scholarly journals Estimating the size of the COVID-19 outbreak in Italy: Application of an exponential decay model to the weighted and cumulative average daily growth rate

2020 ◽  
Author(s):  
Nicola Bartolomeo ◽  
Paolo Trerotoli ◽  
Gabriella Serio
Keyword(s):  
Growth Rate ◽  
Exponential Decay ◽  
Weighted Average ◽  
Gompertz Model ◽  
Exponential Growth Phase ◽  
Credibility Interval ◽  
Daily Growth Rate ◽  
Daily Growth ◽  
Decay Model ◽  
Exponential Decay Model

To estimate the size of the novel coronavirus (COVID-19) outbreak in Italy, this paper introduces the cumulated and weighted average daily growth rate (WR) to evaluate an epidemic curve, On the basis of an exponential decay model (EDM), we provide estimations of the WR in four-time intervals from February 27 to April 07, 2020. By calibrating the parameters of the EDM to the reported data in Hubei Province of China, we also attempt to forecast the evolution of the outbreak. We compare the EDM applied to WR and the Gompertz model, which is based on exponential decay and is often used to estimate cumulative events. Specifically, we assess the performance of each model to short-term forecast of the epidemic, and to predict the final epidemic size. Based on the official counts for confirmed cases, the model applied to data from February 27 until the 17st of March estimate that the cumulative number of infected could reach 131,280 (with a credibility interval 71,415-263,501) by April 25 (credibility interval April 12 to May 3). With the data available until the 24st of March the peak date should be reached on May 3 (April 23 to May 23) with 197,179 cumulative infections expected (130033-315,269); with data available until the 31st of March the peak should be reached on May 4 (April 25 to May 18) with 202,210 cumulative infections expected (155.235-270,737); with data available until the 07st of April the peak should be reached on May 3 (April 26 to May 11) with 191,586 (160,861-232,023) cumulative infections expected. Based on the average mean absolute percentage error (MAPE), cumulated infections forecasts provided by the EDM applied to WR performed better across all scenarios than the Gompertz model. An exponential decay model applied to the cumulated and weighted average daily growth rate appears to be useful in estimating the number of cases and peak of the COVID-19 outbreak in Italy and the model was more reliable in the exponential growth phase.

SUBSTITUSI FERMENTASI BUNGKIL KELAPA SAWIT DALAM PAKAN BUATAN TERHADAP PERTUMBUHAN DAN KELANGSUNGAN HIDUP BENIH IKAN GURAMI (OSPHRONEMUS GOURAMY)

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Farida . ◽  
Eka Indah Raharjo ◽  
Arnis Maylinda Sari
Keyword(s):  
Growth Rate ◽  
Palm Oil ◽  
Palm Kernel ◽  
Specific Weight ◽  
Feed Conversion ◽  
Daily Growth Rate ◽  
Daily Growth ◽  
Average Growth ◽  
Fermentation Residue ◽  
Average Average

ABSTRAKPenelitian bertujuan untuk mengetahui penggunaan fermentasi bungkil kelapa sawit dalam pakan buatan.Penelitian menggunakan Rancangan Acak Lengkap (RAL) yang terdiri dari 4 perlakuan 3 ulangan.Susunan perlakuan adalah Perlakuan A : bungkil kelapa sawit 12%, Perlakuan B : fermentasi bungkil kelapa sawit 15%, Perlakuan C : fermentasi bungkil kelapa sawit 18%, Perlakuan D : fermentasi bungkil kelapa sawit 21%. Penelitian ini dilakukan selama 60 hari untuk mengetahui laju pertumbuhan spesifikberat, laju pertumbuhan harianpanjang, konversi pakan, kelangsungan hidup dan kualitas air sebagai penunjang.Hasil penelitian menunjukkan pemberian pakan buatan dengan fermentasi bungkil kelapa sawit menghasilkan respon yang baik terhadap pertumbuhan ikan gurami. Pemberian pakan buatan dengan fermentasi bungkil kelapa sawit 18% (perlakuan C), memberikan hasil terbaik dengan laju pertumbuhan dengan rata – rata laju pertumbuhan spesifik berat 1.502%, laju pertumbuhan harian panjang 4.06%, nilai konversi pakan rata – rata 3.48 dan kelangsungan hidup rata – rata 90%.Kata Kunci : Fermentasi Bungkil Kelapa Sawit, Ikan Gurami, Laju PertumbuhanThe study aims to determine the use of fermentation residue oil palm in artificial feed .Research using a completely randomized design ( CRD ), which consists of 4 treatment three replications.The composition of the treatment is the treatment  A : 12 % of palm oil cake , Treatment B : fermented palm oil cake 15 % , Treatment C : fermented palm oil cake 18 % , Treatment D : fermentation residue palm oil 21 %.This research was conducted for 60 days to determine the specific growth rate of heavy , long daily growth rate , feed conversion , survival and quality of water as a supporter.The results showed the artificial feeding with fermented palm cake to produce a good response to the growth of carp.Feeding artificially by fermentation cake palm oil 18 % ( treatment C ) , gives the best results with a growth rate with the average - average growth rate of the specific weight of 1.502 % daily growth rate long- 4:06 % , the value of feed conversion average - average 3:48 and median survival - average of 90 % .Keywords : Fermentation Palm Kernel Oil, Fish carp, Growth Rate

scholarly journals Public Compliance With Social Distancing Measures and SARS-CoV-2 Spread

2021 ◽  
pp. 003335492110112
Author(s):  
Hongjie Liu ◽  
Chang Chen ◽  
Raul Cruz-Cano ◽  
Jennifer L. Guida ◽  
Minha Lee
Keyword(s):  
Growth Rate ◽  
Reproduction Number ◽  
Early Stage ◽  
Human Mobility ◽  
The United States ◽  
Density Change ◽  
Regression Coefficients ◽  
Daily Growth Rate ◽  
Daily Growth ◽  
Social Distancing

Objective We quantified the association between public compliance with social distancing measures and the spread of SARS-CoV-2 during the first wave of the epidemic (March–May 2020) in 5 states that accounted for half of the total number of COVID-19 cases in the United States. Methods We used data on mobility and number of COVID-19 cases to longitudinally estimate associations between public compliance, as measured by human mobility, and the daily reproduction number and daily growth rate during the first wave of the COVID-19 epidemic in California, Illinois, Massachusetts, New Jersey, and New York. Results The 5 states mandated social distancing directives during March 19-24, 2020, and public compliance with mandates started to decrease in mid-April 2020. As of May 31, 2020, the daily reproduction number decreased from 2.41-5.21 to 0.72-1.19, and the daily growth rate decreased from 0.22-0.77 to –0.04 to 0.05 in the 5 states. The level of public compliance, as measured by the social distancing index (SDI) and daily encounter-density change, was high at the early stage of implementation but decreased in the 5 states. The SDI was negatively associated with the daily reproduction number (regression coefficients range, –0.04 to –0.01) and the daily growth rate (from –0.009 to –0.01). The daily encounter-density change was positively associated with the daily reproduction number (regression coefficients range, 0.24 to 1.02) and the daily growth rate (from 0.05 to 0.26). Conclusions Social distancing is an effective strategy to reduce the incidence of COVID-19 and illustrates the role of public compliance with social distancing measures to achieve public health benefits.

Tree windthrow and forest soil turnover

1989 ◽  
Vol 19 (3) ◽  
pp. 386-389 ◽  
Author(s):  
D. A. Norton
Keyword(s):  
Forest Soil ◽  
Exponential Decay ◽  
Half Life ◽  
Soil Development ◽  
Turnover Time ◽  
Important Influence ◽  
Plant Distribution ◽  
Canopy Trees ◽  
Decay Model ◽  
Exponential Decay Model

Soil turnover as a result of tree windthrow has an important influence on soil development and plant distribution in forests. Estimates of the time needed for soil turnover in a given area are often made, but unless these take into account the potential for reestablishment of canopy trees onto sites previously affected by windthrow, they are likely to substantially underestimate turnover time. Soil turnover is not a regular, uniform process, but rather results in a mosaic of soils with different turnover histories. Because soil turnover follows an exponential decay model, some area of soil will never be turned over. As it is therefore not possible to define the time when all the soil in an area has been turned over, it is proposed that soil turnover half-life (the time at which half the soil has been turned over) be used as a measure of soil turnover.

scholarly journals Pengaruh Nitrat (NO3) Terhadap Pertumbuhan Alami Eceng Gondok (Eichornia crassipes Solms.) Berdasarkan Biomassa Basah Di Danau Batur, Kintamani, Bali

2017 ◽  
Vol 3 (2) ◽  
pp. 215
Author(s):  
Lisa Rosalia Prayuda ◽  
I Wayan Arthana ◽  
Ayu Putu Wiweka Krisna Dewi
Keyword(s):  
Growth Rate ◽  
Water Hyacinth ◽  
High Fertility ◽  
Natural Growth ◽  
Initial Weight ◽  
Daily Growth Rate ◽  
Daily Growth ◽  
Natural Lakes ◽  
High Fertility Rate ◽  
Eichornia Crassipes

Batur Lake is one of the natural lakes in the province of Bali where the activity of fishing, agriculture, tourism and housing available. This study aims to determine the effect of nitrate relation to the natural growth of the water hyacinth (Eichornia crassipes). Increased water hyacinth biomass in Songan station is the highest among the three other stations (Batur, Buahan, and Trunyan). At the end of the study (day 42 ), water hyacinth biomass of Songan station increased by 338.2 % from the initial weight, while at another station the increase weight  ranges from 75 % -158 %. The highest daily growth rate in Trunyan station 3.68% / day, and the lowest in station Buahan which only reached 0.88% / day. At the Songan station where are many floating net which contribute to increase nitrate. There is a tendency of growth of water hyacinth faster at higher nitrate conditions. Nitrate conditions ranged from 0,35 to 0,62 m /l which shows that the waters of Batur Lake classified into waters that have a high fertility rate (eutrophic).

scholarly journals UTILIZATION OF MARINE FUNGAL Nodulisporium sp. KT29 METABOLITES TO IMPROVE THE PRODUCTION PERFORMANCE OF MARINE CULTURE OF WHITE SHRIMP

2017 ◽  
Vol 8 (2) ◽  
pp. 747
Author(s):  
Fazril Saputra ◽  
Dinamella Wahjuningrum ◽  
Kustiariyah Tarman ◽  
Irzal Effendi
Keyword(s):  
Growth Rate ◽  
Survival Rate ◽  
Conversion Ratio ◽  
Feed Conversion Ratio ◽  
Production Performance ◽  
White Shrimp ◽  
Feed Conversion ◽  
Daily Growth Rate ◽  
Daily Growth ◽  
Marine Culture

<em>This study aimed to determine the best dose of administration of marine fungal <span style="text-decoration: underline;">Nodulisporium</span> sp. KT29 metabolites to improve the production performance of marine culture of white shrimp. The experimental animals used were white shrimp <span style="text-decoration: underline;">Litopenaeus</span> <span style="text-decoration: underline;">vannamei</span> post larvae 12, which were reared in the sea using floating net cages with a stocking density of 700 post larvae/net. Experimental design used was a completely randomized design consisting of 3 treatments with 3 replications; control without the administration of <span style="text-decoration: underline;">Nodulisporium</span> sp. KT29 metabolites, dietary of feed containing <span style="text-decoration: underline;">Nodulisporium</span> sp. KT29 metabolites at doses of 20 mL/kg of feed and 40 mL/kg of feed. The results showed that survival rate, absolute length growth, weight gain, daily growth rate and feed conversion ratio in treatment groups were better than the control (P&lt;0.05). The administration of marine fungal <span style="text-decoration: underline;">Nodulisporium</span> sp. KT29 metabolites at a dose of 20 mL/kg of feed could improve the production performance of white shrimp cultivated in the sea with survival rate, daily growth rate and feed conversion ratio: 66.61±6.94%, 20.18±0.39 %/day and 3.20±0.22, respectively.</em>

scholarly journals PENGARUH SUBSTITUSI TEPUNG IKAN DENGAN TEPUNG KEPALA IKAN PATIN (Pangasius sp) TERHADAP PERTUMBUHAN IKAN LELE SANGKURIANG (Clarias sp)

2018 ◽  
Vol 6 (2) ◽  
pp. 129-140
Author(s):  
Yesica Manullang ◽  
Limin Santoso ◽  
Tarsim .
Keyword(s):  
Growth Rate ◽  
Fish Meal ◽  
Daily Growth Rate ◽  
Daily Growth ◽  
Protein Retention ◽  
Weight Growth ◽  
Randomized Design ◽  
Absolute Growth ◽  
Completely Randomized Design ◽  
Difference Test

ABSTRACTThe research was conducted at the Aquaculture Laboratory, University of Lampung in May to July,  2018. The aim of this study is to determine the effect of substitution of fish meal with catfish head flour on the growth of catfish, and head flour dosage the best for catfish growth. The study used a Completely Randomized Design with 3 treatments and 3 replications A (100% fish meal), B (70% fish meal and 30% catfish flour), and C (40% fish meal and 60% catfish flour). Parameters observed included absolute growth, daily growth rate, protein retention, feed convertion ratio (FCR), survival rate (SR), and supporting parameters that is feed cost and water quality. The data obtained were analyzed by variance and continued with smallest real difference test with a 95% confidence level. The results showed that the proportion of catfish head flour in artificial feed had an effect on absolute weight growth and daily growth rate (P, 0.001). The proportion of the use of 30% starch in the feed of catfish has a real influence on absolute growth (40.25 ± 5.67 g), and daily growth rate (0.67 ± 0.09 g/day).Keywords : Catfish, catfish head waste, substitution, feed, growth

scholarly journals Effect of periodic fasting on growth and feed efficiency in Giant Freshwater Prawn (Macrobrachium rosenbergii, de Man 1879)

2019 ◽  
Vol 2 (2) ◽  
pp. 53
Author(s):  
Waskito Dwi Utomo ◽  
Riza Rahman Hakim ◽  
Ganjar Adhywirawan Sutarjo
Keyword(s):  
Growth Rate ◽  
Feed Efficiency ◽  
Macrobrachium Rosenbergii ◽  
Freshwater Prawn ◽  
High Price ◽  
Daily Growth Rate ◽  
Daily Growth ◽  
Absolute Weight ◽  
Weight Growth ◽  
De Man

There are obstacles in the aquaculture business that is still often facedbyfarmers, one of the challengesisthe high price of commercial feed. Feed as an energy source for growth is a reasonably high-cost component in production that reaches 40-89 %. In the control of food for efficiency, it could be done by the fasting method. This research was aimedtoanalyze the effect of periodic fastedofgiant prawn (Macrobrachium rosenbergii de Man, 1879) against growth and feed efficiency. This research was conducted at IBAP Installation, Probolinggo District - East Java Province. The experimental method used completely randomized design with five treatments and three replications, such as; P0: feeding without fasting (as control), P1: a-day fasted, a-day feeding, P2: a-day fasted, two-days feeding, P3: a-day fasted, three-day feeding, P4: a-day fasted, four-days feeding, P5: a-day fasted, five-day feeding. The results showed that periodic fasted of M. rosenbergii no significant effect on the daily growth rate, absolute weight growth, and feed efficiency. However, by looking at the rate of growth, thisfasting methodcouldbe used as an alternative to saving feed. The P5 showed the most effective in increasing daily growth rate, absolute weight growth, and effectiveness of giant prawn feeding. The strategy of periodic fasted to increase the production of giant prawns should consider the other supporting factors such as ideal water quality (pH, temperature, and DO), proper stocking density, and feeding periods on schedule.

The effect of adding a feed flavour to the diets of young pigs before and after weaning

1979 ◽  
Vol 19 (101) ◽  
pp. 695 ◽  
Author(s):  
RH King
Keyword(s):  
Growth Rate ◽  
Feed Intake ◽  
Factorial Experiment ◽  
Feed Consumption ◽  
Daily Growth Rate ◽  
Daily Growth ◽  
Weaning Weight ◽  
Young Pigs ◽  
Creep Feed ◽  
Before And After

Sixteen sows and their progeny were allotted to treatments in a 23 factorial experiment involving two levels of feed flavour (0 and 50 ppm of Firanor No. 24) in each of the sow, creep and starter diets. Weaning occurred at a mean piglet age of 26.9 days and observations continued for 31 days after weaning. The feed flavour, when added to the sow diet, was incorporated in sow's milk; milk from one sow fed the flavoured diet contained 9 ppm of Firanor No. 24. The addition of the feed flavour to the creep diet failed to improve creep feed consumption or weaning weight; the average daily creep feed intake and daily growth rate prior to weaning being 47.8 g/head and 207 g/head, respectively. During the postweaning period, pigs that were weaned from sows receiving the flavour and then given the flavoured starter diet ate more feed (P<0.05) and tended to grow faster (839 and 400 g day-1, respectively) than pigs given the unflavoured starter diet, or those weaned from sows given no flavour; their average feed intake and growth rate being 764 and 362 g day-1, respectively.

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