Toward a mathematical theory of Keller–Segel models of pattern formation in biological tissues

2015 ◽  
Vol 25 (09) ◽  
pp. 1663-1763 ◽  
Author(s):  
N. Bellomo ◽  
A. Bellouquid ◽  
Y. Tao ◽  
M. Winkler
Keyword(s):  
Blow Up ◽  
Existence Of Solutions ◽  
Biological Tissues ◽  
Original Model ◽  
Future Research ◽  
Macroscopic Models ◽  
The Third ◽  
Research Activities ◽  
Classical Models ◽  
Chemotaxis Models

This paper proposes a survey and critical analysis focused on a variety of chemotaxis models in biology, namely the classical Keller–Segel model and its subsequent modifications, which, in several cases, have been developed to obtain models that prevent the non-physical blow up of solutions. The presentation is organized in three parts. The first part focuses on a survey of some sample models, namely the original model and some of its developments, such as flux limited models, or models derived according to similar concepts. The second part is devoted to the qualitative analysis of analytic problems, such as the existence of solutions, blow-up and asymptotic behavior. The third part deals with the derivation of macroscopic models from the underlying description, delivered by means of kinetic theory methods. This approach leads to the derivation of classical models as well as that of new models, which might deserve attention as far as the related analytic problems are concerned. Finally, an overview of the entire contents leads to suggestions for future research activities.

SME’s Performance Through Comparative Performance Indicators, Measured by Business Statistics- Albania Case

2017 ◽  
Vol 9 (1) ◽  
pp. 361
Author(s):  
Godiva Rembeci
Keyword(s):  
Economic Performance ◽  
National Economy ◽  
Performance Indicators ◽  
Future Research ◽  
Productivity Measurement ◽  
Comparative Performance ◽  
Global Consensus ◽  
Research Activities ◽  
Business Statistics ◽  
National Economies

Now days there is a global consensus among all stakeholders that SMEs represent a driving force to the overall economic development, due to their significant contribution both on GDP and employment of national economies. SMEs also by numbers dominate the world business stage, although their contribution does vary among the countries. SMEs in Albania represents about 98% of the total enterprises with a contribution to national GDP for about 70%. The structure and the performance of national economy is depended very much on the economic performance and contribution of SME, that’s why most of the governments have strategic programmes which support the SME’s development. To measure SMEs’ performance and their ability to compete on national and international markets requires a lot of information in all aspects. Through this paper the author aims to measure and analyze the economic performance of SMEs operating in Albania. To achieve this objective, official data on business statistics published by national the statistical office (INSTAT) are used for two years period 2014-2015. In addition using an international framework addressed to the objective “improve the techniques for SMEs productivity measurement”, for the first time, a set of comparative performance indicators is established and in doing so, those results can be used as term of reference in future research activities in SMEs sector. From the results it came out that although the positive growth rate of GDP during the last years , the performance indicators of SMEs show a slightly negative trend, indicating indirectly the need for support, in order to empower their contribution in national economy.

scholarly journals Local Anesthetics and Recurrence after Cancer Surgery-What’s New? A Narrative Review

2021 ◽  
Vol 10 (4) ◽  
pp. 719
Author(s):  
Sarah D. Müller ◽  
Jonathan S. H. Ziegler ◽  
Tobias Piegeler
Keyword(s):  
Tumor Cells ◽  
Circulating Tumor Cells ◽  
Local Anesthetics ◽  
Experimental Studies ◽  
Perioperative Period ◽  
Cancer Surgery ◽  
Narrative Review ◽  
Future Research ◽  
Inflammatory Stress ◽  
Research Activities

The perioperative use of regional anesthesia and local anesthetics is part of almost every anesthesiologist’s daily clinical practice. Retrospective analyses and results from experimental studies pointed towards a potential beneficial effect of the local anesthetics regarding outcome—i.e., overall and/or recurrence-free survival—in patients undergoing cancer surgery. The perioperative period, where the anesthesiologist is responsible for the patients, might be crucial for the further course of the disease, as circulating tumor cells (shed from the primary tumor into the patient’s bloodstream) might form new micro-metastases independent of complete tumor removal. Due to their strong anti-inflammatory properties, local anesthetics might have a certain impact on these circulating tumor cells, either via direct or indirect measures, for example via blunting the inflammatory stress response as induced by the surgical stimulus. This narrative review highlights the foundation of these principles, features recent experimental and clinical data and provides an outlook regarding current and potential future research activities.

Climate change and security in Canada

2021 ◽  
Vol 76 (2) ◽  
pp. 183-203
Author(s):  
Wilfrid Greaves
Keyword(s):  
Climate Change ◽  
National Security ◽  
Human Security ◽  
Climate Change Impacts ◽  
Future Research ◽  
National Interests ◽  
Domestic Conflict ◽  
The Third ◽  
Current State ◽  
Humanitarian Crises

This article examines the implications of human-caused climate change for security in Canada. The first section outlines the current state of climate change, the second discusses climate change impacts on human security in Canada, and the third outlines four other areas of Canada’s national interests threatened by climate change: economic threats; Arctic threats; humanitarian crises at home and abroad; and the threat of domestic conflict. In the conclusion, I argue that climate change has clearly not been successfully “securitized” in Canada, despite the material threats it poses to human and national security, and outline directions for future research.

Modeling of Piezo-Actuated Stick-Slip Micro-Drives: An Overview

2012 ◽  
Vol 81 ◽  
pp. 39-48 ◽  
Author(s):  
Ha Xuan Nguyen ◽  
Christoph Edeler ◽  
Sergej Fatikow
Keyword(s):  
Mechanical Model ◽  
Integrated Model ◽  
Friction Model ◽  
Fundamental Importance ◽  
Future Research ◽  
Stick Slip ◽  
Research Activities ◽  
Model Combining ◽  
Friction Models

This paper gives an overview about problems of modeling of piezo-actuated stick-slip micro-drives. It has been found that existing prototypes of such devices have been investigated empirically. There is only few research dealing with the theory behind this kind of drives. By analyzing the current research activities in this field, it is believed that the model of the drive depends strongly on the friction models, but in most cases neglecting any influences of the guilding system.These analyses are of fundamental importance for an integrated model combining friction model and mechanical model offering promising possibilities for future research.

scholarly journals Bifurcation Phenomena of Nonlinear Waves in a Generalized Zakharov-Kuznetsov Equation

2013 ◽  
Vol 2013 ◽  
pp. 1-14
Author(s):  
Yun Wu ◽  
Zhengrong Liu
Keyword(s):  
Solitary Waves ◽  
Nonlinear Waves ◽  
Blow Up ◽  
Periodic Waves ◽  
The Third ◽  
Bifurcation Phenomena ◽  
Kink Waves ◽  
Fourth Kind

We study the bifurcation phenomena of nonlinear waves described by a generalized Zakharov-Kuznetsov equationut+au2+bu4ux+γuxxx+δuxyy=0. We reveal four kinds of interesting bifurcation phenomena. The first kind is that the low-kink waves can be bifurcated from the symmetric solitary waves, the 1-blow-up waves, the tall-kink waves, and the antisymmetric solitary waves. The second kind is that the 1-blow-up waves can be bifurcated from the periodic-blow-up waves, the symmetric solitary waves, and the 2-blow-up waves. The third kind is that the periodic-blow-up waves can be bifurcated from the symmetric periodic waves. The fourth kind is that the tall-kink waves can be bifurcated from the symmetric periodic waves.

Digital competences of the workforce – a research topic?

2017 ◽  
Vol 23 (3) ◽  
pp. 721-734 ◽  
Author(s):  
Matthias Murawski ◽  
Markus Bick
Keyword(s):  
Research Topic ◽  
Future Research ◽  
Digital Competence ◽  
Content Type ◽  
Research Activities ◽  
Starting Point ◽  
Pros And Cons ◽  
Definition Of ◽  
The Individual ◽  
Practical Implications

Purpose Considering working in the digital age, questions on the consequences for the individual workers are, so far, often neglected. The purpose of this paper is to deal with the question of whether the digital competences of the workforce is a research topic. The authors argue for the thesis that it is indeed a research topic. Design/methodology/approach In addition to a literature analysis of the top IS, HR, and learning publications, non-scientific sources, as well as the opinions of the authors, are included. The authors’ thesis is challenged through a debate of corresponding pros and cons. Findings The definition of digital competences lacks scientific depth. Focussing on the workforce is valid, as a “lifelong” perspective is not mandatory for research. Digital competence research is a multidisciplinary task to which the IS field can make a valuable contribution. Research limitations/implications Although relevant references are included, some aspects are mainly driven by the opinions of the authors. The theoretical implications encompass a call for a scientific definition of digital competences. Furthermore, scholars should focus on the competences of the workforce, including occupations, roles, or industries. The authors conclude by providing a first proposal of a research agenda. Practical implications The practical implications include the alignment of multiple stakeholders for the design of “digital” curricula and the integration by HR departments of the construct of digital competences, e.g. for compensation matters and job requirements. Originality/value This paper is one of very few contributions in the area of the digital competences of the workforce, and it presents a starting point for future research activities.

Aplikasi Teori Mahjub terhadap Pembaikan Sebutan Bunyi Bahasa Arab dalam Kalangan Pelajar Sabah - Application of Mahjub Theory in Arabic Pronunciation among Sabahan Students

2017 ◽  
Author(s):  
ISSRAQ BIN RAMLI ◽  
MOHD ZAKI ABD. RAHMAN
Keyword(s):  
Secondary School ◽  
Arabic Language ◽  
Future Research ◽  
Learning And Teaching ◽  
The Third ◽  
Alternative Approach ◽  
Holy Quran ◽  
Post Test ◽  
Arab Students ◽  
The Holy Quran

Terdapat banyak modul sebutan berada di pasaran yang memperkenalkan teknik pembelajaran dan pengajaran sebutan al-Quran al-Karim dan bahasa Arab. Ada yang menggunakan kaedah klasik, moden dan ada juga yang menggunakan kedua-dua kaedah secara komprehensif. Namun, amat sedikit kita lihat kaedah yang dapat memperbaiki sebutan dan menumpukan secara khusus teknik kepada pelajar bukan Arab. Sering kali diperkatakan tentang masalah sebutan pelajar Sabah tanpa membuat kajian secara terperinci dan ilmiah. Justeru, kajian ini dibuat untuk melihat masalah sebenar sebutan bunyi bahasa Arab pelajar Sabah dan seterusnya mengaplikasikan teori Mahjub (1993) untuk memperbaiki masalah sebutan bahasa Arab. Kajian ini dilakukan di sebuah sekolah menengah kebangsaan di Kota Kinabalu yang responden kajiannya ialah pelajar sekolah tingkatan empat. Objektif kajian adalah untuk mengenal pasti secara ilmiah permasalahan sebutan dalam kalangan pelajar Sabah dan mengaplikasi kaedah fonetik Mahjub, seterusnya melihat keberkesanan modul Mahjub sebagai instrumen terbaik memperbaiki sebutan pelajar Sabah. Kajian kualitatif ini menggunakan huruf-huruf konsonan yang sukar bagi pelajar asing yang dibuat oleh Mahjub (1993) yang menggunakan modul yang digunakan untuk memperbaiki sebutan Arab pelajar asing. Terdapat tiga langkah utama dalam kajian ini, iaitu rakaman ujian pertama (U1) sebagai sebutan bahasa Arab terkini pelajar Sabah, kemudian langkah kedua melaksanakan PdP berdasarkan PdP Mahjub dan langkah yang ketiga membuat rakaman ujian kedua (U2) untuk melihat keberhasilan teori Mahjub dalam memperbaiki sebutan pelajar Sabah. Hasil Kajian menunjukkan nilai yang sangat signifikan antara U1 dan U2. Daripada sembilan huruf yang diuji itu, konsonan ‘Ayn [ع] paling baik disebut oleh pelajar dan huruf Dad [ض] paling sukar disebut dalam U1. Dalam U2, huruf Ta’ [ط] paling sukar disebut dan huruf Sad [ص] paling mudah disebut. Dalam U1 Fathaṯ paling tinggi skor dengan 68.2 berbanding Sukun yang mempunyai skor paling rendah dengan 33.3. Secara puratanya, dalam U1 pelajar atau responden hanya mendapat purata sekitar 55 skor min bagi Dammaṯ dan Kasraṯ. Namun, pada U2 peningkatan masing-masing Dammaṯ dan Kasraṯ. mendapat skor yang hampir sama, iaitu 77.9 dan 76.9. Data menunjukkan bahawa Sukun paling bermasalah kepada responden dalam sebutan. Begitu juga terdapat perubahan yang signifikan dalam ujian kedudukan Fathaṯ, Dammaṯ dan Kasraṯ dari U1 kepada U2. Kajian menunjukkan bahawa teori Mahjub ini berhasil memperbaiki masalah sebutan dalam kalangan pelajar Sabah dan memberikan satu alternatif untuk diaplikasi dalam PdP pelajar dan membuka ruang kepada penulis lain untuk memanjangkan kajian pada masa akan datang. There are many modules/methods available in the market to introduce the techniques of learning and teaching the Holy Quran and the Arabic language. There are classical and modern methods in teaching the Holy Quran, and some might combine both classical and modern to help students to learn the Holy Quran. But there are only few methods which can really help to improve the pronunciation of Arabic especially among the non-Arab students who learn Arabic as a second language. This pronunciation problem is often discussed by the Arabic teachers but there are lack of proper studies to overcome this problem. Therefore, this study aims to identify specifically the pronunciation problem and to measure if the Maḥjub Theory can be applied to help in overcoming it. This study was conducted in a secondary school in Kota Kinabalu. The respondents were all Form 4 students. This qualitative study used the Maḥjub Module (1993) to rectify consonant letters that are difficult to pronounce by the Sabahan students. This study has undergone three phrases. The first phrase is U1 where the pre-test is carried out to evaluate the current capability of the respondents. The second phrase applied the Maḥjub Method in the PdP. The third phrase is U2 where the post-test was carried out after the Maḥjub Method was applied to the respondents. This study showed significant value between U1 and U2. Nine consonant letters were tested in this study. In U1, ‘Ayn [ع]was the easiest to pronounce and Dad [ض] was the most difficult to pronounce by the respondents. In U2, Ta’ [ط] was the hardest to pronounce and Sad [ص] was the easiet. In U1, Fathaṯ was the highest with 68.2 score as compared to Sukun with 33.3 score. Overall, respondents scored a mean of 55 for Dammaṯ and Kasraṯ in U1. However, in U2, Dammaṯ and Kasraṯ showed very close score as of 77.9 and 76.9. The data also showed that Sukun is the hardest part for the respondents.This study had proved that the Maḥjub Method is enabled to enhance and improve the difficulty in pronunciation among the students in Sabah. Therefore, the Mahjub Method gives educators an alternative approach to apply in their teaching and also other researchers for ideas to carry out future research in this field.

scholarly journals Perceptions of Shared Leadership within Academic Libraries Suggest Room for Improvement

2011 ◽  
Vol 6 (3) ◽  
pp. 82
Author(s):  
Genevieve C. Gore
Keyword(s):  
Pacific Northwest ◽  
Academic Libraries ◽  
Shared Leadership ◽  
Middle Managers ◽  
The United States ◽  
Future Research ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
The Third ◽  
Level Of Agreement

Objective – To survey middle managers’ beliefs regarding their participation in shared leadership and their libraries’ practices of shared leadership. Design – Cross-sectional survey. Setting – Twenty-two academic libraries within four-year public master’s level institutions in the Pacific Northwest of the United States. Subjects – A total of 115 middle managers were invited to participate; 77 completed the survey for a response rate of 66.9%. Methods – Selected middle managers were contacted by email a total of five times and were invited to complete a Web-based survey composed of three sections. The first section contained 10 statements for rating shared leadership within their own institutions, which they were asked to rate on an eight-point Likert scale from 1 (strongly agree) to 7 (strongly disagree), with 8 as an option for no opinion. The second section used the same scale to rate their levels of agreement with conceptual definitions of shared leadership from Jackson’s Framework. Jackson’s Framework consists of four components for ascertaining levels of shared leadership from both managerial and staff perspectives: accountability, equity, partnership and ownership. The third section invited subjects to provide their own definition of shared leadership. A three-part pretest served to validate the survey instrument. Mean scores were calculated for each statement. Main Results – In the first section, there was the highest overall level of agreement (1.52) with the statement “I am accountable for the decisions within the scope of my responsibility” followed by “I share information with the senior library administration” (1.71). There was the lowest overall level of agreement (3.65) with the statement that “Ideas presented at all levels of staff in the library are equally considered.” In the second section, respondents’ mean scores for Jackson’s definitions of four concepts of shared leadership were 2.62 for ownership, 2.68 for both partnership and equity, and 2.77 for accountability. In the third section, respondents most often linked their definitions of shared leadership with communication, learning and collaboration. Conclusion – Examining middle managers’ perceptions of shared leadership may help us understand organizational trends and capacity for leadership within libraries. Future research could examine shared leadership at levels below middle management as well as the relationship between accountability and shared leadership throughout the organization.

Business process model patterns: state-of-the-art, research classification and taxonomy

2019 ◽  
Vol 25 (5) ◽  
pp. 972-994 ◽  
Author(s):  
Michael Fellmann ◽  
Agnes Koschmider ◽  
Ralf Laue ◽  
Andreas Schoknecht ◽  
Arthur Vetter
Keyword(s):  
Business Process ◽  
Process Model ◽  
Pattern Language ◽  
Future Research ◽  
Business Process Model ◽  
Content Type ◽  
Research Activities ◽  
Starting Point ◽  
Research Classification

Purpose Patterns have proven to be useful for documenting general reusable solutions to a commonly occurring problem. In recent years, several different business process management (BPM)-related patterns have been published. Despite the large number of publications on this subject, there is no work that provides a comprehensive overview and categorization of the published business process model patterns. The purpose of this paper is to close this gap by providing a taxonomy of patterns as well as a classification of 89 research works. Design/methodology/approach The authors analyzed 280 research articles following a structured iterative procedure inspired by the method for taxonomy development from Nickerson et al. (2013). Using deductive and inductive reasoning processes embedded in concurrent as well as joint research activities, the authors created a taxonomy of patterns as well as a classification of 89 research works. Findings In general, the findings extend the current understanding of BPM patterns. The authors identify pattern categories that are highly populated with research works as well as categories that have received far less attention such as risk and security, the ecological perspective and process architecture. Further, the analysis shows that there is not yet an overarching pattern language for business process model patterns. The insights can be used as starting point for developing such a pattern language. Originality/value Up to now, no comprehensive pattern taxonomy and research classification exists. The taxonomy and classification are useful for searching pattern works which is also supported by an accompanying website complementing the work. In regard to future research and publications on patterns, the authors derive recommendations regarding the content and structure of pattern publications.

CROSSING RESONANCES IN A NON-SCALING FFAG

2011 ◽  
Vol 26 (10n11) ◽  
pp. 1852-1864 ◽  
Author(s):  
D. TRBOJEVIC ◽  
M. BLASKIEWICZ ◽  
E. FOREST
Keyword(s):  
Cancer Therapy ◽  
Blow Up ◽  
Proton Accelerator ◽  
Fast Proton ◽  
Phase Jump ◽  
Proton Acceleration ◽  
Fixed Field ◽  
The Third ◽  
Theoretical Predictions

There are many possible applications for the non-scaling Fixed Field Alternating Gradient (NS-FFAG): accelerating non-relativistic ions, ion cancer therapy, proton drivers, accelerator driven subcritical reactors, heavy radioactive ions, recirculating linacs, and etc. They are confronted with two significant challenges: first is crossing integer resonances as the tunes vary with energy, and that the required fast acceleration has not yet been achieved in practice. An example of a small 30–250 MeV NS-FFAG proton accelerator is used to study both problems. After an introduction, the second chapter shows theoretical predictions for the emittance blow up from crossing the integer resonances. In the third part, the lattice of the ring is briefly described. The fourth chapter describes the "phase jump" a method for fast proton acceleration, while in the chapter five a six dimensional simulations of acceleration is described, ending with conclusions.

Sign in / Sign up

Export Citation Format

Share Document