Review of: How Behavior Spreads: The Science of Complex Contagions by Centola, Damon, reviewed by Srebrenka Letina

J Jumadi, Nick Malleson, Steve Carver and Duncan Quincey: Managing disasters caused by natural events, especially volcanic crises, requires a range of approaches, including risk modelling and analysis. Risk modelling is commonly conducted at the community/regional scale using GIS. However, people and objects move in response to a crisis, so static approaches cannot capture the dynamics of the risk properly, as they do not accommodate objects’ movements within time and space. The emergence of Agent-Based Modelling makes it possible to model the risk at an individual level as it evolves over space and time. We propose a new approach of Spatio-Temporal Dynamics Model of Risk (STDMR) by integrating multi-criteria evaluation (MCE) within a georeferenced agent-based model, using Mt. Merapi, Indonesia, as a case study. The model makes it possible to simulate the spatio-temporal dynamics of those at risk during a volcanic crisis. Importantly, individual vulnerability is heterogeneous and depends on the characteristics of the individuals concerned. The risk for the individuals is dynamic and changes along with the hazard and their location. The model is able to highlight a small number of high-risk spatio-temporal positions where, due to the behaviour of individuals who are evacuating the volcano and the dynamics of the hazard itself, the overall risk in those times and places is extremely high. These outcomes are extremely relevant for the stakeholders, and the work of coupling an ABM, MCE, and dynamic volcanic hazard is both novel and contextually relevant.

Qing Xu, Sylvie Huet, Eric Perret and Guillaume Deffuant: The drivers of conversion to organic farming, which is still a residual choice in agriculture, are poorly understood. Many scholars argue that farm characteristics can determine this choice but do not exclude the role of social dynamics. To study this issue, we developed an agent-based model in which agents' decisions to shift to organic farming are based on a comparison between satisfaction with the current situation and potential satisfaction with an alternative farming strategy. A farmer agent’s satisfaction is modelled using the Theory of Reasoned Action. This makes it necessary to compare an agent's productions over time with those of other agents to whom the former attributes considerable credibility (“important others”). Moreover, farmers make technical changes that affect their productions by imitating other credible farmers. While we first used this model to examine simple and abstract farm populations, here we also adapted it for use with data from an Agricultural Census concerning the farm characteristics of dairy farming in 27 French “cantons”. Based on domain expertise, data and previous research, we propose certain laws for modelling the impact of conversion on the farm production of milk and the environment. The simulations with “real” populations of farms confirm the important impact of farm characteristics. However, our results also suggest a complex impact of social dynamics that can favour or impede the diffusion of organic farming through dynamic implicit networks of similarity and credibility. We confirm the great importance of demographic changes in farm characteristics.

Bruno Pietzsch, Sebastian Fiedler, Kai G. Mertens, Markus Richter, Cédric Scherer, Kirana Widyastuti, Marie-Christin Wimmler, Liubov Zakharova and Uta Berger: The recent advancement of agent-based modeling is characterized by higher demands on the parameterization, evaluation and documentation of these computationally expensive models. Accordingly, there is also a growing request for "easy to go" applications just mimicking the input-output behavior of such models. Metamodels are being increasingly used for these tasks. In this paper, we provide an overview of common metamodel types and the purposes of their usage in an agent-based modeling context. To guide modelers in the selection and application of metamodels for their own needs, we further assessed their implementation effort and performance. We performed a literature research in January 2019 using four different databases. Five different terms paraphrasing metamodels (approximation, emulator, meta-model, metamodel and surrogate) were used to capture the whole range of relevant literature in all disciplines. All metamodel applications found were then categorized into specific metamodel types and rated by different junior and senior researches from varying disciplines (including forest sciences, landscape ecology, or economics) regarding the implementation effort and performance. Specifically, we captured the metamodel performance according to (i) the consideration of uncertainties, (ii) the suitability assessment provided by the authors for the particular purpose, and (iii) the number of valuation criteria provided for suitability assessment. We selected 40 distinct metamodel applications from studies published in peer-reviewed journals from 2005 to 2019. These were used for the sensitivity analysis, calibration and upscaling of agent-based models, as well to mimic their prediction for different scenarios. This review provides information about the most applicable metamodel types for each purpose and forms a first guidance for the implementation and validation of metamodels for agent-based models.

Volker Grimm, Steven F. Railsback, Christian E. Vincenot, Uta Berger, Cara Gallagher, Donald L. DeAngelis, Bruce Edmonds, Jiaqi Ge, Jarl Giske, Jürgen Groeneveld, Alice S.A. Johnston, Alexander Milles, Jacob Nabe-Nielsen, J. Gareth Polhill, Viktoriia Radchuk, Marie-Sophie Rohwäder, Richard A. Stillman, Jan C. Thiele and Daniel Ayllón: The Overview, Design concepts and Details (ODD) protocol for describing Individual- and Agent-Based Models (ABMs) is now widely accepted and used to document such models in journal articles. As a standardized document for providing a consistent, logical and readable account of the structure and dynamics of ABMs, some research groups also find it useful as a workflow for model design. Even so, there are still limitations to ODD that obstruct its more widespread adoption. Such limitations are discussed and addressed in this paper: the limited availability of guidance on how to use ODD; the length of ODD documents; limitations of ODD for highly complex models; lack of sufficient details of many ODDs to enable reimplementation without access to the model code; and the lack of provision for sections in the document structure covering model design rationale, the model’s underlying narrative, and the means by which the model’s fitness for purpose is evaluated. We document the steps we have taken to provide better guidance on: structuring complex ODDs and an ODD summary for inclusion in a journal article (with full details in supplementary material; Table 1); using ODD to point readers to relevant sections of the model code; update the document structure to include sections on model rationale and evaluation. We also further advocate the need for standard descriptions of simulation experiments and argue that ODD can in principle be used for any type of simulation model. Thereby ODD would provide a lingua franca for simulation modelling.

Governor Markell orders flags to be lowered in honor of Neil Armstrong and longtime Delaware Representative Philip Corrozi through September 5, 2012.

The Delaware Office of Management and Budget will be holding three public hearings to gather public comment on regulations under Governor Markell’s Executive Order 36, a statewide review by all agencies to identify and remove regulatory hurdles.

Governor Markell orders flags to be lowered as a mark of respect for Connecticut shooting victims.

Flags will remain at half-staff until Monday, December 24, in honor of the late Senator Daniel K. Inouye.

Governor Markell orders flags to be lowered as a mark of respect for the passing of former Lieutenant Governor Gene Bookhammer.

Governor Markell ordered flags to be lowered between March 7 and 11 as a mark of respect for the passing of former Delaware Judge and civil rights leader Leonard Williams.

Governor Markell ordered flags to be lowered between April 16 and 22 as a mark of respect for the victims of the April 15 bombings in Boston, Massachusetts.

Flags to be lowered in remembrance of victims of the September 11, 2001 terrorist attack.

US and Delaware flags have been ordered lowered to half-staff until sunset on Friday, September 20, 2013, as a mark of respect for the victims of the Navy Yard shootings.

U.S. and Delaware flags have been ordered lowered to half-staff until the start of business on Monday, October 7, 2013, to honor firefighters who have died protecting Delawareans and in recognition of the National Fallen Firefighters Memorial Service.

Governor Jack Markell has ordered the U.S. and Delaware flags at all state buildings and facilities lowered on Friday, November 1, to mark the passing of two former Delaware leaders.

Governor Markell has ordered the U.S. and Delaware flags at all state buildings and facilities lowered in memory of Nelson Mandela and to mark National Pearl Harbor Remembrance Day.

Governor Markell has ordered the American and Delaware flags at state buildings and facilities be flown at half-staff in memory of former State Representative William Vernon.

Governor Markell has ordered the American and Delaware flags at state buildings and facilities be flown at half-staff on Peace Officers Memorial Day, Thursday, May 15.

Governor Markell Orders Flags Lowered on Tuesday, June 17, for the passing of former State Representative Thomas E. Brady Jr.

Governor Markell Orders Flags Lowered on Wednesday, July 30, for the passing of former State Representative and Judge Vincent Bifferato.

Governor Markell orders flags lowered for the passing of retired Delaware Supreme Court Justice Joseph Walsh.

Governor Markell orders flags lowered for the passing of former State Representative C. Leslie Ridings Jr.

DOVER – This afternoon, President Obama ordered American flags at all government buildings and facilities to be flown at half-staff on Thursday, September 11, in observance of Patriot Day and National Day of Service to honor the individuals who lost their lives on September 11, 2001. In concurrence with the President’s order and in remembrance […]

In recognition of National Fallen Firefighters Memorial Weekend, Governor Markell has ordered the American and Delaware flags at state buildings and facilities to be lowered to half-staff.

Governor Markell has ordered the American and Delaware flags lowered to half-staff for the passing of former State Representative Clifford G. "Biff" Lee.

American and Delaware flags at state buildings and facilities are to remain lowered to half-staff until Monday, December 8, to recognize Pearl Harbor Remembrance Day.

To honor the life and legacy of President Abraham Lincoln and in concurrence with an order issued by President Obama, Governor Markell has ordered both the U.S. and Delaware State flags be lowered to half-staff on Wednesday, April 15, 2015.​

Governor Markell has ordered the American and Delaware flags at state buildings and facilities be flown at half-staff on Peace Officers Memorial Day, Friday, May 15.

Governor Markell has ordered the American and Delaware flags at state buildings and facilities be lowered to half-staff as a mark of respect for the victims of the shooting that took place on July 16, 2015 in Chattanooga, Tennessee.

Governor Markell has ordered the American and Delaware flags lowered to half-staff on Wednesday, September 2, for the passing of former State Representative Joseph R. Petrilli, Sr.

Governor Markell has ordered the Delaware and American flags to be lowered to half-staff on Friday, September 11, in remembrance of the victims who lost their lives on September 11, 2001.

Governor Markell has ordered the Delaware flag at state buildings and facilities be flown at half-staff in honor of civil rights activist James H. Gilliam, Sr.

Governor Markell has ordered the American and Delaware flags lowered to half-staff for the passing of former State Representative Charles P. West.

Governor Markell has ordered the American and Delaware flags lowered on Thursday, October 22, in honor of Family Court Judge Alan N. Cooper and his many years of public service to the State of Delaware.

Governor Markell has ordered the American and Delaware flags at state buildings and facilities lowered as a mark of respect for the victims of the terrorist attacks in Paris on November 13.

Governor Markell has ordered the American and Delaware flags at state buildings and facilities be lowered to half-staff as a mark of respect for the victims of the shooting that took place on December 2, 2015 in San Bernardino, California.

Governor Markell has ordered the American and Delaware flags at state buildings and facilities lowered in honor of former State Representative Benjamin Ewing.

Governor Markell has ordered the American and Delaware flags lowered in honor of U.S. Supreme Court Justice Antonin Scalia.

With the passing of former First Lady Nancy Reagan on Sunday, March 6, 2016, Governor Markell has ordered American and Delaware flags at state buildings and facilities be flown at half-staff beginning immediately as a mark of respect for the memory of Mrs. Reagan. The lowering of the flags also marks the passing of Former Delaware Supreme Court Justice Henry Ridgely Horsey on March 3, 2016.

President Obama today ordered American flags at all U.S. government buildings and facilities to be flown at half-staff “as a mark of respect for the victims of the senseless acts of violence perpetrated on March 22, 2016, in Brussels, Belgium.” In concurrence with the President’s order and as an expression of Delaware’s sympathy for the […]

President Obama Sunday ordered American flags at all U.S. government buildings and facilities to be flown at half-staff “as a mark of respect for the victims of the act of hatred and terror perpetrated on Sunday, June 12, 2016, in Orlando, Florida.” In concurrence with the President’s order and as an expression of Delaware’s sympathy […]

On Sunday, Delaware will lay to rest fallen firefighter Tim McClanahan. Mr. McClanahan passed away on Monday, July 11, 2016, following a Delaware Air Rescue Team training accident. He was a graduate of Cape Henlopen High School, was a past member of Milton and Rehoboth Beach Fire Departments, and a current member of the Lewes […]

On July 14, Governor Markell ordered the Delaware flag to be flown at half-staff until July 18, 2016 as a remembrance of fallen firefighter Tim McClanahan. This afternoon, President Obama ordered American flags at all U.S. government buildings and facilities to be flown at half-staff until July 19, 2016 “as a mark of respect for […]

With the passing of State Representative Harold J. “Jack” Peterman yesterday, Governor Markell has ordered the American and Delaware flags at state buildings and facilities be flown at half-staff beginning the morning of Friday, August 12 as a mark of respect for Representative Peterman and his service to Delaware. Representative Peterman served in the Delaware […]

Governor Jack Markell has ordered state and federal flags lowered to honor the life and passing of former Delaware Supreme Court Justice William T. Quillen. Quillen served on the Supreme Court from 1978 to 1983. He also was Delaware Secretary of State from 1993 to 1994 under the administration of Governor Tom Carper. During his […]

With the passing of former State Representative V. George Carey on September 11, 2016 Governor Markell has ordered the American and Delaware flags at state buildings and facilities be flown at half-staff beginning Tuesday morning, September 13th as a mark of respect for Representative Carey and his service to Delaware. Representative Carey faithfully served the […]

Governor Markell today ordered both the U.S. and State flags to be flown at half-staff in memory of fallen Wilmington firefighters Lt. Christopher Leach and Senior Firefighter Jerry Fickes. Both firefighters died this morning serving their community and fellow Delawareans valiantly, while battling a blaze in Wilmington. Flags are to remain at half-staff until further […]

Everyday across Delaware, thousands of firefighters serve their communities and protect the public by responding to not only fires but almost any emergency situation. In honor of the men and women who have died while protecting Delawareans, in recognition of the National Fallen Firefighters Memorial Service (to be held on Sunday, October 9) and in […]

Governor Markell today ordered both the U.S. and State flags to be flown at half-staff in memory of fallen Wilmington Senior Firefighter Ardythe Hope. Senior Firefighter Hope passed away from her injuries as a result of battling a blaze in Wilmington the morning of September 24. Flags are to remain at half-staff until further notice.