinase undergoes major conformational rearrangements in response to binding of its substrates, ATP and AMP. ATP is sandwiched between two binding surfaces in the closed and active enzyme conformation. Thus, adenylate kinase harbors two spatially distant surfaces in the substrate free open conformation, of which one is responsible for the initial interaction with ATP. Here, we have performed primarily nuclear magnetic resonance experiments on Escherichia coli adenylate kinase (AK(eco)) variants that allowed identification of the site responsible for the initial ATP interaction. This allowed a characterization of the structural topology of an initial equilibrium complex between AK(eco) and ATP. On the basis of the results, we suggest that the ATP binding mechanism for AK(eco) is a mixture between "induced fit" and "conformational selection" models. It is shown that ATP is activated in the initial enzyme-bound complex because it displays an appreciable rate of nonproductive ATP hydrolysis. In summary, our results provide novel structural and functional insights into adenylate kinase catalysis.

Functional separation of septic and aseptic surgical procedures.

Current evidence does not favour constructional over functional separation of septic and aseptic surgical procedures in terms of overall hygiene maintenance and incidence of skin and soft tissue infections. In both laminar and turbulent flow air operating theatres, air is not a relevant source of pathogens if surface disinfection is carried out properly.Final cleaning after a septic procedure includes a thorough wipe-disinfection of all potentially contaminated near and distant surfaces, including maintaining the necessary and effective exposure time of the chosen surface disinfectant. Cleaning utensils and clothes of all team members must be disposed of before leaving the theatre, and a complete change of gowns is mandatory before re-entering the operating room area. Strict adherence to this code of behaviour will allow for efficient functional separation of clean and contaminated surgical procedures without compromising patient safety.

Local and non-local effects on surface-mediated stereoscopic depth

The magnitude and precision of stereoscopic depth between two probes is often determined by the disparity each has to a common background. If stereoscopic slant of the background is underestimated, a bias is introduced in the PSE of the probes (G. Mitchison & G. Westheimer, 1984). Using random dot stimuli, we show here how more remote surfaces can influence probe PSE via their influence on perceived background surface slant. The bias was reduced when frontal flanking surfaces were placed above and below the background surface, increasing its perceived slant. In a similar experiment, the flankers were slanted and the central background surface was frontal. For flankers alone, probe bias did not diminish up to a 4.4° separation of flankers and probes. When the central surface was present, the effect of the flankers on probe bias was mediated by this surface and diminished with flanker separation, presumably because of the diminishing contrast slant of the background surface. Stereoscopic depth between probes is thus influenced by a common background surface, by neighboring surfaces acting (contiguously or non-contiguously) on the background surface, and by distant surfaces acting directly on the probes.