Project Snow Machine

Much of my research deals with appropriating the marginal languages of disused and abandoned urban forms, and through public sculptural intervention, reintroducing people to their built environment. Project Snow Machine is such an urban intervention that borrows from the typology of municipal forms (signposts, signpost anchors, and parking meters) and recodes them to build a new public space. Divorced from the bonds of bureaucratic functionality, the powder-coated steel snow-ball makers designate a slightly subversive space for play and quite possibly battle. Three Snow Machines were installed for two weeks this winter throughout the city - one green, one yellow, one red - each bearing a sticker describing how to properly use the machine. The photograph depicts the boots of a Chicagoan chancing upon the absurd object, preparing to make the perfect snowball. What she does with it is up to her

Fig 1 -

A-C: Schematic representation of the test arena showing the timing of the tests. A) After 5 minutes in the start box hatch 1 was removed and (B) the open field (OF) test started, which lasted 5 minutes. C) Subsequently hatch 2 was removed, the mirror became visible, and the fish was video recorded for a final 20 minutes in the mirror image stimulation (MIS) test.</p

Pearson’s correlation coefficient and robust correlation coefficients between behavioral variables.

Activity and boldness were determined at minute -1, at the end of the OF test when hatch 2 was still in place and the mirror was not visible yet. Aggression variables were determined at minute 5 of the MIS test, when aggression variables peaked.</p

Head direction during minute 5 of the MIS test.

“L” refers to mirror being place on the left side of the arena and “R” refers to the mirror being on the right side of the arena. A) Examples of how the variable head direction (in degrees, from -180 to 180) was recoded into eight octants (45 degree ‘cake pieces’). Left panel: when the fish has a head direction falling into octant L1-L4 this indicates a preference to use the left eye when looking at the mirror. Right panel: a head direction in octant R1-4 indicates a preference to use the right eye. Note that the octant division is equivalent for arenas with the mirror on the left side (left panel) and on the right side (right panel). B) The number of fish per octant in minute 5. The height of the colored rim represents the number of fish per aggression group. C) The same as B), but now the mean head direction was calculated for those instances that the fish was in the mirror zone.</p

Descriptive statistics of the behavioral variables per aggression group and timepoint.

Minute -1 was the last minute of the OF test, and minute 5 and 10 minutes were 5 and 10 minutes into the MIS test. Values represent means ± SEM. Capital letters in superscript (H, M, L and/or Z) indicate (a) significant difference(s) from other aggression groups, i.e. high (H), medium (M), low (L) or zero (Z) aggression groups, according to post-hoc pair-wise comparisons on mixed-effects models. Note that the values here represent the untransformed values, while some variables were transformed in statistical models, see Methods section.</p

Schematic representation of the virtual division of the arena into zones used for the video tracking analysis.

The arena was divided into three zones: whole arena, center zone and mirror zone. The image is not drawn on scale.</p

Video tracking variables in the MIS test for the four aggression groups, as well as the overall mean.

(A) Distance moved in arena (activity) (cm). (B) Duration moving in arena (activity) (s). (C) Frequency of visits to in center zone (boldness). (D) Duration in center zone (boldness)(s). (E) Duration in mirror zone (aggression)(s). (F) Distance moved in mirror zone (aggression)(cm). In each graph, the black line represents the overall mean. The x-axis represents time (in minutes), e.g. -5 indicates minute -05:00 to -04:00. From minute -5 to 0 the arena served as an open field arena, while the dashed vertical line at minute 0 indicates the minute in which hatch 2 was opened and the mirror became visible.</p

Relationship between manually scored variables and variables extracted from video tracking software at minute 5 of the MIS test.

Duration in the mirror zone against velocity in the mirror zone for each individual parr. In A) The continuous color scale indicates the number of seconds spent displaying “striking” behavior. The colored dots represent the subset of fish manually scored and the grey dots represents all fish from the study. In B) the discrete color scale indicates the aggression group to which each individual was assigned using discriminant analysis.</p

Mechanistic Aspects of Hydrosilylation Catalyzed by (ArN=)Mo(H)(Cl)(PMe₃)₃

The reaction of (ArN=)­MoCl₂(PMe₃)₃ (Ar = 2,6-diisopropylphenyl) with L-Selectride gives the hydrido-chloride complex (ArN=)­Mo­(H)­(Cl)­(PMe₃)₃ (<b>2</b>). Complex <b>2</b> was found to catalyze the hydrosilylation of carbonyls and nitriles as well as the dehydrogenative silylation of alcohols and water. Compound <b>2</b> does not show any productive reaction with PhSiH₃; however, a slow H/D exchange and formation of (ArN=)­Mo­(D)­(Cl)­(PMe₃)₃ (<b>2</b>_<b>D</b>) was observed upon addition of PhSiD₃. Reactivity of <b>2</b> toward organic substrates was studied. Stoichiometric reactions of <b>2</b> with benzaldehyde and cyclohexanone start with dissociation of the <i>trans</i>-to-hydride PMe₃ ligand followed by coordination and insertion of carbonyls into the Mo–H bond to form alkoxy derivatives (ArN=)­Mo­(Cl)­(OR)­(PMe₂)­L₂ (<b>3</b>: R = OCH₂Ph, L₂ = 2 PMe₃; <b>5</b>: R = OCH₂Ph, L₂ = η²-PhC­(O)­H; <b>6</b>: R = OCy, L₂ = 2 PMe₃). The latter species reacts with PhSiH₃ to furnish the corresponding silyl ethers and to recover the hydride <b>2</b>. An analogous mechanism was suggested for the dehydrogenative ethanolysis with PhSiH₃, with the key intermediate being the ethoxy complex (ArN=)­Mo­(Cl)­(OEt)­(PMe₃)₃ (<b>7</b>). In the case of hydrosilylation of acetophenone, a D-labeling experiment, i.e., a reaction of <b>2</b> with acetophenone and PhSiD₃ in the 1:1:1 ratio, suggests an alternative mechanism that does not involve the intermediacy of an alkoxy complex. In this particular case, the reaction presumably proceeds via Lewis acid catalysis. Similar to the case of benzaldehyde, treatment of <b>2</b> with styrene gives <i>trans</i>-(ArN=)­Mo­(H)­(η²-CH₂CHPh)­(PMe₃)₂ (<b>8</b>). Complex <b>8</b> slowly decomposes via the release of ethylbenzene, indicating only a slow insertion of styrene ligand into the Mo–H bond of <b>8</b>

Mechanistic Aspects of Hydrosilylation Catalyzed by (ArN=)Mo(H)(Cl)(PMe₃)₃

The reaction of (ArN=)­MoCl₂(PMe₃)₃ (Ar = 2,6-diisopropylphenyl) with L-Selectride gives the hydrido-chloride complex (ArN=)­Mo­(H)­(Cl)­(PMe₃)₃ (<b>2</b>). Complex <b>2</b> was found to catalyze the hydrosilylation of carbonyls and nitriles as well as the dehydrogenative silylation of alcohols and water. Compound <b>2</b> does not show any productive reaction with PhSiH₃; however, a slow H/D exchange and formation of (ArN=)­Mo­(D)­(Cl)­(PMe₃)₃ (<b>2</b>_<b>D</b>) was observed upon addition of PhSiD₃. Reactivity of <b>2</b> toward organic substrates was studied. Stoichiometric reactions of <b>2</b> with benzaldehyde and cyclohexanone start with dissociation of the <i>trans</i>-to-hydride PMe₃ ligand followed by coordination and insertion of carbonyls into the Mo–H bond to form alkoxy derivatives (ArN=)­Mo­(Cl)­(OR)­(PMe₂)­L₂ (<b>3</b>: R = OCH₂Ph, L₂ = 2 PMe₃; <b>5</b>: R = OCH₂Ph, L₂ = η²-PhC­(O)­H; <b>6</b>: R = OCy, L₂ = 2 PMe₃). The latter species reacts with PhSiH₃ to furnish the corresponding silyl ethers and to recover the hydride <b>2</b>. An analogous mechanism was suggested for the dehydrogenative ethanolysis with PhSiH₃, with the key intermediate being the ethoxy complex (ArN=)­Mo­(Cl)­(OEt)­(PMe₃)₃ (<b>7</b>). In the case of hydrosilylation of acetophenone, a D-labeling experiment, i.e., a reaction of <b>2</b> with acetophenone and PhSiD₃ in the 1:1:1 ratio, suggests an alternative mechanism that does not involve the intermediacy of an alkoxy complex. In this particular case, the reaction presumably proceeds via Lewis acid catalysis. Similar to the case of benzaldehyde, treatment of <b>2</b> with styrene gives <i>trans</i>-(ArN=)­Mo­(H)­(η²-CH₂CHPh)­(PMe₃)₂ (<b>8</b>). Complex <b>8</b> slowly decomposes via the release of ethylbenzene, indicating only a slow insertion of styrene ligand into the Mo–H bond of <b>8</b>