Ground Glasses Research Articles

Speckle-based deep learning approach for classification of orbital angular momentum modes.

We present a speckle-based deep learning approach for orbital angular momentum (OAM) mode classification. In this method, we have simulated the speckle fields of the Laguerre-Gauss (LG), Hermite-Gauss (HG), and superposition modes by multiplying these modes with a random phase function and then taking the Fourier transform. The intensity images of these speckle fields are fed to a convolutional neural network (CNN) for training a classification model that classifies modes with an accuracy >99%. We have trained and tested our method against the influence of atmospheric turbulence by training the models with perturbed LG, HG, and superposition modes and found that models are still able to classify modes with an accuracy >98%. We have also trained and tested our model with experimental speckle images of LG modes generated by three different ground glasses. We have achieved a maximum accuracy of 96% for the most robust case, where the model is trained with all simulated and experimental data. The novelty of the technique is that one can do the mode classification just by using a small portion of the speckle fields because speckle grains contain the information about the original mode, thus eliminating the need for capturing the whole modal field, which is modal dependent.

Exploring the efficacy of emerging reactivity tests in screening pozzolanic materials

This paper presents the assessment of the reactivity of pozzolans using various emerging reactivity test methods. A wide range of pozzolans representing different classes, including coal combustion products, natural pozzolans and ground glasses, were used in this study. Pozzolans were tested for reactivity quantification in calcite-lime-pozzolan systems in mortar cubes at 40 °C in a modified lime-reactivity test. The existing strength-activity index test, ASTM C311/C618, was modified by producing mortars of portland cement-pozzolan systems at a constant water-to-binder ratio. The bulk electrical resistivity of mortar cubes was measured in both modified lime-reactivity and modified ASTM C311/C618 tests before compressive strength was measured. Select pozzolans were also investigated in pastes using the recently developed R3 heat release test using isothermal calorimetry. The same pastes were then tested for lime consumption by pozzolans using thermogravimetric analysis. The outputs of the modified lime-reactivity test at 7 days are in moderate to strong agreement with the results of other reactivity tests. In mixtures with binders containing portland cement resistivity measurements better differentiate pozzolans based on reactivity; whereas, early-age strength developments are favored by the physical contribution of pozzolans. The resistivity and strength of portland cement-pozzolan mortars in the modified ASTM C311/C618 at 28 days or later and in the modified lime-reactivity test at 7 days are found to be reliable proxies of the reactivity of pozzolans. When strength and resistivity both are jointly considered a sound and balanced quantification of the pozzolanic reactivity is achieved.

Efficiency of natural pozzolans, ground glasses and coal bottom ashes in mitigating sulfate attack and alkali-silica reaction

The use of pozzolans to partially replace Portland cement in concrete has generally demonstrated beneficial impacts on the durability characteristics of concrete for decades. In this paper a diverse range of pozzolans including natural pozzolans, ground glasses and industrial by-products such as coal ash (fly ash and bottom ash) and silica fume were investigated for their synergistic potential in binary or ternary blends with Portland cement in improving resistance to chemical sulfate attack and alkali-silica reaction (ASR). It is generally considered that pozzolans improve most of the durability issues encountered in concrete, including reducing the risk of sulfate attack or ASR. But this is not always the case. For example, it was found that ground glasses were very efficient in improving sulfate resistance, but their ability to mitigate expansion due to ASR was dictated by the equivalent alkalis content (Na2Oe) of the glass and high-alkali soda glass was generally not effective in this role. On the other hand, metakaolin, a highly reactive pozzolan, was highly effective in reducing ASR expansion, but may actually increase the damage due to sulfate attack when used at moderate replacement levels. Most pozzolans, such as low-CaO coal fly ash and ground coal bottom ash, silica fume, and pumice, were effective in controlling expansion due to both ASR and sulfate attack. The results demonstrated that the extent of the positive impact of using natural pozzolans on both properties was variable. The pozzolanic reactivity of materials alone was an unreliable indicator to assess the ability of the pozzolan to suppress expansion due to sulfate attack or ASR.

Generalizing the Gerchberg–Saxton algorithm for retrieving complex optical transmission matrices

The Gerchberg–Saxton (GS) algorithm, which retrieves phase information from the measured intensities on two related planes (the source plane and the target plane), has been widely adopted in a variety of applications when holographic methods are challenging to be implemented. In this work, we showed that the GS algorithm can be generalized to retrieve the unknown propagating function that connects these two planes. As a proof-of-concept, we employed the generalized GS (GGS) algorithm to retrieve the optical transmission matrix (TM) of a complex medium through the measured intensity distributions on the target plane. Numerical studies indicate that the GGS algorithm can efficiently retrieve the optical TM while maintaining accuracy. With the same training data set, the computational time cost by the GGS algorithm is orders of magnitude less than that consumed by other non-holographic methods reported in the literature. Besides numerical investigations, we also experimentally demonstrated retrieving the optical TMs of a stack of ground glasses and a 1-m-long multimode fiber using the GGS algorithm. The accuracy of the retrieved TM was evaluated by synthesizing high-quality single foci and multiple foci on the target plane through these complex media. These results indicate that the GGS algorithm can handle a large TM with high efficiency, showing great promise in a variety of applications in optics.

Pozzolanic reactivity of natural pozzolans, ground glasses and coal bottom ashes and implication of their incorporation on the chloride permeability of concrete

It is well understood that the partial replacement of portland cement with pozzolans in sufficient proportions results in improved long-term performance of concrete. However, dwindling availability of the most widely used pozzolan in the construction industry, fly ash, is forecast due to the termination of coal-fired electricity power stations around the world, necessitating the exploration of alternative pozzolans. Experimental investigations are conducted to study the performance of traditional pozzolans such as fly ash, silica fume and natural pozzolans (metakaolin, pumice, perlite and lassenite) together with novel pozzolans, including ground glasses (high-alkali and low-alkali), and ground bottom ash. Twenty-one concrete mixtures are examined for compressive strength, electrical conductivity, electrical resistivity, chloride permeability, and chloride migration coefficient. The reactivity of pozzolans studied is also determined in terms of compressive strength in lime-pozzolan mortar using a modified lime-reactivity test method. Many of the materials tested demonstrate the potential to be used in place of fly ash. However, a wide variation in the performance of these materials is evident which highlights the need for a reliable test to determine the level of reactivity of a pozzolan. The results indicate that the 7-day strength in the modified lime-reactivity test provides a good indication of the pozzolanic reactivity of the material and of how the material can be expected to contribute to the strength and permeability of concrete. The use of electrical resistivity as an indicator of the performance of pozzolans in terms of strength development and chloride penetration resistance when used to partially replace portland cement in concrete is also discussed.

Utilizing multiple scattering effect for highly sensitive optical refractive index sensing

The sensitivity of random optical diffraction to refractive index inhomogeneity is usually considered as a challenging obstacle for imaging or controlling light through scattering media. Here, on the opposite side, we utilize the natural randomness of strongly scattering media and their sensitivity to refractive index inhomogeneity to develop a novel optical sensor. Unlike various sensing technologies with trade-off between complexity and sensitivity, we demonstrate a very simple sensing technique, which uses just ground glass optical diffusers to achieve very high sensitivity. Light propagating through a scattering medium is scattered multiple times at multiple interfaces between ground glass and the surrounding environment creating a speckle pattern, which is sensitive to the environment’s refractive index. The correlation of speckle patterns indicates the change of refractive index around the scattering medium. Simply placing the rough surface of ground glasses in contact with sensing solution, we are able to detect the solution’s refractive index change at resolution of 3.87 × 10−6 RIU, which is equivalent to the glucose concentration change of 12 ppm. More interestingly, the sensitivity of the proposed approach could be improved simply by adding more scattering surfaces in contact with the target medium. Our simple technique could be very useful for prominent applications in refractive index sensing such as measuring concentration of solution or gas.

INFLUENZA A VIRAL PNEUMONIA ASSOCIATED WITH DIFFUSE ALVEOLAR HEMORRHAGE

SESSION TITLE: Chest Infections 2 SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: Diffuse alveolar hemorrhage (DAH) represents a life-threatening complication of many respiratory infections. We present a case of Influenza A pneumonia associated with DAH, an uncommon but likely unrecognized complication. CASE PRESENTATION: An 80-year-old female was admitted with lethargy, dyspnea and chest pain. Medical history included end stage renal disease and compensated systolic heart failure. On examination, she was afebrile with bilateral basal inspiratory crackles. Laboratory evaluation was unremarkable apart from mild anemia. Chest-roentgenogram revealed retro-cardiac infiltrate; computed tomography of chest showed left lower lobe consolidation and scattered ground glasses opacification. The patient required intubation and pressors for acute hypoxic respiratory failure and septic shock. Nasopharyngeal swabs rapid testing was positive for influenza A. She received vancomycin, piperacillin-tazobactam, azithromycin and oseltamivir. Bronchoscopy showed bilateral airway erythema and diffuse bleeding, and no endobronchial lesions. Bronchoalveolar lavage (BAL) of the left lower lobe had progressively bloody returns, consistent with DAH (Fig 1). Respiratory, urine and blood cultures were negative. Methylprednisolone 250 mg daily was started, with improvement in oxygenation. Repeat bronchoscopy 2 days later revealed normal mucosa and no mucosal bleeding (Fig 2). The patient's clinical status continued to deteriorate and she died two weeks after admission. DISCUSSION: In immunocompromised patients, the main infectious diseases that cause DAH are cytomegalovirus, adenovirus, invasive aspergillosis, Mycoplasma, Legionella, and Strongyloides. In immunocompetent patients, the infections most frequently causing DAH are influenza A (H1N1), dengue, leptospirosis, malaria, and Staphylococcus aureus infection (1). Higher fatality has been reported in patients with influenza A complicated by DAH (2). Pathological review of the influenza A (H1N1) 2009 pandemic reported mild-intense alveolar hemorrhage and intraalveolar edema (3). Advanced age and the presence of significant co-morbidities may predispose a patient not only to the development of influenza, but also to one if its most feared complications. The use of steroids, while controversial, may be a useful adjunct in patients with influenza A pneumonia and DAH. CONCLUSIONS: Elderly patients with significant co-morbidities may be at increased risk of developing DAH with influenza A pneumonia. Clinicians should maintain a high suspicion for DAH, as it may increase fatality rate. Steroids, in addition to supportive care, may have a role in management. Reference #1: von Ranke FM, Zanetti G, Hochhegger B, Marchiori E. Infectious diseases causing diffuse alveolar hemorrhage in immunocompetent patients: a state-of-the-art review. Lung. 2013 Feb;191(1):9-18 Reference #2: Prasad HB, Puranik SC, Kadam DB, Sangle SA, Borse RT, Basavraj A, Umarji PB, Mave V, Ghorpade SV, Bharadwaj R, Jamkar AV, Mishra AC (2011) Retrospective analysis of necropsy findings in patients of H1N1 and their correlation to the clinical features. J Assoc Physicians India 59:498-500 Reference #3: Soto-Abraham MV, Soriano-Rosas J, Díaz-Quiñónez A, Silva-Pereyra J, Vazquez-Hernandez P, Torres-López O, et al. Pathological Changes associated with the 2009 H1N1 virus. N Engl J Med 2009;361(20):2001-2003. DISCLOSURES: No relevant relationships by Gilda Diaz-Fuentes, source=Web Response No relevant relationships by OMESH TOOLSIE, source=Web Response

Photon superbunching of classical light in the Hanbury Brown–Twiss interferometer

Two-photon superbunching of pseudothermal light is observed with single-mode continuous-wave laser light in a linear optical system. By adding more two-photon paths via three rotating ground glasses,g(2)(0) = 7.10 is experimentally observed. The second-order temporal coherence function of superbunching pseudothermal light is theoretically and experimentally studied in detail. It is predicted that the degree of coherence of light can be increased dramatically by adding more multi-photon paths. For instance, the degree of the second- and third-order coherence of the superbunching pseudothermal light with five rotating ground glasses can reach 32 and 7776, respectively. The results are helpful to understand the physics of superbunching and to improve the visibility of thermal light ghost imaging.

Research on the interference fringe contrast in ground glass shape measurement

To measure the ground glass surface shape, the oblique incidence method applied using a Fizeau interferometer. Interferograms with sufficient contrast values are needed during the measurement. The formula to calculate the fringe contrast in ground glass shape measurement is derived to give an optimum incident angle for the ground glass with different surface roughness. Four specimens grinded by abrasives numbered #400, #700, #1500 and #2000 are measured, using aluminum coated mirror as the reflective flat in the experiment. The minimum incident angles of the four specimens are 83°, 82°, 76° and 75° respectively. The contrast values of the interferograms with the specimens at different incident angles are measured using phase shifting interferometry and the results match the theoretical ones. The oblique incidence method can be used to measure ground glasses grinded by #400 abrasive and finer ones. A sufficient contrast can be achieved with the incident angle slightly greater than the minimum angle.

Effect of subsurface damage on indentation behavior of ground ULE™ glass

The subsurface damage in ground optical glasses was characterized using the ball-dimple technique. At the same lapping conditions, larger abrasive size introduced deeper subsurface damage, and the surface damage was proportional to the surface roughness. Surface degradation in the ground glasses due to the formation and propagation of the subsurface damage was evaluated using microindentation method. A two parameters empirical equation was used to describe the indentation behavior of the ground glasses. It was found that the nominal near-surface elastic constant decreases with the indentation load, suggesting the propagation and formation of surface cracks during the indentation.

Lateral shifting sensitivity of a ground glass for holographic encryption and multiplexing using phase conjugate readout algorithm

An encryption-selectable holographic storage algorithm with use of random phase encoding and angular multiplexing is proposed and demonstrated. The pattern for storage can be encrypted and multiplexed with use of a ground glass, which is also used to decrypt the pattern. A phase conjugation of the reference beam is used to generate phase conjugate waves of the stored patterns. The lateral shifting sensitivity of the ground glass used to decrypt the information is theoretically analyzed and is compared with experimental measurement. The shifting tolerance for various ground glasses under imperfection phase reconstruction in the decryption processing is studied.

Disposable Syringe Used as a Grease Applicator

Plastic disposable syringes have many applications in laboratories of natural sciences. This article describes the use of a disposable syringe as a grease applicator. It is possible to grease ground glasses and quickfit joints directly from the tube but then one tube can be used only by one person (whereas sometimes grease is supplied in 250 mg tin packs).

Etudes des etats de surface par les proprietes de diffusion a l'infini en lumiere transmise

We apply Beckmann's theory on the reflection scattering of electromagnetic waves to the case of laser light transmitted by a ground glass. The variance of surface height and the correlation length were calculated and experimentally measured for different ground glasses. In order to obey the theoretical condition that the surface should be slightly rough, we immersed the ground glass surface in a liquid of suitable index of refraction. Our results show that the usual assumption about the statistical characteristics of rough surfaces do not apply to the surfaces we studied.

Kohärenz höherer Ordnung in der Optik und ihre Meßbarkeit / Higher-Order Coherence in Optics and Its Measurability

An experiment is proposed to demonstrate higher-order coherence in an optical radiation field. An ensemble of longitudinal modes illuminates a set of different ground glasses (diffusors). It is shown that the superposition of the far-fields emerging from the diffusors is able to give information about higher-order coherence. For the following considerations the theoretical basis is Glauber's generalized coherence function.

The Determination of rms Roughness and Correlation Length of Rough Surface by Measuring Spatial Coherence Function

The rms roughness and correlation length are determined by measuring the degree of coherence for a fluctuating laser beam transmitted from a moving rough surface illuminated by a diverging beam. The determination is made by using the theoretical formula derived on the assumption that the rough surface is a phase filter. In case of the adequately small spread of the illumination beam and optically smooth roughness, the measured variations of the degree of coherence are in good agreement with the theoretical calculation, and the rms roughness and correlation length of ground glasses can be evaluated. The experimental results support the assumption that the statistics of the surface irregularities is characterized by the Gaussian distribution and correlation functions. The limitations on the dimensions of two diffracting apertures and on the beam spread are demonstrated and discussed.

The determination of light absorption in diffusing materials by a photon diffusion model

The mechanism of light reflection from diffusing materials is considered as a photon diffusion process. Equations from neutron diffusion theory are adapted to give reflection factors in terms of the scattering and absorption cross sections of the diffusing material. Measurements of the reflection spectra from blue and green ground glass are used to calculate the absorption spectra of the original glass using diffusion theory. Good agreement is obtained between the absorption spectra measured by transmission on the original glass and that calculated from the reflectance spectra of the ground glass. Comparison with the Kubelka and Munk coefficients of scatter and absorption calculated from the same data shows that diffusion theory gives a more accurate description of the absorption process. The variation of the scattering cross section and scattering coefficient of Kubelka and Munk with wavelength is similar for the ground glasses considered.

Reponses electro-corticales de l'homme normal eveille a des eclairs lumineux. Resultats obtenus a partir d'enregistrements sur le cuir chevelu, a l'aide d'un dispositif d'integration

The authors have recorded in normal waking man the electro-cerebral phenomena following short repeated light stimuli. In order to obtain this record on the scalp they have made use of a summative technique. After briefly summarizing the method, they give the results obtained with the different leads they have used, and under various experimental conditions. With the subject's eyes fixed on the flashbulb, in a dark and soundproof experimental room, it appears that the response is made of series of electrical deflections, which differ from one lead to another. The first event recorded in the occipital area is a triphasic wave initially positive, with a latency of 50 msec, then a diphasic wave, negative-positive, larger in amplitude, with a latency of 135 msec. In the somesthetic and vertex areas first a diphasic initially negative wave with a latency of 45 msec is recorded, then a diphasic wave, negative-positive, larger in amplitude, with a latency of 100 msec. In the nasial area early phenomena of retinal origin are chiefly recorded, presenting as a diphasic, negative-positive wave, with a latency of 10 msec. The authors analyze then the response changes in different experimental conditions. Closure of the eyes, and, to a lesser extent, interposition of ground glasses, are followed by a prominent reduction, in the occipital area, of the secondary diphasic wave, and by the later appearance of rhythmical waves, the period of which is either identical to that of the alpha rhythm, or definitely shorter. Variations in the absolute or relative intensity of the light flashes, influence mostly the retinal electrical phenomena. Of the occipital response they modify, in the experimental limits, only the initial triphasic wave. Variations in the visual fixation on the flash bulb are followed by a selective reduction of the secondary diphasic wave recorded in the occipital area. Relative shifts of the glance and flash bulb modify selectively the retinal response. These results are compared to those obtained by other authors in the animal, and to those obtained in man by the authors themselves with the same technique, using sound or somesthetic stimuli. These responses are obviously of higher complexity than the simple evoked potential. They consist of a larger number of components, have longer duration and extend beyond the primary projection area where, however, they display a characteristic pattern. By varying the experimental conditions, differences of behaviour between the different phases of the occipital responses, and between the responses recorded in the various leads become apparent. The authors discuss these findings, and more particularly their relation to the classical evoked potential, Davis' non-specific response, vertex spikes, the alpha rhythm and the mechanisms of attention.

Escape of Fluorine during Smelting of Porcelain Enamel Frit

Considering the trend of the frit composition of today towards softer, selected three ground glasses (Fig. 1) and added tenth of sodium fluoride and sodium silicofluoride respectively. By means of the heat balance, it was known the carbonic acid gas exhausting reaction in fluorine containing batches begins at about 120°C lower and ends at about 80°C lower temperature than that of fluorineless batches. The difference of effect was scarcely found between two fluorides.100g batch of each was smelted in platinum basin, weight loss measured, chemically analysed from which escaping forms were deduced as just melted down and melted on as long as three hours. While in the former fluorine loss was attsibuted to NaF and F2 (conveniently represents fluorine loss which accompanies no cation) for the most, SiF4 for only one case, in the latter in no case to SiF4.In smelting of moderne type of titanium frit on plant scale, fluorine loss amounts to 15-20% and its increase with smelting period was relatively small reversely to the above mentioned results.

A new type of visual spectrophotometer

The paper describes a new type of spectrophotometer in which there are no moving optical media. Two light sources consisting of gas-filled tungsten lamps each behind ground glass are used. The ground glasses are used as secondary light sources of high uniform brightness (up to 400 candles per square inch). The photometric scale of the instrument is in terms of the voltage intensity relation of one of the light sources at a standard wave-length in conjunction with rotating sector discs of known transmission. The voltage intensity relation at other wave-lengths is shown to be deducible from that at the standard wave-length by simple computation. Special provision is made whereby the wave-length scale of the instrument is not affected by mechanical alteration in slit width. The Maxwellian method of view is utilized. The precision of the instrument is high, the average deviation from the mean of determinations of spectral transmission throughout most of the spectrum being about 0.5 per cent.