An investigation of human capability to predict the future location of objects in motion

Hitting a Major League fastball pitch may be the most difficult task in the sports realm. Anecdotal evidence suggests that certain individuals are able to perform this task reasonably well, perhaps because of superior sensitivity to changes in motion. However, the substantial lack of research investigating detection and assessment of changes in motion renders this conclusion problematic (Kelling, 2008). Two experiments, using expert and novice participants, assessed sensitivity to changes in motion. Experts for these studies were defined as current members of the Georgia Institute of Technology Yellow Jacket softball team. Experimental procedures included assessments of capabilities in batting and motion tracking tasks. Experiment One presented participants with recorded softball pitches thrown from a pitching machine. Experiment Two required participants to predict multiple landing locations for incomplete motion paths resulting from a single main target exploding into additional shrapnel pieces. Results suggest minimal expertise effects in the softball task with high performance by all participants, while distinct expertise effects exist in the shrapnel task. The motion tracking task resulted in fewer errors by experts, while all participants demonstrated a significantly large drop in performance with increasing number of shrapnel pieces. Findings from this work not only have application to the sport of softball, but are critical for identifying the people's capability to detect and assess changes in motion.Ph.D.Committee Chair: Dr. Gregory M. Corso; Committee Member: Dr. Arthur D. Fisk; Committee Member: Dr. Bruce Walker; Committee Member: Dr. Lawrence R. James; Committee Member: Dr. Paul Corballis; Committee Member: Dr. Robert Grego

Radical Bonding: Structure and Stability of Bis(Phenalenyl) Complexes of Divalent Metals from across the Periodic Table

We examine the bonding possibilities of the bis(phenalenyl) MP2 sandwich complexes of the divalent metals M = Be, Mg, Ca, Sr, Ba, Zn, Cd, and Hg, at the B3LYP level of theory. The outcome is an extraordinarily diverse class of low symmetry bis(phenalenyl)metal complexes in which bonding preferences and binding enthalpies differ dramatically. The lowest energy group 2 metal MP2 complexes include an intriguing η1,η3 BeP2 structure, and bent η6,η6 systems for M = Ca, Sr, and Ba. The group 12 bis(phenalenyl) complexes are thermodynamically unstable η1,η1 slip-sandwich structures. To better understand changes in the structural preferences going from the (η6,η6) group 2 to the (η1,η1) group 12 complexes, we explored the bonding in the bis(phenalenyl) complexes of transition metals with stable +2 oxidations states between Ca and Zn in period 4. The computed binding enthalpies are large and negative for nearly all of the minimum energy bis(phenalenyl) complexes of the group 2 and the transition metals; they are tiny for MgP2, and are quite positive for the group 12 systems. The structural preferences and stability of the complexes is a subtle negotiation of several influences: the (un)availability of (n - 1)d and np, orbitals for bonding, the cost of the rehybridization at carbon sites in the phenalenyl rings in preparation for bonding to the metals, and the (P—P) interaction between the phenalenyl radicals

Bending Ternary Dihalides: A Single Functional Form For Linearization Energies

IntroductionAlthough the bonding in the symmetric groups 2 and 12 dihalides (MX2) has been studied extensively1,2, remarkably little work –experimental or theoretical – has been done on the mixed (ternary) dihalides, MXY. Previously, a criterion3,4 based on atomic softness (σ) was proposed for the bending of MX2 and MXY molecules. We extend this softness criterion on the slate of the mixed dihalides and the predicted separation is achieved between the bent and linear structures with almost the same cutoff, and with quasilinear species straddling the boundary. In this work, we report a complete assessment of the bonding preferences and vibrational frequencies of the mixed dihalides of the groups 2 and 12 metals MX2 and MXY

Just Noticeable Differences for Vehicle Rates of Closure

The goal for this research was to identify the just noticeable difference (JND) for vehicle rates of closure. In our attempt to identify the JND we used two traditional psychophysical methods. However, these procedures resulted aberrant relationships between rate of closure and percent correct. Both of the traditional procedures used a sequential presentation of a standard animation and a comparison animation. The final method used a change in the rate of closure within the animation. This method provided us with a JND of between 12.9 to 16.1 km/h (8 to 10 mph). Reasons for the aberrant findings using the traditional methods are discussed

First principles predictions of van der Waals bonded inorganic crystal structures: Test case, HgCl2

We study the crystals structure and stability of four possible polymorphs of HgCl2 using first principles density functional theory. Mercury (II) halides are a unique class of materials which, depending on the halide species, form in a wide range of crystal structures, ranging from densely packed solids to layered materials and molecular solids. Predicting the groundstate structure of any member of this group from first principles, therefore, requires a general purpose functional that treats van der Waals bonding and covalent/ionic bonding adequately. Here, we demonstrate that the non-local van der Waals density functional paired with the C09 exchange functional meets this bar for HgCl2. In particular, this functional is able to predict the correct groundstate among the structures tested as well as having extremely good agreement with the experimentally known crystal structure. These results highlight the maturity of this functional and open the door to using this method for truly first principles crystal structure predictions

Extremely large scale simulation of a Kardar-Parisi-Zhang model using graphics cards

The octahedron model introduced recently has been implemented onto graphics cards, which permits extremely large scale simulations via binary lattice gases and bit coded algorithms. We confirm scaling behaviour belonging to the 2d Kardar-Parisi-Zhang universality class and find a surface growth exponent: beta=0.2415(15) on 2^17 x 2^17 systems, ruling out beta=1/4 suggested by field theory. The maximum speed-up with respect to a single CPU is 240. The steady state has been analysed by finite size scaling and a growth exponent alpha=0.393(4) is found. Correction to scaling exponents are computed and the power-spectrum density of the steady state is determined. We calculate the universal scaling functions, cumulants and show that the limit distribution can be obtained by the sizes considered. We provide numerical fitting for the small and large tail behaviour of the steady state scaling function of the interface width.Comment: 7 pages, 8 figures, slightly modified, accepted version for PR

Tuning σ-Holes: Charge Redistribution in the Heavy (Group 14) Analogues of Simple and Mixed Halomethanes Can Impose Strong Propensities for Halogen Bonding

Halogen bonding between halide sites (in substituted organic molecules or inorganic halides) and Lewis bases is a rapidly progressing area of exploration. Investigations of this phenomenon have improved our understanding of weak intermolecular interactions and suggested new possibilities in supramolecular chemistry and crystal engineering. The capacity for halogen bonding is investigated at the MP2(full) level of theory for 100 compounds, including all 80 MH4-nXn systems (M = C, Si, Ge, Sn, and Pb; X = F, Cl, Br, and I). The charge redistribution in these molecules and the (in)stability of the σ-hole at X as a function of M and n are catalogued and examined. For the mixed MH3-mFmI compounds, we identify a complicated dependence of the relative halogen bond strengths on M and m. For m = 0, for example, the H3C-I----NH3 halogen bond is 6.6 times stronger than the H3Pb-I----NH3 bond. When m = 3, however, the F3Pb-I----NH3 bond is shorter and ∼1.6 times stronger than the F3C-I----NH3 bond. This substituent-induced reversal in the relative strengths of halogen bond energies is explained

Study of Dairy Manure N Cycling in Soil-Plant Continuum Using \u3csup\u3e15\u3c/sup\u3eN and Other Methods

Ruminant livestock manure impacts on N cycling in the soil-plant continuum. Most studies of manure N cycling are short-term and rely on indirect methods, i.e. apparent N recovery, fertiliser N equivalents or incorporate 15N into ammonium-N fractions. Direct and perhaps more precise measurements may be achieved by long-term studies using 15N incorporated into all manure N components. This paper summarises results of a 6- year trial to compare indirect and direct measures of manure N uptake by corn for 3 years after application

Charge Saturation and Neutral Substitutions in Halomethanes and Their Group 14 Analogues

A computational analysis of the charge distribution in halomethanes and their heavy analogues (MH4-nXn: M= C, Si, Ge, Sn, Pb; X = F, Cl, Br, I) as a function of n uncovers a previously unidentified saturation limit for fluorides when M ≠ C. We examine the electron densities obtained at the CCSD, MP2(full), B3PW91, and HF levels of theory for 80 molecules for four different basis sets. A previously observed substituent independent charge at F in fluoromethanes is shown to be a move toward saturation that is restricted by the low polarizability of C. This limitation fades into irrelevance for the more polarizable M central atoms such that a genuine F saturation is realized in those cases. A conceptual model leads to a function of the form [qM(n) -- qM(n)] = a[χA\u27 -- χA] + b that links the electronegativities (χ) of incoming and leaving atoms (e.g., A\u27 = X and A = H for the halogenation of MH4-nXn) and the associated charge shift at M. We show that the phenomenon in which the charge at the central atom, qM, is itself independent of n (e.g., at carbon in CH4-nBrn) is best described as an “M-neutral substitution”—not saturation. Implications of the observed X saturation and M-neutral substitutions for larger organic and inorganic halogenated molecules and polymeric materials are identified