Green Marble Research Articles

Global Forest Visualization; From Green Marbles to Storyworlds, by Lynda Olman and Birgit Schneider

Global Forest Visualization; From Green Marbles to Storyworlds, by Lynda Olman and Birgit Schneider

White and some colored marbles as alternative radiation shielding materials for applications

ABSTRACT In this paper, the radiation shielding parameters such as linear attenuation coefficients (LAC, µ), mass attenuation coefficients (MAC, µ/ρ), effective atomic numbers (Zeff), effective electron densities (Neff), half value of layers (HVL), mean free paths (MFP) and buildup factors (exposure (EBF) and energy absorption (EABF)) were investigated for cream (M1), pink (M2), white (M3), maroon (M4) and green (M5) marbles. Attenuation coefficients were measured in the energy region 31.18–661.66 keV photon energies. The values of Zeff and Neff were then calculated using these coefficients with logarithmic interpolation method, and HVLs and MFPs were calculated using the values of LAC of marble samples at the same photon energies. The experimental results were compared with the theoretical values obtained from WinXCom program, and good agreements were observed between the experimental and theoretical results. HVLs and MFPs of all marble samples were compared with those of some concretes, glasses and commercial radiation shielding glasses (SCHOTT Co.). The studied marbles were better radiation shielding materials than standard shielding concretes due to lower HVL and MFP values lower than the ordinary concrete. Finally, EBFs and EABFs of the marbles were calculated in the energy region 0.015–1 MeV up to penetration depths of 40 mfps by Geometric Progression method (G-P), and the results were discussed in terms of photon energies and chemical compositions of the marbles.

Tracking with (Un)Certainty.

One of the highest ambitions in educational technology is the move towards personalized learning. To this end, computerized adaptive learning (CAL) systems are developed. A popular method to track the development of student ability and item difficulty, in CAL systems, is the Elo Rating System (ERS). The ERS allows for dynamic model parameters by updating key parameters after every response. However, drawbacks of the ERS are that it does not provide standard errors and that it results in rating variance inflation. We identify three statistical issues responsible for both of these drawbacks. To solve these issues we introduce a new tracking system based on urns, where every person and item is represented by an urn filled with a combination of green and red marbles. Urns are updated, by an exchange of marbles after each response, such that the proportions of green marbles represent estimates of person ability or item difficulty. A main advantage of this approach is that the standard errors are known, hence the method allows for statistical inference, such as testing for learning effects. We highlight features of the Urnings algorithm and compare it to the popular ERS in a simulation study and in an empirical data example from a large-scale CAL application.

Learning Probabilities: Towards a Logic of Statistical Learning

We propose a new model for forming beliefs and learning about unknown probabilities (such as the probability of picking a red marble from a bag with an unknown distribution of coloured marbles). The most widespread model for such situations of 'radical uncertainty' is in terms of imprecise probabilities, i.e. representing the agent's knowledge as a set of probability measures. We add to this model a plausibility map, associating to each measure a plausibility number, as a way to go beyond what is known with certainty and represent the agent's beliefs about probability. There are a number of standard examples: Shannon Entropy, Centre of Mass etc. We then consider learning of two types of information: (1) learning by repeated sampling from the unknown distribution (e.g. picking marbles from the bag); and (2) learning higher-order information about the distribution (in the shape of linear inequalities, e.g. we are told there are more red marbles than green marbles). The first changes only the plausibility map (via a 'plausibilistic' version of Bayes' Rule), but leaves the given set of measures unchanged; the second shrinks the set of measures, without changing their plausibility. Beliefs are defined as in Belief Revision Theory, in terms of truth in the most plausible worlds. But our belief change does not comply with standard AGM axioms, since the revision induced by (1) is of a non-AGM type. This is essential, as it allows our agents to learn the true probability: we prove that the beliefs obtained by repeated sampling converge almost surely to the correct belief (in the true probability). We end by sketching the contours of a dynamic doxastic logic for statistical learning.

Provenance of white and colored marbles from the Petra garden and pool complex, Petra, South Jordan

This study investigates the provenance of architectural white and colored marbles excavated from the Petra Garden and Pool Complex (PGPC), south Jordan. Although the original context of the studied material is unidentified, sourcing these marbles adds to the classical and late antique studies of marble exploited in the decoration of Petra’s luxury architecture. Macroscopic characterization of all white and colored samples was followed by detailed thin section petrography and δ13C and δ18O isotope and X-ray diffraction analyses of selected 18 white and 1 green samples. The data obtained were compared with the main published reference databases of known Mediterranean white and colored marble quarries exploited in antiquity. The green marble is most likely cipollino verde from Euboea (Greece). The results of the twelve fine-grained white marbles show one sample from Carrara (Italy), two samples from the Paros-1 (Greece), seven samples from Penteli (Greece), and two samples from unknown sources. The latter two samples represent anomalous cases of dolomitic marble of very fine grains and high negative δ18O values. Of the six medium-coarse-grained white marbles, one is Naxian (Greece), two are Thasos-3 (Greece), and three are Paros-2 (Greece). The colored marbles are most likely africano and pavonazzetto from Teos and Afyon, respectively (Anatolia), cipollino verde from Euboea (Greece), giallo antico from Chemtou (Tunisia) and alabaster from Beni Suef and Asyut provinces (Egypt). The absence of the Anatolian white marbles from the PGPC assemblage corresponds with its date to the first century BCE—the first century CE before the diffusion of Prokonnesos marble. The results improve our understanding of Petra’s stones trade for both white and colored marbles to quarries hitherto not identified.

Foreign Body in the Sphenoid Sinus

Dear Editor,
 Foreign bodies in the paranasal sinuses are not so common, but are still possible. The structures most often involved are maxillary and the frontal sinuses.1 In our case, the sphenoid sinus, which is posterior and deep, was involved. Having a foreign body lodged in the sphenoid sinus, and considering how it got there, put the patient at great risk of possible involvement of the optic nerve and the carotid artery. Accessing the sphenoid sinus and removing the foreign body lodged in it would be a big challenge to any surgeon. We report one such case.
 Case Report
 A 22 year old man, was accidentaly shot in the face by a fellow criminology student while playing with a polyvinyl chloride (PVC) handmade gun two weeks prior to admission. The patient, who was conscious, coherent, and ambulatory at that time, was brought to a local government hospital where facial CT scans revealed a radio-opaque, well rounded foreign body, approximately measuring 1.5 cm x 1. 5 cm in diameter, lodged in the sphenoid sinus. (Figure 1 A, B)
 He was subsequently admitted on Penicillin G and was eventually discharged. On his fourth post-injury day, he had profuse epistaxis from the right nostril and consulted at the emergency room of our medical center. Anterior nasal packing did not control the bleeding, and was converted to a posterior nasal pack. A sutured wound with a scab on the left lateral nasal root was also noted. (Figure 2) The rhinology Service consultants advised endoscopic removal of the foreign body under general anesthesia. Intraoperatively, the nasal cavity was congested, with slight septal deviation to the right and a collapsed postero-superior septal wall. Behind the postero-superior 3rd segment of the middle meatus, sphenoethmoidal recess was appreciated. On further exploration, a 1.5 cm x 1.5 cm green marble was seen lodged in the sphenoid sinus. An initial attempt to remove the foreign body using a nasal foreign body extractor failed. An improvised large metallic paper clip, molded to the shape of a curved foreign body extractor was also unsuccessful. A cotton pledget tip dipped in cyanoacrylate (super glue) also failed to have the marble attach to it. Two angulated sharp foreign body extractors insinuated using the four hand technique yet again failed. The collapsed posterior end of the nasal septum was removed using a cutting forceps for better visualization and access, and on the last attempt, a bent spoon was used to scoop out marble out of the sphenoid sinus was successful. (Figure 3) Full extraction of the foreign body was achieved by dislodging the marble towards the nasopharynx and into the oral cavity, without compromising the optic nerve and the carotid artery. (Figure 4)
 
 Discussion
 It is very common to see a foreign body in the nasal cavity or in the external ear canal, but seeing it in unlikely places like the sphenoid sinus is such a surprise. Many factors need to be considered in the decision to extract it. One factor to consider is the approach to the sphenoid sinus. There are two different approaches to the sphenoid sinus, external and internal. The external, trans-ethmoidal approach involves subperiosteal elevation and ethmoidectomy.2 Internal approaches such as the trans-septal and trans-nasal are less-invasive ways to access the sphenoid sinus. Because of ease in access, minimal damage to surrounding mucosa, and good exposure, the trans-nasal approach was used. Whatever approach the surgeon chooses, it is important to be familiar with the surgical anatomy to prevent unwanted complications. Creativity also played a role in this procedure, and quick thinking was needed, since the foreign body was a round object and extracting it from such a limited space with utmost care, using makeshift instruments, was critically challenging.
 Alvin B. Javierto, MD
 Josefino G. Hernandez, MD
 Rodante A. Roldan, MD
 Rizal Medical Center
 Pasig Blvd., Pasig City 1600 
 Tel: 671-9740 Fax: 671-4216 Email: info@rizalmedicalcenter.gov.ph

On the Investigation of the Energy Efficiency Using PID and Fuzzy Logic Controllers in a Marble Machine

Energy consumption is the main cost item in the cutting machines with diamond segmented circular sawblade. Therefore, there are many benefits of taking measures for reducing the energy consumption. The aim of presented experimental study is to develop control methods to reduce energy consumption in marble cutting process. In the study, cutting experiments were performed with a fully computer controlled test rig for three natural rocks (Burdur beige and Usak green marbles and Afyon travertine). The experiments were carried out on two modes (manual and automatic). While travel speed is kept fixed in manual mode as usual in industry, it is controlled by a controller embedded closed control loop during the cutting process in automatic mode. Other machine parameters, such as sawblade rotation speed, cutting depth and flowing speed of cooling water, are kept fixed in all experiments. In designed closed control loop, PID and FL controllers widely used in industry were used to control travel speed. Obtained results show that if the travel speed is controlled during cutting process, energy saving can be ensured by of controllers for the three rocks.

Control Applications for Energy Saving in Marble Machining Process

Energy consumption is the main cost item in the marble cutting process by using segmented circular sawblade. Therefore, there are many benefits to take measures for reducing the energy consumption. The aim of this study is to reduce electricity consumption in marble cutting process by using control methods. In the study, cutting experiments were performed with a fully computer controlled test rig for three natural rocks (Burdur beige and Usak green marbles and Afyon travertine). The experiments were carried out on two modes (manual and automatic). In the experiments, travel speed is kept fixed in manual mode as usual in industry. In the experiments performed on automatic mode, travel speed is controlled by a controller embedded closed control loop during the cutting process. In addition other machine parameters such as sawblade rotation speed, cutting depth, flowing speed of cooling water are kept fixed in all experiments. In designed control systems, floating and PID controllers are used to control travel speed. Obtained results are showed that, if the travel speed is controlled during cutting process, energy saving can be provided in both of two controllers for all of three rocks.

Serpentinites from Cabo Ortegal (Galicia, Spain): a search for correct use as ornamental stones

Abstract Different varieties of serpentinites present at Cabo Ortegal were studied. For many years, the ‘Verde Pirineos’ type has been quarried and sold commercially, but its physical characteristics do not fulfil the requirements for its use as an ornamental stone. ‘Piedra de Doelo’ is the local name for a serpentinite that has been quarried and used for many centuries in a large number of historical buildings distributed throughout the area. The preservation status of the rock is very poor and the stone is severely affected by weathering. A third variety, similar to the ‘ophicalcite’ described in the literature, is currently under investigation with a view to studying the possibility of the resumption of serpentinite quarrying. Although serpentinites are commercially known as ‘green marbles’, Galician serpentinites do not fulfil the mineral requirements to be described as such. Study of the characteristics of serpentinites, including their mineralogy, may offer a clue to the correct use of Galician serpentinites.

Laser-induced breakdown spectroscopic studies of marbles

We present laser-induced breakdown spectroscopic studies of variety of marbles extracted from Quetta region of Boluchistan, Pakistan using a Nd:YAG laser (532 nm) in conjunction with LIBS 2000 detection system. The emission spectra of Onyx (white spot) and Quetta Green Marble samples have been recorded as a function of laser irradiance. The elemental composition and their relative abundance in each sample are fond to be quite different. In Onyx (white spot), calcium dominates while in the Quetta Green marble magnesium is the dominant element. In addition the effect of the laser irradiance on the emission intensity, width and shift of the transition lines have been studied.

Dental Health among Green Marble Mine Laborers, India

ABSTRACTObjectiveTo determine the oral health status among Green Marble Mine laborers; to provide epidemiological data for planning and evaluation of oral health care programme.MethodsThe study area was divided into 4 geographic zones, and participants were selected by stratified cluster sampling technique. A total of 513 subjects were included in final study which were divided among the four age cohort (18-25, 26-34, 35-44, 45-more respectively), following the guidelines for research methodology recommended by WHO oral health surveys 1997. Clinical examination was conducted by one of the three examiners with the aid of an artificial light sorce. The agreement (kappa statistics) for diagnosis of DMFT and CPI was determined (field teams versus expert) 91.2 % two days prior to the examination. Data was analyzed using Bivariate and multivariate analysis.ResultsThe mean DMFT and DMFS scores were (2.79±2.44) and (5.47±5.40) respectively. The caries prevalence was 71.1% with maximum in 25-34 years while 148 participants were caries free. A higher prevalence of periodontal disease was present with only 1.75% having healthy gingiva. Mean number of sextant involved was maximum among 35-44 years. Alcohol and Stress due to physical load and noisy environment among laborers have shown highly significant relationship with CPI scores (P<0.001). Fracture of tooth, mainly maxillary central incisor was high (10.5%) as an occupational peril.ConclusionsThe findings highlighted the low caries prevalence, higher periodontal disease which requires primary anticipation. Prevention of tooth fracture and improvement of overall nutritional status, with stress reduction protocol should also be given consideration.

Characterization of serpentinites to define their appropriate use as dimension stone

Abstract Many questions arise when considering the appropriate use of building stones such as serpentinites. The commercial names of these rocks, collectively grouped as ‘Green marbles’, have no correspondence to their actual mineralogy, geochemistry and/or physical characteristics. Serpentinite being the hydrated product of an ultramafic parent rock and not a metamorphic product of limestone as implied by the term ‘marble’. However, the serpentinites most widely used for ornamental purposes come from India (e.g. Rajasthan Green, Emerald Green) and in these the original mineralogy has been almost completely converted into carbonates. By contrast, serpentinites from elsewhere (e.g. Vermont Verde Antique from the USA and Verde Pirineos from Spain) do preserve some of their original mineralogy. The different physical and chemical behaviour of carbonates and serpentine minerals can result in significantly different behaviour of commercial building stones. Thus, carbonates are resistant to weathering but suffer from acidic cleaning agents in interior use; whereas serpentinites, with a high content of talc, used on external faces undergo an increase in volume and a consequent rapid degradation. Accurate and precise characterization of serpentinites, including information on their mineralogy and geochemistry (including major, trace and volatile elements together with oxygen isotopes), in conjunction with their physical properties, would enable architects to select the appropriate interior or exterior use of these handsome building stones.

Narrative and allegory in Giambologna's Rape of a Sabine

How should a viewer begin interpreting human figures in a representational sculpture group? If the sculpture in question suggests inspiration from an earlier literary work, the problem becomes interdisciplinary. Reading the story commonly referred to as the ‘rape of the Sabine Women,’ in the first book of ab urbe condita, the history of Rome, by Titus Livius (Livy) and viewing Giambologna's il Ratto delle Sabine (Rape of a Sabine) poses such an interdisciplinary problem. In Chambéry's Musée des Beaux Arts, there is a small, beautiful version in green Prato marble of Giambologna's Rape of a Sabine, a work known to students of Italian Mannerist sculpture from the monumental masterpiece set in the Loggia dei Lanzi in Florence. The Chambéry statue, standing 210 centimeters high with its pedestal, adeptly reflects on a much smaller scale Giambologna's most celebrated monumental sculpture. Like the monumental sculpture in Florence, the Chambéry statue bears a relief sculpture on the pedestal that refers to the story first recounted in Livy. Also like the masterpiece in Florence, the Chambéry statue shows a dramatic, upward-twisting group of three figures all carved from a single block of marble. At the bottom of the group a nude, finely built, mature, bearded man crouches, supporting himself with his right arm, and shielding his face with his bent left arm. A young, nude, robust male strides over the crouching bearded man, and carries in his arms a nude, young woman. The young woman's arms, torso, and legs form an amazing pattern of interconnected S-shapes, a virtuoso display of the figura serpentinata. She thrusts her left leg downwards and backwards while bending her right leg at the knee. As she struggles in the arms of the youth she tosses her head back, thus pushing her small and shapely breasts forwards. Meanwhile she stretches her left arm upwards while letting her bent right arm fall down towards the bearded man.