scholarly journals Two Calving Laws for Grounded Iceberg-Calving Glaciers (Abstract only)

1983 ◽  
Vol 4 ◽  
pp. 295 ◽  
Author(s):  
C. S. Brown ◽  
W. G. Sikonia ◽  
Austin Post ◽  
L. A. Rasmussen ◽  
M. F. Meier
Keyword(s):  
Water Depth ◽  
Variance Reduction ◽  
Coefficient Of Determination ◽  
Time Intervals ◽  
Cross Sectional ◽  
Glacial Stream ◽  
Iceberg Calving ◽  
Average Water ◽  
Image Position ◽  
Best Fit

Prediction of the future retreat of Columbia Glacier, Alaska, required a calving law for the boundary condition at the terminus. Qualitative observations on the variations of all major iceberg-calving glaciers of Alaska suggest that calving is high whenever glaciers terminate in deep water, and greatly reduced whenever they terminate in shallow water. Calving relations were investigated based on calculations of calving speed, defined as the volume rate of iceberg discharge from the terminus divided by the cross-sectional area of the terminus. The calving speed was determined for 12 glaciers for which measurements of glacier speed, advance and retreat rates, and other variables were obtained. To extend the range of data, four additional periods of rapid retreat were examined. Values for the terminus characteristics of water depth, cliff height, and thickness of the terminus, averaged over the width of the glacier and over a year, were then examined in relation to the calculated speeds of calving. A statistical analysis to determine the form and coefficients of an empirical calving relation that approximates the data shows that calving speed is best fitted by a simple proportionality to average water depth at the terminus: 1 where v c is the calving speed and h w the water depth, both averaged over the width and over a year, and c a constant of proportionality. This gives a variance reduction fraction (similar to the coefficient of determination r2) of 0.90. To investigate seasonal changes in calving, data based on shorter time intervals were obtained at the head of embayments from Columbia Glacier. At intervals of approximately two months, the following expression fits intra-yearly calving at Columbia Glacier: 2 where D is the meltwater discharge from the glacier, hj is the height of the ice column unsupported by water buoyancy, a, b, c are constants, and vc and hu are evaluated at the embayment head. D was determined by correlation with a nearby glacial stream, and hu = h _ hw PW/PJ, where h is glacier thickness and pi and pw the densities of ice and water. Best-fit values of b and c are approximately 0.5 and -2, respectively. This yields a variance reduction fraction r2 of 0.83. Equation (2) does not fit data averaged over a year and over the width of the glacier and Equation (1) does not fit data obtained over shorter periods at the head of the embayment. Although the two equations are different in form, for similar or average values of D and h - hw (ice-cliff height), they give approximately similar results over the present range of the geometry of the terminus of Columbia Glacier. Whether this will be true after rapid retreat begins remains to be seen.

scholarly journals Two Calving Laws for Grounded Iceberg-Calving Glaciers (Abstract only)

1983 ◽  
Vol 4 ◽  
pp. 295-295 ◽  
Author(s):  
C. S. Brown ◽  
W. G. Sikonia ◽  
Austin Post ◽  
L. A. Rasmussen ◽  
M. F. Meier
Keyword(s):  
Water Depth ◽  
Variance Reduction ◽  
Coefficient Of Determination ◽  
Time Intervals ◽  
Cross Sectional ◽  
Glacial Stream ◽  
Iceberg Calving ◽  
Average Water ◽  
Image Position ◽  
Best Fit

Prediction of the future retreat of Columbia Glacier, Alaska, required a calving law for the boundary condition at the terminus. Qualitative observations on the variations of all major iceberg-calving glaciers of Alaska suggest that calving is high whenever glaciers terminate in deep water, and greatly reduced whenever they terminate in shallow water. Calving relations were investigated based on calculations of calving speed, defined as the volume rate of iceberg discharge from the terminus divided by the cross-sectional area of the terminus. The calving speed was determined for 12 glaciers for which measurements of glacier speed, advance and retreat rates, and other variables were obtained. To extend the range of data, four additional periods of rapid retreat were examined. Values for the terminus characteristics of water depth, cliff height, and thickness of the terminus, averaged over the width of the glacier and over a year, were then examined in relation to the calculated speeds of calving. A statistical analysis to determine the form and coefficients of an empirical calving relation that approximates the data shows that calving speed is best fitted by a simple proportionality to average water depth at the terminus: 1 where vc is the calving speed and hw the water depth, both averaged over the width and over a year, and c a constant of proportionality. This gives a variance reduction fraction (similar to the coefficient of determination r2) of 0.90.To investigate seasonal changes in calving, data based on shorter time intervals were obtained at the head of embayments from Columbia Glacier. At intervals of approximately two months, the following expression fits intra-yearly calving at Columbia Glacier: 2 where D is the meltwater discharge from the glacier, hj is the height of the ice column unsupported by water buoyancy, a, b, c are constants, and vc and hu are evaluated at the embayment head. D was determined by correlation with a nearby glacial stream, and hu = h _ hw PW/PJ, where h is glacier thickness and pi and pw the densities of ice and water. Best-fit values of b and c are approximately 0.5 and -2, respectively. This yields a variance reduction fraction r2 of 0.83.Equation (2) does not fit data averaged over a year and over the width of the glacier and Equation (1) does not fit data obtained over shorter periods at the head of the embayment. Although the two equations are different in form, for similar or average values of D and h - hw (ice-cliff height), they give approximately similar results over the present range of the geometry of the terminus of Columbia Glacier. Whether this will be true after rapid retreat begins remains to be seen.

scholarly journals Error analysis of hydraulic radius evaluation in hydraulic calculation

2021 ◽  
Vol 260 ◽  
pp. 03016
Author(s):  
Ye Yin ◽  
Dangwei Wang ◽  
Hantao Wang ◽  
Anjun Deng ◽  
Shenghang Feng
Keyword(s):  
Cross Section ◽  
Water Depth ◽  
Hydraulic Calculation ◽  
Hydraulic Radius ◽  
Rectangular Section ◽  
Cross Sectional ◽  
Water Level Changes ◽  
Average Water ◽  
Cross Sectional Average ◽  
Natural Rivers

Hydraulic radius is an important parameter in hydraulic calculation. It is often deemed that hydraulic radius can be replaced by the cross-sectional average water depth when the width to depth ratio (B/H) is greater than a certain value in traditional. Based on the various artificial cross-section and natural ones, value-taking errors of hydraulic radius are studied in this paper. The results show that it is feasible to adopt the average water depth as the hydraulic radius when B/H of rectangular section is larger than 40 or B/H of isosceles triangular section is larger than 12. But for natural river, B/H is different when water level changes and there is no single-valued corresponding relationship between relative error and B/H. Therefore, we advise that hydraulic radius could not be replaced by other variables in hydraulic calculation of natural rivers.

scholarly journals Glacier–plume or glacier–fjord circulation models? A 2-D comparison for Hansbreen–Hansbukta system, Svalbard

2021 ◽  
pp. 1-14
Author(s):  
Eva De Andrés ◽  
Jaime Otero ◽  
Francisco J. Navarro ◽  
Waldemar Walczowski
Keyword(s):  
Water Depth ◽  
Seasonal Variations ◽  
Stress Fields ◽  
Two Dimensional ◽  
Coupled Models ◽  
Fjord Circulation ◽  
Glacier Front ◽  
Iceberg Calving ◽  
Best Fit ◽  
Frontal Ablation

Abstract Up to 30% of the current tidewater mass loss in Svalbard corresponds to frontal ablation through submarine melting and calving. We developed two-dimensional (2-D) glacier–line–plume and glacier–fjord circulation coupled models, both including subglacial discharge, submarine melting and iceberg calving, to simulate Hansbreen–Hansbukta system, SW Svalbard. We ran both models for 20 weeks, throughout April–August 2010, using different scenarios of subglacial discharge and crevasse water depth. Both models showed large seasonal variations of submarine melting in response to transient fjord temperatures and subglacial discharges. Subglacial discharge intensity and crevasse water depth influenced calving rates. Using the best-fit configuration for both parameters our two coupled models predicted observed front positions reasonably well (±10 m). Although the two models showed different melt-undercutting front shapes, which affected the net-stress fields near the glacier front, no significant effects on the simulated glacier front positions were found. Cumulative calving (91 and 94 m) and submarine melting (108 and 118 m) along the simulated period showed in both models (glacier–plume and glacier–fjord) a 1:1.2 ratio of linear frontal ablation between the two mechanisms. Overall, both models performed well on predicting observed front positions when best-fit subglacial discharges were imposed, the glacier–plume model being 50 times computationally faster.

Karakteristik Fisik, Kimia, Dan Biologi Tempat Perindukan Potensial Larva Anopheles Sp. Dan Indeks Habitat Di Desa Sukamaju Kecamatan Punduh Pidada Kabupaten Pesawaran

2021 ◽  
Vol 1 (2) ◽  
pp. 122-133
Author(s):  
Akmal Taher ◽  
Tusy Triwahyuni ◽  
Ismalia Husna ◽  
Devita Febriani
Keyword(s):  
Water Depth ◽  
Sampling Site ◽  
Physical Characteristics ◽  
Biological Characteristics ◽  
Water Salinity ◽  
Chemical Characteristics ◽  
Cross Sectional ◽  
Physical Chemical ◽  
Average Water ◽  
Breeding Place

ABSTRACT: PHYSICAL, CHEMICAL, AND BIOLOGICAL CHARACTERISTICS OF POTENTIAL FARMING PLACE OF LARVA Anopheles sp. AND HABITAT INDEX IN SUKAMAJU VILLAGE DISTRICT PUNDUH PIDADA PESAWARAN DISTRICT Background:  Malaria is an infectious disease transmitted through mosquitoes and has become a health problem both in the world and Indonesia especially in Lampung. The population of the malaria vector is strongly influenced by the location of the breeding place. Purpose: Knowing the Physical, Chemical, and Biological Characteristics of Potential Breeding Places for Anopheles Sp. and Habitat Index in Sukamaju Village, Punduh District, Pesawaran Regency, Lampung Province, 2020. Methods: This was a descriptive study with a cross-sectional study research design. The physical characteristics have done by measuring temperature and water depth, the chemical characteristics by measuring pH and water salinity, and the biological characteristics by looking at organisms found at the sampling site. As well as calculating the habitat index. Results: The physical characteristics of the brooding sites have an average water temperature of 31.33 ° C and an average water depth of 25.840 cm. Chemical characteristics of brooding sites mean 2.4280 ‰ of water salinity, and most of the acidity (pH) of water is acidic. The biological characteristics of breeding sites are mostly water and plant predators. Habitat index obtained a value of 1%.Conclusion: That these places have the potential to transmit malaria. Keywords: Anopheles sp., breeding place, malaria   INTISARI: KARAKTERISTIK FISIK, KIMIA, DAN BIOLOGI TEMPAT PERINDUKAN POTENSIAL LARVA Anopheles sp. DAN INDEKS HABITAT DI DESA SUKAMAJU  KECAMATAN PUNDUH PIDADA KABUPATEN PESAWARAN  Latar Belakang : Malaria merupakan penyakit infeksi yang ditularkan melalui nyamuk dan telah menjadi masalah kesehatan baik di dunia maupun di Indonesia khususnya di daerah Lampung. Populasi vektor malaria sangat dipengaruhi oleh lokasi tempat perindukannya. Tujuan : Mengetahui Karakteristik Fisik, Kimia, dan Biologi Tempat Perindukan Potensial Nyamuk Anopheles Sp. dan Indeks Habitat Di Desa Sukamaju Kecamatan Punduh Kabupaten Pesawaran Provinsi Lampung Tahun 2020. Metode : Jenis penelitian ini merupakan penelitian deskriptif dengan pendekatan cross sectional. Karakteristik fisik dilakukan dengan mekukur suhu dan kedalaman air, karakteristik kimia dengan mengukur pH dan salinitas air, dan karakteristik biologi dengan melihat organisme yang ditemukan di tempat pengambilan sampel. Serta melakukan penghitungan indeks habitat. Hasil : Karakteristik fisik pada tempat perindukan rata-rata suhu air 31,33°C, dan rata-rata kedalaman air 25,840 cm. Karakteristik Kimia pada tempat perindukan rata-rata salinitas air 2,4280‰, dan sebagian besar derajat keasaman (pH) air adalah asam. Karakteristik Biologi pada tempat perindukan sebagian besar terdapat predator air dan tumbuhan. Indeks habitat didapatkan nilai 1%. Kesimpulan : Bahwa tempat-tempat tersebut berpotensi untuk penularan penyakit malaria. Kata Kunci : Anopheles sp., malaria, tempat perindukan

Development and evaluation of trans-Amadi groundwater parameters: The integration of finite element techniques

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Finite Element ◽  
Polynomial Regression ◽  
Nitrate Concentration ◽  
Strong Relationship ◽  
Total Iron ◽  
Coefficient Of Determination ◽  
Port Harcourt ◽  
Polynomial Expression ◽  
The Relationship ◽  
Best Fit

Mathematical model was developed and evaluated to monitor and predict the groundwater characteristics of Trans-amadi region in Port Harcourt City. In this research three major components were considered such as chloride, total iron and nitrate concentration as well as the polynomial expression on the behavious on the concentration of each component was determined in terms of the equation of the best fit as well as the square root of the curve. The relationship between nitrate and distance traveled by Nitrate concentration by the model is given as Pc = 0.003x2 - 0.451x + 14.91with coefficient of determination, R² = 0.947, Chloride given as Pc = 0.000x2 - 0.071x + 2.343, R² = 0.951while that of Total Iron is given as Pc = 2E-05x2 - 0.003x + 0.110, R² = 0.930. All these show a strong relationship as established by Polynomial Regression Model. The finite element techniques are found useful in monitoring, predicting and simulating groundwater characteristics of Trans-amadi as well as the prediction on the variation on the parameters of groundwater with variation in time.

scholarly journals Correlation of Students’ Academic Achievements at a Professional Course of Ethics and Pediatrics Clinical Practice at Mizan-Tepi University, South Nations, Nationalities and People’s Region, Ethiopia

2021 ◽  
Vol 8 ◽  
pp. 2333794X2110037
Author(s):  
Lalisa Chewaka Gamtessa
Keyword(s):  
Academic Achievement ◽  
Clinical Practice ◽  
Nursing Students ◽  
Professional Ethics ◽  
Nursing Practice ◽  
Coefficient Of Determination ◽  
Significant Positive Association ◽  
Cross Sectional ◽  
Academic Achievements ◽  
Clinical Nursing

Nursing is a respect for dignity and treating every person equally. Qualifying competent and ethical nurses requires the incorporation of a professional code of ethics with clinical nursing practice. However, no study was conducted on the relationship between professional ethics and clinical nursing practice. Therefore this study aimed to determine correlation between professional ethics and pediatrics clinical practice from an achievement perspective. Accordingly, cross-sectional study design was conducted at Mizan-Tepi University using nursing students’ academic achievements at professional ethics and pediatric practice. Collected data were entered into Epi info 7. SPSS version 21.0 was used to calculate spearman’s rho correlation ( rs) and coefficient of determination ( R2) at P  < .05. A total of 316 study participants comprising of 209 (66.14%) male and 107 (33.86%) female nursing students included in the current study. Nursing students’ academic achievements at professional ethics was significantly and positively associated with achievements at pediatrics clinical practice ( rs  = 0.4-0.6), P < .001. Linear regression results revealed 25% to 26.7% coefficient determination for regular students and 18% to 22.9% for summer nursing students. To sum up, there was a significant positive association between achievements of students at professional ethics and pediatrics clinical practice. Therefore increasing students’ academic achievement in professional ethics can further improve their achievements at pediatrics clinical practice. However, academic achievement in professional ethics explained 22.35% of the variability in achievements at pediatric clinical practice. 77.65% of the variability in pediatrics clinical practice was due to other factors that deserve another study.

Dynamics of cardiac muscle: analysis of isotonic, isometric, and isochronal curves

1987 ◽  
Vol 253 (3) ◽  
pp. H645-H653
Author(s):  
O. N. Nwasokwa
Keyword(s):  
Muscle Force ◽  
Isometric Force ◽  
Impedance Matching ◽  
Time Intervals ◽  
Cross Sectional ◽  
Contraction Coupling ◽  
Force Development ◽  
Pentobarbital Sodium Anesthesia ◽  
Matching Transformer ◽  
Isotonic Shortening

Canine papillary muscle force-length-time relation (F-L-t) was investigated under pentobarbital sodium anesthesia. The time intervals taken from end diastole to any point (P) on the force-length plane was determined for isometric (t1) and isotonic (t2) systole and corrected for excitation contraction coupling duration. The ratio t1/t2, designated km, was approximately constant for widely scattered positions of P chosen systematically. The km in the 10 dogs ranged from 0.36 to 0.94 with means +/- SD of 0.66 +/- 0.16; km correlated negatively with muscle average cross-sectional area (r = -0.82; P less than 0.005). Assuming constancy of km, a general relationship was derived between (delta F/delta t)t1L, the rate of isometric force development at P; (delta L/delta t)t2F, the velocity of isotonic shortening at P; (delta F/delta L)(t1,t2)t, the stiffness; and (delta L/delta F)(t1,t2)t, the compliance of the myocardium (all taken at P) as follows (delta F/delta L)t1,t2t = -km(delta F/delta t)t1L/(delta L/delta t)t2F and (delta L/delta F)t1,t2t = -km-1(delta L/delta t)t2F/(delta F/delta t)t1t. The ratio of (delta F/delta t)t1L to (delta L/delta t)t2F defines functional proclivity and measures the differential propensity to force development relative to shortening. Thus myocardial stiffness or compliance determines functional proclivity by acting as an impedance-matching transformer that steps up or steps down force development of shortening as warranted by the loading conditions.

scholarly journals Nonlinear modeling growth body weight of Mangalarga Marchador horses

2017 ◽  
Vol 47 (4) ◽  
Author(s):  
Felipe Amorim Caetano Souza ◽  
Tales Jesus Fernandes ◽  
Raquel Silva de Moura ◽  
Sarah Laguna Conceição Meirelles ◽  
Rafaela Aparecida Ribeiro ◽  
...  
Keyword(s):  
Body Weight ◽  
Linear Models ◽  
Nonlinear Modeling ◽  
Growth Curves ◽  
Live Weight ◽  
Information Criterion ◽  
Coefficient Of Determination ◽  
Cross Sectional ◽  
Adult Body Weight ◽  
The Cross

ABSTRACT: The analysis of the growth and development of various species has been done using the growth curves of the specific animal based on non-linear models. The objective of the current study was to evaluate the fit of the Brody, Gompertz, Logistic and von Bertalanffy models to the cross-sectional data of the live weight of the MangalargaMarchador horses to identify the best model and make accurate predictions regarding the growth and maturity in the males and females of this breed. The study involved recording the weight of 214 horses, of which 94 were males and 120 were non-pregnant females, between 6 and 153 months of age. The parameters of the model were estimated by employing the method of least squares, using the iteratively regularized Gauss-Newton method and the R software package. Comparison of the models was done based on the following criteria: coefficient of determination (R²); Residual Standard Deviation (RSD); corrected Akaike Information Criterion (AICc). The estimated weight of the adult horses by the models ranged between 431kg and 439kg for males and between 416kg and 420kg for females. The growth curves were studied using the cross-sectional data collection method. For males the von Bertalanffymodel was found to be the most effective in expressing growth, while in females the Brody model was more suitable. The MangalargaMarchador females achieve adult body weight earlier than the males.

scholarly journals Drying kinetics of ‘babassu’ mesocarp

2017 ◽  
Vol 21 (10) ◽  
pp. 709-714 ◽  
Author(s):  
Jhonatas C. Rosa ◽  
Andreza P. Mendonça ◽  
Angélica dos S. Oliveira ◽  
Sylviane B. Ribeiro ◽  
Andréia do R. Batista ◽  
...  
Keyword(s):  
Experimental Data ◽  
Water Content ◽  
Animal Feed ◽  
Coefficient Of Determination ◽  
Residual Distribution ◽  
Solar Dryer ◽  
Error Standard Deviation ◽  
Forced Air ◽  
Final Water Content ◽  
Best Fit

ABSTRACT ‘Babassu’ mesocarp flour has been used by the pharmaceutical, human food and animal feed industries. However, there is lack of standardization in the production, as well as absence of information on the management of the product’s quality. Thus, the objective of this study was to dry the ‘babassu’ mesocarp in forced-air oven and solar dryer, adjust different mathematical models to the experimental data, as well as to quantify the levels of proteins and crude fiber of the produced flour. The criteria for the adjustment were the coefficient of determination, magnitude of the mean relative error, standard deviation of estimate and the residual distribution trend. Drying in the shortest time occurred in oven at 60 °C (370 min), leading to water content of 4.62%, while in the solar dryer the final water content was 8.07% in 6 days. The mathematical model Two Terms showed the best fit to the experimental data for oven drying and the Midilli model showed the best fit in solar dryer. There was an increase in protein content with the drying in solar dryer and oven at 40, 50 and 60 °C (1.36, 1.33, 1.15 and 1.37%, respectively) in relation to fresh mesocarp (0.88%). Drying in both oven and solar dryer promoted increase of protein in the flour.

scholarly journals Reconsidering the ‘Decline’ of Dental Student Empathy within the Course in Latin America

2017 ◽  
Vol 30 (11) ◽  
pp. 775 ◽  
Author(s):  
Víctor Patricio Díaz-Narváez ◽  
Ana María Erazo Coronado ◽  
Jorge Luis Bilbao ◽  
Farith González ◽  
Mariela Padilla ◽  
...  
Keyword(s):  
Latin America ◽  
Dental Students ◽  
Coefficient Of Determination ◽  
Dental Student ◽  
Cross Sectional ◽  
The Mean ◽  
Physician Empathy ◽  
Dental Schools ◽  
Academic Year ◽  
Made In

Introduction: The controversy over the presence of empathic decline within the course in students of medicine, dentistry and health sciences in general, has not fully been studied. This controversy could be partially solved if massive studies of empathy levels are made in similar cultural, social and economic contexts.Material and Methods: Empathy levels within the course were studied in eighteen dental schools from six countries in Latin America (2013). The mean of the empathy levels were used to study the behavior between first and fifth academic years. The values of empathy levels within the course were observed by applying the Jefferson Scale of Physician Empathy, the Spanish version. All these studies were cross-sectional. The value of means observed, were subjected to regression studies and further adjustment curves were obtained and the coefficient of determination were calculated.Results: Six different models of behavior were observed, which found that five of them suffer empathic decline within the course, but with different final results: in some the decline persists until the fifth academic year and in others, this decline ‘recovers’ persistently until the fifth academic year. The sixth model is characterized by a constant and persistent increase of levels of empathy within the course until the last academic year.Discussion: There are six different models for the behavior of means of levels of empathy within the course evaluated by a common methodology in eighteen dental schools from six countries of Latin America. These findings support the existence of variability of empathic response and a comprehensive approach is needed to find the causes that give rise to this variability.Conclusion: In dental students of Latin America, there is variability in the behavior of the distribution in means between the academic years of the dentistry schools examined in this study.

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