GIT Compactifications of M_{0,n} and Flips

We use geometric invariant theory (GIT) to construct a large class of compactifications of the moduli space M_{0,n}. These compactifications include many previously known examples, as well as many new ones. As a consequence of our GIT approach, we exhibit explicit flips and divisorial contractions between these spaces.Comment: Final version to appear in Advance

Степи Північної Америки та Росії

У статті порівнюються два степових регіони зі схожим навколишнім природним середовищем та схожими екологічними історіями: Великі рівнини Північної Америки та степи Росії і України. В центрі уваги опинилися “Пиловий котел” на Великих рівнинах у 1930-х роках як приклад всеохоплюючої та руйнівної ерозії ґрунту, та посуха, неврожай і голод у Російській імперії в 1891–1892 роках, що отримали найбільше розповсюдження в лісостеповій та степовій зонах. Історики та науковці в галузі точних та природничих наук оцінили взаємопов‟язане значення антропогенного та природного факторів цих двох катастроф, звернувши увагу на проблеми хліборобства в умовах напівпосушливого клімату

Seasonal Survival of Adult Female Mottled Ducks

The mottled duck (Anas fulgivula) is a non‐migratory duck dependent on coastal habitats to meet all of its life cycle requirements in the Western Gulf Coast (WGC) of Texas and Louisiana, USA. This population of mottled ducks has experienced a moderate decline during the past 2 decades. Adult survival has been identified as an important factor influencing population demography. Previous work based on band‐recovery data has provided only annual estimates of survival. We assessed seasonal patterns of female mottled duck survival from 2009 to 2012 using individuals marked with satellite platform transmitter terminals (PTTs). We used temperature and movement sensors within each PTT to indicate potential mortality events. We estimated cumulative weekly survival and ranked factors influential in patterns of mortality using known‐fate modeling in Program MARK. Models included 4 predictors: week; hunting and non‐hunting periods; biological periods defined as breeding, brooding, molt, and pairing; and mass at time of capture. Models containing hunt periods, during and outside the mottled duck season, comprised essentially 100% of model weights where both legal and illegal harvest had a negative influence on mottled duck survival. Survival rates were low during 2009–2011 (12–38% annual rate of survival), when compared with the long‐term banding average of 53% annual survival. During 2011, survival of female mottled ducks was the lowest annual rate (12%) ever documented and coincided with extreme drought. Management actions maximizing the availability of wetlands and associated upland habitats during hunting seasons and drought conditions may increase adult female mottled duck survival. © 2017 The Authors. Journal of Wildlife Management Published by Wiley Periodicals, Inc. on behalf of The Wildlife Society

Cyber-Herding: Exploiting Islamic Extremists Use of the Internet

The internet has many characteristics that support extremists' information operations, such as being able to reach large audiences. Yet the internet also has inherent weaknesses that can be exploited. One of these weaknesses is the ambiguous nature of the net. You trust that when you go to a website that it is legitimate. If it looks professional, you tend to believe that the site is real. However, criminals or terrorists could just as easily be running that website. The same is true when you chat with someone online. […]. Terrorist organizations also have an inherent weakness that can be exploited using the internet. This weakness is the decentralized nature of terrorist organizations. Many terrorist organizations that do not have state sponsorship organize and accomplish work utilizing social networks versus a hierarchy command structure. This only makes sense. Individuals engaged in criminal activities need to work with people they trust so they can accomplish their mission. In the physical world, social networks are very reliable. However, in the virtual world social networks can be exploited because personalities in the virtual world can be real or fictitious. In order to exploit these weaknesses, a cyber system that invisibly drives Islamic extremists from terrorist websites to covertly controlled websites can be developed. I will generically refer to this system as cyber-herding

Cyber-herding and cyber activism countering Qutbists on the internet

The Internet provides Islamic militants ("Qutbists") a golden opportunity to bypass normal media outlets and take their message directly to the people. This allows them to spread their ideas to an ever-growing audience. What should be done about these web sites has been the focus of an ongoing debate. Some advocate shutting down these web sites while others prefer to monitor them for information. Both views have merit, and both have problems. The purpose of this thesis is to propose and evaluate three strategies for countering Qutbists on the internet: a covert active strategy of cyber-herding, an overt passive strategy of cyber activism, and a combination of these two strategies.http://archive.org/details/cyberherdingndcy109453092US Air Force (USAF) author.Approved for public release; distribution is unlimited

Steppe by Steppe : Exploring Environmental Change in Southern Ukraine

This article considers the environmental legacy of Soviet central planning, that began in the late-1920s, and also longer-term human intervention, in the ‘natural’ world of rural Southern Ukraine. It is based on a journey across the steppe, what the author learned from people, especially scientists, he met, and research in written sources. The first section considers ‘nature transformed’. Since the conquest by the Russian Empire in the 18th century, the steppe grassland has been transformed from pasture for livestock into arable land farmed by settlers of European origin. The second section, ‘nature protected’, discusses the Askania Nova biosphere reserve, where an area of grassland has been protected since the late-19th century. The reserve also contains an artificial woodland park and a collection of grazing animals from all over the world. The third section, ‘nature destroyed’, is about the Oleshkivs’ki sands, on the left bank of the estuary of the Dnipro river opposite the city of Kherson. In ancient times, a forest grew on the sands. From the 18th century, European settlers cleared much of the forest for grazing, leading to erosion. Trees have since been replanted surrounding a curious landscape of sand dunes, which have become a habitat for rare plant species. The sands were also used a bombing range for Warsaw Pact air forces during the Cold War, but part if now protected as a nature reserve

Sums and differences of correlated random sets

Many fundamental questions in additive number theory (such as Goldbach's conjecture, Fermat's last theorem, and the Twin Primes conjecture) can be expressed in the language of sum and difference sets. As a typical pair of elements contributes one sum and two differences, we expect that $|A-A| > |A+A|$ for a finite set $A$. However, in 2006 Martin and O'Bryant showed that a positive proportion of subsets of $\{0, \dots, n\}$ are sum-dominant, and Zhao later showed that this proportion converges to a positive limit as $n \to \infty$. Related problems, such as constructing explicit families of sum-dominant sets, computing the value of the limiting proportion, and investigating the behavior as the probability of including a given element in $A$ to go to zero, have been analyzed extensively. We consider many of these problems in a more general setting. Instead of just one set $A$, we study sums and differences of pairs of \emph{correlated} sets $(A,B)$. Specifically, we place each element $a \in \{0,\dots, n\}$ in $A$ with probability $p$, while $a$ goes in $B$ with probability $\rho_1$ if $a \in A$ and probability $\rho_2$ if $a \not \in A$. If $|A+B| > |(A-B) \cup (B-A)|$, we call the pair $(A,B)$ a \emph{sum-dominant $(p,\rho_1, \rho_2)$-pair}. We prove that for any fixed $\vec{\rho}=(p, \rho_1, \rho_2)$ in $(0,1)^3$, $(A,B)$ is a sum-dominant $(p,\rho_1, \rho_2)$-pair with positive probability, and show that this probability approaches a limit $P(\vec{\rho})$. Furthermore, we show that the limit function $P(\vec{\rho})$ is continuous. We also investigate what happens as $p$ decays with $n$, generalizing results of Hegarty-Miller on phase transitions. Finally, we find the smallest sizes of MSTD pairs.Comment: Version 1.0, 19 pages. Keywords: More Sum Than Difference sets, correlated random variables, phase transitio

Discovery of halloysite books in a ~270,000 year-old buried tephra deposit in northern New Zealand

As part of a wider study examining the geomechanical properties, especially sensitivity, of sequences of Quaternary pyroclastic and associated deposits and buried soils in the landslide-prone western Bay of Plenty area near Tauranga, eastern North Island, we examined the mineralogy of a pale pinkish-grey tephra deposit directly beneath non-welded, siliceous Te Ranga Ignimbrite (~2 m thick) in a ~25 m high cutting at Tauriko.http://www.smectech.com.au/ACMS/ACMS_Conferences/ACMS21/ACMS%202010%20Abstracts/ACMS%202010%20S1A6_Wyatt%20et%20al%20(Lowe).pd

Lisp Machine Choice Facilities

This document is a draft copy of a portion of the Lisp Machine window system manual. It is being published in this form now to make it available, since the complete window system manual is unlikely to be finished in the near future. The information in this document is accurate as of system 70, but is not guaranteed to remain 100% accurate. To understand some portions of this document may depend on background information which is not contained in any published documentation. The window system contains several facilities to allow the user to make choices. These all work by displaying some arrangement of choices in a window; by pointing to one with the mouse the user can select it. This document explains what the various facilities are, how to use them, and how to customize them for your own purposes.MIT Artificial Intelligence Laborator