Matrix Types Research Articles

Associated Factors and Prevention of Upper Pole Rippling in Prepectoral Direct-to-Implant Breast Reconstruction.

Background Despite its many advantages, prepectoral breast reconstruction also carries the risk of implant rippling. The recent introduction of partial superior implant coverage using a pectoralis muscle slip in prepectoral direct-to-implant (DTI) breast reconstruction has shown the potential to minimize upper pole rippling. The purpose of this study was to identify factors associated with rippling and the effectiveness of our surgical technique. Methods In total, 156 patients (186 breasts) who underwent prepectoral DTI breast reconstruction between August 2019 and March 2021 were identified retrospectively. Patient data were analyzed from medical records. Univariable and multivariable logistic analyses were performed to contextualize the risks associated with rippling deformity relative to demographic characteristics and other clinical factors. Retrospective propensity-matched analysis was performed to identify the relationship between rippling deformity and the reconstruction method. Results Patients with body mass index (BMI; odds ratio [OR], 0.736; p < 0.001), those with a postoperative chemotherapy history (OR, 0.324; p = 0.027) and those who received breast reconstruction via the superior coverage technique (OR, 0.2; p = 0.004), were less likely to develop rippling deformity. The median follow-up period was 64.9 weeks, and there were no significant differences between patients in types of mastectomy, implant, or acellular dermal matrix. Patients who underwent superior coverage technique-based reconstruction showed significantly reduced rippling (OR, 0.083; p = 0.017) Conclusion Patients with higher BMI and prior postoperative chemotherapy were less likely to develop rippling deformity. The superior coverage technique can be effective in minimizing upper pole rippling.

An update on formaldehyde adulteration in food: sources, detection, mechanisms, and risk assessment.

Formaldehyde is added illegally to food to extend its shelf life due to its antiseptic and preservation properties. Several research has been conducted to examine the consequences of adulteration with formaldehyde in food items. These findings suggest that adding formaldehyde to food is considered harmful as it accumulates in the body with long-term consumption. In this review includes study findings on food adulteration with formaldehyde and their assessment of food safety based on the analytical method applied to various geographical regions, food matrix types, and their sources in food items. Additionally, this review sought to assess the risk of formaldehyde-tainted food and the understanding of its development in food and its impacts on food safety in light of the widespread formaldehyde adulteration. Finally, the study would be useful as a manual for implementing adequate and successful risk assessment to increase food safety.

The persistence of emamectin benzoate in marine sediments with different organic matter regimes, temperature conditions, and antibiotic presence

The objectives of this 318-day study are to determine half-lives of the anti-sea lice medication emamectin benzoate (EMB) under conditions present in sediments at aquaculture sites and document the degradation of EMB into its main metabolite desmethyl emamectin benzoate (DES). Tested conditions include different matrix types (sand, mud), two temperatures (4, 10 degrees), organic matter presence (fish feed waste and feces), and the presence of oxytetracycline. We document a transformation ratio of EMB to DES of 0.16 to 4.4 % and show that the co-presence of oxytetracycline increases EMB calculated half-lives to values >6000 days for mud matrices. EMB incubated in high organic enrichment regimes was not observed to degrade at 4 degrees. Multivariate analyses show interactions between sediment conditions (matrix, temperature, organic matter [OM], oxytetracycline) influence EMB persistence and DES:EMB ratios. Ranges of EMB half-lives and information on metabolites can be used to anticipate potential effects on marine communities.

Creep mechanism in ductile dual-phase aluminum alloys with a fully continuous fiber state

To understand the creep behavior of a practical alloy that has a multiphase consisting of a matrix and several types of precipitate phases, the role of individual phases needs to be studied. However, it is difficult to elucidate the contribution of each phase to creep owing to their complex microstructural morphologies and very complex creep behavior. To understand the role of individual phases and the creep behavior, fundamental creep theories for ductile dual-phase (DDP) alloys must be established initially for specimens with simple microstructural morphologies. To apply these theories practically, they must also be experimentally verified. In this study, DDP alloys composed of 99.99 % Al (matrix phase) and an Al–Mg solid-solution alloy (reinforced phase) were fabricated as a fully continuous fiber state by accumulative roll bonding. Tensile and creep tests at elevated temperatures were performed on alloys composed of systematically varying volume fractions of the reinforced phase. Tensile data at 546 K indicated a linear relationship between the maximum stress and volume fraction of the reinforced phase; the lines were also connected to the data from single-phase materials of the matrix and reinforced phase. Thus, the amount of strain in the matrix and reinforced phases was the same as that during the tensile test, and the relationship between the maximum stress and volume fraction of a DDP alloy followed the classical linear law of mixtures (CLLM). The creep data for Al + Al–2Mg (DDP alloy) at 546 K were nearly equal to those calculated using the CLLM. Thus, the matrix and reinforced phases deformed at the same creep rate. Creep tests were also conducted for Al + Al-1M(5ARB), which had a fine-grained reinforced phase. The creep data for Al + Al-1M(5ARB) at 523 K were also a good approximation to the lines representing the data calculated using the CLLM. Hence, although the grain sizes of the two phases were very different, corresponding to different rate-controlling mechanisms, the creep data for a DDP alloy could be analyzed using the CLLM. Consequently, the creep behavior of the DDP alloys was a superposition of the creep behavior in both phases, and the interpretation of the creep data for DDP alloys using the creep theory of single-phase materials would lead to incorrect conclusions. These findings will contribute to a better understanding of the creep behaviors of practical alloys and will aid in the correct estimation of the creep lifetime.

The Use of a Stable Super-Resolution Generative Adversarial Network (SSRGAN) on Remote Sensing Images

Because of the complicated imaging conditions in space and the finite imaging systems on satellites, the resolution of remote sensing images is limited. The process of increasing an image’s resolution, image super-resolution, aims to obtain a clearer image. High-resolution (HR) images are affected by various input conditions, such as motion, imaging blur, down-sampling matrix, and various types of noise. Changes in these conditions seriously affect low-resolution (LR) images, so if the imaging process is a pathological problem, super-resolution reconstruction is a pathological anti-problem. To optimize the imaging quality of satellites without changing the optical system, we chose to reconstruct images acquired by satellites using deep learning. We changed the original super-resolution generative adversarial nets network, upgraded the generator’s network part to ResNet-50, and inserted an additional fully connected (FC) layer in the network of the discriminator part. We also modified the loss function by changing the weight of regularization loss from 2 × 10−8 to 2 × 10−9, aiming to preserve more detail. In addition, we carefully and specifically chose remote sensing images taken under low-light circumstances from GF-5 satellites to form a new dataset for training and validation. The test results proved that our method can obtain good results. The reconstruction peak signal-to-noise ratio (PSNR) at the scaling factors of 2, 3, and 4 reached 32.6847, 31.8191, and 30.5095 dB, respectively, and the corresponding structural similarity (SSIM) reached 0.8962, 0.8434, and 0.8124. The super-resolution speed was also satisfactory, making real-time reconstruction more probable.

Cortical spheroid on perfusable microvascular network in a microfluidic device.

Human induced pluripotent stem cell (hiPSC)-derived brain spheroids can recapitulate the complex cytoarchitecture of the brain, as well as the genetic/epigenetic footprint of human brain development. However, hiPSC-derived 3D models such as spheroid and organoids does not have a perfusable microvascular network, which plays a vital role in maintaining homeostasis in vivo. With the critical balance of positive and negative angiogenic modulators, 3D microvascular network can be achieved by angiogenesis. This paper reports on a microfluidic-based three-dimensional, cortical spheroid grafted on the vascular-network. Vascular network was formed by inducing angiogenic sprouting using concentration gradient-driven angiogenic factors in the microfluidic device. We investigate critical factors for angiogenic vascular network formation with spheroid placement, including 1) a PKCα activator, phorbol-12-myristate-13-acetate (PMA); 2) orientation of endothelial cells under perfusion and permeability of vascular network; 3) effect of extracellular matrix (ECM) types and their densities on angiogenesis; and 4) integration with cortical spheroid on vascular network. This paper demonstrates proof of concept for the potential utility of a membrane-free in vitro cortical spheroid tissue construct with perfusable microvascular network that can be scaled up to a high throughput platform. It can provide a cost-effective alternative platform to animal testing by modeling brain diseases and disorders, and screening drugs.

Induced Pluripotent Stem Cells for Modeling Physiological and Pathological Striated Muscle Complexity.

Neuromuscular disorders (NMDs) are a large group of diseases associated with either alterations of skeletal muscle fibers, motor neurons or neuromuscular junctions. Most of these diseases is characterized with muscle weakness or wasting and greatly alter the life of patients. Animal models do not always recapitulate the phenotype of patients. The development of innovative and representative human preclinical models is thus strongly needed for modeling the wide diversity of NMDs, characterization of disease-associated variants, investigation of novel genes function, or the development of therapies. Over the last decade, the use of patient's derived induced pluripotent stem cells (hiPSC) has resulted in tremendous progress in biomedical research, including for NMDs. Skeletal muscle is a complex tissue with multinucleated muscle fibers supported by a dense extracellular matrix and multiple cell types including motor neurons required for the contractile activity. Major challenges need now to be tackled by the scientific community to increase maturation of muscle fibers in vitro, in particular for modeling adult-onset diseases affecting this tissue (neuromuscular disorders, cachexia, sarcopenia) and the evaluation of therapeutic strategies. In the near future, rapidly evolving bioengineering approaches applied to hiPSC will undoubtedly become highly instrumental for investigating muscle pathophysiology and the development of therapeutic strategies.

An overview on spalling behavior, mechanism, residual strength and microstructure of fiber reinforced concrete under high temperatures

Recent research has shown that the incorporation of fibres, such as steel and polypropylene fibres, in concrete can significantly improve its resistance to spalling under high-temperature conditions. However, the reported outcomes of studies on the spalling performance of Fibre Reinforced Concrete (FRC) vary significantly due to differences in cementitious matrix and fibre types, mix design, and testing techniques. Existing review studies have struggled to systematically and precisely consolidate the diverse aspects of the literature. To address these limitations, this paper adopts the latest approach for mining, processing, and analyzing data to interpret bibliographic data on the fire resistance of FRC. The primary objective of this study is to comprehensively explore the viability of FRC as a fire-resistant and refractory material. In pursuit of this goal, the paper thoroughly reviews various aspects of FRC behavior at elevated temperatures, including pore pressure behaviors. Moreover, this review also discusses spalling behaviors, mechanisms, and residual mechanical properties under high temperatures. The microstructural analysis of FRC is also discussed comprehensively to gain an in-depth understanding of its behavior under elevated temperatures. By analyzing available data, this study aims to shed light on the potential of FRC as a suitable material for resisting spalling in high-temperature scenarios. Additionally, the research delves into prospects and challenges in achieving sustainable FRC with enhanced spalling resistance, considering both material and structural levels.

Internal Validation of the ASFV MONODOSE dtec-qPCR Kit for African Swine Fever Virus Detection under the UNE-EN ISO/IEC 17025:2005 Criteria.

African swine fever virus is considered an emerging virus that causes African swine fever, a disease characterised by high mortality and elevated transmission rates and that, as it is for most other viral diseases, cannot be treated with specific drugs. Effective and reliable detection of the virus is relevant to prevent uncontrolled contagion among boar populations and to reduce economic losses. Moreover, animal health laboratories are demanding standardisation, optimisation and quality assurance of the available diagnostic assays. In the present study, the ASFV MONODOSE dtec-qPCR kit was validated following the UNE-EN ISO/IEC 17025:2005 guidelines. Analytical validation terms include in silico and in vitro specificity, sensitivity, efficiency and reliability (repeatability/reproducibility). Diagnostic validation of the method was assessed through the analysis of a total of 181 porcine samples originating from six different matrix types doped with African swine fever virus DNA received from the European reference laboratory for African Swine Fever (INIA-CISA, Madrid, Spain): whole blood, blood serum, kidney, heart, liver and tonsil. Results agreed with those obtained from a reference detection method also based on real-time PCR, endorsed by WOAH, but the ASFV MONODOSE dtec-qPCR kit incorporates some technical innovations and improvements which may benefit end-users. This kit, available worldwide with full analytical and diagnostic validation, can recognise all known ASFV genotypes and brings additional benefits to the current qPCR technology.

Prepectoral Direct-To-Implant One-Stage Reconstruction With ADMs: Safety and Outcome in “Thin Patients”

BackgroundPrepectoral direct-to-implant reconstruction with acellular dermal matrix (ADM) represents a safe, fast, and successful option in breast reconstruction in a selected cohort of patients. Nowadays, this procedure is considered challenging in thin. Meanwhile, his cohort has not been accurately analyzed yet. MethodsA single institution retrospective cohort study was performed between January 2019 and March 2023 in all women who underwent mastectomy. Biometrical and clinical data were recorded. Also, surgical technique, operating room (OR) time, mastectomy weights, implant choice, and acellular dermal matrix (ADM) types were properly noted. Postoperative complications represented the main topic: these were classified into early and late ones based on onset time. At least 12-month follow-up was required. A comparison between thin and ideal body mass index (BMI) populations was performed. ResultsEarly complications did not seem to differ between the 2 groups with 37.8% and 38.9% of women having at least 1 early complication in thin and ideal-weight women, respectively (P = .919). In univariable regression analysis, compared with women with a BMI of 22.1 to 25.0, women with a BMI ≤ 22.0 were associated with an increased risk of late complications of 2.84 (1.13-7.14). Specifically, thin women appeared to have a 3-fold increased risk (OR = 2.97, 95% CI 1.08-8.18) of ripples/wrinkles compared with women with ideal weight. ConclusionsPrepectoral reconstruction with ADM in thin patients may be considered as safe as in standard BMI patients. Rippling may be more frequent, but, whenever needed, easy to correct with a few sessions of lipo-grafts. Level of EvidenceIII.

Recent progress in thermal and acoustic properties of natural fiber reinforced polymer composites: Preparation, characterization, and data analysis

AbstractNatural fiber reinforced polymer composites (NFRPCs) have emerged as promising eco‐friendly alternatives over conventional synthetic fiber composites due to their inherent biodegradability, renewability, low environmental impact, and lightweight properties. It has been seen a significant growth in both invention and innovation in the field of NFRPCs. Natural fibers (NFs) reduce the cost of the material by 5%, the weight of the composite by 10%, and the energy required for production by 80%. In terms of thermal, and acoustic properties, NFs can successfully compete with synthetic fibers. As a result, the development of NFRPCs for industrial use has increased significantly in the past decade to meet the growing demands of industrial sectors. To improve the thermal and acoustic properties of NFRPCs, researchers have done a lot of investigation. The aim of the current review is to provide a comprehensive analysis of the existing literature on the thermal and acoustic properties of natural fiber reinforced polymer composites. Thermal properties such as thermal conductivity, TGA, DSC, DMA, and acoustic properties of natural fiber reinforced composites with several parameters, such as different fiber types, different matrix types, fiber weight ratio, fiber to matrix ratio, chemical treatment of fiber have been summarized and analyzed very concisely. This review also emphasizes a summary of different natural fibers, their chemical compositions, composite preparation, characterizations, and future research directions. This article enables the readers, researchers, and manufacturers to realize several opportunities about the latest developments in NFRPCs for the application of thermal and acoustic purposes.Highlights Natural fibers can successfully compete with synthetic fibers, in terms of thermal and acoustic properties. Thermal properties of natural fiber reinforced composites including thermal conductivity, TGA, DSC, and DMA are summarized. Acoustic properties of natural fiber reinforced polymer composites are discussed. Composite materials made of treated fibers result better thermal stability than untreated fiber composites. Sound absorption coefficient generally increases as fiber content increases.

A Novel Tandem Differential Edge Sensor Layout for Segmented Mirror Telescopes.

The performance of an active control system, crucial for the co-phase maintenance of segmented mirrors, is closely related to the spatial layout of sensors and actuators. This article compares two types of edge sensor layouts, vertical and horizontal, and proposes a novel tandem differential sensor layout that saves layout space and reduces the number of positioning references. The control performance of this scheme is analyzed in terms of error propagation, mode representation, and the scalable construction of the control matrix. Finally, we constructed a tandem differential-based sensor detection system to examine the performance of edge sensors and the effect of laboratory environmental variables on sensor measurements. Simulations and experiments demonstrate that this scheme has the same ability to fully characterize actuator modification modes as the Keck edge sensor layout. Although the total error multiplier is slightly larger than the latter, it has fewer scalable control matrix types and stronger spatial and segmental shape adaptation capabilities. Actual measurements show that the sensor's own noise in a tandem differential layout is less than 20 nm, which meets the requirements for future segmented co-phase maintenance. This layout type can potentially be applied to future small and medium-sized segmented splices.

Injection molding of highly filled microcrystalline cellulose/polycaprolactone composites with the aid of reversible Diels-Alder reaction

To tackle the challenge of producing highly filled polymer composites using the traditional injection molding technique, which is characterized by the fairly high melt viscosity that makes mold filling difficult, the authors propose a solution based on dynamic covalent chemistry. As demonstrated by the proof-of-concept experiments, the 4-arm star-shaped polycaprolactone (PCL) oligomers and microcrystalline cellulose (MCC) are crosslinked by the reversible Diels-Alder (DA) bonds. The flowability of the compounds greatly decreases due to the dissociation of the intercomponent DA bonds at the retro-reaction temperature, and the networked architecture is reconstructed during cooling as a result of the forward DA reaction. Consequently, the high-loading MCC fillers are well distributed in the matrix and covalently bonded to the nearby PCL, forming a striking contrast to the control in which linear PCL acts as the matrix. The DA bonds crosslinked biodegradable PCL composites exhibit decent mechanical strength (20.7 MPa) even at the MCC fraction of 65 wt%, which is superior to those (5–12.2 MPa) of the highly filled PCL composites (with filler contents of 50–63.8 wt%) reported so far. The proposed approach has sufficient expansibility for the fabrication of the highly filled polymer composites constructed by other types of matrix and fillers.

Preparation of an experimental dental composite with different Bis-GMA/UDMA proportions

ABSTRACT Three types of matrix with constant amount of TEGDMA (30 wt.%), and Bis-EMA (10 wt.%) and variable values of Bis-GMA (10, 5, or 0 wt.%) and UDMA (50, 55, or 60 wt.%) were prepared. Composites were filled with 45 wt.% of silanized silica. Both matrices and composites were tested for flexural strength (FS), diametral tensile strength (DTS), hardness (HV) and polymerization shrinkage stress. There were no significant differences for the DTS test. All materials meet the FS requirements for type 2 dental composites. A significant decrease in HV was observed for matrix non-containing Bis-GMA. The highest value of shrinkage stress had material without Bis-GMA and it amounted 16,6 ± 1.0 MPa (filled) or 13.6 ± 0.8 MPa (unfilled). It was also shown that increasing the amount of UDMA while simultaneously reducing Bis-GMA in the studied materials increases polymerization shrinkage stress, which could be unfavorable for dental materials.

Improved Transformer-Based Target Matching of Terahertz Broadband Reflective Metamaterials With Monolayer Graphene

On-demand metamaterial designs aided by artificial intelligence have hitherto received tremendous attention recently. However, the traditional deep neural networks (DNNs) still show the limited generalization ability in the inverse design of tunable graphene-based terahertz (THz) metamaterial. In this article, we propose two kinds of DNNs based on the self-attention mechanism to implement the inverse design of tunable broadband reflectors working in the THz band. Moreover, the proposed networks have been improved, so that they could adapt to different types of input vector or matrix in terms of different kinds of on-demand design requirements. Besides, adaptive batch normalization (BN) layers are introduced in our improved networks to accelerate the converging speed with low computational consumption. It could be shown in experiments that the proposed networks exhibit higher accuracy and faster convergence speed than the traditional neural networks, such as multilayer perceptron (MLP) and convolutional neural network (CNN). Finally, this work may provide a key guide for developing THz metamaterials with 2-D materials employing DNNs based on self-attention mechanism.

Novel design of micropump based on multi-angle paper-based capillary approach for enhanced and well-controlled flow rates

Paper-capillary micropumps are advantageous as they are small in size, cost-effective, and easily disposable. However, capillary-based micropumps fabricated using the photolithography technique prevent exchanging of the pumping element. The liquid movement in paper-based micropumps is also difficult to control and manipulate as compared to non-paper-based micropumps. Therefore, in this study, the performance of a multi-angle paper-based capillary micropump that utilizes both hydrostatic and paper-capillary effects with a detachable paper matrix is presented. The design offers enhanced and controllable flow rates based on paper matrix types and platform inclination angles. In addition, the paper matrix pumping element does not involve in the analytical processes but rather only for fluid driving. Standalone operation shows a working range of flow rate comparable to some purely capillary- and hydrostatic-based micropumps reported in the literature. The proposed micropump shows that the flow rate is linearly increasing based on the types of capillary papers and platform inclination angles, giving a flow rate range of 2.3 μL/s ≤ [Formula: see text] ≤ 2.44 µL/s.

An adaptive approach for compression format based on bagging algorithm

ABSTRACT The traditional parallel Sparse matrix vector multiplication (SpMV) method has been optimized by an application-specific or compression format-specific. However, a single compression format cannot deal with all sparse matrix types effectively in practical applications. To solve this problem, an adaptive compression format based on Bagging ensemble learning algorithm is proposed in this paper. Experiments show that the adaptive compression format has higher prediction and computational performance on NVIDIA V100 and NVIDIA RTX 2080Ti. Compared with SpMV of the four compression formats, SpMV based on adaptive compression format reduces the execution time of 1.5×, 6.6×, 9× and 1.1×, respectively.

High-pressure glass-ceramics for iodine nuclear waste immobilization: Preliminary experimental results

Several matrix types have been considered for the immobilization of iodine radioisotopes from which glass-ceramics represent a serious candidate; however, I-bearing glass-ceramics are challenging owing to the iodine volatility. We have synthesised glass-ceramics from the partial crystallization of a parental glass enriched with different iodine sources (I2 and I2O5) under high-pressure conditions (up to 1.5 GPa). The samples were characterized using Scanning and Transmission Electron Microscopy and X-ray Diffraction. Using standard synthesis protocol: melting, nucleation and crystal growth, we have obtained glass-ceramics showing the coexistence between I-bearing glass (<0.8 mol.% I), nepheline (NaAlSiO4) and iodosodalite (Na8Al6Si6O24I2 with up to 14 mol.% I). For several samples, we observed also the presence NaPt3O4 witnessing a chemical reaction between the container walls and the inside experimental charge. The structure of iodosodalite is entirely resolved by Rietveld refinement of the XRD pattern for I2 experiments whereas it cannot be solved for I2O5 experiments suggesting a change in the iodosodalite structure probably due to the β cage filling by IO3− clusters instead of I−. Our present work could represent a potential solution to tackle the problem of iodine radioisotopes immobilization.

Influence of matrix physical properties on flow characteristics in dual network model

The tight oil formation develops with microfractures and matrix pores, it is important to study the influence of matrix physical properties on flow characteristics. At first, the representative fracture and matrix samples are selected respectively in the dual media, the fracture and matrix digital rocks are constructed with micro-CT scanning at different resolutions, and the corresponding fracture and matrix pore networks are extracted, respectively. Then, the modified integration method is proposed to build the dual network model containing both fracture and matrix pore-throat elements, while the geometric-topological structure equivalent matrix pores are generated to fill in the skeleton domain of fracture network, the constructed dual network could describe the geometric-topological structure characteristics of fracture and matrix pore-throat simultaneously. At last, by adjusting the matrix pore density and the matrix filling domain factor, a series of dual network models are obtained to analyze the influence of matrix physical properties on flow characteristics in dual-media. It can be seen that the matrix system contributes more to the porosity of the dual media and less to the permeability. With the decrease in matrix pore density, the porosity/permeability contributions of matrix system to dual media keep decreasing, but the decrease is not significant, the oil–water co-flow zone decreases and the irreducible water saturation increases, and the saturation interval dominated by the fluid flow in the fracture keeps increasing. With the decrease in matrix filling domain factor, the porosity/permeability contributions of matrix system to dual media decreases, the oil–water co-flow zone increases and the irreducible water saturation decreases, and the saturation interval dominated by the fluid flow in the fracture keeps increasing. The results can be used to explain the dual-media flow pattern under different matrix types and different fracture control volumes during tight oil production.

Listeria spp. transfers further from boots and wheels across flooring surfaces, compared with Salmonella, in the dairy context

Listeria spp. and Salmonella are important foodborne pathogens to control; their likely dissemination on floor material in dairy processing plants via contaminated vectors, like manufacturing boots and trolley wheels, and in two matrix types (reconstituted skim milk and yoghurt) was therefore evaluated. The types of microorganisms present, matrices, and vectors all statistically significantly impacted the relationship between steps/wheel rotations and the resulting concentration of bacteria transferred. Trolley wheels were shown to transfer both pathogens over a greater distance than boots alone, based on a linear model; however, taking into account the median stride of an individual, operators wearing contaminated processing boots were estimated to disseminate Listeria further than Salmonella, particularly in a yoghurt matrix (550 m2). The dissemination of Listeria and Salmonella by movable vectors may account for the apparent re-occurrence of the same strains within food manufacturing environments that appear to be too distant from known harbourage niches.