we compare beginning special and general education teachers' access to school-based colleagues. Ourfindings demonstrate that colleague relationships are critical for the experiences of beginning teachers, asare the school organizational norms that these beginning teachers experience. For special education teachers in particular, perception ofcolleague support was a strongpredictor of retention plans. Similar results were seen with respect to their perception ofthe level of collective responsibility among thefaculty. laken together, these results suggest that schools and districts should make efforts tofizcilitate productive relationships between general and special education faculty, as well asto differentiate induction supportfor beginning special educators.

A primary focus of recent educational policymaking has been on improving measures of teaching effectiveness, attributable in part to recent federal policies such as the Race to the Top initiative and Investing in Innovation. To date, neither researchers nor practitioners have arrived at a consensus on the best methods for evaluating special educators. While value-added scores are likely not suitable for the majority of special education teachers, observation systems appear to be more promising because they can be used across a variety of instructional settings and formats. To illustrate the steps that would be necessary to validate observation systems for use with special educators, we examine the observation system being most commonly used in school districts-Charlotte Danielson's Framework for Teaching (FFT). Drawing on empirical research, we propose a definition of effective special education teaching, and we then use this definition to frame our investigation into FFT. We conclude with a series of recommendations for research that would establish the validity of using FFT to evaluate special educators. We also describe how the challenges specific to FFT would generalize to other observation systems.

Retroviruses must integrate their linear viral cDNA into the host genome for a productive infection. Integration is catalysed by the retrovirus-encoded integrase (IN), which forms a tetramer or octamer complex with the viral cDNA long terminal repeat (LTR) ends termed an intasome. IN removes two 3′-nucleotides from both LTR ends and catalyses strand transfer of the recessed 3′-hydroxyls into the target DNA separated by 4–6 bp. Host DNA repair restores the resulting 5′-Flap and single-stranded DNA (ssDNA) gap. Here we have used multiple single molecule imaging tools to determine that the prototype foamy virus (PFV) retroviral intasome searches for an integration site by one-dimensional (1D) rotation-coupled diffusion along DNA. Once a target site is identified, the time between PFV strand transfer events is 470 ms. The majority of PFV intasome search events were non-productive. These observations identify new dynamic IN functions and suggest that target site-selection limits retroviral integration.

The organolithium dimer [Li2C(Ph2PNSiMe3)2]2 ([Li2-1]2) reacts with 2 equiv of [PtCl2(cod)] (cod = 1,5-cyclooctadiene) in Et2O solution to give the novel Pt−carbene complex [(η4-cod)Pt{C(Ph2PNSiMe3)2-κC,κN}] (2), which is characterized by a relatively long Pt−C(carbene) bond and relatively short Pt−C(olefin) interactions indicative of an electron-rich Pt center. Under oxygen- and moisture-free conditions, 2 is remarkably inert; the cod ligand is not displaced by either monodentate or bidentate phosphines, phosphine sulfide, phosphite, or pyridine at room temperature, nor is the four-membered C,N-chelate ring opened by these reagents. However, 2 reacts with the electrophiles MeOTf (OTf = trifluoromethanesulfonate) and CO2. In the former case, the uncoordinated N atom of 2 is methylated to form [(η4-cod)Pt{C(Ph2PNSiMe3)(Ph2PN(Me)SiMe3-κC,κN}][OTf] (3). In the latter, initial nucleophilic attack by the uncoordinated N atom on CO2, followed by trimethylsilyl group migration from N to O, gives [(η4-cod)Pt{C(Ph2PNSiMe3)(Ph2PNC(O)OSiMe3-κC,κN}] (4). Heating a benzene solution of 2 to 100 °C in a sealed tube for several hours, or to 60 °C for 10 min in the presence of H2O, yields the ortho-metalated complex [(η4-cod)Pt{CH(Ph(C6H4)PNSiMe3)(Ph2PNSiMe3)-κC,κC ‘}] (5), which is characterized by Pt−C distances that are in the typical range for Pt−C(alkyl) and Pt−C(arene) interactions. The diastereoselectivity of the ortho metalation is consistent with an oxidative addition (nucleophilic) reaction mechanism for the ortho metalation. In contrast to 2, 5 displays typical cod substitution reactivity with chelating phosphines. The reaction between [Li2-1]2 and [PtCl2(cod)] in C6H6 solution proceeds only very slowly and gives [Li][Pt{CH(Ph(C6H4)PNSiMe3)(Ph2PNSiMe3)-κC,κC ‘}{CH(Ph2PNSiMe3)2-κC,κN}] (7) in low yield.