A single G-to-C change causes human centromere TGGAA repeats to fold back into hairpins.

Recently, we established that satellite III (TGGAA)n tandem repeats, which occur at the centromeres of human chromosomes, pair with themselves to form an unusual "self-complementary" antiparallel duplex containing (GGA)2 motifs in which two unpaired guanines from opposite strands intercalate between sheared G.A base pairs. In separate studies, we have also established that the GCA triplet does not form bimolecular (GCA)2 motifs but instead promotes the formation of hairpins containing a GCA-turn motif in which the loop contains a single cytidine closed by a sheared G.A pair. Since TGCAA is the most frequent variant of TGGAA found in satellite III repeats, we reasoned that the potential of this variant to form GCA-turn miniloop fold-back structures might be an important factor in modulating the local structure in natural (TGGAA)n repeats. We report here the NMR-derived solution structure of the heptadecadeoxynucleotide (G)TGGAATGCAATGGAA(C) in which a central TGCAA pentamer is flanked by two TGGAA pentamers. This 17-mer forms a rather unusual and very stable hairpin structure containing eight base pairs in the stem, only four of which are Watson-Crick pairs, and a loop consisting of a single cytidine residue. The stem contains a (GGA)2 motif with intercalative 14G/4G stacking between two sheared G.A base pairs; the loop end of the stem consists of a sheared 8G.10A closing pair with the cytosine base of the 9C loop stacked on 8G. The remarkable stability of this unusual hairpin structure (Tm = 63 degrees C) suggests that it probably plays an important role in modulating the folding of satellite III (TGGAA)n repeats at the centromere.

Modeling back propagating action potential in weakly excitable dendrites of neocortical pyramidal cells.

Simultaneous recordings from the soma and apical dendrite of layer V neocortical pyramidal cells of young rats show that, for any location of current input, an evoked action potential (AP) always starts at the axon and then propagates actively, but decrementally, backward into the dendrites. This back-propagating AP is supported by a low density (-gNa = approximately 4 mS/cm2) of rapidly inactivating voltage-dependent Na+ channels in the soma and the apical dendrite. Investigation of detailed, biophysically constrained, models of reconstructed pyramidal cells shows the following. (i) The initiation of the AP first in the axon cannot be explained solely by morphological considerations; the axon must be more excitable than the soma and dendrites. (ii) The minimal Na+ channel density in the axon that fully accounts for the experimental results is about 20-times that of the soma. If -gNa in the axon hillock and initial segment is the same as in the soma [as recently suggested by Colbert and Johnston [Colbert, C. M. & Johnston, D. (1995) Soc. Neurosci. Abstr. 21, 684.2]], then -gNa in the more distal axonal regions is required to be about 40-times that of the soma. (iii) A backward propagating AP in weakly excitable dendrites can be modulated in a graded manner by background synaptic activity. The functional role of weakly excitable dendrites and a more excitable axon for forward synaptic integration and for backward, global, communication between the axon and the dendrites is discussed.

Back in Blue: The Successful Reintegration of Combat Veteran Law Enforcement Officers.

In the past ten plus years, several million national guard and reserve component military personnel have been deployed in support of the global war on terrorism. Tens of thousands of those personnel also serve as full-time law enforcement officers in police and sheriff's offices around the country. Life as a law enforcement officer is tough enough, but when combined with the psychological baggage brought on by months of war, reintegrating into civilian life and the role of a law enforcement officer can be extremely difficult. This article discusses a reintegration program specifically for law enforcement agencies that is designed to promote long-term psychological and social health in combat veteran officers. The program's costs are offset by the many assets (leadership, tactical training, etc.) these men and women bring to the department. By committing to the long-term successful reintegration of these individuals, departments enhance their own forces and improve community safety.

Looking Back: A Granddaughter's Quest for Redemption and Understanding

On December 7th, 1941 Japan attacked Pearl Harbor in Hawaii. This event signaled the beginning of America's involvement in World War II. It also signaled the beginning of a change of life for the Japanese living in the United States. Following the attack, 120,000 persons of Japanese ancestry were placed in ten internment camps across the United States. Two-thirds of those interned were American citizens, including my grandmother. The fact that these American citizens were treated as prisoners in their own country had a devastating effect on the relationships of those interned and the generations of Japanese Americans that followed. This essay recounts my grandma's experience and explores how her internment changed her life and the lives of her descendants.

Screen-printed electrode based electrochemical detector coupled with ionic liquid dispersive liquid–liquid microextraction and microvolume back-extraction for determination of mercury in water samples

A novel approach is presented, whereby gold nanostructured screen-printed carbon electrodes (SPCnAuEs) are combined with in-situ ionic liquid formation dispersive liquid–liquid microextraction (in-situ IL-DLLME) and microvolume back-extraction for the determination of mercury in water samples. In-situ IL-DLLME is based on a simple metathesis reaction between a water-miscible IL and a salt to form a water-immiscible IL into sample solution. Mercury complex with ammonium pyrrolidinedithiocarbamate is extracted from sample solution into the water-immiscible IL formed in-situ. Then, an ultrasound-assisted procedure is employed to back-extract the mercury into 10 µL of a 4 M HCl aqueous solution, which is finally analyzed using SPCnAuEs. Sample preparation methodology was optimized using a multivariate optimization strategy. Under optimized conditions, a linear range between 0.5 and 10 µg L−1 was obtained with a correlation coefficient of 0.997 for six calibration points. The limit of detection obtained was 0.2 µg L−1, which is lower than the threshold value established by the Environmental Protection Agency and European Union (i.e., 2 µg L−1 and 1 µg L−1, respectively). The repeatability of the proposed method was evaluated at two different spiking levels (3 and 10 µg L−1) and a coefficient of variation of 13% was obtained in both cases. The performance of the proposed methodology was evaluated in real-world water samples including tap water, bottled water, river water and industrial wastewater. Relative recoveries between 95% and 108% were obtained.

Plan of Back Bay, Boston, Massachusetts, 1859 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Part of a plan presented to the Commissioners for the improvement of the Back Bay, [by] T. & J. Doane's Office, published in 1859. Scale [1:2,400]. It shows a plan for a 36 acre lake and surrounding area, Back Bay, Boston, Massachusetts. This is an updated version of the 1854 ed. "Amended for the use of the City: Boston, Janr. 5th, 1859." The image inside the map neatline is georeferenced to the surface of the earth and fit to the Massachusetts State Plane Coordinate System, Mainland Zone (in Feet) (Fipszone 2001). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, or other information associated with the principal map. This map shows features such as roads (with street and alley dimensions), drainage, property lots with dimensions, land ownership boundaries with names of landowners, parks, and more. This layer is part of a selection of digitally scanned and georeferenced historic maps of Massachusetts from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of regions, originators, ground condition dates (1755-1922), scales, and purposes. The digitized selection includes maps of: the state, Massachusetts counties, town surveys, coastal features, real property, parks, cemeteries, railroads, roads, public works projects, etc.

Back Bay, Boston, Massachusetts, 1861 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Plan of lands on the Back Bay : belonging to the Boston Water Power Co., the Commonwealth, and other parties, showing the system of streets & grades as laid out and recommended by the Back Bay Commissioners, compiled and surveyed under the direction of the Commissioners by James Slade ; H.M. Wightman, surveyor ; E.R. Brown, de. It was printed by A. Meisel, lith., Dec. 31st, 1861. Covers Back Bay and South End, Boston, Massachusetts, and portions of Roxbury and Brookline. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Massachusetts State Plane Coordinate System, Mainland Zone (in Feet) (Fipszone 2001). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, or other information associated with the principal map. This map shows features such as roads, railroads, drainage, property owners, selected public buildings, parks, radial distances from City Hall, and more. This layer is part of a selection of digitally scanned and georeferenced historic maps of Massachusetts from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of regions, originators, ground condition dates (1755-1922), scales, and purposes. The digitized selection includes maps of: the state, Massachusetts counties, town surveys, coastal features, real property, parks, cemeteries, railroads, roads, public works projects, etc.

Cognitive Characteristics of Expert, Middle of the Pack, and Back of the Pack Ultra-Endurance Triathletes

Objectives The purpose of this study was to examine cognitive differences between expert and non-expert UE triathletes. Design Twenty-one UE triathletes were stratified according to finishing times into three groups; experts (<9.5 h), middle of the pack (∼12.5 h), and back of the pack triathletes (>14.0 h). Methods Cognition was examined using a think-aloud protocol with the aid of a video montage of segments from an UE triathlon representing periods of high decision-making or cognition. Inductive qualitative analyses supported the classification of athlete cognitions as passive, active, or proactive. Results Expert triathletes reported a greater emphasis on thoughts related to their performance, while middle of the pack and back of the pack triathletes reported a greater number of passive thoughts. Furthermore, experts were more proactive in their approach to performance situations than mid- and back-pack triathletes. Conclusions Expert UE triathletes are cognitively different from non-experts, although future research is needed to determine the role these differences play in promoting expert performance.