Dark Vessels Research Articles

Dark pottery from the early Iron Age in southern Veneto, Italy: The provenance issue under the adoption of specific technological procedures

One of the earliest known settlements of Pre-Roman Padua, Veneto Region (north-eastern Italy) was located in the very centre of the present-day city. The archaeological excavations revealed structures related to craft activities (metallurgical and pottery workshops) and residential areas datable from the late 9th to the 1st century BCE. A large pyrotechnic structure formed by an earthen block densely filled and covered by broken ceramic vessels was found, bringing to light the earliest foundry of the Pre-Roman Padua known to date. Many potsherds found in the site correspond to a regional ceramic class that included coarse and fine wares mainly composed of very dark ceramic bodies. A multi-analytical study based on macroscopic and petrographic descriptions as well as mineralogical, geochemical and microstructural analyses, was carried out in order to state the technological choices adopted for producing these dark vessels and the provenance of the raw materials. A poorly manufacturing was adopted to produce the common pottery, resulting coarse wares uneven textured, while the fine wares were produced by adopting the purification of the base clays and/or the tempering of the clay pastes. Common geo-resources were used, consisting in illitic-chloritic clays rich in quartz and feldspars, the firing regime conditions covered a range of maximum temperatures (normally under 850 °C) and the temper was constituted by silicate (chiefly quartzite, rhyolite and trachyte rock fragments) and/or carbonate (calcite and/or dolomite) inclusions, that were added after having been grounded and/or sieved. The specific mineral and lithic markers of provenance identified in the sherds confirmed the correspondence of this pottery with a local production. However, the specific technological choices that were carried out must be taking into consideration, since the purification removed the larger grains originally present in the base clays and the tempering influenced the chemical composition of the sherds. The different degree of purification of the base clays and the differential tempering procedures that were accomplished point out the adoption of very specific recipes to produce the fine wares, suggesting the correspondence of this local ceramic class with diverse sub-productions and the high level of specialization achieved by the potters in southern Veneto during the Early Iron Age.

The Big Picture: An Improved Method for Mapping Shipping Activities

Density maps support a bird’s eye view of vessel traffic, through providing an overview of vessel behavior, either at a regional or global scale in a given timeframe. However, any inaccuracies in the underlying data, due to sensor noise or other factors, evidently lead to erroneous interpretations and misleading visualizations. In this work, we propose a novel algorithmic framework for generating highly accurate density maps of shipping activities, from incomplete data collected by the Automatic Identification System (AIS). The complete framework involves a number of computational steps for (1) cleaning and filtering AIS data, (2) improving the quality of the input dataset (through trajectory reconstruction and satellite image analysis) and (3) computing and visualizing the subsequent vessel traffic as density maps. The framework describes an end-to-end implementation pipeline for a real world system, capable of addressing several of the underlying issues of AIS datasets. Real-world data are used to demonstrate the effectiveness of our framework. These experiments show that our trajectory reconstruction method results in significant improvements up to 15% and 26% for temporal gaps of 3–6 and 6–24 h, respectively, in comparison to the baseline methodology. Additionally, a use case in European waters highlights our capability of detecting “dark vessels”, i.e., vessel positions not present in the AIS data.

Automated remote sensing tools to counter illicit maritime activity: vessel detection, bathymetry and topography from WorldView imagery

ABSTRACT Illicit maritime activity, such as piracy and smuggling, is a global issue that often occurs in areas where interdiction authorities are sparse, ground-based monitoring technologies like radar lack range and coverage, and dark vessels abound. Our objective was to assess vessel congregation patterns, identify likely beaching areas based on terrain maps, and use them to narrow the search for potential smuggling transfer and overland routes in a specific region along the Puntland coast of Somalia. To accomplish this goal, we developed automated protocols applied to WorldView satellite imagery for (1) vessel detection and size classification, (2) shallow-water bathymetric characterization, and (3) coastal topography mapping. Utilizing a single sensor for vessel detection and topographic and bathymetric extraction at high spatial resolution and at a high re-visit rate provides a simplification to near-shore characterization for monitoring purposes. The extracted topography and bathymetry are then presented as a single, comprehensive perspective of a coastal region. The vessel-detection algorithm identified all vessels larger than approximately 15 metres in length (35 of 35), but misidentified six artefacts (i.e. false positives), resulting in an overall accuracy of 85%. The combined vessel and terrain maps facilitated the identification of a potential beaching and overland transportation route location.

Towards Automatic Recognition of Wakes Generated by Dark Vessels in Sentinel-1 Images

The recognition of wakes generated by dark vessels is a tremendous and interesting challenge in the field of maritime surveillance by Synthetic Aperture Radar (SAR) images. The paper aims at assessing the detection performance in different scenarios by processing Sentinel-1 SAR images along with ground truth data. Results confirm that the Radon-based approach is an effective technique for wake-based detection of dark vessels, and they lead to a deeper understanding of the effects of different sea and wind conditions. In general, the best applicative scenario is a marine image characterized by homogeneous sea clutter; the presence of natural surface film or strong transition from low wind speed areas to more windy zones worsen the detection performance. Nonetheless, the proposed approach features dark vessel detection capabilities by identifying their wakes, without any a priori knowledge of their positions.

No longer a secret: advanced satellite technologies monitor illegal ‘dark vessels’

The activity of ‘dark vessels’ – vessels that do not share their locations – hampers nations’ efforts to make fisheries transparent and accountable. Using cutting-edge satellite technologies, we uncovered the largest illegal fishing in history conducted by dark vessels in North Korea. - submission by Jaeyoon Park

Near-infrared reflectance imaging of neovascularization in proliferative diabetic retinopathy

BackgroundBlood is one of the main absorbers in the near-infrared spectrum and thus retinal vessels appear dark in near-infrared reflectance (NIR) images. Proliferative diabetic retinopathy (PDR) is characterized by abnormal neovascularization which also absorbs light and appears dark against a lighter fundus background. We analyzed neovascularization in PDR using NIR imaging, by observing changes in the neovascular complexes (NVCs) contrast and reflectivity over time.MethodsRetrospective case series of 20 eyes of 17 patients with PDR who underwent NIR imaging with optical coherence tomography (OCT) using the Spectralis System. NVCs presence and activity was determined using clinical, tomographic and angiographic criteria. At baseline, all NVCs were qualitatively graded in the NIR image into 3 groups (absent, present and inactive and present and active) and their evolution over time was registered as progression, regression or same status.ResultsTwenty-seven NVCs were imaged, of which, 52% were neovascularization of the disc (NVD) and 48% were elsewhere (NVE). Consecutive NIR images were obtained from baseline to up to 5 time-points with a mean follow-up of 3.2 ± 1.7 years. All eyes underwent laser treatment and 30% had additional intravitreal therapy. Using NIR imaging, NVCs were classified at baseline as absent, present and inactive and present and active, respectively in 11, 4 and 85% of cases. NIR identified active neovascularization as hyporeflective irregular dark vessels originating from the retinal venules in NVE or from the disc in NVD. In all groups during follow-up, progression was identified as the development of new vascular hyporeflective dark fronds while regression was shown by reduced dark perfusion. Five eyes developed a wolf’s jaw configuration with vascular hyporeflective new vessels and hyperreflective tissue from extensive fibrosis. Fibrosis was more apparent in later images, reaching 86%. In 3 cases (11%), the NVC was no longer seen in NIR, although was still identifiable on OCT over the NVC area.ConclusionsNIR is a non-invasive imaging modality commonly performed alongside OCT and frequently overlooked which can be useful to evaluate NVCs in PDR. Changes in NVC contrast and reflectivity due to blood perfusion can help in the detection and monitoring of diabetic proliferative disease and aid clinicians in daily practice.

Compositional study of bronze vessels from the Derveni tombs of central Macedonia of the fourth century bce using energy‐dispersive micro‐X‐ray fluorescence (EDμXRF) spectrometry

The chemical composition of 61 copper alloy vessels was studied non‐invasively by energy‐dispersive micro‐X‐ray fluorescence (EDμXRF) spectrometry. The vessels were found in five tombs (A, B, D, Z and H) at Derveni in central Macedonia, Greece, which belong to the cemetery of the ancient city of Lete. The tombs are dated to the last quarter of the fourth century bce. The opulence of the numerous grave offerings denotes the high social status of the deceased within Macedonian society. The material under study was divided into two main groups according to their appearance and use. The first group included 44 vessels with a golden appearance for use in banquets; the second group consisted of 17 dark vessels for domestic use. The aim of this research was to study the vessels' technology according to their chemical composition. Both golden and dark vessels consisted of a binary Cu‐Sn alloy and a slight amount of impurities (Fe, Ni, Zn, Pb, As, Co, Sb, Ag, Ti). It is probable that during construction the ancient metalsmiths were taking into account criteria such as the desired appearance, cost of metals, future use and physical properties such as resistance to corrosion. Banquet vessels had a consistent chemical composition in all their different parts compared with those for domestic use. The only chemical element used systemically for alloying purposes, except Sn, was Pb in order to improve the castability of the bases and handles of the vessels. The study provides additional information about the metalworking of bronzes in central Macedonia in the fourth century bce, as well as about the access Macedonian metalworkers had at the time to the raw materials for such use.

Large-Scale Automatic Vessel Monitoring Based on Dual-Polarization Sentinel-1 and AIS Data

This research addresses the use of dual-polarimetric descriptors for automatic large-scale ship detection and characterization from synthetic aperture radar (SAR) data. Ship detection is usually performed independently on each polarization channel and the detection results are merged subsequently. In this study, we propose to make use of the complex coherence between the two polarization channels of Sentinel-1 and to perform vessel detection in this domain. Therefore, an automatic algorithm, based on the dual-polarization coherence, and applicable to entire large scale SAR scenes in a timely manner, is developed. Automatic identification system (AIS) data are used for an extensive and also large scale cross-comparison with the SAR-based detections. The comparative assessment allows us to evaluate the added-value of the dual-polarization complex coherence, with respect to SAR intensity images in ship detection, as well as the SAR detection performances depending on a vessel’s size. The proposed methodology is justified statistically and tested on Sentinel-1 data acquired over two different and contrasting, in terms of traffic conditions, areas: the English Channel the and Pacific coastline of Mexico. The results indicate a very high SAR detection rate, i.e., >80%, for vessels larger than 60 m and a decrease of detection rate up to 40 % for smaller size vessels. In addition, the analysis highlights many SAR detections without corresponding AIS positions, indicating the complementarity of SAR with respect to cooperative sources for detecting dark vessels.

Production of Chocolate Powdered Beverage with Enhanced Instant Properties

Instant properties of chocolate powder such as solubility and dispersibility are important factors for the quality and consequently consumer acceptance of the final powdered beverage. With the aim of producing a novel powdered chocolate beverage with enhanced instant solubility, we studied the effect of spray drying process on the components of the chocolate powder. Spray drying of chocolate beverage formulation (complete recipe provided and protected by Domori s.r.l., Italy) was performed using a mixture of cocoa powder and sucrose 30:70 (w/w). Liquid feed was prepared by dissolving 17.5 g of powder in 100 mL of deionized water at 60 °C and mixed until complete homogenization. The solution was fed to a mini spray dryer B-290 (Buchi, Huddersfield, UK). In this work an inlet temperature of 150 °C was used. Maltodextrin concentration (0, 3.5 and 7 % w/w) and drying air flow rate (22, 27 and 32 m3/h) were varied. Powders were stored at 4 °C in closed dark vessels before analysis. The results of full factorial design showed that operating at a drying air flow rate of 27 m3/h and a maltodextrin concentration of 3.5 % w/w, powder with solubility of 74.2 ± 6.8% and dispersibility of 58.7 ± 2.9% was achieved. At this operative condition, powder recovery yield was almost consistent with the industrial one (45.5 ± 2.5%). Therefore, spray drying presents a useful way to produce chocolate powder with better instant solubility, which can also be dissolved in less amount of water (70 mL instead of 120 mL).

Bright and dark vessels on stroke imaging: different sides of the same coin?

Prominent hypointense cerebral vessels on susceptibility-weighted imaging (SWI) and the hyperintense vessel sign (HVS) on fluid-attenuated inversion recovery (FLAIR) imaging are considered as markers of compromised tissue perfusion in cerebral ischemia. In this study, we aimed to identify the correlation between HVS on FLAIR and hypointense vessels on SWI, and to determine whether these imaging features provide independent prognostic information in patients with ischemic stroke. We retrospectively analyzed consecutive ischemic stroke patients with proximal middle cerebral artery (MCA) occlusion who underwent SWI and FLAIR within 24 h of symptom onset. The presence of hypointense vessels on SWI and hyperintense vessels on FLAIR in >4 of 10 slices encompassing the MCA territory were considered to represent prominent hypoperfusion. Among 50 patients, 62% had a prominent HVS on FLAIR and 68% had prominent hypointense vessels on SWI. There was a moderate but significant correlation between the number of slices with HVS on FLAIR and prominent hypointense vessels on SWI (r=0.425, P = 0.002). In multivariate analyses, the prominence of hypointense vessels on SWI, but not HVS on FLAIR, was significantly associated with a higher discharge NIHSS score (P = 0.027), mRS score (P = 0.021), and lesion growth (P = 0.050). The significant, albeit moderate, correlation between markers of compromised tissue perfusion on FLAIR and SWI suggests that these imaging features reflect different but interrelated aspects of cerebral hemodynamics during ischemic stroke. Our findings highlight that while HVS on FLAIR denotes the presence of leptomeningeal collaterals, hypointense vessels on SWI signify the sufficiency of cerebral blood flow at the tissue level and are therefore more critical in terms of prognosis.

Gradient-based enhancement of tubular structures in medical images.

Vesselness filters aim at enhancing tubular structures in medical images. The most popular vesselness filters are based on eigenanalyses of the Hessian matrix computed at different scales. However, Hessian-based methods have well-known limitations, most of them related to the use of second order derivatives. In this paper, we propose an alternative strategy in which ring-like patterns are sought in the local orientation distribution of the gradient. The method takes advantage of symmetry properties of ring-like patterns in the spherical harmonics domain. For bright vessels, gradients not pointing towards the center are filtered out from every local neighborhood in a first step. The opposite criterion is used for dark vessels. Afterwards, structuredness, evenness and uniformness measurements are computed from the power spectrum in spherical harmonics of both the original and the half-zeroed orientation distribution of the gradient. Finally, the features are combined into a single vesselness measurement. Alternatively, a structure tensor that is suitable for vesselness can be estimated before the analysis in spherical harmonics. The two proposed methods are called Ring Pattern Detector (RPD) and Filtered Structure Tensor (FST) respectively. Experimental results with computed tomography angiography data show that the proposed filters perform better compared to the state-of-the-art.

Introduction to QCA, IVUS and OCT in interventional cardiology

with the image data widely available throughout the hospital by means of cardiovascular PACS systems. Major differences were of course that on cinefilm the coronary arteries were displayed as bright arteries on a darker background, and there was always an associated pincushion distortion caused by the concave input screen of the image intensifier. With the digital systems the arteries are now displayed as dark vessels on a bright background and the modern flat panel X-ray detectors are free from geometric distortions. Although there have been many years of debate about the resolution of cinefilm versus digital, the higher contrast resolution of the digital approach has compensated much of the higher spatial resolution of the 35 mm cinefilm, and thus digital has been completly accepted. Also, extensive validation studies have not proven major differences in accuracy and precision between cinefilm and digital: the variability in the analysis is for both in the order of about pixel, or 0.11 mm [2, 3]. For many years, quantitative coronary arteriography (QCA) has been used in clinical research in the hospitals and in core laboratories to assess regression and progression of coronary obstructions in pharmacological interventions, to assess the efficacy of coronary interventions after the introduction of PTCA and stenting by bare-metal (BMS), drug-eluting (DES) and presently biodegradable stents, and of course for vessel sizing. In all these cases, the analyses were done on straight vessels. New developments have been directed at bifurcation stenting and the associated QCA, and on 3D QCA and registration with IVUS/ OCT. These new issues are elegantly described in the section guest edited by Ricardo A. Costa. It has been well recognized for many years that despite the wide availability of the angiogram and the QCA, an angiogram is only a lumenogram, and that the disease is in the vessel wall. For proper decision making purposes, the interventionalist must know what the composition is of the plaque. This was made possible with intravascular ultrasound, but with the recent advent of Virtual Histology and the iMAP, even more information has become available, which has revived the field of intravascular ultrasound. In this issue, all the possibilities, limitations and applications of IVUS in interventional cardiology are clearly described in the papers selected by guest

Advantages and limitations of two software calipers in quantitative coronary arteriography

Software calipers allowing the measurement of the distances between pairs of manually defined picture elements in digitized images may be useful tools for a rapid assessment of the morphology of coronary vessels, e.g. for choosing the appropriate balloon or stent sizes before or during cardiac intervention procedures. In this paper we have studied extensively the advantages and limitations of two manual software calipers--one developed for a PC-based cinefilm analysis workstation, the other for the Philips DCI system. Based on analyses of a perspex vessel phantom with 17 sectors of known size filled with different concentrations (50 and 100%) of the contrast agent and acquired at two kV-levels (68 and 92 kV), it was found that the cinefilm approach is characterized by a very small overall (averaged over te data from three observers) systematic overestimation of 0.03 mm, and the DCI system by a systematic underestimation of 0.07 mm; the worst case accuracy value for an individual observer on frames with 100% contrast dye concentration was 0.20 mm for cinefilm, and -0.34 mm for the DCI, respectively. The overall variabilities in the measurements (precision) were almost identical for the two approaches (overall 0.07 and 0.08 mm for the cinefilm and digital approaches, respectively, and worst case for individual observers on the 100% contrast frames, 0.16 and 0.13 mm, respectively. Inverting the images (bright or dark contrast containing structures) of the phantom at 100% contrast concentration and acquired at 62 kV had no significant effect on the results obtained with the cinefilm analysis system (overall accurary -0.12 mm for both situations), whereas it had on the results from the DCI system (overall accuracies -0.29 (dark vessels on bright background) and -0.08 mm (bright vessels on dark background), respectively). Enhancing the digital images on the DCI with unsharp masking techniques did not significantly influence the measurement accuracy and precision. Finally, it was found that woven dacron, polyurethane and polyvinylchloride catheters filled with 100% contrast dye can be measured with an overall accuracy of better than 0.13 mm on the DCI system. On the PC-based system the woven dacron and polyvinylchloride catheters would result in an overall accuracy better than 0.17 mm, and the polyurethane catheter better than 0.30 mm. The evaluation study has made clear that the nylon catheter should not be applied in QCA-studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxygen utilization by fishes and other aquatic animals.

A. Lowering of the temperature causes a reduction in the rate of oxygen consumption. In one case, while one lot of fishes consumed 78 per cent. of the available oxygen supplied at 12° C; a similar lot of fishes in water 4° colder consumed but 60 per cent. In a second case, a fish in water at 20° C. consumed 94 per cent. of the oxygen present while a similar fish at 3° C. consumed but 57 per cent. Breathing had ceased in this case but was resumed on return to warmer water.B. It was noted that oxygen was consumed more rapidly in tall, narrow vessels of water than in broad shallow ones. Fishes moving about in shallow vessels of water tend to reaerate the same. In one experiment to test this, one lot of fishes in tall narrow vessels of water consumed 80 per cent. of the oxygen supply, while in the broad shallow water at the end of the same period, the analysis indicated a reduction of but 20 per cent. of the original oxygen supply.C. Fishes kept in dark vessels apparently consume oxygen at a less rapid rate t...