scholarly journals The influence of cactus spine surface structure on puncture performance and anchoring ability is tuned for ecology

2018 ◽  
Vol 285 (1891) ◽  
pp. 20182280 ◽  
Author(s):  
S. B. Crofts ◽  
P. S. L. Anderson
Keyword(s):  
Surface Structure ◽  
Large Scale ◽  
Biological Materials ◽  
Morphological Features ◽  
Ecological Functions ◽  
Defensive Mechanisms ◽  
Evolutionary Convergence ◽  
Almost All

Spines are common morphological features found in almost all major biological groups offering an opportunity to explore large-scale evolutionary convergence across disparate clades. As an example, opuntioid cacti have spines with barbed ornamentation that is remarkably similar in form and scale to that found on porcupine quills, suggesting specific biomechanical convergence across the animal and plant kingdoms. While the mechanics of porcupine quills as defensive mechanisms has been previously tested, the mechanics of cactus spines (which have evolved to fill a number of functions including defence, climbing and dispersal) has not been characterized. Here we study the puncturing and anchoring ability of six species of cactus, including both barbed and non-barbed spines. We found that barbed spines require less work to puncture a variety of targets than non-barbed spines. Barbed spines also require more work than non-barbed spines to withdraw from biological materials, owing to their barbs engaging with tissue fibres. These results closely match those found previously for barbed versus non-barbed porcupine quills, implying biomechanical convergence. The variation in performance of barbed versus non-barbed spines, as well as between barbed spines from different species, is probably tied to the diversity of ecological functions of cactus spines.

RESEARCH OF EXTERNAL MASS TRANSFER PROCESSES FOR ADSORPTION FROM SOLUTIONS IN A APPARATUS WITH STIRRING

2021 ◽  
pp. 11-20
Author(s):  
V. Solovej ◽  
K. Gorbunov ◽  
V. Vereshchak ◽  
O. Gorbunova
Keyword(s):  
Mass Transfer ◽  
Energy Spectrum ◽  
Energy Dissipation ◽  
Large Scale ◽  
Isotropic Turbulence ◽  
Wave Number ◽  
Wave Form ◽  
Local Isotropy ◽  
Stirred Vessel ◽  
Almost All

A study has been mode of transport-controlled mass transfer-controlled to particles suspended in a stirred vessel. The motion of particle in a fluid was examined and a method of predicting relative velocities in terms of Kolmogoroff’s theory of local isotropic turbulence for mass transfer was outlined. To provide a more concrete visualization of complex wave form of turbulence, the concepts of eddies, of eddy velocity, scale (or wave number) and energy spectrum, have proved convenient. Large scale motions of scale contain almost all of the energy and they are directly responsible for energy diffusion throughout the stirring vessel by kinetic and pressure energies. However, almost no energy is dissipated by the large-scale energy-containing eddies. A scale of motion less than is responsible for convective energy transfer to even smaller eddy sires. At still smaller eddy scales, close to a characteristic microscale, both viscous energy dissipation and convection are the rule. The last range of eddies has been termed the universal equilibrium range. It has been further divided into a low eddy size region, the viscous dissipation subrange, and a larger eddy size region, the inertial convection subrange. Measurements of energy spectrum in mixing vessel are shown that there is a range, where the so called -(5/3) power law is effective. Accordingly, the theory of local isotropy of Kolmogoroff can be applied because existence of the internal subrange. As the integrated value of local energy dissipation rate agrees with the power per unit mass of liquid from the impeller, almost all energy from the impeller is viscous dissipated in eddies of microscale. The correlation for mass transfer to particles suspended in a stirred vessel is recommended. The results of experimental study are approximately 12 % above the predicted values.

Why Do People Stay Poor?

2021 ◽  
Author(s):  
Clare Balboni ◽  
Oriana Bandiera ◽  
Robin Burgess ◽  
Maitreesh Ghatak ◽  
Anton Heil
Keyword(s):  
Occupational Choice ◽  
Large Scale ◽  
Choice Model ◽  
Effective Means ◽  
Threshold Level ◽  
Poverty Traps ◽  
Asset Transfer ◽  
Small Livestock ◽  
Program Costs ◽  
Almost All

Abstract There are two broad views as to why people stay poor. One emphasizes differences in fundamentals, such as ability, talent, or motivation. The other, the poverty traps view, emphasizes differences in opportunities which stem from access to wealth. To test between these two views, we exploit a large-scale, randomized asset transfer and an 11-year panel of 6,000 households who begin in extreme poverty. The setting is rural Bangladesh and the assets are cows. The data supports the poverty traps view—we identify a threshold level of initial assets above which households accumulate assets, take on better occupations (from casual labor in agriculture or domestic services to running small livestock businesses), and grow out of poverty. The reverse happens for those below the threshold. Structural estimation of an occupational choice model reveals that almost all beneficiaries are misallocated in the work they do at baseline and that the gains arising from eliminating misallocation would far exceed the program costs. Our findings imply that large transfers which create better jobs for the poor are an effective means of getting people out of poverty traps and reducing global poverty.

Opuntia ficus-indica (prickly pear).

2021 ◽  
Author(s):  
Nick Pasiecznik
Keyword(s):  
Vitamin C ◽  
Large Scale ◽  
Time Lag ◽  
Prickly Pear ◽  
Invasive Weeds ◽  
Historical Records ◽  
Opuntia Ficus Indica ◽  
Actual Risk ◽  
Invasive Spread ◽  
Almost All

Abstract O. ficus-indica is highly valued as a fruit-producing cactus, also yielding 'leaves' that are used as a vegetable and browsed by livestock. It has been introduced widely from its native Mexico to almost all countries where the climate is suitable. The fruit is very rich in vitamin C and is exploited commercially in many areas. Many countries, especially in Asia, have recently established large-scale commercial plantations. However, O. ficus-indica, like several other species of Opuntia, have been known to spread and become invasive weeds. Historical records, however, appear to indicate a time-lag of about 100 years between introduction and the beginnings of invasive spread thus the actual risk may be low.

What Kind of Friction Model Is Needed to Predict Brake Squeal?

2012 ◽  
Author(s):  
Tore Butlin ◽  
Jim Woodhouse
Keyword(s):  
Large Scale ◽  
Dynamic Properties ◽  
Theoretical Work ◽  
Friction Model ◽  
Coupled Systems ◽  
Brake Squeal ◽  
Model Framework ◽  
Wide Range ◽  
Pin On Disc ◽  
Almost All

Predictive models of friction-induced vibration have proved elusive despite decades of research. There are many mechanisms that can cause brake squeal; friction coupled systems can be highly sensitive to small perturbations; and the dynamic properties of friction at the contact zone seem to be poorly understood. This paper describes experimental and theoretical work aimed at identifying the key ingredients of a predictive model. A large-scale experiment was carried out to identify squeal initiations using a pin-on-disc test rig: approximately 30,000 squeal initiations were recorded, covering a very wide range of frequencies. The theoretical model allows for completely general linear systems coupled at a single sliding point by friction: squeal is predicted using a linearised stability analysis. Results will be presented that show that almost all observed squeal events can be predicted within this model framework, but that some subsets require innovative friction modelling: predictions are highly dependent on the particular choice of friction model and its associated parameters.

Adaptive-Curvature Structures with Auxetic Materials

2018 ◽  
Vol 1149 ◽  
pp. 53-63
Author(s):  
Roberto Naboni ◽  
Stefano Sartori ◽  
Lorenzo Mirante
Keyword(s):  
Large Scale ◽  
Morphological Features ◽  
Geometrical Parameters ◽  
Computational Tools ◽  
Auxetic Materials ◽  
Initial Geometry ◽  
Tools And Methods

Advancements in computational tools are offering designers the possibility to change their relationship with materials and establishing new synergies between matter, form and behaviour. This work explores this paradigm by introducing the use of auxetic metamaterials, specifically engineered to obtain properties beyond those found in nature, to generate structures with adaptive curvature obtained from planar construction elements. It is discussed how through programming an initial geometry with the strategic negotiation of several geometrical parameters it is possible to control finely the structural and morphological features of a structure. The paper presents approach, tools and methods for designing auxetics for large scale applications, and use them to create heterogeneous active-bending structures.

scholarly journals A Novel Dual-Band Conformal Surface Plasmons Waveguide With Tunable Frequency Response In Large-scale

2021 ◽  
Author(s):  
Yijiao Fang ◽  
Jiangwei Zhong
Keyword(s):  
Surface Plasmons ◽  
Fundamental Mode ◽  
Large Scale ◽  
Dual Band ◽  
Single Frequency ◽  
Dual Frequency ◽  
Microwave Frequencies ◽  
Frequency Tunability ◽  
Tunable Frequency ◽  
Almost All

Abstract A novel dual-band conformal surface plasmons (CSPs) waveguide is designed and well studied in this paper. In earlier researches, we have recognized that electromagnetic field of CSPs waveguide are always confined to a sub-wavelength area and have a strong potential to be applied in devices designing. However, almost all of the earlier CSP structures is mainly focus on the fundamental mode characteristics with only single resonance frequency. Here we propose a innovative dual inverted-L structure with excellent performance not only on the fundamental mode but also on a new upper mode. This structure operates in microwave frequencies regime and shows outstanding frequency tunability characteristic. Being different from frequency characteristics in the earlier CSP waveguides which always used to be designed single-frequency device, dual-frequency tunability can be obtained via the dual L-type bending branch of the periodical CSP structure. In present paper, we also realize a tunable dual-frequency filter by changing the scaling factor of inverted-L stubs.

scholarly journals Analisis Perkembangan Kasus COVID-19 Berkaitan dengan Kebijakan Pemerintah di Pulau Jawa

2021 ◽  
Vol 9 (1) ◽  
pp. 01-12
Author(s):  
Charvia Ismi Zahrani ◽  
Setia Pramana
Keyword(s):  
Local Government ◽  
Large Scale ◽  
Government Policies ◽  
High Increase ◽  
Public Places ◽  
The Public ◽  
Social Restriction ◽  
Almost All ◽  
Death Cases ◽  
Very High

AbstractCOVID-19 is a serious problem that faced by almost all countries in the world. Since announced as a pandemic by WHO on March, the number of positive COVID-19 cases in Indonesia has reached 287,008 patients until the end of September 2020. COVID-19 cases dispersion depends on the local government policies and the awareness of the public to obey. About 60 percent of positive cases and 65 percent of death cases were in Java. Therefore, the aim of this study is to analyze the growth of the COVID-19 case in Java from March to September 2020 in relation to the local government policies. The results showed that six provinces in Java had the same pattern. The large-scale social restriction (PSBB), which was implemented since April 10 2020, seen to be able to contain the dispersion of cases because from April to June the positive cases did not increase significantly. A very high increase occurred in August and September, this was probably due to the easing of the PSBB become new-normal where various public places and facilities have been reopened. Meanwhile, death cases, the number is very high in mid-April and June and late July to September 2020. For cured cases, there was a significant increase in late August to September 2020. The importance of information about the growth of the COVID-19 cases can help government to formulate strategies and policies to prevent the dispersion of COVID-19.Keyword: COVID-19, Pandemic, Java, cases growth AbstrakCOVID-19 merupakan suatu masalah serius yang sedang dihadapi oleh hampir seluruh negara. Sejak diumumkan sebagai pandemi oleh WHO pada Maret lalu, jumlah kasus positif COVID-19 di Indonesia mencapai 287.008 pasien hingga akhir September. Penyebaran kasus COVID-19 sangat bergantung pada kebijakan yang ditetapkan oleh pemerintah serta kesadaran masyarakat untuk mematuhinya. Sebesar 60 persen kasus positif dan 65 persen kasus meninggal berada di Pulau Jawa. Oleh karena itu, tujuan penelitian ini adalah menganalisis perkembangan kasus COVID-19 di Pulau Jawa sejak Bulan Maret-September 2020 dikaitkan dengan kebijakan pemerintah setempat. Hasil penelitian menunjukkan bahwa keenam provinsi memiliki pola yang sama. Pembatasan Sosial Berskala Besar (PSBB) yang dilakukan sejak 10 April 2020 terlihat dapat menahan penyebaran kasus karena pada bulan April-Juni 2020 kasus positif tidak mengalami kenaikan yang signifikan. Kenaikan yang sangat tinggi terjadi pada bulan Agustus dan September 2020, hal ini mungkin disebabkan oleh dilonggarkannya kebijakan PSBB menjadi PSBB Transisi dimana berbagai tempat dan fasilitas umum telah dibuka kembali. Sementara untuk kasus meninggal, angka tertinggi terjadi pada pertengahan April dan Juni serta akhir Juli hingga September 2020. Untuk kasus sembuh, terjadi peningkatan yang signifikan pada akhir Agustus hingga September 2020. Pentingnya informasi tentang perkembangan kasus COVID-19 ini dapat membantu pemerintah daerah untuk membuat strategi dan kebijakan untuk mencegah penyebaran rantai virus COVID-19.Kata Kunci: COVID-19, Pandemi, Jawa, perkembangan kasus 

scholarly journals The Influence of COVID-19 on Indonesian Investment

2020 ◽  
Vol 1 (1) ◽  
pp. 1-6
Author(s):  
Jeliastiva Jeliastiva ◽  
Farid Fachrurazi
Keyword(s):  
Economic System ◽  
Large Scale ◽  
Domestic Investment ◽  
Social Distancing ◽  
Work From Home ◽  
The Social ◽  
The World ◽  
Almost All

The COVID-19 outbreak has had a serious impact on almost all countries in the world, including Indonesia. In response to this case, various policies began to emerge. Starting from the implementation of work from home, social distancing and physical distancing, until the implementation of large-scale social restrictions (PSBB). overseas investors are busy focusing their finances on the needs of their respective countries to fight the virus. Domestic investment (PMDN) is also predicted to experience a slowdown. The social distancing policy resulted in the community not being able to run the economic system well, especially in the Indonesian investment sector so that the perokoniman namely investment in Indonesia decreased and there were some delays in investment by other countries in Indonesia.

scholarly journals End-to-End Transition-Based Online Dialogue Disentanglement

2020 ◽  
Author(s):  
Hui Liu ◽  
Zhan Shi ◽  
Jia-Chen Gu ◽  
Quan Liu ◽  
Si Wei ◽  
...  
Keyword(s):  
Large Scale ◽  
Online Algorithm ◽  
Research Field ◽  
Semantic Coherence ◽  
Large Scale Dataset ◽  
End To End ◽  
Sequential Information ◽  
Almost All ◽  
Classification And Clustering ◽  
Sequential Semantics

Dialogue disentanglement aims to separate intermingled messages into detached sessions. The existing research focuses on two-step architectures, in which a model first retrieves the relationships between two messages and then divides the message stream into separate clusters. Almost all existing work puts significant efforts on selecting features for message-pair classification and clustering, while ignoring the semantic coherence within each session. In this paper, we introduce the first end-to- end transition-based model for online dialogue disentanglement. Our model captures the sequential information of each session as the online algorithm proceeds on processing a dialogue. The coherence in a session is hence modeled when messages are sequentially added into their best-matching sessions. Meanwhile, the research field still lacks data for studying end-to-end dialogue disentanglement, so we construct a large-scale dataset by extracting coherent dialogues from online movie scripts. We evaluate our model on both the dataset we developed and the publicly available Ubuntu IRC dataset [Kummerfeld et al., 2019]. The results show that our model significantly outperforms the existing algorithms. Further experiments demonstrate that our model better captures the sequential semantics and obtains more coherent disentangled sessions.

Residency and movement dynamics of southern rock lobster (Jasus edwardsii) after a translocation event

2015 ◽  
Vol 66 (7) ◽  
pp. 623 ◽  
Author(s):  
Adrian Linnane ◽  
Shane Penny ◽  
Peter Hawthorne ◽  
Matthew Hoare
Keyword(s):  
Large Scale ◽  
South Australia ◽  
Rock Lobster ◽  
Directed Movement ◽  
Translocation Event ◽  
South West ◽  
Movement Dynamics ◽  
Close Proximity ◽  
Jasus Edwardsii ◽  
Almost All

Previous movement studies on the southern rock lobster (Jasus edwardsii) have all involved releasing tagged animals at the point of capture. In 2007, 5298 lobsters, in total, were tagged and translocated from an offshore site (>100-m depth) to two inshore sites (<20-m depth) in South Australia. After a period of 735 days, 510 (9.6%) had been recaptured. The majority of translocated lobsters were located within close proximity to the release points, with 306 (60%) having moved <5km. Of the remainder, 133 (26%) were recaptured within 5–10km, with a further 71 (14%) individuals having moved >10km. Movement patterns were highly directional in nature, with individuals consistently travelling in a south-west bearing, regardless of distance moved. In almost all cases, movement was from inshore to offshore sites, with female lobsters travelling significantly further (mean 5.66km ±6.41s.d.) than males (mean 5.02km ±9.66s.d.). The results are consistent with previous large-scale tagging studies of J. edwardsii, which indicated high residency levels but with occasional directed movement by some individuals.

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