My Way or the Highway: a More Naturalistic Model of Altruism Tested in an Iterative Prisoners' Dilemma

There are three prominent solutions to the Darwinian problem of altruism, kin selection, reciprocal altruism, and trait group selection. Only one, reciprocal altruism, most commonly implemented in game theory as a TIT FOR TAT strategy, is not based on the principle of conditional association. On the contrary, TIT FOR TAT implements conditional altruism in the context of unconditionally determined associates. Simulations based on Axelrod\'s famous tournament have led many to conclude that conditional altruism among unconditional partners lies at the core of much human and animal social behavior. But the results that have been used to support this conclusion are largely artifacts of the structure of the Axelrod tournament, which explicitly disallowed conditional association as a strategy. In this study, we modify the rules of the tournament to permit competition between conditional associates and conditional altruists. We provide evidence that when unconditional altruism is paired with conditional association, a strategy we called MOTH, it can out compete TIT FOR TAT under a wide range of conditions.Game Theory; Altruism; Prisoners' Dilemma; TIT FOR TAT; MOTH; Docking; Netlogo

A New Horned Crocodile from the Plio-Pleistocene Hominid Sites at Olduvai Gorge, Tanzania

BACKGROUND: The fossil record reveals surprising crocodile diversity in the Neogene of Africa, but relationships with their living relatives and the biogeographic origins of the modern African crocodylian fauna are poorly understood. A Plio-Pleistocene crocodile from Olduvai Gorge, Tanzania, represents a new extinct species and shows that high crocodylian diversity in Africa persisted after the Miocene. It had prominent triangular "horns" over the ears and a relatively deep snout, these resemble those of the recently extinct Malagasy crocodile Voay robustus, but the new species lacks features found among osteolaemines and shares derived similarities with living species of Crocodylus. METHODOLOGY/PRINCIPAL FINDINGS: The holotype consists of a partial skull and skeleton and was collected on the surface between two tuffs dated to approximately 1.84 million years (Ma), in the same interval near the type localities for the hominids Homo habilis and Australopithecus boisei. It was compared with previously-collected material from Olduvai Gorge referable to the same species. Phylogenetic analysis places the new form within or adjacent to crown Crocodylus. CONCLUSIONS/SIGNIFICANCE: The new crocodile species was the largest predator encountered by our ancestors at Olduvai Gorge, as indicated by hominid specimens preserving crocodile bite marks from these sites. The new species also reinforces the emerging view of high crocodylian diversity throughout the Neogene, and it represents one of the few extinct species referable to crown genus Crocodylus

Control of style-of-faulting on spatial pattern of earthquake-triggered landslides

Predictive mapping of susceptibility to earthquake-triggered landslides (ETLs) commonly uses distance to fault as spatial predictor, regardless of style-of-faulting. Here, we examined the hypothesis that the spatial pattern of ETLs is influenced by style-of-faulting based on distance distribution analysis and Fry analysis. The Yingxiu–Beichuan fault (YBF) in China and a huge number of landslides that ruptured and occurred, respectively, during the 2008 Wenchuan earthquake permitted this study because the style-of-faulting along the YBF varied from its southern to northern parts (i.e. mainly thrust-slip in the southern part, oblique-slip in the central part and mainly strike-slip in the northern part). On the YBF hanging-wall, ETLs at 4.4–4.7 and 10.3–11.5 km from the YBF are likely associated with strike- and thrust-slips, respectively. On the southern and central parts of the hanging-wall, ETLs at 7.5–8 km from the YBF are likely associated with oblique-slips. These findings indicate that the spatial pattern of ETLs is influenced by style-of-faulting. Based on knowledge about the style-of-faulting and by using evidential belief functions to create a predictor map based on proximity to faults, we obtained higher landslide prediction accuracy than by using unclassified faults. When distance from unclassified parts of the YBF is used as predictor, the prediction accuracy is 80%; when distance from parts of the YBF, classified according to style-of-faulting, is used as predictor, the prediction accuracy is 93%. Therefore, mapping and classification of faults and proper spatial representation of fault control on occurrence of ETLs are important in predictive mapping of susceptibility to ETLs

Development and testing of the AXBT Realtime Editing System (ARES)

Thesis: S.M., Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2020Cataloged from student-submitted PDF of thesis.Includes bibliographical references (pages 129-130).Airborne eXpendable BathyThermographs (AXBTs) are air-launched, single use temperature-depth probes that telemeter temperature observations as a VHF-modulated frequency. This study describes the AXBT Realtime Editing System (ARES), which was developed to receive and quality control temperature-depth profiles with no external hardware other than a VHF radio receiver. The ARES Data Acquisition System performs fast Fourier transforms on windowed segments of demodulated signal transmitted from the AXBT and uses the resulting spectra to identify valid temperature-depth observations. When evaluated using 389 profiles, the ARES data acquisition system produced temperature-depth profiles nearly identical to those generated using a Sippican MK-21 processor, while reducing the amount of noise from VHF interference included in those profiles. The ARES Profile Editor applies a series of automated checks to identify and correct common profile discrepancies, before displaying the profile on an editing interface that provides simple user controls to make additional corrections. When evaluated against 1,177 tropical Atlantic and Pacific AXBT profiles, the ARES automated quality control system successfully corrected 87% of the profiles without any manual intervention necessary. The ARES Data Acquisition and Profile Editing Systems performed exceptionally well when operationally tested with 44 AXBTs during Hurricane Dorian (2019), enabling high resolution observations across key oceanic features including Dorian's cold wake and the Gulf Stream. Necessary future work includes improvements on the automated quality control algorithm and evaluation against a more diverse dataset of temperature-depth profiles.by Casey R. Densmore.S.M.S.M. Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution

Zippering: Managing Intermittent Connectivity in DIANA

This paper describes an approach for handling intermittent connectivity between mobile clients and network-resident applications, which we call zippering. When the client connects with the application, communication between the client and the application is synchronous. When the client intermittently connects with the application, communication becomes asynchronous. The DIANA (Device-Independent, Asynchronous Network Access) approach allows the client to perform a variety of operations while disconnected. Finally, when the client reconnects with the application, the operations performed independently on the client are replayed to the application in the order they were originally done. Zippering allows the user at the client to fix errors detected during reconciliation and continues the transaction gracefully instead of aborting the whole transaction when errors are detected. 1 Introduction 1.1 The Problem People want to access their applications not only while in the workplace but al..

Zippering: Managing Intermittent Connectivity

3 Work done while a student at Stanford University This paper describes an approach for handling intermittent connectivity between mobile clients and network-resident applications, which we call zippering. When the client connects with the application, communication between the client and the application is synchronous. When the client intermittently connects with the application, communication becomes asynchronous. The DIANA (Device-Independent, Asynchronous Network Access) approach allows the client to perform a variety of operations while disconnected. Finally, when the client reconnects with the application, the operations performed independently on the client are replayed to the application in the order they were originally done. Zippering allows the user at the client to x errors detected during reconciliation and continues the transaction gracefully instead of aborting the whole transaction when errors are detected