COMPARISON OF PREDATION RATES

1981 ◽  
Vol 113 (11) ◽  
pp. 1047-1048 ◽  
Author(s):  
N. Gilbert

Consider a predator which, when hungry, has a discovery rate (= search rate × probability of finding prey) of a prey per unit time. When satiated, its demand rate for prey is 1/T, where T is the time-interval between successive prey captures when the predator is surrounded by excess of prey. Both a and T may vary with temperature, etc. Let s(N) be the expression for prey survival rate, during an infinitesimal time-period dt, as a function of prey density N.

2017 ◽  
Vol 920 (2) ◽  
pp. 57-60
Author(s):  
F.E. Guliyeva

The study of results of relevant works on remote sensing of forests has shown that the known methods of remote estimation of forest cuts and growth don’t allow to calculate the objective average value of forests cut volume during the fixed time period. The existing mathematical estimates are not monotonous and make it possible to estimate primitively the scale of cutting by computing the ratio of data in two fixed time points. In the article the extreme properties of the considered estimates for deforestation and reforestation models are researched. The extreme features of integrated averaged values of given estimates upon limitations applied on variables, characterizing the deforestation and reforestation processes are studied. The integrated parameter, making it possible to calculate the averaged value of estimates of forest cutting, computed for all fixed time period with a fixed step is suggested. It is shown mathematically that the given estimate has a monotonous feature in regard of value of given time interval and make it possible to evaluate objectively the scales of forest cutting.


2018 ◽  
Vol 13 (3) ◽  
pp. 213
Author(s):  
Jojo Subagja ◽  
Vitas Atmadi Prakoso

Ikan baung (Hemibagrus nemurus) memiliki prospek bagus untuk dikembangkan sebagai komoditas budidaya di Indonesia karena citarasa daging yang enak banyak diminati konsumen. Dewasa ini, peningkatan produksi benih dapat dilakukan melalui pemijahan buatan dengan manipulasi hormonal. Penelitian yang dilakukan bertujuan untuk mengevaluasi produksi induk ikan baung melalui pemijahan buatan dengan dosis penyuntikan GnRH-a berbeda. Penelitian dilakukan di Instalasi Riset Plasma Nutfah Perikanan Air Tawar, Cijeruk, Bogor pada bulan November 2017. Induk betina ikan baung yang digunakan berukuran 465,0 ± 71,8 g; dan induk jantan 426,3 ± 46,8 g. Induksi dilakukan dengan penyuntikan hormon GnRH-a dengan tiga dosis yang berbeda pada induk betina (0,3; 0,5; dan 0,7 mL/kg bobot badan), dan ikan jantan dengan dosis 0,4 mL/kg bobot badan. Masing-masing perlakuan terdiri atas tiga ekor induk betina sebagai ulangan. Hormon disuntikkan secara intramuskular, diberikan dua kali penyuntikan 35% dari dosis total pada penyuntikan pertama, dan 65% diberikan pada penyuntikan kedua, dengan interval waktu penyuntikan delapan jam. Parameter yang diamati yaitu jumlah telur ovulasi, derajat pembuahan, derajat penetasan, dan sintasan larva selama tujuh hari. Hasil penelitian menunjukkan bahwa dosis penyuntikan hormon GnRH-a 0,5 mL/kg pada induk ikan baung saat proses pemijahan buatan menghasilkan derajat penetasan yang lebih tinggi dibandingkan dosis 0,3 dan 0,7 mL/kg; serta sintasan larva yang lebih baik dibandingkan dosis 0,7 mL/kg. Sedangkan nilai jumlah telur yang berhasil ovulasi dan derajat pembuahan yang relatif lebih baik ditemukan pada perlakuan dosis 0,7 mL/kg dibandingkan dengan dosis 0,3 dan 0,5 mL/kg.Asian redtail catfish (Hemibagrus nemurus) has a good prospect to be developed as aquaculture commodity in Indonesia. It was proved by the demand of consumers regarding to its delicious flesh taste. Recently, efforts to increase seedling production could be implemented through artificial spawning with hormonal manipulation. This study was conducted to evaluate the production of broodstocks through artificial spawning with different doses of GnRH-a. Study was conducted at Research Institute for Freshwater Fisheries Germplasm, Cijeruk, Bogor in November, 2017. The broodstock used in this study was 465.0 ± 71.8 g for females, and 426.3 ± 46.8 g for males. Induction was performed by injection of GnRH-a hormone with three different doses on female broodstocks (0.3, 0.5 and 0.7 mL/kg of body weight), and male broodstocks with a dose of 0.4 mL/kg of body weight. Each treatment consisted of three females as replications. The hormone was injected intramuscularly, given twice injection: 35% of the total dose is given at the first injection, and the remaining 65% was given at the second injection, with an injection time interval of eight hours. The results showed the observed parameters of number of the ovulated eggs, fertilization rate, hatching rate, and larval survival for seven days, treatment dosage of 0.5 mL/kg showed better results (P<0.05) than the dosage of 0.3 mL/kg and 0.7 mL/kg. Parameters observed were number of ovulated eggs, fertility rate, hatching rate, and survival rate for seven days. The results showed that the dosage of 0.5 mL/kg GnRH-a injection to the broodstock during artificial spawning resulted in higher hatching rate compared to 0.3 and 0.7 mL/kg and better larval survival rate than the dosage of 0.7 mL/kg. Meanwhile, the number of ovulated eggs and fertility rate was relatively better in the treatment of 0.7 mL/kg compared with the dosage of 0.3 and 0.5 mL/kg.


2015 ◽  
Vol 229 (3) ◽  
Author(s):  
Jeffrey G. Bell ◽  
Jichang Wang

AbstractIn this research, it was found that following the photo-dissolution of the intermediate product N-bromo-1,4-benzoquinone-4-imine in the bromate – 4-aminophenol reaction, removal of illumination may allow the system to exhibit spontaneous chemical oscillations. This new observation complements the earlier report that the bromate – 4-aminophenol reaction could only oscillate under continuous illumination. Our exploration illustrates that the initial concentrations of bromate, 4-aminophenol and sulfuric acid have great influence on whether or not the system requires constant illumination for exhibiting oscillatory behavior. There is indeed an optimal illumination time interval at which the subsequently un-illuminated system would exhibit a large number of high frequency oscillations with or without an induction time period. Similar influences were also observed in the presence of cerium, in which the system exhibited sequential oscillations. Being able to respond to light in both a negative and constructive way makes this oscillatory system an attractive model for investigating perturbed nonlinear reaction dynamics.


2014 ◽  
Vol 1030-1032 ◽  
pp. 1775-1778
Author(s):  
Hui Fen Li ◽  
Jian Wei He ◽  
Hong Yan Li ◽  
Zheng Xu Dai ◽  
Qing Ji

Releasing beacon balloons is an effective way for space TT&C ship to obtain accurate comparison data and an important resource for accuracy evaluation. However, it is hard for theodolite to keep track beacon balloon stably for a long time. Its function has not been realized because the time period of the effective data is so short that it can not satisfy the request of traditional accuracy evaluation test. Aiming at this problem, this paper suggests an assumption of accuracy evaluation based on dynamic time interval non-continuous variable data. Utilizing self–adaptive outlier detection method and fitting residual error method, this paper solves the puzzle of dealing with dynamic time interval data which can not be treated by existing method, and realizes the self-determination of space TT&C ship accuracy evaluation test.


Author(s):  
Xiaoping Du

Quality characteristics (QC’s) are often treated static in robust design optimization while many of them are time dependent in reality. It is therefore desirable to define new robustness metrics for time-dependent QC’s. This work shows that using the robustness metrics of static QC’s for those of time-dependent QC’s may lead to erroneous design results. To this end, we propose the criteria of establishing new robustness metrics for time-dependent QC’s and then define new robustness metrics. Instead of using a point expected quality loss over the time period of interest, we use the expectation of the maximal quality loss over the time period to quantify the robustness for time-dependent QC’s. Through a four-bar function generator mechanism analysis, we demonstrate that the new robustness metrics can capture the full information of robustness of a time-dependent QC over a time interval. The new robustness metrics can then be used as objective functions for time-dependent robust design optimization.


2018 ◽  
Vol 225 ◽  
pp. 04008 ◽  
Author(s):  
Shaharin A. Sulaiman ◽  
M. Rosman M. Razif ◽  
Tan Dei Han ◽  
Samson M. Atnaw ◽  
S. Norazilah A. Tamili

There are some weaknesses of using solar PV system especially when there is issue of soiling on the surface of solar PV panel. The consequences for absence of this such study can cause unanticipated cost in the operation of solar PV panel. The objective of this project is to study the trend of soiling rate over different time period and its effect on the performance of solar PV panel in Malaysia and to develop a simple prediction model for cleaning interval of solar PV system in Malaysia. The study was conducted on real-time basis on a building’s roof. Measurements of solar irradiance, voltage, current and the mass of dust collected were performed from both clean and dirty panels. It was discovered that the Monthly Test was significant with 4.53% of performance drop. Further analysis was conducted by running prediction model for cleaning interval. Intersection of graph plotting and fixed cleaning cost gives answer of cleaning interval that can be performed. It can be concluded that for every two and half month is the recommended time interval to perform regular cleaning to maximise electrical power generation by solar PV system in Malaysia.


2012 ◽  
Vol 77 (1) ◽  
pp. 182-191 ◽  
Author(s):  
Bruno Malaizé ◽  
Elsa Jullien ◽  
Amandine Tisserand ◽  
Charlotte Skonieczny ◽  
E. Francis Grousset ◽  
...  

A high resolution analysis of benthic foraminifera as well as of aeolian terrigenous proxies extracted from a 37 m-long marine core located off the Mauritanian margin spanning the last ~ 1.2 Ma, documents the possible link between major continental environmental changes with a shift in the isotopic signature of deep waters around 1.0–0.9 Ma, within the so-called Mid-Pleistocene Transition (MPT) time period. The increase in the oxygen isotopic composition of deep waters, as seen through the benthic foraminifera δ18O values, is consistent with the growth of larger ice sheets known to have occurred during this transition. Deep-water mass δ13C changes, also estimated from benthic foraminifera, show a strong depletion for the same time interval. This drastic change in δ13C values is concomitant with a worldwide 0.3‰ decrease observed in the major deep oceanic waters for the MPT time period. The phase relationship between aeolian terrigeneous signal increase and this δ13C decrease in our record, as well as in other paleorecords, supports the hypothesis of a global aridification amongst others processes to explain the deep-water masses isotopic signature changes during the MPT. In any case, the isotopic shifts imply major changes in the end-member δ18O and δ13C values of deep waters.


2017 ◽  
Vol 21 (3) ◽  
pp. 146-151
Author(s):  
Jelena Galovic ◽  
Tatjana Vukojevic ◽  
Jelena Nikolic Ivosevic ◽  
Mirjana Perin ◽  
Kristina Vicko ◽  
...  

SummaryBackground/Aim: The aim of the present study was to investigate the treatment options, survival rate of traumatized primary teeth and evaluate the factors influencing the outcome. Material and Methods: The sample consisted of all dental trauma cases treated over a 14 years period at the Department of Pediatric and Preventive Dentistry, Dental Clinic of Vojvodina, Novi Sad. Criteria for inclusion in this study were: dental trauma to primary teeth and age in the moment of injury up to seven years. Dental trauma records were analyzed in order to obtain the following: gender and age of the child at the time of trauma, type of trauma, as well as the type and timing of treatment received. After data analysis a survival rate of traumatized primary teeth was evaluated. Results: The study was designed as retrospective and it included 225 children, with 346 traumatized primary teeth. The occurrence of trauma was higher in male patients (60,4%) and in children up to 4 years of age. Luxations were more frequent (72.8%) compared to isolated teeth fractures (20.8%), while the two types of injury combined were rare (6,3%). One year following dental trauma 231 teeth (0.67%) developed complications. Falls were the main cause of trauma (68.9%) and the presence of more than one traumatized tooth was frequent. A percentage of 48.8 children received dental care during first 24 h after the injury. Conclusions: Survival of injured primary teeth is relatively low, regardless of trauma type, time interval between injury and treatment and the type of provided treatment.


2012 ◽  
Vol 12 (11) ◽  
pp. 4885-4891 ◽  
Author(s):  
R. Sussmann ◽  
F. Forster ◽  
M. Rettinger ◽  
P. Bousquet

Abstract. Trends of column-averaged methane for the time period (1996, Sep 2011) are derived from the mid-infrared (mid-IR) solar FTIR time series at the Zugspitze (47.42° N, 10.98° E, 2964 m a.s.l.) and Garmisch (47.48° N, 11.06° E, 743 m a.s.l.). Trend analysis comprises a fit to the de-seasonalized time series along with bootstrap resampling for quantifying trend uncertainties. We find a positive trend during [1996, 1998] of 9.0 [3.2, 14.7] ppb yr−1 for Zugspitze (95% confidence interval), an insignificant growth during [1999, mid 2006] of 0.8 [−0.1, 1.7] ppb yr−1 (Zugspitze), and a significant renewed increase during [mid 2006, Sep 2011] of 5.1 [4.2, 6.0] ppb yr−1 for Garmisch, which is in agreement with 4.8 [3.8, 5.9] ppb yr−1 for Zugspitze. The agreement of methane trends at the two closely neighboring FTIR sites Zugspitze and Garmisch within the uncertainties indicates a good station-to-station consistency as a basis for future trend analyses by the ground-based mid-IR FTIR network on the global scale. Furthermore, the Zugspitze FTIR trend for the time interval [Jul 2006, Jun 2009] is found to agree with the trend derived from SCIAMACHY (WFM-DOAS v2.0.2) data within the 95% confidence intervals. In case a 1000-km pixel selection radius around the Zugspitze is used, the confidence interval is narrower for the FTIR trend (6.9 [4.2, 9.5] ppb yr−1) compared to SCIAMACHY (7.1 [5.1, 8.6] ppb yr−1). If, however, a loosened pixel selection is used (&amp;approx;1000-km half-width latitudinal band), the SCIAMACHY trend significance interval is narrower (6.8 [5.1, 8.6] ppb yr−1) compared to Zugspitze FTIR (5.7 [3.0, 8.3] ppb yr−1). While earlier studies using surface network data revealed changes of 8.0 ± 0.6 ppb in 2007, 6.4 ± 0.6 ppb in 2008, and 4.7 ± 0.6 ppb in 2009 (Dlugokencky et al., 2011), our updated result proves that the renewed methane increase meanwhile has been persisting for >5 years [mid 2006, Sep 2011]. This is either the longest and largest positive trend anomaly since the beginning of systematic observations more than 25 years ago or the onset of a new period of strongly increasing CH4 levels in the atmosphere. Several scenarios have been developed to explain the persistent increase observed, mainly invoking an increase in emissions from natural wetlands, an increase in fossil fuel-related emissions or a decrease in OH concentrations. However, more work is needed to fully attribute this increase to a particular source or sink.


2020 ◽  
Author(s):  
Iuliana Vasiliev ◽  
Daniela Boehn ◽  
Darja Volkovskaja ◽  
Clemens Schmitt ◽  
Konstantina Agiadi ◽  
...  

&lt;p&gt;Between 5.97-5.33 Ma several kilometre-thick evaporite units were deposited in the Mediterranean Basin during the Messinian Salinity Crisis (MSC). The MSC reflects a period featured by a negative hydrological budget, with a net evaporative loss of water exceeding precipitation and riverine runoff. The contemporary changes in continental and marine circum-Mediterranean temperature are, however, poorly constrained. Here we reconstruct continental mean annual temperatures (MAT) using branched glycerol dialkyl glycerol tetraether (GDGT) biomarkers for the time period corresponding to MSC Stage 3 (5.55-5.33 Ma). Additionally, for the same time interval, we estimate sea surface temperatures (SSTs) of the Mediterranean Sea using isoprenoidal GDGTs based TEX&lt;sub&gt;86&lt;/sub&gt; proxy. The excellently preserved organic biomarkers were extracted from outcrops and DSDP cores spread over a large part of the onland (Malaga, Sicily, Cyprus) and offshore (holes 124 and 134 from the Balearic abyssal plane and hole 374 from the Ionian Basin) Mediterranean Basin domain. The calculated MATs for the 5.55 to 5.33 Ma interval show values around 16 to 18 &amp;#186;C for the Malaga, Sicily and Cyprus outcrops. The MAT values calculated for DSDP Leg 13 holes 124, 134 and Leg 42A hole 374 are lower, around 11 to 13 &amp;#186;C.&lt;/p&gt;&lt;p&gt;For samples where the branched and isoprenoid tetraether (BIT) index was lower than the 0.4 we could calculate TEX&lt;sub&gt;86&lt;/sub&gt; derived SSTs averaging around 27 &amp;#186;C for all sampled locations. Where available (i.e. Sicily), we compared the TEX&lt;sub&gt;86&lt;/sub&gt; derived SSTs with alkenone based, U&lt;sup&gt;k&lt;/sup&gt;&lt;sub&gt;37&lt;/sub&gt; derived SST estimates from the same samples. The TEX&lt;sub&gt;86&lt;/sub&gt; derived SST values are slightly higher than the U&lt;sup&gt;k&lt;/sup&gt;&lt;sub&gt;37&lt;/sub&gt; derived SST of 20 to 28 &amp;#186;C. For the Mediterranean region, values between 19 and 27 &amp;#186;C of the U&lt;sup&gt;k&lt;/sup&gt;&lt;sub&gt;37&lt;/sub&gt; derived SSTs were calculated for the interval between the 8.0 and 6.4 Ma (Tzanova et al., 2015), close to our calculations for Sicily section (20 to 28 &amp;#186;C). Independent of common pitfalls that may arise in using molecular biomarkers as temperature proxies, both SST estimates independently hint towards much warmer Mediterranean Sea water during the latest phase (Stage 3) of the MSC. These elevated temperatures coincide with higher &amp;#948;D values measured on alkenones and long chain n-alkanes (both records indicating for more arid and/or warmer conditions than today between 5.55 and 5.33 Ma). We therefore conclude that the climate between 5.55 to 5.33 Ma was warmer than present-day conditions, recorded both in the Mediterranean Sea and the land surrounding it.&lt;/p&gt;


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