Time Variation Research Articles

The relative importance of forced and unforced temperature patterns in driving the time variation of low-cloud feedback

Abstract Atmospheric models forced with observed sea-surface temperatures (SSTs) suggest a trend toward a more-stabilizing cloud feedback in recent decades, partly due to the surface cooling trend in the eastern Pacific (EP) and the warming trend in the western Pacific (WP). Here we show model evidence that the low-cloud feedback has contributions from both forced and unforced feedback components, and that its time variation arises in large part through changes in the relative importance of the two over time, rather than through variations in forced or unforced feedbacks themselves. Initial-condition large ensembles (LEs) suggest that the SST patterns are dominated by unforced variations for 30-year windows ending prior to the 1980s. In general, unforced SSTs are representative of an ENSO-like pattern, which corresponds to weak low-level stability in the tropics and less-stabilizing low-cloud feedback. Since the 1980s, the forced signals have become stronger, outweighing the unforced signals for the 30-year windows ending after the 2010s. Forced SSTs are characterized by relatively uniform warming with an enhancement in the WP, corresponding to a more-stabilizing low-cloud feedback in most cases. The time-evolving SST pattern due to this increasing importance of forced signals is the dominant contributor to the recent stabilizing shift of low-cloud feedback in the LEs. Using single-forcing LEs, we further find that if only greenhouse gases evolve with time, the transition to the domination of forced signals occurs 10-20 years earlier compared to the LEs with full forcings, which can be understood through the compensating effect between aerosols and greenhouse gases.

Interconnection between adolescents' and family members' sleep.

Deficient sleep has been linked to a broad range of physical, cognitive and mental health impacts, in particular during adolescence. It is thus essential to understand its underlying mechanisms, including family factors. The goal of our study was to assess through combined subjective and objective assessments, how family members' daily variations in sleep are interconnected, between parents and siblings of adolescents. A total of 111 participants within 30 families were included, of whom 30 adolescents (14.5 years +/- 2.1 years, 46.7% boys), 30 siblings (12.8 years + /- 3.8, 40% boys), 30 mothers (43.5 years +/- 5.5) and 21 fathers (47.5 years +/- 7.6). Sleep was objectively assessed using parallel actigraphy recordings during a single week for all family members. Adolescents' daily variation in sleep duration and timing displayed many concordances with their siblings' and their mothers' sleep, but not with their fathers' sleep. Adolescents whose parents did not set limits on sleep time or screen use went to bed over an hour later (p < 0.001) and slept over 30 min less on school nights. Our study demonstrates the important role of family sleep on adolescent sleep, through rule-setting and congruence between each family members sleep, in particular regarding sleep duration and timing.

Does the Fundamental Metallicity Relation Evolve with Redshift? II: The Evolution in Normalisation of the Mass-Metallicity Relation

Abstract The metal content of galaxies is a direct probe of the baryon cycle. A hallmark example is the relationship between a galaxy’s stellar mass, star formation rate (SFR), and gas-phase metallicity: the Fundamental Metallicity Relation (FMR). While low-redshift (z ≲ 4) observational studies suggest that the FMR is redshift-invariant, recent high-z JWST data indicate deviations from the FMR established at low-z. In this study, we utilize the FMR to predict the evolution of the normalisation of the mass-metallicity relation (MZR) using the cosmological simulations Illustris, IllustrisTNG, EAGLE, and SIMBA. Our findings demonstrate that a z = 0 calibrated FMR struggles to predict the evolution in the MZR of each simulation. To quantify the divergence of the predictions, we introduce the concepts of a “static” FMR, where the role of the SFR in setting the normalization of the MZR does not change with redshift, and a “dynamic” FMR, where the role of SFR evolves over time. We find static FMRs in SIMBA and dynamic FMRs in Illustris, IllustrisTNG and EAGLE. We suggest that the differences between these models likely points to the subtle differences in the implementation of the baryon cycle. Moreover, we echo recent JWST results at z &amp;gt; 4 by finding significant offsets from the FMR in IllustrisTNG and EAGLE, suggesting that the observed FMR may have a similar dynamic trend as these simulations. Overall, our findings imply that the current FMR framework neglects important time variations of these simulations’ baryon cycles.

SYNTHESIS AND CHARACTERIZATION OF ZEOLITES FROM COAL FLY ASH WASTE

South Sumatra had coal production through PT Bukit Asam Tbk, which had coal production since 1950. Tanjung Enim Steam Power Plant (PLTU) is the largest coal ash producer because coal is the primary fuel. Coal combustion by-products include coal fly ash (CFA) and coal bottom ash (CBA). The current utilization of the CFA Tanjung Enim Steam Power Plant is for a cement mixture of PT Semen Baturaja and planting media. This work attempts to optimize zeolite synthesis from CFA by examining the effects of hydrothermal duration on reducing coal waste. This research studies the effect of hydrothermal time with time variations of 5, 12, and 24 on the morphology and phase of zeolite obtained. CFA from the Tanjung Enim Steam Power Plant contains SiO₂ and Al₂O₃, which account for 47.7% and 28.7% of the total composition, respectively. The SEM characterization result shows that the synthesized zeolite forms aggregates with a particle size of about 8-15 μm. Based on XRD characterization of CFA hydrothermal time of 5 hours, the dominant phase is the gibbsite phase, but there is a sodalite phase. The 12-hour hydrothermal time showed the formation of quartz, gibbsite, and sodalite phases. The 24-hour hydrothermal time shows that the dominant phase is sodalite, but there are gibbsite and quartz phases. The peak of the quartz phase decreases the longer the hydrothermal time. In this study, the duration of the hydrothermal process affects the formation of the zeolite phase.

HPB SO37 - GTN Patch for Medical Relaxation of the Sphincter of Oddi: “A Safe and Effective Pre-ERCP Treatment for Controlled Bile Leak Post-Cholecystectomy"

Abstract Background Bile leak is a frequent complication following laparoscopic total, subtotal cholecystectomy, and bile duct exploration (BDE) with an incidence up to 2.8%. It can contributing significantly to postoperative morbidity and mortality. GTN has demonstrated efficacy in reducing papillary muscle contraction and Sphincter of Oddi pressure. Similarly GTN might promote healing and closure of bile leaks post total or subtotal cholecystectomy. This study aims to assess the safety and effectiveness of GTN in treating bile leaks post total, subtotal cholecystectomy or bile duct exploration. Method Data was prospectively collected from patients who developed bile leaks after total or subtotal cholecystectomy between June 2020 and June 2024. Inclusion criteria were patients with a bile leak post-surgery during this period. Exclusion criteria included unstable patients, uncontrolled bile leaks, the presence of biliary obstruction, or major bile duct injuries. Suitable patients were treated with a GTN patch as first line management before potential ERCP. A 5 mg GTN skin patch was applied every 24 hours, starting at least 48 hours post-surgery if drain output exceeded 100 ml/hour. Patients were consented about side effects including hypotension and headache. Results Seven patients were treated with GTN, with mean age of 51 years, four were females. Four cases were emergencies and four had subtotal cholecystectomies, one in the elective group. Bile leaks occurred after biloma drainage and one after removal of trans-cystic drain post trans-cystic BDE. All patients experienced significant drain output reduction the day after starting GTN. There were no complications during or after treatment. One required ERCP two months later for persistent low-volume bile leak of 5-10 ml per day. Headaches occurred in two cases, treatment was discontinued in one. The average time to GTN treatment was 3.4 days. Conclusion This study demonstrates GTN treatment's safety and effectiveness for managing bile leaks following total, subtotal cholecystectomy or BDE. We recommend GTN as the primary therapy for controlled bile leaks, barring biliary obstruction or major injury. Response can be evaluated within 24-48 hours through significant output reduction. Implementing local protocols can minimize variations in GTN treatment initiation times. GTN should be prioritized over ERCP to prevent complications like perforation, pancreatitis, and bleeding. We aim for this study to underscore GTN's efficacy to surgeons and promote multicentre research initiatives.

Repeated Fed-Batch Culture Strategy for the Synthesis of Polyhydroxybutyrate (PHB) Biopolymers from Sugar Cane Juice Using Azotobacter vinelandii

In this research work, a main biopolymer group of polyhydroxyalkanoates (PHAs) in the form of polyhydroxybutyrate (PHB) was synthesised by a pure bacterial strain of Azotobacter vinelandii via repeated fed-batch fermentation. An agricultural crop, sugar cane, was used as the sole carbon source. Firstly, batch fermentation was investigated considering variations in incubation times (24 h, 48 h, and 96 h). The highest dry cell weight (DCW) and PHAs of 5.15 ± 0.04 g/L and 4.00 ± 0.04 g/L were obtained after 48 h of incubation time. The optimum time obtained was further varied to investigate the effect of the sugar concentrations in the medium. It was found that bacteria could grow very well and produced the highest DCW and PHAs (11.17 ± 0.15 g/L and 8.77 ± 0.06 g/L) when the culture medium with a 100 g/L sugar concentration was added. Later, repeated fed-batch fermentation was carried out to improve productivity. The results obtained revealed that PHA production was increased in the next cycle of the process. Furthermore, the final productivity (0.104 g/L·h) was increased 1.65-fold compared to the first cycle (0.063 g/L·h). Moreover, the culture strategy showed remarkable results, with reductions in both fermentation time and preparation cost.

Comparison and identification of human coronary plaques with/without erosion using patient-specific optical coherence tomography-based fluid-structure interaction models: a pilot study.

Plaque erosion (PE) with secondary thrombosis is one of the key mechanisms of acute coronary syndrome (ACS) which often leads to drastic cardiovascular events. Identification and prediction of PE are of fundamental significance for disease diagnosis, prevention and treatment. In vivo optical coherence tomography (OCT) data of eight eroded plaques and eight non-eroded plaques were acquired to construct three-dimensional fluid-structure interaction models and obtain plaque biomechanical conditions for investigation. Plaque stenosis severity, plaque burden, plaque wall stress (PWS) and strain (PWSn), flow shear stress (FSS), and ΔFSS (FSS variation in time) were extracted for comparison and prediction. A logistic regression model was used to predict plaque erosion. Our results indicated that the combination of mean PWS and mean ΔFSS gave best prediction (AUC = 0.866, 90% confidence interval (0.717, 1.0)). The best single predictor was max ΔFSS (AUC = 0.819, 90% confidence interval (0.624, 1.0)). The average of maximum FSS values from eroded plaques was 76% higher than that from the non-eroded plaques (127.96 vs. 72.69 dyn/cm2) while the average of mean FSS from erosion sites of the eight eroded plaques was 48.6% higher than that from sites without erosion (71.52 vs. 48.11 dyn/cm2). The average of mean PWS from plaques with erosion was 22.83% lower than that for plaques without erosion (83.2kPa vs. 107.8kPa). This pilot study suggested that combining plaque stress, strain and flow shear stress could help better identify patients with potential plaque erosion, enabling possible early intervention therapy. Further studies are needed to validate our findings.

Motion-induced blindness shows spatial anisotropies in conscious perception.

Polar angle asymmetries (PAAs), the differences in perceptual experiences and performance across different regions of the visual field are present in various paradigms and tasks of visual perception. Currently, research in this area is sparse, particularly regarding the influence of PAAs during perceptual illusions, highlighting a gap in visual cognition studies. We aim to fill this gap by measuring PAAs across the visual field during an illusion applied to test conscious vision widely. Motion-induced blindness (MIB) is an illusion when a peripheral target disappears from consciousness as the result of a continuously moving background pattern. During MIB we separately measured the average disappearance time of peripheral targets in eight equidistant visual field positions. Our results indicate a significant variation in MIB disappearance times and frequencies as a function of target location. Specifically, we found shorter and fewer disappearances along the cardinal compared to oblique directions, and along the horizontal compared to the vertical meridian. Our results suggest specific consistencies between visual field asymmetries and conscious visual perception.

Influence of the variation in hydrothermal reaction time on the structural, optical and electrical properties of NiTiO3 perovskite and its application for gas sensing

Influence of the variation in hydrothermal reaction time on the structural, optical and electrical properties of NiTiO3 perovskite and its application for gas sensing

Oxidative Desulfurization of Dibenzothiophene Using Catalyst of NiO Impregnated on Magnetic Silica Sand from Parangtritis Beach

Oxidative desulfurization of dibenzothiophene (ODS-DBT) using catalyst of NiO impregnated on magnetic silica sand from Parangtritis beach (Ps) had been evaluated. The NiO-Ps catalyst was prepared using wet impregnation method with Ps to Ni (NO3)2·6H2O weight ratio of 1:1. The catalyst was calcined at a temperature of 400 °C for 5 h under flow of 20 mL min-1 of N2 gas. The ODS-DBT process was carried out using NiO-Ps catalyst on solution of n-hexane with a sulfur content of 500 ppm under variations of temperature, time, and H2O2 volume. The results of XRD and FTIR indicated the main minerals of Ps were quartz, alumina, and magnetite. The Ps and NiO-Ps had crystallinities of 59.97 and 70.32% with crystal sizes of 16.32 and 10.95 nm. The SEM-EDX and TEM analysis showed the surface of Ps was flat and NiO-Ps was rough. The BET-nitrogen absorption-desorption indicated the Ps and NiO-Ps were mesoporous materials with average pore diameters of 11.98 and 24.01 nm, total pore volumes of 0.008 and 0.057 cm3 g-1, and specific surface areas of 2.611 and 9.502 m2 g-1. The Ps and NiO-Ps have acidity values of 1.14 and 1.74 mmol g-1. The optimum desulfurization using NiO-Ps catalyst in the ODS-DBT was 79.40% obtained at a temperature, time, and H2O2 volume of 60 °C, 30 min, and 0.42 mL.

Analysis of Ash Content of Red Salak Bean Coffee (Salacca edulis) Based on Duration of Roasting Length

Maluku province, Seram district in the west, found a strawberry. Fruit is a tropical and horticultural commodity with a fairly high availability. Protein, ash, fat, and water are the closest analysis, carbohydrates as well as fiber. Coffee has a distinctive aroma from the coffee plant and contains high levels of caffeine compounds. The presence of this compound under certain conditions will make coffee unsuitable for consumption, so several types of coffee have emerged which are made from grains from certain plants. One of the potential seeds is snake fruit seeds. Coffee seeds are a new beverage product, the researchers used the old coagulation factor, because long coagulation will affect the formation of aroma and the color of the coffee powder produced will determine the characteristic taste of coffee, which is caused by long variations in coagulation times that vary. The results obtained are presented in the form of tables and analyzed descriptively. The resulting ash composition of red coffee seeds (Salacca edulis) based on different grain durations was 3.46% for 30 minutes, 4.24% for 60 minutes, and 4.70% for 90 minutes. The highest ash content found in red coffee was 4.70% and the lowest grain is 2.46%. Keywords: Red Salak, ash content, roasting duration

Travel Time Reliability Analysis on Paratransit, case study: Substação-Muahivire route, Nampula - Mozambique

In numerous medium-sized cities in Sub-Saharan Africa, such as Nampula, the reliability of mini-bus travel time is frequently a subject of inquiry. One contributing factor to this uncertainty is the considerable number of stops made throughout the route for passenger-related purpose, including boarding and disembarking. This study utilizes data collected during off-peak periods to scrutinize the day-to-day travel time patterns of mini-buses along the route. The route has been segmented into intervals of 500 meters each, and the analysis focuses on the duration of trips at each segment. The evaluation is based on the Coefficient of Variation (CoV) of travel time, indicating the extent of dispersion in mini-bus travel time at the segment level. The results reveal that the CoVs at nearly all segments along the route are minimal, measuring less than 15%. This suggests that day-to-day variability of travel time at the segment level is negligible. However, on road segments characterized by commercial activities, the CoVs range from 15% to 22%.

Machine learning for epithelial ovarian cancer platinum resistance recurrence identification using routine clinical data

BackgroundMost epithelial ovarian cancer (EOC) eventually develops recurrence. Identification of high-risk patients can prompt earlier intervention and improve long-term outcomes. We used laboratory and clinical data to create models based on machine learning for EOC platinum resistance recurrence identification.MethodsThis study was designed as a retrospective cohort analysis. Initially, we identified 1,392 patients diagnosed with epithelial ovarian cancer who underwent platinum-based chemotherapy at Yunnan Cancer Hospital between January 1, 2012, and June 30, 2022. We collected data on the patients’ clinicopathologic characteristics, routine laboratory results, surgical information, details of chemotherapy regimens, and survival outcomes. Subsequently, to identify relevant variables influencing the recurrence of platinum resistance, we screened thirty potential factors using two distinct variable selection methods: Lasso regression and multiple logistic regression analysis. Following this screening process, five machine learning algorithms were employed to develop predictive models based on the selected variables. These included decision tree analysis (DTA), K-Nearest neighbor (KNN), support vector machine (SVM), random forest (RF), and eXtreme gradient boosting (XGBoost). The performance of these models was compared against that of traditional logistic regression. To ensure robust internal validation and facilitate comparison among model performance metrics, a five-fold cross-validation method was implemented. Key performance indicators for the models included the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and average accuracy. Finally, we will visualize these models through nomograms, decision tree diagrams, variable importance plots, etc., to assist clinicians in their practice.ResultsMultiple logistic regression analysis identified eight variables associated with platinum resistance recurrence. In the lasso regression, seven variables were selected. Based on the findings from both Lasso regression and multiple logistic regression analysis, models were developed using these 7 and 8 factors. Among these, the XGBoost model derived from multiple logistic regression exhibited superior performance and demonstrated good discrimination during internal validation, achieving an AUC of 0.784, a sensitivity of 0.735, a specificity of 0.713, an average accuracy of 80.4%, with a cut-off value set at 0.240. Conversely, the LR model based on lasso regression yielded commendable results as well; it achieved an AUC of 0.738, a sensitivity of 0.541, a specificity of 0.836, with a cut-off value established at 0.154 and an accuracy rate of 79.6%. Finally, we visualized both models through nomograms to illustrate the significance of each variable involved in their development.ConclusionsWe have successfully developed predictive models for platinum-resistant recurrence of epithelial ovarian cancer, utilizing routine clinical and laboratory data. Among these models, the XGBoost model—derived from variables selected through multiple logistic regression—demonstrated the best performance. It exhibited high AUC values and average accuracy during internal validation, making it a recommended tool for clinical use. However, due to variations in time and context, influencing factors may change over time; thus, continuous evolution of the model is necessary. We propose a framework for this ongoing model adaptation.

Wavelet-based vibration denoising for structural health monitoring

In the context of civil engineering applications, vibration responses are complex, exhibiting variations in time and space and often containing nonlinearity and uncertainties not considered during data collection. These responses can also be contaminated by various sources, impacting damage identification processes. A significant challenge is how to effectively remove noise from these data to obtain reliable damage indicators that are unresponsive to noise and environmental factors.This study proposes a new denoising algorithm based on discrete wavelet transform (DWT) that addresses this issue. The suggested method offers a strategy for denoising using distinct thresholds for positive and negative coefficient values at each band and applying denoising process to both detail and trend components. The results prove the effectiveness of the technique and show that Bayes thresholding performs better than the other techniques in terms of the evaluated metrics. This suggests that Bayes thresholding is a more accurate and robust technique for thresholding compared to other common techniques.

Variation in population size, nest distribution, colony extent, and timing of movements at the largest known parrot colony

Variation in population size, nest distribution, colony extent, and timing of movements at the largest known parrot colony

Local haplotyping reveals insights into the genetic control of flowering time variation in wild and domesticated soybean.

The timing of flowering in soybean [Glycine max(L.) Merr.], a key legume crop, is influenced by many factors, including daylight length or photoperiodic sensitivity, that affect crop yield, productivity, and geographical adaptation. Despite its importance, a comprehensive understanding of the local linkage landscape and allelic diversity within regions of the genome influencing flowering and contributing to phenotypic variation in subpopulations has been limited. This study addresses these gaps by conducting an in-depth trait association and linkage analysis coupled with local haplotyping using advanced bioinformatics tools, including crosshap, to characterize genomic variation using a pangenome dataset representing 915 domesticated and wild-type individuals. The association analysis identified eight significant loci on seven chromosomes. Moving beyond traditional association analysis, local haplotyping of targeted regions on chromosomes 6 and 20 identified distinct haplotype structures, variation patterns, and genomic candidates influencing flowering in subpopulations. These results suggest the action of a network of genomic candidates influencing flowering time and an untapped reservoir of genomic variation for this trait in wild germplasm. Notably, GlymaLee.20G147200 on chromosome 20 was identified as a candidate gene that may cause delayed flowering in soybean, potentially through histone modifications of floral repressor loci as seen in Arabidopsis thaliana (L.) Heynh. These findings support future functional validation of haplotype-based alleles for marker-assisted breeding and genomic selection to enhance latitude adaptability of soybean without compromising yield.

The effect of probiotic, prebiotic, and synbiotic supplements on anthropometric measures and respiratory infections in malnourished children: a systematic review and meta-analysis of randomized controlled trials

BackgroundMalnutrition remains a significant concern in many societies. This study systematically reviewed the effects of probiotics, prebiotics, and synbiotics on anthropometric measures in malnourished children, focusing on changes in weight, height, and respiratory infections (primary outcomes), and head circumference, hemoglobin, hematocrit, and body mass index (BMI) as secondary outcomes.MethodsThis systematic review and meta-analysis involved searching various databases in both Persian and English, including Scopus, Web of Science Core Collection, Cochrane Library, Science Direct, and PubMed up to October 5, 2024. Non-randomized controlled trials (RCTs) were excluded. The Cochrane Handbook Risk of Bias Version 2 tool was used to assess risk of bias, and RevMan 5.3 software was employed for analysis. Subgroup analyses were conducted based on the type of supplement received. Meta-regression was applied to identify factors influencing results, and the GRADE approach was used to evaluate evidence certainty.ResultsTwelve studies with a total of 3,086 children (aged up to 6 years, equally distributed between boys and girls) were included. All children were malnourished without underlying illnesses. Limitations of the study included variations in intervention type, dose, duration, and timing of outcome measurement. Meta-analysis revealed that probiotics, prebiotics, and synbiotics may increase weight (6 trials, mean difference: 0.33 kg, 95% CI: 0.15 to 0.50, low certainty of evidence), while probiotics and synbiotics may increase height compared to control groups (5 trials, mean difference: 0.44 cm, 95% CI: 0.02 to 0.85, low certainty of evidence). However, probiotics and synbiotics did not show a statistically significant effect on lower respiratory tract infections (5 trials, risk ratio: 0.84, 95% CI: 0.68 to 1.04, moderate certainty of evidence). Meta-regression indicated that intervention type, sample size, and follow-up duration were not significant moderators for outcomes related to weight, height, or respiratory infections.ConclusionThe current evidence suggests that probiotics, prebiotics, and synbiotics supplements may help manage malnutrition-related outcomes in malnourished children, but further research with stronger study designs is needed to confirm these findings due to the low certainty of evidence.

Time length of adaptation phase for subjective thermal environment evaluation based on thermal stability time

The adaptation phase is the primary process of subjective thermal comfort evaluations. The time length of the adaptation phase in existing studies disperses largely, which either risks low evaluation reliability or high time and economic costs. This study proposes to determine the time length of the adaptation phase for reliable subjective thermal environment evaluation and to avoid unnecessarily large time and economic costs. First, the variation and distribution of the initial thermal status of the adaptation phase are inferred from a steady bioheat model with ASHRAE (American Society of Heating, Refrigerating and Air-conditioning Engineers) Thermal Comfort Database II. Second, with the initial thermal status, the variation and distribution of the thermal stability time are inferred from the dynamic bioheat model. Third, the time length of the adaptation phase is quantified from the distribution of the thermal stability time according to the targeted reliability level. Results show that under the summer scenario, the time length of the adaptation phase increases from 16.9 – 31.2 min to 25.2 – 38.9 min when the reliability level increases from 90.0 % to 97.5 %. The time length of the adaptation phase of the winter scenario increases by 5.3 – 9.7 min relative to that of the summer scenario. A strategy of shifting the adaptation phase from thermal neutrality to slight warmth is proposed to effectively shorten the time length of the adaptation phase by 5.6 % – 19.4 % and 7.8 % – 23.9 % in the summer and winter scenarios respectively. These results are tabulated for practical convenience.

Seasonal and Local Time Variation in the Observed Peak of the Meteor Altitude Distributions by Meteor Radars

AbstractMeteoroids of sub‐milligram sizes burn up high in the Earth's atmosphere and cause streaks of plasma trails detectable by meteor radars. The altitude at which these trails, or meteors, form depends on a number of factors including atmospheric density and the astronomical source populations from which these meteoroids originate. A previous study has shown that the altitude of these meteors is affected by long‐term linear trends and the 11‐year solar cycle related to changes in our atmosphere. In this work, we examine how shorter diurnal and seasonal variations in the altitude distribution of meteors are dependent on the geographical location at which the measurements are performed. We use meteoroid altitude data from 18 independent meteor radar stations at a broad range of latitudes and investigate whether there are local time (LT) and seasonal variations in the altitude of the peak meteor height, defined as the majority detection altitude of all meteors within a certain period, which differ from those expected purely from the variation in the visibility of their astronomical source. We find a consistent LT and seasonal response for the Northern Hemisphere locations regardless of latitude. However, the Southern Hemisphere locations exhibit much greater LT and seasonal variation. In particular, we find a complex response in the four stations located within the Southern Andes region, which indicates that the strong dynamical atmospheric activity, such as the gravity waves prevalent here, disrupts, and masks the seasonality and dependence on the astronomical sources.

Factors Influencing Business Students’ Effort When Studying Mathematics

Each student’s effort is an important factor in achievement. Mathematics is an important subject for business students since there is a strong connection between performance in mathematics and success in business courses. The purpose of this paper is to identify the factors influencing a student’s choice of how much effort to put into studying business mathematics by questioning 273 students from two business schools in Norway. There is a considerable variation in the study time. By using a linear regression model, we identify the variables linked to effort. Females, and those who have higher enjoyment of mathematics, exert higher effort in business mathematics. Those with a strong background in mathematics from high school and students with parents who have higher education exert less effort in business mathematics. The attitudes toward mathematics do not seem to considerably affect effort.