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Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 469
Author(s):  
Maxim Eingorn ◽  
Ezgi Canay ◽  
Jacob M. Metcalf ◽  
Maksym Brilenkov ◽  
Alexander Zhuk

We study the effect of the cubic torus topology of the Universe on scalar cosmological perturbations which define the gravitational potential. We obtain three alternative forms of the solution for both the gravitational potential produced by point-like masses, and the corresponding force. The first solution includes the expansion of delta-functions into Fourier series, exploiting periodic boundary conditions. The second one is composed of summed solutions of the Helmholtz equation for the original mass and its images. Each of these summed solutions is the Yukawa potential. In the third formula, we express the Yukawa potentials via Ewald sums. We show that for the present Universe, both the bare summation of Yukawa potentials and the Yukawa-Ewald sums require smaller numbers of terms to yield the numerical values of the potential and the force up to desired accuracy. Nevertheless, the Yukawa formula is yet preferable owing to its much simpler structure.


Author(s):  
Hossam. A. Elaqra ◽  
◽  
Saddam H. Qarmout ◽  
Jehad T. Hamad ◽  
Eyad A. Hadad ◽  
...  

With the growth of the global population, two major problems have emerged. Firstly, a significant amount of domestic and industrial waste is discarded and placed in landfills. Secondly, there is a necessity for more construction and building materials. This research discusses the use of alternative green resources for construction materials taken from recycled organic waste, which represents more than 60% of the total waste generated by humans. Results showed that, after incineration at 750 °C, the reminder represented less than 15% of the original mass of the waste. The waste was separated into five groups: bottom ash (BA) powder, this part represented 5% of the reminder after incineration (for replacing cement); sand; and fine, medium and coarse aggregates. The powder underwent a pozzolanic reaction and the optimum replacement was 10% for the powder, 30% for the sand, and 10% for the fine, medium, and coarse aggregates. A higher compressive strength was applied to the medium aggregate replacement and a lower one for the fine aggregate. In general, BA can be used as an aggregate replacement as the powder undergoes a pozzolanic reaction and can used as a replacement for cement.


2021 ◽  
Author(s):  
Samuel Pascal Levin ◽  
Michael Levin

Prior studies of decision-making generally assume a fixed agent which maximizes utility among its various options. Physarum polycephalum is a popular model for basal cognition that can be cut into pieces that may or may not re-join. We exploited this capacity to develop a novel assay in which radical changes to the agent itself are among the options of the decision-making process. Specifically, we transected a Physarum culture in the presence of a food reward that was located closer to the new smaller piece. In this scenario, the newly created branch must choose between exploiting the reward itself, or first re-connecting with the original mass (and sharing the nutrient reward across a large body). We report a pilot study establishing a protocol in which the number of agents is part of the decision-making process. We observed that despite the presence of food, new branches strongly prefer to merge back to the syncytium before exploiting the reward. Many improvements to the protocol are possible, to extend this effort to understand the interplay between behavioral options and the structure and boundary of the individual making choices in its environment


Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 649
Author(s):  
Charlotte E. Gibson ◽  
Massoud Aghamirian ◽  
Tassos Grammatikopoulos ◽  
Darren L. Smith ◽  
Lindsay Bottomer

In coming years, global lithium production is expected to increase as the result of widespread electric vehicle adoption. To meet the expected increase in demand, lithium must be sourced from both brine and hard-rock deposits. Heavy liquid separation (HLS) and dense media separation (DMS) tests were conducted on the pegmatites from Hidden Lake, NWT, Canada to demonstrate the potential role of this technology in the concentration of spodumene (LiAlSi2O6) from hard-rock sources. A continuously operated DMS circuit test, conducted on +840 µm material, produced a concentrate grading 6.11% Li2O with ~50% lithium recovery. The circuit rejected 50% of the original mass to tailings, with only 8% lithium losses. Sensitivity analysis showed that minor changes (+/−0.05) in the DMS-specific gravity cut point resulted in significant changes to the mass rejected and to the concentrate grade produced; this may limit the feasibility and operability of the downstream grinding and flotation circuits. The results demonstrate the potential for DMS in the concentration of spodumene from the Hidden Lake pegmatites, and by extension, the potential for DMS in the concentration of spodumene from other hard-rock occurrences.


2020 ◽  
Vol 644 ◽  
pp. A46
Author(s):  
Toktarkhan Komesh ◽  
Willem Baan ◽  
Jarken Esimbek ◽  
Jianjun Zhou ◽  
Dalei Li ◽  
...  

Aims. We investigate the role of selective dissociation in the process of star formation by comparing the physical parameters of protostellar-prestellar cores and the selected regions with the CO isotope distributions in photo-dissociation regions. We seek to understand whether there is a better connection between the evolutionary age of star forming regions and the effect of selective dissociation Methods. We used wide-field observations of the 12CO, 13CO, and C18O (J = 1–0) emission lines to study the ongoing star formation activity in the Aquila molecular region, and we used the 70 and 250 μm data to describe the heating of the surrounding material and as an indicator of the evolutionary age of the core. Results. The protostellar-prestellar cores are found at locations with the highest C18O column densities and their increasing evolutionary age coincides with an increasing 70μm/250μm emission ratio at their location. The evolutionary age of the cores may also follow from the 13CO versus C18O abundance ratio, which decreases with increasing C18O column densities. The original mass has been estimated for nine representative star formation regions and the original mass of the region correlates well with the integrated 70 μm flux density. Similarly, the X13CO/XC18O ratio, which provides the dissociation rate for these regions correlates with the 70 μm/250 μm flux density ratio and reflects the evolutionary age of the star formation activity.


2020 ◽  
Vol 501 (1) ◽  
pp. 1215-1227 ◽  
Author(s):  
D Gardiol ◽  
D Barghini ◽  
A Buzzoni ◽  
A Carbognani ◽  
M Di Carlo ◽  
...  

ABSTRACT Two meteorite pieces have been recovered in Italy, near the town of Cavezzo (Modena), on 2020 January 4th. The associated fireball was observed on the evening of New Year’s Day 2020 by eight all-sky cameras of the PRISMA fireball network, a partner of FRIPON. The computed trajectory had an inclination angle of approximately 68° and a velocity at infinity of 12.8 km s−1. Together with the relatively low terminal height, estimated as 21.5 km, those values were indicating the significant possibility of a meteorite dropping event, as additionally confirmed by the non-zero residual total mass. The strewn-field was computed taking into account the presence of two bright light flashes, revealing that the meteoroid had been very likely subject to fragmentation. Three days after the event, two samples, weighing 3.1 and 52.2 g, were collected as a result of a dedicated field search and thanks to the involvement of the local people. The two pieces were immediately recognized as freshly fallen fragments of meteorite. The computed orbital elements, compared with the ones of known Near-Earth Asteroids from the NEODyS database, are compatible with one asteroid only; 2013 VC10. The estimated original mass of the meteoroid, 3.5 kg, and size, approximately 13 cm, is so far the smallest among the current 35 cases in which meteorites were recovered from precise strewn-field computation thanks to observational data. This result demonstrates the effectiveness of accurate processing of fireball network data even on challenging events generated by small size meteoroids.


Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2234 ◽  
Author(s):  
Karel Dvořák ◽  
Adéla Macháčková ◽  
Simona Ravaszová ◽  
Dominik Gazdič

This contribution characterizes the performance of a DESI 11 high-speed disintegrator working on the principle of a pin mill with two opposite counter-rotating rotors. As the ground material, batches of Portland cement featuring 6–7 Mohs scale hardness and containing relatively hard and abrasive compounds with the specific surface areas ranging from 200 to 500 m2/kg, with the step of 50 m2/kg, were used. The character of the ground particles was assessed via scanning electron microscopy and measurement of the absolute/relative increase in their specific surface areas. Detailed characterization of the rotors was performed via recording the thermal imprints, evaluating their wear by 3D optical microscopy, and measuring rotor weight loss after the grinding of constant amounts of cement. The results showed that coarse particles are ground by impacting the front faces of the pins, while finer particles are primarily milled via mutual collisions. Therefore, the coarse particles cause higher abrasion and wear on the rotor pins; after the milling of 20 kg of the 200 m2/kg cement sample, the wear of the rotor reached up to 5% of its original mass and the pins were severely damaged.


Arsitektura ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 84
Author(s):  
Atik Prihatiningrum

<p class="Abstract"><em>The knowledge of building housing by the Rejang </em><em>clan</em><em> in Gunung Alam Village by trial and error using local materials as well as a simple way of reflecting the uniqueness of the form of shelter in the Rejang clan community residing in mountainous rural areas. The focus of this research is to identify the relationship between the form of shelter and the realization of anticipation of occupancy as its role as adaptive shelter in earthquake prone areas. This research is a qualitative descriptive study describing the form of occupancy of the Rejang Clan by exploring the configuration of the building and its structural system to understand the form of occupancy of the Rejang Clan as an adaptive building in earthquake prone areas. The adaptability of the Rejang clan as a shelter in earthquake-prone areas has been implemented through the form of houses on stilts which have a ratio of widths and lengths of buildings 1: 2 with symmetrical and simple spatial arrangements. Ratio of balanced heights in each structure. However, the use of nails has been found in homes and the addition of space that forms a new mass behind the original mass of housing with brick material becomes a risk in the event of an earthquake in the future. Even so, the Rejang Clan occupancy in Gunung Alam Village is still strong to be inhabited by the Rejang Clan and is adaptive in responding to earthquake shocks.</em><em></em></p>


2019 ◽  
Vol 134 (1) ◽  
pp. 267-272 ◽  
Author(s):  
W. Kerkhoff ◽  
E. J. A. T. Mattijssen ◽  
E. A. Zwanenburg ◽  
R. J. Oostra

AbstractExisting literature on the relationship between bullet diameter and bullet defect diameter in the human calvarium is summarized and discussed. The hypothesis, derived from the literature, that bullet deformation influences bullet defect diameter was studied in a small controlled experiment. The mean defect size caused by non-deforming projectiles was found to be smaller than the mean defect size caused by deforming projectiles of equal original mass and size. The p value of the difference between the two means, measured in two different ways, was found to be 0.002 for both in a Mann–Whitney U test and was significant if the confidence level is set at 5%.


2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Wang Wang ◽  
Hesheng He ◽  
Xingwu Chen ◽  
Chenhong Zhang

Abstract Background Myeloid sarcoma (MS) rarely involves the bronchus, and primary bronchial MS has almost never been reported in mainland China. Case presentation A 65-year-old female patient was admitted with a 3-month history of cough. She was initially diagnosed with bronchogenic carcinoma according to chest computed tomography (CT). However, after a biopsy was taken from the endobronchial lesion by bronchoscopy and further immunohistochemical analysis was performed, the diagnosis of MS was made. Because her bone marrow was normal and she had no history of haematologic diseases, we further considered the diagnosis of primary bronchial MS. The patient received chemotherapy with HAG regimens, and the original mass completely resolved, as confirmed by chest CT scan after 3 cycles of treatment. Meanwhile, no abnormalities were found on re-examination via bronchoscopy. Conclusions MS should be considered in the differential diagnosis in the presence of a suspicious pulmonary mass. Immunohistochemical analysis is necessary to confirm the diagnosis. Chemotherapy can lengthen the survival time for patients.


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