scholarly journals A minimal “push–pull” bistability model explains oscillations between quiescent and proliferative cell states

2018 ◽  
Vol 29 (19) ◽  
pp. 2243-2258 ◽  
Author(s):  
Sandeep Krishna ◽  
Sunil Laxman
Keyword(s):  
Oxygen Consumption ◽  
Resource Availability ◽  
Growth Rates ◽  
Minimal Model ◽  
Relaxation Oscillator ◽  
The Other ◽  
Growth State ◽  
Current State ◽  
Metabolic Oscillations ◽  
Proliferative Cell

A minimal model for oscillating between quiescent and growth/proliferation states, dependent on the availability of a central metabolic resource, is presented. From the yeast metabolic cycles, metabolic oscillations in oxygen consumption are represented as transitions between quiescent and growth states. We consider metabolic resource availability, growth rates, and switching rates (between states) to model a relaxation oscillator explaining transitions between these states. This frustrated bistability model reveals a required communication between the metabolic resource that determines oscillations and the quiescent and growth state cells. Cells in each state reflect memory, or hysteresis of their current state, and “push–pull” cells from the other state. Finally, a parsimonious argument is made for a specific central metabolite as the controller of switching between quiescence and growth states. We discuss how an oscillator built around the availability of such a metabolic resource is sufficient to generally regulate oscillations between growth and quiescence through committed transitions.

scholarly journals A minimal “push-pull” bistability model explains oscillations between quiescent and proliferative cell states

2017 ◽  
Author(s):  
Sandeep Krishna ◽  
Sunil Laxman
Keyword(s):  
Oxygen Consumption ◽  
Resource Availability ◽  
Growth Rates ◽  
Minimal Model ◽  
Relaxation Oscillator ◽  
The Other ◽  
Growth State ◽  
Current State ◽  
Metabolic Oscillations ◽  
Proliferative Cell

AbstractA minimal model for oscillating between quiescent and growth/proliferation states, dependent on the availability of a central metabolic resource, is presented. From the yeast metabolic cycles (YMCs), metabolic oscillations in oxygen consumption are represented as transitions between quiescent and growth states. We consider metabolic resource availability, growth rates, and switching rates (between states) to model a relaxation oscillator explaining transitions between these states. This frustrated bistability model reveals a required communication between the metabolic resource that determines oscillations, and the quiescent and growth state cells. Cells in each state reflect memory, or hysteresis of their current state, and “push-pull” cells from the other state. Finally, a parsimonious argument is made for a specific central metabolite as the controller of switching between quiescence and growth states. We discuss how an oscillator built around the availability of such a metabolic resource is sufficient to generally regulate oscillations between growth and quiescence, through committed transitions.

Kinetic Modelling of Anionic Polymerization Involving a Dynamic Equilibrium between Two Growth Centres with Different Growth Rates

1993 ◽  
Vol 58 (10) ◽  
pp. 2349-2361 ◽  
Author(s):  
Jaromír Jakeš
Keyword(s):  
Molecular Weight ◽  
Growth Rates ◽  
Anionic Polymerization ◽  
Dynamic Equilibrium ◽  
Kinetic Modelling ◽  
Polymerization Time ◽  
Fast State ◽  
Growth State ◽  
In The Beginning ◽  
Growth Centres

Kinetic modelling of the molecular weight distribution (MWD) of polymer obtained by an anionic polymerization with two types of growth centres in a dynamic equilibrium, having different growth rates and lifetimes comparable to the polymerization time, was made for low monomer conversions. On the basis of distribution of the growth centres according to the total time spent in the fast growth state, it was shown that MWD of the resulting polymer are mostly bimodal at the beginning of the polymerization and change to unimodal MWD at sufficiently high polymerization degrees depending on the equilibrization rate. When all centres are in the fast state in the beginning, MWD are essentially unimodal throughout. A hint of trimodality is observed in some cases, in an extent hardly detectable in real chromatograms. Hence, a polymodal MWD can be explained only when more than two growth centres with different growth rates are assumed.

scholarly journals Commentary to “Practicing Dialectics of Technoscience During the Anthropocene” by Hub Zwart

2021 ◽  
Author(s):  
Hans-Jörg Rheinberger
Keyword(s):  
Synthetic Biology ◽  
Philosophy Of Science ◽  
The Other ◽  
Scientific Development ◽  
Current State

AbstractHub Zwart’s article is about the idea—and the practice—of an embedded philosophy of science, that is, a philosophy participating in and at the same time reflecting about the current state of the sciences facing the Anthropocene, to which I am very sympathetic. There are, however, two caveats. The first is that participation is always in danger to end up in a more or less uncritical eulogy, in the present case of synthetic biology. The second is that I have doubts about packing the historical path of scientific development into the Procrustes bed of Hegelian dialectics. This usually leads to one or the other form of teleology.

Occupant pre-crash kinematics in rotated seat arrangements

2021 ◽  
pp. 095440702110045
Author(s):  
Alexander Diederich ◽  
Christophe Bastien ◽  
Karthikeyan Ekambaram ◽  
Alexis Wilson
Keyword(s):  
State Of The Art ◽  
The Other ◽  
Human Model ◽  
Multi Objective ◽  
Emergency Braking ◽  
Seating Arrangement ◽  
Current State ◽  
Occupant Comfort ◽  
Occupant Kinematics ◽  
Belt System

The introduction of automated L5 driving technologies will revolutionise the design of vehicle interiors and seating configurations, improving occupant comfort and experience. It is foreseen that pre-crash emergency braking and swerving manoeuvres will affect occupant posture, which could lead to an interaction with a deploying airbag. This research addresses the urgent safety need of defining the occupant’s kinematics envelope during that pre-crash phase, considering rotated seat arrangements and different seatbelt configurations. The research used two different sets of volunteer tests experiencing L5 vehicle manoeuvres, based in the first instance on 22 50th percentile fit males wearing a lap-belt (OM4IS), while the other dataset is based on 87 volunteers with a BMI range of 19 to 67 kg/m2 wearing a 3-point belt (UMTRI). Unique biomechanics kinematics corridors were then defined, as a function of belt configuration and vehicle manoeuvre, to calibrate an Active Human Model (AHM) using a multi-objective optimisation coupled with a Correlation and Analysis (CORA) rating. The research improved the AHM omnidirectional kinematics response over current state of the art in a generic lap-belted environment. The AHM was then tested in a rotated seating arrangement under extreme braking, highlighting that maximum lateral and frontal motions are comparable, independent of the belt system, while the asymmetry of the 3-point belt increased the occupant’s motion towards the seatbelt buckle. It was observed that the frontal occupant kinematics decrease by 200 mm compared to a lap-belted configuration. This improved omnidirectional AHM is the first step towards designing safer future L5 vehicle interiors.

scholarly journals The European Green Capital Award—Is It a Dream or Reality for Belgrade (Serbia)?

2021 ◽  
Vol 13 (11) ◽  
pp. 6182
Author(s):  
Marijana Pantić ◽  
Saša Milijić
Keyword(s):  
Urban Transformation ◽  
The Other ◽  
Transmission Of Knowledge ◽  
Current State ◽  
Transitional Countries ◽  
Great Hope ◽  
Environmentally Responsible ◽  
Potential Benefits ◽  
The City ◽  
Insight Into

An agreement of cooperation and transmission of knowledge regarding the nomination for the European Green Capital Award (EGCA) was signed between the mayors of Belgrade and Ljubljana (EGCA 2016 winner) in September 2018. The candidacy of Belgrade was finally realized in October 2019. Great hope was placed in this endeavour because internationally recognized awards, such as the EGCA, represent enormous capital for both the city and the state. The EGCA requires serious preparation and significant fulfilment of preconditions. Many economically strong and environmentally responsible cities competed for the award, but did not win. On the other hand, the capital of Serbia does not appear to be an obvious winning candidate, especially as it is differentiated from the previous winners by being a non-EU city and by the fact that it is still undergoing an intense urban transformation, characteristic of transitional countries. Therefore, the main aim of this article is to present a review of the current state of Belgrade’s environmental qualities and its comparison with the EGCA criteria and with Grenoble as one of the winning competitors. The article gives a full overview of the EGCA requirements with certain details on required indicators, gives relevant insight into the procedure, which could be of use for any future candidacy, and discusses potential benefits for winners, losers and repeat candidacies.

scholarly journals Phenology of two interdependent traits in migratory birds in response to climate change

2015 ◽  
Vol 282 (1807) ◽  
pp. 20150288 ◽  
Author(s):  
Nadiah Pardede Kristensen ◽  
Jacob Johansson ◽  
Jörgen Ripa ◽  
Niclas Jonzén
Keyword(s):  
Climate Change ◽  
Resource Availability ◽  
Migratory Birds ◽  
Egg Laying ◽  
The Other ◽  
Sufficient Evidence ◽  
Hatching Date ◽  
Arrival Date ◽  
Body Of Knowledge ◽  
Asynchronous Hatching

In migratory birds, arrival date and hatching date are two key phenological markers that have responded to global warming. A body of knowledge exists relating these traits to evolutionary pressures. In this study, we formalize this knowledge into general mathematical assumptions, and use them in an ecoevolutionary model. In contrast to previous models, this study novelty accounts for both traits—arrival date and hatching date—and the interdependence between them, revealing when one, the other or both will respond to climate. For all models sharing the assumptions, the following phenological responses will occur. First, if the nestling-prey peak is late enough, hatching is synchronous with, and arrival date evolves independently of, prey phenology. Second, when resource availability constrains the length of the pre-laying period, hatching is adaptively asynchronous with prey phenology. Predictions for both traits compare well with empirical observations. In response to advancing prey phenology, arrival date may advance, remain unchanged, or even become delayed; the latter occurring when egg-laying resources are only available relatively late in the season. The model shows that asynchronous hatching and unresponsive arrival date are not sufficient evidence that phenological adaptation is constrained. The work provides a framework for exploring microevolution of interdependent phenological traits.

Hypothermia in iron deficiency due to altered triiodothyronine metabolism

1980 ◽  
Vol 239 (5) ◽  
pp. R377-R381 ◽  
Author(s):  
E. Dillman ◽  
C. Gale ◽  
W. Green ◽  
D. G. Johnson ◽  
B. Mackler ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Iron Deficiency ◽  
Ambient Temperature ◽  
The Other ◽  
Other Hand ◽  
Iron Deficient ◽  
Catecholamine Response ◽  
Cutaneous Vasoconstriction

Iron-deficient rats become hypothermic and have an excessive catecholamine response when exposed to an ambient temperature of 4 degrees C. This is not due to changes in body insulation, since thickness is unaltered, since differences persist after removal of hair, and since cutaneous vasoconstriction is intact. On the other hand, oxygen consumption of iron-deficient animals at 4 degrees C is reduced, 39 +/- 3 ml . kg-1 . min-1 compared to 63 +/- 2 in control animals. Thyroxine (T4) values at 4 degrees C were 4.34 +/- 0.20 microgram/dl sera as compared to control values of 3.6 +/- 0.32. Triiodothyronine (T3) values of iron-deficient animals in the cold were 48 +/- 6.8 ng/dl as compared to 72 +/- 5.6 in control animals. Treatment of iron-deficient animals with iron was shown to normalize the plasma T3 response at 4 degrees C within 6 days. Thyroidectomized iron-deficient animals injected with T3 did not show hypothermia at 4 degrees C, whereas thyroidectomized iron-deficient animals injected with T4 showed hypothermia, increased catecholamines, and decreased T3 levels as compared to non-iron-deficient animals similarly treated. It is proposed that iron deficiency impairs conversion of T4 to T3 and that this is primarily responsible for the hypothermia observed.

Summary of the current state of the pathogenesis of glaucoma

1927 ◽  
Vol 23 (8) ◽  
pp. 839-845
Author(s):  
V. P. Roshchin
Keyword(s):  
Single Case ◽  
Disease Process ◽  
The Other ◽  
Medical Attention ◽  
Blind People ◽  
Current State ◽  
Constant State ◽  
The One

The problem of glaucoma has, for many reasons, occupied and continues to occupy a prominent place in the ophthalmic press. It is enough to recall that 19% of all blind people owe their misfortune to glaucoma to understand why interest in this affliction has never faded among ophthalmologists. Furthermore, no ophthalmologist is quite sure that a certain method of treatment, even if the patient has timely applied for medical attention, can definitely prevent a sad outcome in every single case. This plus the absence of a unified and correct view of the essence of glaucoma keeps ophthalmologists in a constant state of flux, constantly striving to uncover the hidden springs of the disease process on the one hand, and to find a more radical means to combat it on the other.

Qillah: A Morphological Extension for Identifying Plural-of-Paucity Arabic Words

2021 ◽  
pp. 2050013
Author(s):  
Ahlam Fuad ◽  
Amany bin Gahman ◽  
Rasha Alenezy ◽  
Wed Ateeq ◽  
Hend Al-Khalifa
Keyword(s):  
State Of The Art ◽  
The Other ◽  
Rule Based ◽  
Current State ◽  
Maximum Accuracy ◽  
Classical Arabic

Plural of paucity is one type of broken plural used in the classical Arabic. It is used when the number of people or objects ranges from three to 10. Based on our evaluation of four current state-of-the-art Arabic morphological analyzers, there is a lack of identification of broken plural words, specifically the plural of paucity. Therefore, this paper presents “[Formula: see text]” Qillah (paucity), a morphological extension that is built on top of other morphological analyzers and uses a hybrid rule-based and lexicon-based approach to enhance the identification of plural of paucity. Two versions of the Qillah were developed, one is based on FARASA morphological analyzer and the other is based on CALIMA Star analyzer, as these are some of the best-performing morphological analyzers. We designed two experiments to evaluate the effectiveness of our proposed solution based on a collection of 402 different Arabic words. The version based on CALIMA Star achieved a maximum accuracy of 93% in identifying the plural-of-paucity words compared to the baselines. It also achieved a maximum accuracy of 98% compared to the baselines in identifying the plurality of the words.

Concentrations of glucose, albumin, inorganic phosphate and sodium in the blood of beef calves at 2 ½ months of age and their relationships with subsequent weight gain

1980 ◽  
Vol 94 (1) ◽  
pp. 95-104 ◽  
Author(s):  
G. J. Rowlands
Keyword(s):  
Growth Rate ◽  
Blood Glucose ◽  
Growth Rates ◽  
Inorganic Phosphate ◽  
The Body ◽  
The Other ◽  
Growth Depression ◽  
Blood Samples ◽  
Beef Calves ◽  
Body Weights

SummaryBlood samples were taken at 9, 10 and 11 weeks of age from 230 male Hereford × Friesian calves, the progeny of 12 Hereford bulls. Concentrations of blood glucose, serum albumin, inorganic phosphate and sodium were measured and correlated with body weights and growth rates until slaughter at 19½ months of age.Correlations between growth rates and glucose concentrations (0·44) and between growth rates and albumin concentrations (0·38) were observed until 4 months of age. Similar correlations between body weights and blood glucose or albumin concentrations persisted until 6 months of age. By 10 months, however, the correlations had begun to decline, and by slaughter they had become insignificant.Correlations between growth rates and inorganic phosphate or sodium concentrations were smaller, and also decreased with age.The effect of hypoglycaemia on growth rate was compared with the effect of enzootic pneumonia. Although the 10% of calves with the lowest glucose concentrations were growing 24% more slowly than the other calves at the time of sampling, this growth depression was not related to pneumonia, and they subsequently made up for most of the early loss of growth.Three blood samples were also taken from 22 Hereford bulls. No significant correlations were observed between the blood composition of the bulls and the body weights or weight gains of their progeny.

Sign in / Sign up

Export Citation Format

Share Document