bluuebunny/crossref_metadata_2025 huggingface dataset:
31 Effect of vitrification of porcine oocytes on production of ATP and mitochondrial DNA copy number
Authors: Gutierrez E. J. , Diaz F. B. , Bondioli K. R.
Published: January 2021

This experiment evaluated the effects of vitrification at different time points of invitro maturation (IVM) on ATP production and mitochondrial DNA (mtDNA) copy number of porcine oocytes. Treatments included vitrification at 24h of IVM (V24), vitrification at 44h of IVM (V44), and a control group consisting of fresh oocytes after 48h of IVM. Porcine cumulus–oocyte complexes (COCs) were obtained from a commercial vendor and underwent the first 24h of IVM during shipment in a portable incubator. Upon arrival, COCs were randomly allocated into treatments. The oocytes in the V44 and control groups were incubated at 38.8°C and 5.5% CO2 to continue IVM. Before vitrification, COCs were denuded in hyaluronidase by vortexing, followed by 3 washes in holding medium (Hanks’ balanced salt solution–HEPES + 4% BSA). Denuded oocytes were vitrified using a 3-step, dimethyl sulfoxide (DMSO)- and ethylene glycol-based protocol (VitriCool kit, IVF Bioscience), Cryolocks as carriers, and liquid nitrogen as cryogenic agent. All steps were carried out at room temperature. Warming was achieved using the VitriWarm kit (IVF Bioscience) consisting of 4 dilution steps. After warming, the oocytes were washed in holding medium and incubated in IVM medium to complete 48h of maturation (24h for V24 and 4h for V44). All warming steps were performed at 38.5°C. Oocytes destined for ATP production assessment (Control n=26, V44 n=27, V24 n=28) were frozen in 50µL of ultra-pure water, whereas oocytes destined for mtDNA copy number quantification (Control n=32, V44 n=30, V24 n=32) were snap-frozen in ∼1µL of holding medium. Samples were kept at −80°C until further processing. The ATP content of single oocytes was determined using an ATP bioluminescent somatic cell kit (FLASC, Sigma-Aldrich). The assessment of mtDNA copy number in single oocytes was performed by amplifying the porcine Mt-ND4 gene (F atccaagcactatccatcacca, R ccgatgattacgtgcaaccc; NC_000845.1) and quantification was carried out using a Droplet Digital PCR system (Bio-Rad Laboratories). Results for ATP production and mtDNA copy number were analysed through ANOVA with Tukey’s adjustment (SAS 9.4; Sas Institute Inc.). No differences were found in mtDNA copy number among groups (Control 178 004.69±19 207.23, V44 170 483.67±18 127.18, V24 176 767.50±27 211.09; P=0.36). In contrast, all groups differed in ATP content (pg/µL) among each other (Control 26.36±4.99, V44 20.26±6.61, V24 16.54±8.07; P<0.0001). These data indicate that although there was no effect on mitochondrial number, ATP production/storage ability is significantly reduced as a result of vitrification-warming. Vitrification at 44h of IVM followed by a 4-h post-warming incubation showed the highest ATP content among the vitrification treatments.
43 Correlates of reproductive tract anatomy and uterine histomorphometrics with fertility in swine
Authors: D'Ambrosio J. , Malopolska M. , Tuz R. , Schwarz T. , Ekanayake L. , Ahmadi B. , Nowicki J. , Tomaszewska E. , Grzesiak M. , Bartlewski P.
Published: January 2021

Economic potential of the swine industry hinges upon the reproductive performance of sows, which may be enhanced by improving uterine capacity, a component trait of litter size and piglet productivity. Previous attempts at characterising morphological traits indicative of high uterine volume have not been completely successful, resulting in the continued need for a reliable method of predicting reproductive value to improve production efficiency of the sow. Hence, the main objective of this study was to scrutinize macro- and micro-morphology of the sow’s reproductive tract for quantitative correlations with fertility indices. Reproductive records from Polish Landrace×Polish Large White sows (mean±s.e.m. parity: 4.3±0.6, range: 2–8) were used to examine the associations between fertility and ovarian/uterine morphology (n=34) or uterine histomorphometry (n=10) posthumously. Simple linear regression was performed to determine the relationship between anatomical or histological parameters and various measures of reproductive performance. Several measures related to the ovary, including right and left ovarian weight (r=0.50, P=0.005, and r=0.49, P=0.006, respectively), were positively correlated with the litter size, whereas left ovarian number of corpora lutea (r=−0.38, P=0.04) was negatively correlated with the mean litter size. Analysis of histomorphological characteristics of the uterine wall collected during the luteal phase of the oestrous cycle revealed correlations between mean litter size and myometrial vascular content (r=0.75, P=0.03), the proportion of myometrial stroma (r=−0.68, P=0.03), and the variability of endometrial thickness (r=−0.72, P=0.02) in sows. Eight ovarian, vaginal, and uterine characteristics were significantly correlated with mean lifetime numbers of live born and stillborn piglets/litter or the last litter size before slaughter. In conclusion, several anatomical and histomorphological metrics that relate to reproductive performance of swine may be used to inform production protocols and as a tool for selection of elite breeding sows, warranting future research into noninvasive or minimally invasive techniques for obtaining such measures.
46 Use of time-lapse imaging technology to assess relationships of morphological and phototextural attributes of presumptive ovine zygotes and early embryos with their developmental competence invitro
Authors: Pena S. , Fryc K. , Murawski M. , Nowak A. , Kij B. , Kochan J. , Bartlewski P.
Published: January 2021

The assessment of morphology and digital image opacity may provide valuable information on embryo viability because such traits are linked to embryonic gene expression, metabolism and ultrastructure. Time-lapse imaging has been used in research to monitor the dynamic nature of the developing pre-implantation embryo, which includes capturing alterations in various morphological parameters over time. The present study examined the effectiveness of time-lapse technology in assessing several morphometric and phototextural parameters for predicting the developmental potential of ovine embryos. The development of 37 long wool sheep embryos from IVF to the blastocyst stage was monitored and evaluated using Primo Vision time-lapse imaging technology. Image-Pro Plus software was then used to measure zona pellucida thickness, embryo diameter, cellular grey-scale pixel intensity and heterogeneity, and total area of the perivitelline space. A one-way analysis of variance (ANOVA) was done using SigmaPlot® 11.0 for all attributes at various time points during embryo development [i.e. presumptive zygote stage, t(0); first cleavage, t(2) or t(3); second cleavage, t(4) or t(6); and third cleavage, t(7) or t(8)]. Our results indicate that most parameters analysed did not differ among embryos varying in their developmental fate, with the exception of the perivitelline space area, which was greater (P<0.05) for non-dividing embryos than for future blastocysts at the presumptive zygote stage (4040±4137 vs. 857±642µm2, respectively; mean±s.d.). Consequently, the measurement of perivitelline space at t(0) could be used to predict developmental potential of invitro-produced ovine embryos, but further investigation is required.
52 Extracellular vesicles from oviduct and uterus in sequential invitro culture affects mitochondrial activity and lipid metabolism transcripts in bovine embryos
Authors: Leal C. L. V. , Cañón-Beltrán K. , Cajas Y. N. , Yaryes A. , Beltrán-Breña P. , Hamdi M. , Gutiérrez-Adán A. , González M. E. , Rizos D.
Published: January 2021

Oviducal fluid (OF) and uterine fluid (UF) improve the quality of embryos during invitro culture, and their extracellular vesicles (EV) may be involved in such an effect. We aimed to evaluate the effect of EV from OF and UF in sequential invitro culture on the development and quality of bovine embryos. Zygotes were cultured in synthetic oviduct fluid supplemented either with 3mg mL−1 BSA (n=1584) or 5% EV-depleted fetal calf serum (dFCS, n=1594) in absence or presence (BSAEV, n=1853 and dFCSEV, n=1473) of 3×105 EV mL−1 from OF (Day 1 to Day 4) and UF (Day 5 to Day 8), mimicking invivo conditions. EV from oviducts (early luteal phase) and uterine horns (mid luteal phase) from slaughtered heifers were isolated by size exclusion chromatography; size and concentration were assessed by nanotracking analysis (NTA) and morphology by transmission electron microscopy (TEM). Blastocyst rate was recorded on Days 7–8 and their quality was assessed for mitochondrial activity by staining with Mitotracker Deep Red (ThermoFisher Scientific), survival rate after vitrification/warming by invitro culture for up to 72h, and relative mRNA abundance of lipid metabolism-related transcripts by quantitative PCR. Housekeeping genes were H2AFZ and ACTB. Data were analysed by one-way ANOVA and Tukey test. TEM confirmed the presence and morphology of EVs, and NTA indicated mode size and concentration of particles (137.2 and 151.2 nm; 2.97×1010 and 7.98×1010 particles mL−1, for OF and UF, respectively). Blastocyst yield was lower (P<0.05) in BSA groups compared with dFCS groups (BSA: 16.2±1.5 and 31.0±1.9; BSAEV: 14.1±1.6 and 26.2±2.0% vs. dFCS: 30.5±2.0 and 40.6±2.4; dFCSEV: 31.1±2.5 and 39.8±2.7%, Day 7 and Day 8, respectively), irrespective of EV supplementation. Blastocyst mitochondrial activity was increased (P<0.05) by EV in dFCSEV compared with the other groups. No differences in survival rate after vitrification/warming were found (range at 72 h: 67.1±8.1 to 87.8±5.7%). PPARGC1B was downregulated and ACC upregulated by EV, irrespective of protein source in medium (P<0.05). In contrast, EV affected some transcripts depending on the protein source in the medium (CD36 upregulated in dFCSEV, downregulated in BSAEV; PLIN2 downregulated in dFCSEV and ATGL downregulated in BSAEV, P<0.05). In conclusion, mimicking physiological conditions using EV from OF and UF in sequential IVC does not affect development but improves embryo quality by increasing blastocysts’ mitochondrial activity and favours the expression of specific lipid metabolism transcripts. Functional effects of EV may be influenced by the protein source in the medium.
This research was funded by MINECO-Spain AGL2015-70140-R, PID2019-111641RB-I00, RTI2018-093548-B-I00; YN Cajas, SENESCYT-Ecuador; CLV Leal, FAPESP-Brazil 2017/20339-3, CNPq-Brazil 304276/2018-9.
76 Effect of season on the superstimulation response, embryo quality, and pregnancy establishment in dromedary camel (Camelus dromedarius)
Authors: Abouhefnawy H. A. , Wani N. A.
Published: January 2021

The present study was conducted to study the effect of season on the superstimulation response, embryo quality and pregnancy establishment in the dromedary camels. Two donors each were superstimulated in the month of June 2019 (non-breeding season) and January 2019 (breeding season) by a combination of 2500IU of equine chorionic gonadotrophin (eCG, Folligon; Intervet), given as a single intramuscular injection on Day 1 of the treatment protocol, and 400mg of pFSH (Folltropin; Bioniche) injected twice daily in declining doses of 2×80mg, 2×60mg, 2×40mg, and 2×20mg over 4 days, also beginning on Day 1. They were scanned by rectal ultrasonography and follicles counted before mating with a fertile bull on Day 11 after the start of treatment. An injection of 20µg of gonadotrophhin-releasing hormone (Receptal, Intervet) was given immediately after mating to induce ovulation. The number of corpora lutea (CL) were counted, and the embryos collected by the non-surgical method on Day 7 after ovulation. All embryos were washed and graded before they were transferred individually into the left uterine horn of recipient animals, synchronized to be on Day 6 after ovulation. All recipients were screened by ultrasonography on Day 22, Day 60, and Day 90 for pregnancies. The data were analysed using a two-sample t-test (Minitab statistical software, Minitab Ltd.). No difference was observed in the mean number of follicles developed (20.5 vs. 18.5) between the donors in breeding and non-breeding season, respectively. The percent mean±s.e.m. of ovulations as observed by counting the CL in nonbreeding season (80.7±3.4) were not different from those in breeding season (85.4±3.7). A total number of 16 embryos collected during non-breeding season and 20 embryos in breeding season were transferred to recipients. The percent mean±s.e.m. of pregnancies established on Day 22 (56.6±3.4 vs. 67.5±7.5) and on Day 90 (47.2±2.8 vs. 60±0.0) were similar in both groups. These observations indicate that embryo transfer technology can be applied to camels during the summer months, which is considered the non-breeding season, and pregnancies can be established at par with breeding season. In conclusion, to the best of our knowledge, this is the first study in camels wherein we have demonstrated that donor camels can be superstimulated, embryos can be collected, recipient animals can be synchronized, and pregnancies can be established in the summer (non-breeding) months. The embryos collected from elite donors can be transferred to synchronized recipients to establish pregnancies or preserved for future use. Some owners do not want calves to be born in summer months, so protocols need to be established for storing these embryos for a few months before their transfer to recipients, to have the calves delivered in the desired winter months.
79 Progesterone-induced acrosome reaction and fertilization rates with bovine intracytoplasmic sperm injection
Authors: Gatenby L. , Bondioli K. R.
Published: January 2021

Intracytoplasmic sperm injection (ICSI) has been a valuable tool in many species because of its ability to overcome male factor infertility problems and eliminate risk of polyspermy; more recently, it been used to improve genome editing technologies. However, limited success with bovine ICSI has hindered these applications in cattle. Numerous treatments have been used to increase the success rate, with marginal improvement. Replicating events synonymous with fertilization, such as the acrosome reaction, may improve fertilization with bovine ICSI. Progesterone (P4) is naturally found in both the cumulus cells surrounding the oocyte and follicular fluid released at ovulation and activates a physiological pathway within sperm to induce an acrosome reaction, a crucial process in fertilization. Progesterone induction of the acrosome reaction as a sperm pretreatment for ICSI has not yet been evaluated in cattle. In this study, frozen–thawed bovine sperm was used. Sperm were first thawed, washed, and separated via gradient to obtain the motile population before capacitation with heparin over 4h before treatment with or without P4 (10 μM) for 15min. To measure the acrosome reacting population, sperm were stained with fluorescein isothiocyanate-conjugated peanut agglutinin (FITC-PNA) and observed over 2h using cytometric flow analysis and fluorescent microscopy to measure the population undergoing and completing an acrosome reaction. For ICSI, a total of 220 oocytes were used, and both treated and nontreated sperm were incubated for 1h before injection to allow for completion of an acrosome reaction. Fertilization rates were measured by observing pronuclear formation and an absence of sperm 18h after ICSI. Means of acrosome reacting population gathered by flow cytometry and microscopy were analysed by ANOVA. Differences in fertilization rates between groups post ICSI were analysed using a Yates’ corrected chi-squared test. A significantly higher proportion of P4 treated versus control sperm initiated an acrosome reaction at hour 1 (80.2%±4.2 vs. 19%±9.1), which increased to (89.3%±3.9 vs. 29%±8.3) after 2h. P4 also increased the percentage of sperm that completed an acrosome reaction, from 50% (±5.1) at hour 1 and 62.5% (±7.4) at hour 2. Only 14.2% (±3.6) completed acrosome reactions in sperm not treated with P4 by hour 2. Motile sperm in both groups did not decrease over the 2-h incubation time period (P<0.05). Progesterone treatment increased the percentage of fertilized embryos after ICSI, with 38.1% fertilized compared with 10.1% with heparin-treated control injections (P<0.001). These results show that P4 has effects on bovine sperm that allow for higher rates of fertilization after ICSI by utilising the sperm’s physiological response to progesterone. Further embryo development using ICSI with P4-treated sperm, or additional physiologically similar treatments, should continue to be assessed.
86 Ultrasonographic evaluation of preovulatory follicle and endometrial echo texture for ovulation prediction in Marwari mares
Authors: Yadav D. , Jhamb D. , Nirwan S. S. , Gaur M.
Published: January 2021

The objective of the present study was to evaluate the application of ultrasonographic changes in the preovulatory follicle and uterus for ovulation prediction in Marwari mares. Mares (n=20) were teased daily by a teaser pony and, from the day of first detected oestrus, the ovaries and uterus were examined by transrectal ultrasonography using Exago ECM ultrasound equipped with linear rectal probe (10MHz) until ovulation. Recorded data were analysed by one-way ANOVA and correlation coefficients. The duration of the oestrus period ranged from 5 to 7 days in all mares, with an average of 6.35±0.13 days, consistent with rectal findings. The last day of oestrus was marked by disappearance of the preovulatory follicle and presence of a corpus haemorrhagicum. The mean diameter of the follicles increased significantly (P<0.01) from Day 1 to Day 7, and the diameter of follicles before ovulation was 44.88±0.46 mm; follicles changed from round to oval or irregular before ovulation. In 65% (13/20) of the mares, ovulation occurred on the left ovary. The daily mean growth rate of size of ovulating follicles from the first day of oestrus until ovulation was 3.51±0.42 mm/d. The mean average growth rate of follicles was significantly different (P ≤ 0.01) on different days of oestrus. The mean endometrial echo texture score was 1.30±0.10 on Day 1, 2.10±0.16 on Day 2, 3.20±0.15 on Day 3, and highest 3.85±0.08 on Day 4, declining thereafter to reach a score of 1.36±0.11 on Day 7 of the oestrous cycle. The mean slope values of pixel intensity for the granulosa and anechoic layers of the preovulatory follicles determined by Image-Pro software (Media Cybernetics) from Days −3 to −1 was 13.8±0.7 on Day −3, 15.7±0.9 on Day −2, and 20.1±1.3 on Day −1. None of the follicles ovulated before granulosa layer echogenicity reached a score of ≥2.5 and prominence of anechoic layer reached a score of ≥2. Significant positive correlations were found between the cross-sectional diameter of the uterine horn and estrual endometrial echotexture score (P<0.01; r=0.95), estrual endometrial echo texture score and preovulatory follicle diameter (P<0.01; r=0.25), and preovulatory follicle diameter and cross-sectional diameter of uterine horn (P<0.01; r=0.36) during the oestrous cycle. We conclude that various ultrasonographic characteristics of preovulatory follicle and uterus can be used to predict ovulation in Marwari mares.
88 Plasma anti-Müllerian hormone as a marker for ovarian follicular population and oocyte quality in alpacas
Authors: Arana N. Z. , Ygnacio H. C. , Zárate F. T. , Malca E. A. , Gallegos-Cárdenas A.
Published: January 2021

The limited success of embryonic transfer technique in alpacas is related to the high variability of superovulation protocols, the response to which depends on, among other factors, the number of antral follicles growing along a follicular wave. The concentration of anti-Müllerian hormone (AMH) is correlated with antral follicle count, making it a reliable biomarker for identifying the number of available follicles and allowing us to ensure the reproductive potential of females. Studies in different production animals exist, but, thus far, no published studies exist on the use of AMH as a biomarker in alpacas. Thus, its study is necessary in order to be able to choose the best donors for embryonic transfer, reducing response variability and unnecessary expenses in superovulation protocols. The objective of this study was to determine whether AMH is a reliable marker for the number of follicles and quality of oocytes in an induced follicular wave in alpacas. We used 52 female, nonpregnant Suri alpacas of reproductive age (3–7 years), with a body condition score between 2.5 and 3.5 (where 1 is extremely thin and 5 is obese), and with the presence of a preovulatory follicle (diameter ≥7mm) determined through transrectal ultrasound. Blood samples were collected from nonpregnant Suri alpacas 5 days post-induction of ovulation and divided into groups according to AMH concentration. AMH concentrations were then correlated with the number of follicles and percentage by sizes of follicles using the least significant difference test with adjusted means. To relate the quality of oocytes with the AMH concentration groups, a Chi-square test was used. The high-AMH group had a greater number of follicles than the low-AMH group (20.51±2.76 vs. 11.58±2.55; P=0.036). There were no significant differences between AMH groups and percentage of follicle sizes. However, the high-AMH group had a greater percentage of follicles 3- to 7-mm long (67.49%). Furthermore, the high-AMH group showed dependence on the quality of oocytes (P=0.02). These results indicate that the plasma concentration of AMH can be a reliable marker for follicle and oocyte quality in Suri alpacas. Future investigations are needed to ensure the optimal timing to collect blood samples, a kit individualized to the species, and improvement of the future donors for current superovulation protocols in alpacas.
94 Myostatin gene editing by CRISPR/Cas9 technology of Brangus fetal fibroblasts to produce edited embryos by cloning
Authors: Bastón J. I. , Viale D. , Olguin M. , Wiedenmann E. , Arnold V. , Suva M. , Luzzani C. , Miriuka S. , Moro L. N. , Vichera G.
Published: January 2021

Some European cattle breeds, such as Charolais and Maine Anjou, have natural mutations in the myostatin gene (MSTN) that inhibit its expression and result in an increase in muscle mass and protein content. An innovative hallmark would be the invitro introduction of this genotype in South America cattle breeds to improve their commercial value. To achieve this, we aimed to disrupt MSTN gene expression in bovine fetal fibroblasts (BFFs) using CRISPR/Cas9 technology and to generate MSTN-edited embryos by somatic cell nuclear transfer (SCNT). BFFs were isolated from a cloned fetus of a Brangus bull with a prized genetic background and nucleofected with the Cas9 ribonucleoprotein-gRNA complex previously assessed to target exon 2 of the bovine MSTN gene. To evaluate MSTN editing, genomic DNA from the wild-type (WT) and nucleofected BFFs were isolated, exon 2 of MSTN was amplified by PCR, and the PCR product was Sanger sequenced. In all cases, the sequencing results were analysed using the indel Synthego software tool. According to indel analysis, MSTN gene editing efficiency of the BFFs was 58.83%±3.2 (n=6). The resulting edit consisted of insertion of thymine in exon 2 of the MSTN gene that shifted the gene reading frame, introducing a premature stop codon and generating a truncated MSTN protein. The nucleofected BFFs were then used to generate embryos by SCNT, and WT BFFs were included as controls. Embryo cleavage and blastocyst development rates were evaluated at Day 2 and 7, respectively (Chi-squared test, P<0.05). Although lower cleavage rates were obtained in the MSTN-edited BFFs group [65.3% (n=273/418) vs. 87.6% (n=169/193)], no differences were observed at the blastocyst stage [19.1% (n=80/418) vs. 25.4% (n=49/193)]. To confirm the efficiency of MSTN editing in the cloned embryos, 10 blastocysts generated with the MSTN-edited BFFs were individually analysed for MSTN exon 2 sequence as described before. The results showed that 30% of the blastocysts (3/10) presented a homozygous biallelic edition, which consisted of a thymine base insertion, as expected. In summary, the strategy we used allowed production of MSTN null cloned Brangus embryos avoiding putative undesired integration of exogenous DNA into the bovine genome, such as plasmid sequence, regardless of off-target occurrences. We conclude that CRISPR/Cas9 is an efficient technique to disrupts MSTN gene expression in bovine embryos; this work represents a step toward improving the production efficiency of South American cattle breeds.
Dealing with the impact of the COVID‐19 outbreak: Are some athletes’ coping profiles more adaptive than others?
Authors: Pété Emilie , Leprince Chloé , Lienhart Noémie , Doron Julie
Published: January 2021

The public health policies and sanitary measures taken by governments in various countries to stem the spread of the COVID‐19 pandemic (e.g. lockdown, social distancing) have major implications for athletes. The radical changes are challenging and risk causing significant career disruption to athletes, with subsequent negative psychological effects. Thus, the ways athletes cope with such adversity is of critical importance. The present study aimed to identify athletes’ coping profiles using a person‐centred approach, based on their reported use of multiple coping strategies in response to the impact of the COVID‐19 outbreak, and to compare levels of anxiety, stress appraisals, interpersonal coping strategies, and availability and appreciation of the major sources of support across profiles. A total of 526 French athletes competing at national to elite levels answered an online questionnaire during the lockdown. Latent profile analysis results yielded four distinct coping profiles (i.e. self‐reliant, engaged, avoidant, active and social). The MANOVA showed that athletes belonging to the four profiles differed on anxiety, stress appraisals, social support, and interpersonal coping. In particular, avoidant copers reported high levels of anxiety, threat, and uncontrollability, and appeared less able to regulate responses to the impact of the COVID‐19 outbreak. Using a person‐centred approach, the findings could inform the development of more adequate care, support, and intervention for athletes, especially avoidant copers, who were characterized by the least effective coping skills and resources. Accordingly, stress reappraisal and stress mindset interventions could be promising approaches to effectively manage pandemic‐related impact during and after the COVID‐19 crisis.

Highlights

The COVID‐19 outbreak has major implications for athletes and is causing significant disruption to their careers. Using a person‐centred approach, four coping profiles emerge showing athletes' preferred use of several coping strategies in response.

The four coping profiles (i.e. self‐reliant, engaged, avoidant, active and social) differentiate distinct groups of athletes in relation to anxiety, stress appraisals, social support, and interpersonal coping.

Avoidant copers were characterized by the least effective coping skills and social context of coping. Management of the COVID‐19 situation may be more problematic for them than other in mitigating its negative psychological effects.

Using a person‐centred approach, the findings could inform the development of more adequate care, support, and intervention for athletes, especially avoidant copers, who were characterized by the least effective coping skills and resources.
Quantum creation of a toy Universe without inflation
Authors: Wang Yi , Zhu Mian
Published: January 2021

We propose a toy model for the origin of the Universe, where the scale-invariant fluctuations are generated together with the quantum creation process of the Universe. The fluctuations arise inside an instanton in the Euclidean domain of time. In the Lorentzian point of view, the Universe emerges with passive, coherent and scale-invariant fluctuations present from the beginning, without the need of inflation or a bounce. For this mechanism to work, we need anisotropic scaling in space and time, which is realized in a toy model of Horava–Lifshitz (HL) gravity with a Lifshitz scalar field.
Refraction and total internal reflection in a prism with an arbitrary apex angle
Authors: Moon Geol , Kim Jin-Tae , Noh Heung-Ryoul
Published: January 2021

We study the reflection and refraction of a monochromatic ray of light in a normal or rhomboid-shaped prism with an arbitrary apex angle. In particular, we investigate the conditions for the occurrence of the total internal reflection and propagation of light on the second surface of the prism by varying the incidence angle, apex angle, and refractive index of the prism. The regions within the two-dimensional incidence angle–apex angle and incidence angle–refractive index spaces, which correspond to refraction or total internal reflection occurring at the surfaces of the prism, are characterized in detail. Thus, this study facilely obtained solutions to the typical problems of refraction and total internal reflection in a prism.
Robertson–Schrödinger uncertainty relation for qubits: a visual approach
Authors: Gutiérrez-Vega Julio C
Published: January 2021

The uncertainty principle sets a limit to our capacity to predict the outcomes of two incompatible measurements. The Heisenberg uncertainty relation for two arbitrary observables

A

and

B

is usually discussed in textbooks. However, little or no attention is paid to the fact that Schrödinger generalised the Heisenberg relation taking into account the covariance between the observables

A

and

B

. This extended inequality is known as the Robertson–Schrödinger uncertainty relation. Here, we demonstrate the less known fact that two-level quantum states, i.e., qubits, satisfy the equality of the Robertson–Schrödinger uncertainty relation for two arbitrary observables

A

and

B

. Taking advantage of the homomorphism between SU(2) and SO(3) groups, it is possible to map the distributions of the expectation values and variances of the observables, and the Heisenberg and covariance terms on the Bloch sphere. The graphical visualisation of the relevant quantities involved in the uncertainty relations allows us to distinguish specific properties and symmetries that are not so evident in the algebraic formalism.
A shadow of the repulsive Rutherford scattering and Hamilton vector
Authors: Shatilov D A , Silagadze Z K
Published: January 2021

The fact that repulsive Rutherford scattering casts a paraboloidal shadow is rarely exploited in introductory mechanics textbooks. Another rarely used construction in such textbooks is the Hamilton vector, a cousin of the more famous Laplace–Runge–Lenz vector. We will show how the latter (Hamilton’s vector) can be used to explain and clarify the former (paraboloidal shadow).
Microfluidic chip fabrication and performance analysis of 3D printed material for use in microfluidic nucleic acid amplification applications
Authors: Tzivelekis Charalampos , Selby Matthew P , Batet Albert , Madadi Hojjat , Dalgarno Kenny
Published: January 2021

Additive manufacturing for microfluidics shows potential to boost research and development in research biology and molecular diagnostics. This paper reports on novel process and material optimisation techniques in the creation of a monolithic microfluidic chip geometry for polymerase chain reaction (PCR) thermocycling using stereolithography (SLA). A two-stage printing protocol with projection SLA is assessed in printing disposable oscillating-flow microfluidic cartridges for PCR. Print performance was characterized in terms of critical channel dimensions and surface quality. Post-treatment with ultraviolet light and solvent washes was shown to reduce PCR inhibiting residuals and facilitate the reaction, indicating material compatibility for fluidic and milli-fluidic PCR architectures. Residuals leaching from the polymer were shown via quantitative PCR that interact with enzyme activity. Passivation of channel surfaces with a polyethylene glycol and a silane static coating reduced the leaching interface improving overall PCR efficiency. The discussed protocols can serve as a low-cost alternative to clean-room and micromachined microfluidic prototypes for various microfluidic concepts.
Negative-curvature spacetime solutions for graphene
Authors: Gallerati Antonio
Published: January 2021

We provide a detailed analysis of the electronic properties of graphene-like materials with charge carriers living on a curved substrate, focusing in particular on constant negative-curvature spacetime. An explicit parametrization is also worked out in the remarkable case of Beltrami geometry, with an analytic solution for the pseudoparticles modes living on the curved bidimensional surface. We will then exploit the correspondent massless Dirac description, to determine how it affects the sample local density of states.
An improved TDCP-GNSS/INS integration scheme considering small cycle slip for low-cost land vehicular applications
Authors: Chen Kai , Chang Guobin , Chen Chao , Zhu Ting
Published: January 2021

An improved global navigation satellite system (GNSS)/inertial navigation system (INS) tightly coupled scheme based on a time-differenced carrier phase (TDCP) was proposed for a low-cost vehicle navigation system. The proposed scheme aims to improve the navigation performance and computational efficiency of the system for low-cost GNSS receivers and low-accuracy INS. The traditional measurement model based on the TDCP has either high accuracy with a large computational load or high efficiency with low accuracy. Considering both the positioning accuracy and computational burden, an accurate and efficient measurement model was derived in this paper. In positioning based on the carrier phase, it is an indispensable task to handle the cycle slips, especially small ones. However, the cycle slip of a certain moment only contaminates the current TDCP measurement, but not the subsequent TDCP measurements. Based on this characteristic of the TDCP measurement, a novel cycle slip processing strategy was proposed for the TDCP-GNSS/INS integration scheme, in which cycle slip is directly handled as a gross error with a robust extended Kalman filter (EKF). The vehicular test has been conducted to evaluate the performance of the improved TDCP-GNSS/INS integration scheme. Experiment results show: (a) compared with the traditional position error parameter-based measurement model, the proposed measurement model can improve the accuracy of the horizontal and vertical position by 58.4% and 12.5%, respectively. Compared with the traditional velocity error parameter-based measurement model, the proposed measurement model does not improve the positioning accuracy, but improves the computational efficiency by 25.2%. (b) The strategy of treating cycle slip as a gross error is feasible in the TDCP-GNSS/INS tightly coupled navigation system. Although a small cycle slip can seriously affect the positioning performance of the system, the robust EKF can effectively avoid the long-term harm caused by small cycle slips.
Phase transitions of two spin-1/2 Baxter–Wu layers coupled with Ising-type interactions
Authors: Liu Wei , Yan Zhengxin , Wang Yixian
Published: January 2021

Using a Monte Carlo simulation and the single histogram reweighting technique, we study the critical behaviors and phase transitions of the Baxter–Wu (BW) model on a two-layer triangular lattice with Ising-type interlayer couplings. Via the finite-size analysis, we obtain the transition temperatures and critical exponents at repulsive and attractive interlayer couplings. The data for the repulsive interlayer coupling suggest continuous transitions, and the critical behaviors are the same as those of the 2D BW model, belonging to the four-state Potts universality class. The reduced energy cumulants and the histograms reveal that attractive coupling leads to weak first-order phase transitions. The pseudocritical exponents with the existence of the interlayer couplings indicate that the first-order transition is very close to the critical point of the 2D standard BW model.
16.9 MW, efficient 486.1 nm blue optical parametric oscillator using single BBO crystal
Authors: Zhang Jiale , Ma Jian , Lu Tingting , Wang Jianlei , Zhu Xiaolei , Chen Weibiao
Published: January 2021

A single-resonant beta barium borate crystal optical parametric oscillator with high pulse energy output at the H-β Fraunhofer line of 486.1 nm was demonstrated. Pumped by a single-frequency 355 nm ultraviolet pulsed laser at 10 Hz repetition rate with maximum pulse energy of 411 mJ, maximum output energy of 162 mJ blue laser pulse at 486.1 nm was successfully obtained from a plano-concave cavity with a 40% output coupler, the corresponding optical-to-optical conversion efficiency was up to 39.4%, and the pulse width was around 9.6 ns. The blue laser beam size was 4.4 mm × 5.1 mm with the beam divergence angles of θx
= 2.2 mrad and θy
= 2.5 mrad. The peak power of output blue laser was 16.9 MW, and the signal linewidth was around 0.34 nm.
Continuous-variable quantum key distribution based on photon addition operation*
Authors: Chen Xiao-Ting , Zhang Lu-Ping , Chang Shou-Kang , Zhang Huan , Hu Li-Yun
Published: January 2021

It is shown that the non-Gaussian operations can not only be used to prepare the nonclassical states, but also to improve the entanglement degree between Gaussian states. Thus these operations are naturally considered to enhance the performance of continuous variable quantum key distribution (CVQKD), in which the non-Gaussian operations are usually placed on the right-side of the entangled source. Here we propose another scheme for further improving the performance of CVQKD with the entangled-based scheme by operating photon-addition operation on the left-side of the entangled source. It is found that the photon-addition operation on the left-side presents both higher success probability and better secure key rate and transmission distance than the photon subtraction on the right-side, although they share the same maximal tolerable noise. In addition, compared to both photon subtraction and photon addition on the right-side, our scheme shows the best performance and the photon addition on the right-side is the worst.
Influence of interface conditions on hydrogen transport studies
Authors: Delaporte-Mathurin Rémi , Hodille Etienne A. , Mougenot Jonathan , Charles Yann , De Temmerman Gregory , Leblond Floriane , Grisolia Christian
Published: January 2021

This work investigates the influence of hydrogen chemical potential continuity across solid material interfaces. The implementation of the mathematical model in FESTIM is verified using the method of exact solutions (MES) and the method of manufactured solutions (MMS) in 1D, 2D, with complex material properties and inhomogeneous temperature fields. A comparison test between FESTIM, TMAP7 and Abaqus codes is also performed and the codes show good agreement. The chemical potential continuity condition has an impact up to 40% on the outgassing particle flux on 4 mm composite slabs (W/Cu and Cu/EUROFER) compared to mobile concentration continuity. A method for rapid identification of materials properties from outgassing flux measurements is given. The influence of chemical potential conservation on monoblock inventory is then studied. It is shown that, for the 1D and 2D ITER divertor monobolocks cases, discrepancies only start to appear after approximately 5 × 106 s of full power.
Comparison multi-layer perceptron and linear regression for time series prediction of novel coronavirus covid-19 data in West Java
Authors: Yulita I N , Abdullah A S , Helen A , Hadi S , Sholahuddin A , Rejito J
Published: January 2021

Until now, the pandemic conditions of Covid-19 are still ravaging the world, even in Indonesia and West Java. Various attempts have been made to stop it. West Java implements Large Scale Social Restrictions, is known as Pembatasan Sosial Skala Besar (PSBB). However, over time, a discourse emerged to loosen PSBB. One of the World Health Organization’s (WHO) requirements to loosen is the effective reproduction rate of Corona Virus cases below 1. Therefore, this study focuses on predicting the number of cases in West Java. The methods based on multi-layer perception (MLP) and linear regression (LR). The data were obtained from the C Covid -19 positive case from March to mid-August 2020 in West Java. The experiments show that MLP reaches optimal if it used 13 hidden layers with learning rate and momentum = 0.1. The MLP had a smaller error than LR. Both of them predict the number of cases in the next 30 days from August 14, 2020. The results show that West Java will still have an increase in the number of new cases of Covid -19.
Application of Generalized Space Time Autoregressive Integrated (GSTARI) model in the phenomenon of covid-19
Authors: Alawiyah M , Kusuma D A , Ruchjana B N
Published: January 2021

Covid-19 has occurred throughout the world, including Indonesia. The spread of the coronavirus from human to human is happening very rapidly. This has caused the spread of covid-19 that occurred in Indonesia to have spread to all regions in Indonesia, one of which is Bandung Raya area. covid-19 cases that occur in Bandung Raya are increasing every day. In addition, the characteristics of covid-19 that occurred in each area of Bandung Raya also different. So that the covid-19 that occurred in Bandung Raya can be modelled with the Generalized Space-Time Autoregressive Integrated (GSTARI) model. The GSTARI model is a development of the GSTAR non-stationary model which assumes each location has heterogeneous characteristics and has a different parameter. The GSTARI model is applied to the patient of positive covid-19 data in the area of Bandung Raya including 4 regencies/cities in Bandung Regency, West Bandung Regency, Bandung City and Cimahi City. The result of the estimation of the GSTARI model to the covid-19 phenomenon shows that this model produces forecasting data that is close to the actual data in few days.
Modelling the spread of atherosclerosis considering relapse and linear treatment
Authors: Islamilova A , Aldila D , Giyarti W , Tasman H
Published: January 2021

Atherosclerosis is a narrowing of the arteries due to a build-up of plaque in the artery walls. One of the reasons for the spread of atherosclerosis is the widespread of improper lifestyle in a population because of the tendency to follow the improper lifestyle of people in the surrounding environment. Atherosclerosis can cause complications such as heart disease, stroke, etc. This study aims to construct a model for the spread of atherosclerosis among human population by considering relapse and linear treatment rates. The model was then analyzed analytically and numerically. Analytical study reveals the existence and local stability criteria of the equilibrium points, determine the basic reproduction numbers and investigate the existence of bifurcations of the constructed model using the center-manifold theorem. Some numerical simulations were conducted for some possible prevention scenarios in the field.
Optimization of coriander nutrition on leached chernozem of Central Caucasus
Authors: Kasatkina A O , Yesaulko A N , Korostylev S A , Gromova N V , Voskoboynikov A V
Published: January 2021

The article reflects the results of studies on the responsiveness of coriander “Amber” variety to a combination of doses and types of mineral fertilizers. As a result of the conducted researches for 2016–2018, it was established that the maximum crop yield was obtained on options N60P60-1.60 t/ha and N60P60K60-1.53 t/ha. It should be noted that for the Stavropol territory there are no scientifically sound recommendations for the practical application of mineral fertilizer systems, introduced under the culture of coriander. During the three-year field experiments, the influence of types and combinations of doses of mineral fertilizers was studied and the seed productivity of coriander when growing on leached chernozem of the Central Caucasus was established. The method of introduction of mineral fertilizers according to the Georges-Ville scheme (control, N60, P60, K60, N60P60, N60K60, P60K60, N60P60K60) used during the field experiment allowed us to obtain information about the effectiveness of types and combinations of mineral fertilizers. It was noted that the application of nitrogen fertilizers increased the NO3 content: when applying N60 – 11.6 mg/kg; N60P60 – 7.3 mg/kg; N60K60 – 3.6 mg/kg; N60P60K60 – 6.1 mg/kg. The result of the field experiment showed that the content of the mobile forms of phosphorus in the soil increased significantly to the control, and the difference was 3.4–5.6 mg/kg of soil. The effectiveness of potassium in many cases is moderate. The maximum value of exchangeable potassium was observed on the option with the use of K60-260 mg/kg of soil, and the minimum concentration of exchangeable potassium when applying N60P60-232 mg/kg of soil.
Using refrigeration machines and heat pumps in the cycle of steam generator in agricultural industry
Authors: Osintsev K V , Kuskarbekova S I , Klepikov N A
Published: January 2021

Chillers are required at all plant-processing plants. Refrigeration can be obtained from energy industry facilities. Absorption chillers are the most reliable units for use in thermal power plant cycles. Such units usually work in conjunction with heating networks and cooling systems of steam turbine power units. For example, in a heated water cooling system after a steam turbine condenser, absorption chillers are already in use. At the same time, the authors of the article offer another application of such aggregates. Low-power steam turbines use air cooling and water-air heat exchangers. In this cooling system, an absorption chiller can be used to increase the efficiency of the thermal power plant. Such chillers are highly reliable, so they must work until the end of the payback period of new equipment.
Soil protection measures during sunflower farming on slopes of Rostov oblast
Authors: Gaevaya E A , Ilyinskaya I N , Bezuglova O S , Taradin S A
Published: January 2021

The article presents data on the study of sunflower in two crop rotations located on the slope of the Bolshoi Log beam, Aksay District of Rostov Oblast in 2015 - 2019. Studies have shown that to prevent possible water erosion it is recommended to use chisel processing as the main tillage. This will reduce soil washout by 14–26% and runoff by 16–32%. It was revealed that replacing naked fallow in crop rotation with perennial grasses reduced the amount of washed-out soil by 28% and reduced water flow by 25%. It is shown that all farming methods on sunflower must be performed in the direction across the slope, along the lines close to the horizontals. In the case of a surface runoff caused by melt or storm water, It is recommended to create the irrigation and drainage structures of the shafts - ditches across the slope. The economic assessment of sunflower growing in the system of contour-strip organization of the territory is given.