bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the time variable in on-site concrete production
Authors: Angarita Uscategui P , Gallardo Amaya R , Afanador García N 
Published: December 2020

Abstract
Time is one of the most important magnitudes of physics; it is considered a variable that determines movements, positions, and speeds. Consequently, its adequate study, in the context of construction activities, allows for the dimensioning of its incidence and the correct way in which this variable should be analyzed. The objective of this research was to establish how the time variable determines productivity in the production of concrete on site. In this way, it was possible to find that this variable, when analyzed in construction activities, should not be analyzed with a unique definition, but rather it should be analyzed from 3 points of view, as productive time, contributory time, and non-contributory time. The final results indicated that the time variable measured in concrete production activity on site corresponds to productive time by 46%, to contributory time by 30%, and to non-contributory time by 24%. These results allow concluding that, for the case of activities related to the construction sector, time cannot be conceived with an absolute definition, but it should be analyzed in a discriminated way, according to the time measured for an activity, contributing or not to the improvement of productivity in a construction work. It was found that these times are not within the optimal times proposed in the literature to decrease losses in the work performed, which are around 60% for contributory time, 25% for productive time, and 15% for non-contributory time. The above indicates that the measurement of the time variable and its adequate analysis is essential to implement processes of productivity improvement in the construction sector, particularly in the way time is distributed for the production of concrete on site.
Analysis of pollutant emissions using calcium carbonate in the manufacture of ceramic materials
Authors: Guerrero Goméz G , Noriega Sanchez C J , Moreno Contreras G G 
Published: December 2020

Abstract
In the research work, an isokinetic sampling of the evaluation of pollutant emissions to the atmosphere generated by a Hoffman continuous kiln was carried out in samples with two dosages, one composed of 100% clay and the other with 70% clay and 30% calcium carbonate. The methods for the evaluation of pollutant emissions in stationary sources were used and 3 runs were performed, and in each run 4 measurements were made every 15 minutes. The results in the emissions of the firing using calcium carbonate with respect to the samples composed of 100% clay reduced the discharges to the atmosphere by 7.30% in particulate matter, 20.18% in nitrogen oxides, 21.65% in sulfur dioxide, and 15.35% and 8.89% in hydrochloric and hydrofluoric acid respectively. The concentration of particulate material emitted to the environment in the two firing processes does not meet the permissible emission standard of less than 250 mg/mm3, while the other pollutants comply with Colombian environmental regulations. The use of fluxes for the manufacture of bricks reduced the concentrations of gases emitted into the environment decreasing possible health effects such as acute respiratory disease, eye irritation, and aggravation of heart disease.
Gelation kinetics of colloidal dispersion gels by viscoelasticrheological methods
Authors: Mantilla G , Villamizar J , Sánchez E , Ardila J , Roa M 
Published: December 2020

Abstract
Colloidal dispersion gels are one of the methodologies implemented, such as chemical recovery processes, in mature wells, their components are mainly polyacrylamide and aluminum citrate, both aqueous unlike other types of gelling, in this there is an intramolecular process, between the polymer chains and the crosslinker, generating a ball of polyacrylamide of nanometric dimensions. The usual gelling processes increase the viscosity of a fluid because of an increase in the molecular weight of the polymer, but in this case, the viscosity of the fluid decreases to the point of being close to that of the solvent, for this reason a monitoring of its gelation kinetics, in a conventional way is not possible, in view of this problem, this research implements techniques of viscoelastic characterization of fluids, to determine the loss and storage modules G′ and G″, as well as the phase angle in the time, in order to learn more about the gelling mechanism, as well as to be able to estimate a reaction speed, from the point of view of viscoelastic variables, the results obtained revealed that despite being gelling, there is a decrease in the storage modulus, to a greater extent than the loss modulus, which implies that the material loses elastic properties, that is, from solid to become a material more viscous or liquid. With this information, an equation was proposed that can be used both in the laboratory and in oil field work. In addition to being extended to fluids with similar behaviors, where the interactions between the polymeric chains and their crosslinker generate a decrease in their elastic properties.
Leakage diagnosis through experimental modeling and simulation
Authors: Gómez J A , Jaramillo H Y , Guevara W 
Published: December 2020

Abstract
The detection and location of leaks in water pipes is an important research topic, not only because of the waste of energy and material resources used in the extraction but also to avoid serious environmental, social and economic consequences. This paper describes experimental modeling and simulation of leaks using computational fluid dynamics software, and LabVIEW software where a virtual instrument was designed to test the simulation when detecting a leak in a pipeline. These techniques were tested on a piping bench carried out as an experiment in the automation laboratory of the Universidad Francisco de Paula Santander, Ocaña, Colombia. Simulations and experiments were carried out and it was discovered that using simulation techniques it is possible to obtain a result that detects the leak and shows its location.
Study of the Thomson effect on the performance of thermoelectric modules with application to the energy recovery
Authors: Rojas Suárez J P , Medina Delgado B , Orjuela Abril M S 
Published: December 2020

Abstract
This paper analyzes the impact of the Thomson effect on the performance of thermoelectric modules. For this, different mathematical models are carried out that involves the relationship between temperature and the seebeck coefficient. These mathematical models are based on the equations that describe thermoelectric effects and are solved using finite element methods. Through linear and polynomial functions of the seebeck coefficient, the different behaviors that can occur in the Thomson coefficient and their effect on the power and efficiency of thermoelectric modules are analyzed. The results show that by not considering the Thomson effect, there is a variation of 31% and 32% in the power and efficiency of the thermoelectric module when the temperature conditions change, which makes it difficult to estimate the performance of the module. This problem can be solved by considering the Thomson effect since it predicts an approximately constant value of electrical power and efficiency for a wide temperature range. For the analyzed conditions, power and efficiency of 5.25 W and 13%, respectively, were observed. The proposed methodology allows an adequate estimation to determine the performance of the modules. Therefore, it could be implemented to search for materials that provide better thermoelectric characteristics.
Numerical simulation of water hammer and cavitation phenomena including the convective term in pipeline problems
Authors: Sanín-Villa D , Serrano Florez D , del Rio J Sierra 
Published: December 2020

Abstract
Water hammer problems occurs where restrictions flow suddenly change in pipelines, usually the closing or opening of valves. Presence of a high velocity pressure wave traveling though the fluid could cause damages in the pipeline structures due to the implosion of gas cavities formed by a physical phenomenon called cavitation. On this work, it is studied the water hammer physical problem considering the influence of the convective terms in the momentum and continuity equations, the cavitation problem has been evaluated by the discrete vapour cavity physical model. A MATLAB code is developed to solve the transient problem and find the hydraulic head evolution in some points along the pipeline. The method of characteristics is used to find a numerical solution of the coupled partial differential equation system. Results shows good agreement with result presented in literature reviewed, also, it is found that the influence of the convective term is small compared with a simple model where those terms are neglected, the maximum difference value of 2.4x10−4 where found, considering and neglecting the convective term on the physical model.
Factors associated with learning physics in the elderly
Authors: Mariño J A , Rojas-Suarez J , Vergel-Ortega M 
Published: December 2020

Abstract
The research aims to identify the factors associated with learning physics in older students. A quantitative investigation is carried out with a field-type factorial analysis method, correlational in a sample of 80 physics students, university students over 30 years of age, who apply science, technology, art and physics through designs and simulations in vector fields, perceptual geo-materializations and electrical physics. The research used as a technique the metacognitive skills inventory test (α = 0.82), the educational motivation scale (α = 0.71), the Tennessee self-concept scale (α = 0.725), the psychological well-being scale adult (α = 0.75) and the social skills scale (α = 0.801). The results show that variables associated with the learning of physics in elderly were the extrinsic motivation index, the motivation intrinsic and demotivating; the active, reflective, theoretical and pragmatic learning style; performance variables, level of learning, spatial reasoning and sensitivity. The results obtained indicate an acceptable fit in the proposed model (X
2 = 652.55/gl = 3.05), GFI (goodness of fit index) = 0.894, AGFI (corrected goodness of fit index) = 0.848, RMSEA (mean square approximation error) = 0.09, IFI (incremental adjustment index) = 0.930. The explained variance is 31.9% regarding learning style, 38.8% regarding motivation and 15.1% regarding cognitive score and 15.1% regarding consciousness deficit. It is concluded that the predictive factors of learning of physics in older adults were learning style, motivation indices, cognitive score and consciousness deficit.
Development of software to predict academic performance using data mining techniques and tools
Authors: Chindoy Chasoy B Y , Diaz Pedroza K Y , Rosado Gómez A A 
Published: December 2020

Abstract
Student desertion due to academic performance is understood as the interruption that a student makes voluntarily or by warning of his academic continuity by not achieving an acceptable accumulated average that keeps him active within his curriculum. The objective of this research was to develop a software that allows from the extraction of the data to the prediction of the academic performance of the students of the systems engineering program of the Universidad Francisco de Paula Santander, Ocana, Colombia, in order to create strategies to reduce student dropout rates within the career. The methodology used was qualitative research with a descriptive approach. The life cycle in the development of the software whose name is Universidad Francisco de Paula Santander, Ocana, Colombia, desertion was followed with the merger between open up and the knowledge extraction process. The type of learning used was supervised, obtaining that the highest percentage of correctly classified instances was achieved with algorithm randomizable filtered classifiers as well as J48 with a percentage of 92.6307% and 79.3185%, respectively. In addition, this software is applicable for any area in science and academia, since they worked with standard variables of which, the attributes with the highest incidence in low academic performance are, student status, academic sanction, the assessment of the proof of status, age, gender, social status and place of origin.
Design of a metropolitan network based on fiber optic and wireless links to support COVID-19 monitoring
Authors: Cuesta-Quintero F R , Areniz-Arévalo Y , Barrientos-Avendaño E , Coronel-Rojas L A , Cuesta-Quintero B , Rico-Bautista D W 
Published: December 2020

Abstract
This article aims to design a metropolitan network based on fiber optic and wireless links to support the monitoring of COVID-19. Its main function is to support the monitoring and control of the COVID-19, through intelligent technologies of both software and hardware needed to obtain data in real-time, which facilitates decision making. There is currently no platform that allows real-time communication between the entities involved. This first phase was developed through a description of the integration of these bodies through the infrastructure of the Universidad Francisco de Paula Santander, Ocana, Colombia. Among the results obtained, it is noted that the 28 GHz subcarrier can cross the 25 km fiber link without any problem and the physical topology of the Metropolitan network is designed, which integrates both wireless and wired technology, including their properties and physical, mechanical, and electrical characteristics more representative as distances, speeds, interfaces, coding, and signaling.
3D-ordered porous composite microparticles formed via substrate-free optical 3D lithography
Authors: Ahn Jinseong , Ahn Junyong , Park Junyong 
Published: December 2020

Abstract
This paper proposes a cutting-edge photolithography-based top-down approach to produce functional porous microparticles with three-dimensional (3D) periodic nanostructures. The developed fabrication process employs proximity-field nanopatterning (PnP), a representative optical 3D nanofabrication technique in which a new type of phase mask and exposure scheme have been introduced. In the modified PnP mode, where the photoresist is directly coated on the phase mask, a 3D nanostructured membrane detaches from the mask during the development process. The freestanding 3D nanostructured membrane is electromagnetically shredded through simple ultrasonication to produce a large amount of 3D-ordered porous microparticles. A Gaussian distribution of particle sizes with an average size of ∼37 µm can be obtained through an optimization of the sonication time. In addition, composite porous microparticles that exhibit exceptional magnetically responsive properties can be generated by incorporating iron oxide nanoparticles into the rinsing solution as nanofillers.
Dynamics of Rényi entanglement entropy in diffusive qudit systems
Authors: Huang Yichen 
Published: December 2020

Abstract
My previous work [arXiv:1902.00977] studied the dynamics of Rényi entanglement entropy R

α
in local quantum circuits with charge conservation. Initializing the system in a random product state, it was proved that R

α
with Rényi index

α
>
1

grows no faster than ‘diffusively’ (up to a sublogarithmic correction) if charge transport is not faster than diffusive. The proof was given only for qubit or spin-1/2 systems. In this note, I extend the proof to qudit systems, i.e., spin systems with local dimension

d
≥
2

.
An approach for computing generators of class fields of imaginary quadratic number fields using the Schwarzian derivative
Authors: Jorgenson Jay , Smajlović Lejla , Then Holger 
Published: December 2020

Let

N
N

be one of the

38
38

distinct square-free integers such that the arithmetic group

Γ
0

(
N

)
+

\Gamma _0(N)^+

has genus one. We constructed canonical generators

x
N

x_N

and

y
N

y_N

for the associated function field (see Jorgenson, L. Smajlović, and H. Then [Exp. Math. 25 (2016), pp. 295–319]). In this article we study the Schwarzian derivative of

x
N

x_N

, which we express as a polynomial in

y
N

y_N

with coefficients that are rational functions in

x
N

x_N

. As a corollary, we prove that for any point

e
e

in the upper half-plane which is fixed by an element of

Γ
0

(
N

)
+

\Gamma _0(N)^+

, one can explicitly evaluate

x
N

(
e
)

x_N(e)

and

y
N

(
e
)

y_N(e)

. As it turns out, each value

x
N

(
e
)

x_N(e)

and

y
N

(
e
)

y_N(e)

is an algebraic integer which we are able to understand in the context of explicit class field theory. When combined with our previous article (see Jorgenson, L. Smajlović, and H. Then [Exp. Math. 29 (2020), pp. 1–27]), we now have a complete investigation of

x
N

(
τ
)

x_N(\tau )

and

y
N

(
τ
)

y_N(\tau )

at any CM point

τ
\tau

, including elliptic points, for any genus one group

Γ
0

(
N

)
+

\Gamma _0(N)^+

. Furthermore, the present article when combined with the two aforementioned papers leads to a procedure which we expect to yield generators of class fields, and certain subfields, using the Schwarzian derivative and which does not use either modular polynomials or Shimura reciprocity.
DockIT: a tool for interactive molecular docking and molecular complex construction
Authors: Iakovou Georgios , Alhazzazi Mousa , Hayward Steven , Laycock Stephen D 
Published: December 2020

Abstract

Summary
DockIT is a tool that has a unique set of physical and graphical features for interactive molecular docking. It enables the user to bring a ligand and a receptor into a docking pose by controlling relative position and orientation, either with a mouse and keyboard, or with a haptic device. Atomic interactions are modelled using molecular dynamics-based force-fields with the force on the ligand being felt on a haptic device. Real-time calculation and display of intermolecular hydrogen bonds and multipoint collision detection either using maximum force or maximum atomic overlap, mean that together with the ability to monitor selected intermolecular atomic distances, the user can find physically feasible docking poses that satisfy distance constraints derived from experimental methods. With these features and the ability to output and reload docked structures it can be used to accurately build up large multi-component molecular systems in preparation for molecular dynamics simulation.

Availability and implementation
DockIT is available free of charge for non-commercial use at http://www.haptimol.co.uk/downloads.htm. It requires a windows computer with GPU that supports OpenCL 1.2 and OpenGL 4.0. It may be used with a mouse and keyboard, or a haptic device from 3DSystems.
When Politicization Stops Algorithms in Criminal Justice
Authors: König Pascal D , Wenzelburger Georg 
Published: December 2020

Abstract
The present paper sheds light on the conditions for successfully implementing pretrial risk assessment tools by looking at barriers to their implementation and, specifically, political factors that can derail this process. Drawing on theoretical assumptions about the role of agenda-setting and public discourse in policy change, we examine three US states where the implementation of pretrial tools was halted or heavily restricted. Our findings suggest that a politicization of these tools plays a central role for thwarting their implementation. This has less to do with their technical properties or performance. Rather, through reaching high-level politics, those tools are publicly linked to concerns about opacity, fairness and public safety such that it simply becomes politically safer for politicians to stick with the status quo.
Food Restriction Engages Prefrontal Corticostriatal Cells and Local Microcircuitry to Drive the Decision to Run versus Conserve Energy
Authors: Santiago Adrienne N , Makowicz Emily A , Du Muzi , Aoki Chiye 
Published: December 2020

Abstract
Food restriction (FR) evokes running, which may promote adaptive foraging in times of food scarcity, but can become lethal if energy expenditure exceeds caloric availability. Here, we demonstrate that chemogenetic activation of either the general medial prefrontal cortex (mPFC) pyramidal cell population, or the subpopulation projecting to dorsal striatum (DS) drives running specifically during hours preceding limited food availability, and not during ad libitum food availability. Conversely, suppression of mPFC pyramidal cells generally, or targeting mPFC-to-DS cells, reduced wheel running specifically during FR and not during ad libitum food access. Post mortem c-Fos analysis and electron microscopy of mPFC layer 5 revealed distinguishing characteristics of mPFC-to-DS cells, when compared to neighboring non–DS-projecting pyramidal cells: 1) greater recruitment of GABAergic activity and 2) less axo-somatic GABAergic innervation. Together, these attributes position the mPFC-to-DS subset of pyramidal cells to dominate mPFC excitatory outflow, particularly during FR, revealing a specific and causal role for mPFC-to-DS control of the decision to run during food scarcity. Individual differences in GABAergic activity correlate with running response to further support this interpretation. FR enhancement of PFC-to-DS activity may influence neural circuits both in studies using FR to motivate animal behavior and in human conditions hallmarked by FR.
Sirolimus in renal transplant recipients with malignancies in Germany
Authors: Naik Marcel G , Arns Wolfgang , Budde Klemens , Diekmann Fritz , Eitner Frank , Gwinner Wilfried , Heyne Nils , Jürgensen Jan Steffen , Morath Christian , Riester Udo , Heller Katharina M , Fischereder Michael 
Published: December 2020

Abstract

Background
Renal transplant recipients have an increased cancer risk. The mammalian target of rapamycin inhibitor sirolimus (SRL) has immunosuppressive and antitumour activities but knowledge about its use in recipients with cancer is limited.

Methods
We retrospectively analysed 726 renal allograft recipients converted to SRL from 10 German transplant centres. Patient and graft survival were analysed depending on malignancy status prior to conversion and tumour entity.

Results
Malignancy before conversion to SRL was reported in 230 patients, with 137 patients having skin cancers and 101 having solid cancers. Cancer occurred 4.6 ± 9.4 (median 3.0) years after transplantation. Basal cell carcinoma, squamous cell carcinoma and Bowen’s disease were the most prevalent skin cancers, while carcinomas of the kidney, colon and breast were the most prevalent solid cancers before conversion. Patients with prior malignancy were older and had better renal function at conversion compared with patients without a history of cancer. After conversion to SRL, cancer incidence rates (IRs) of all tumours were lower compared with rates before conversion. Cancer IRs after conversion were higher in patients with malignancy before conversion compared with those without. Patient survival was worse in patients with solid cancers compared with patients with skin cancers or without malignancies. Biopsy-proven acute rejections in the first year after conversion were less frequent in patients with malignancy compared with those without. Graft survival and renal function in all cancer types were better than in patients converted to SRL without cancers.

Conclusions
Conversion to SRL in patients with a history of cancer is safe regarding renal function and graft survival, while patient survival is largely dependent on tumour entity.