Activation of the phosphosignaling protein CheY. I. Analysis of the phosphorylated conformation by 19F NMR and protein engineering

CheY, the 14-kDa response regulator protein of the Escherichia coli chemotaxis pathway, is activated by phosphorylation of Asp57. In order to probe the structural changes associated with activation, an approach which combines 19F NMR, protein engineering, and the known crystal structure of one conformer has been utilized. This first of two papers examines the effects of Mg(II) binding and phosphorylation on the conformation of CheY. The molecule was selectively labeled at its six phenylalanine positions by incorporation of 4-fluorophenylalanine, which yielded no significant effect on activity. One of these 19F probe positions monitored the vicinity of Lys109, which forms a salt bridge to Asp57 in the apoprotein and has been proposed to act as a structural "switch" in activation. 19F NMR chemical shift studies of the labeled protein revealed that the binding of the cofactor Mg(II) triggered local structural changes in the activation site, but did not perturb the probe of the Lys109 region. The structural changes associated with phosphorylation were then examined, utilizing acetyl phosphate to chemically generate phsopho-CheY during NMR acquisition. Phosphorylation triggered a long-range conformational change extending from the activation site to a cluster of 4 phenylalanine residues at the other end of the molecule. However, phosphorylation did not perturb the probe of Lys109. The observed phosphorylated conformer is proposed to be the first step in the activation of CheY; later steps appear to perturb Lys109, as evidenced in the following paper. Together these results may give insight into the activation of other prokaryotic response regulators

Long range transport of ultra cold atoms in a far-detuned 1D optical lattice

We present a novel method to transport ultra cold atoms in a focused optical lattice over macroscopic distances of many Rayleigh ranges. With this method ultra cold atoms were transported over 5 cm in 250 ms without significant atom loss or heating. By translating the interference pattern together with the beam geometry the trap parameters are maintained over the full transport range. Thus, the presented method is well suited for tightly focused optical lattices that have sufficient trap depth only close to the focus. Tight focusing is usually required for far-detuned optical traps or traps that require high laser intensity for other reasons. The transport time is short and thus compatible with the operation of an optical lattice clock in which atoms are probed in a well designed environment spatially separated from the preparation and detection region.Comment: 14 pages, 6 figure

Spectroscopy of the a^3\Sigma_u^+ state and the coupling to the X^1\Sigma_g^+ state of K_2

We report on high resolution Fourier-transform spectroscopy of fluorescence to the a^3\Sigma_u^+ state excited by two-photon or two-step excitation from the X^1\Sigma_g^+ state to the 2^3\Pi_g state in the molecule K_2. These spectroscopic data are combined with recent results of Feshbach resonances and two-color photoassociation spectra for deriving the potential curves of X^1\Sigma_g^+ and a^3\Sigma_u^+ up to the asymptote. The precise relative position of the triplet levels with respect of the singlet levels was achieved by including the excitation energies from the X^1\Sigma_g^+ state to the 2^3\Pi_g state and down to the a^3\Sigma_u^+ state in the simultaneous fit of both potentials. The derived precise potential curves allow for reliable modeling of cold collisions of pairs of potassium atoms in their ^2S ground state

Solitons in the one-dimensional forest fire model

Fires in the one-dimensional Bak-Chen-Tang forest fire model propagate as solitons, resembling shocks in Burgers turbulence. The branching of solitons, creating new fires, is balanced by the pair-wise annihilation of oppositely moving solitons. Two distinct, diverging length scales appear in the limit where the growth rate of trees, $p$, vanishes. The width of the solitons, $w$, diverges as a power law, $1/p$, while the average distance between solitons diverges much faster as $d \sim \exp({\pi}^2/12p)$.Comment: 4 pages with 2 figures include

Die sozial-emotionale Entwicklung pränatal opioid-und alkoholexponierter Kinder

Methode: Mit der CBCL wurden 69 Pflegekinder, davon 22 FAS-, 10 Opioid-, 21 Misch- (Alkohol + Opioide) und 16 Kontrollkinder getestet. Zusätzlich wurden mit einem Fragebogen Daten zu dem Umfeld der Kinder erhoben und damit die Entwicklung und das Umfeld der Kinder im Langzeitverlauf erfasst. Ergebnisse: Es wurde kein Entwicklungsunterschied bei exponierten Kindern in Bezug auf frühe-, späte, viele- oder wenige Wechsel in eine Pflegefamilie gefunden. Alle exponierten Kinder zeigten Auffälligkeiten bezüglich sozialer Probleme. Aufmerksamkeitsprobleme schienen in der Gruppe der Exponierten konstant zu bleiben. FAS-Kinder wiesen die meisten somatischen Beschwerden auf. Alle Kinder verbesserten ihre Schul- und Aktivitätskompetenzen im Verlauf. Diskussion: Daraus lässt sich schlussfolgern, dass pränatal drogenexponierte Kinder langzeitlich Förderung bedürfen. Besonders die Opioidkinder stellen im Langzeitverlauf eine Hochrisikogruppe bezüglich der sozial-emotionalen Entwicklung dar

An Innovative Approach to the Mental Health Needs of Humanitarian Mine Action Personnel

In the fields of humanitarian demining and explosive ordnance disposal (EOD), physical traumas related to blast and fragmentation injuries receive a great deal of research attention. In contrast, focus on the psychological health and wellness of humanitarian mine action personnel (HMAP) is lacking. Although research on the incidence of mental health disorders among HMAP is extremely limited, compared with the general population, this group likely suffers more from psychiatric conditions such as posttraumatic stress disorder (PTSD), depression, and anxiety. HMAP work in a high state of hypervigilance because at any given moment in a demining operation, there is risk of death and/or severe maiming. In addition to the inherent risk associated with searching for and working with live unexploded ordnance, deminers are exposed to the constant stress of conflict, which can include shouldering the psychological burden of responsibility for the physical well-being of innocent civilians exposed to explosive devices and witnessing the death and injury of others. Because of the multiple and unique stressors associated with this inherently dangerous work, HMAP likely experience trauma-related mental health conditions at a rate equal to, if not greater than, other high-risk professionals such as military personnel and first-responders (e.g., firefighters, law enforcement, emergency medical technicians). Although estimates vary, rates of PTSD for the latter groups range from 10 percent to over 30 percent depending on the study cited.1,2,3 Therefore, it is critical to identify effective strategies for mitigating the effects of psychological trauma in this high-risk group

Cuestiones de proceso y procedimiento en materia de juicios de desocupación de bienes del dominio público y privado del Estado

En el presente trabajo, se aborda el tema relacionado con el proceso de desalojo de los bienes del dominio privado y público del Estado desde un aspecto procesal y procedimental sin pasar por alto que esa decisión adoptada por Administración es un verdadero acto administrativo. Así, se hace un breve análisis de esta cuestión. Se pone de resalto en esta pieza que, a diferencia de lo que ocurre en el juicio de desalojo de bienes inmuebles del derecho Civil, los procesos de desalojo incoados por la Administración, que pueden ser motivados por situaciones fácticas diferentes, dependen de la finalidad que dé origen el mentado proceso judicial para cumplir, finalmente, con los objetivos públicos que se encuentran en una norma, la cual, en definitiva, es el instrumento que refleja la cristalización del comportamiento estatal. Todo este análisis es estudiado con apoyatura en un estudio comparativo entre lo que ocurre en el plano federal y en la Ciudad Autónoma de Buenos Aires. De la característica que posee el derecho administrativo en el orden local dependen, en consecuencia, la jurisdicción y la normativa aplicable; en cambio, la Administración contará con soluciones o herramientas diferentes para llevar a cabo el proceso de desalojo. Para finalizar, solo cabe señalar que entendí importante revisar aspectos conceptuales que –según mi modesta opinión- resultan de fundamental importancia para entender cómo la Administración –en su caso- llega a la decisión de promover un pleito. Así como, también, la peculiar relación de propiedad del Estado con sus bienes

Study of coupled states for the (4s^{2})^{1}S + (4s4p)^{3}P asymptote of Ca_{2}

The coupled states A^{1}\Sigma_{u}^{+} (^{1}D +}1}S), c^{3}\Pi_{u} (^{3}P + ^{1}S) and a^{3}\Sigma_{u}^{+} (^{3}P +}1}S) of the calcium dimer are investigated in a laser induced fluorescence experiment combined with high-resolution Fourier-transform spectroscopy. A global deperturbation analysis of the observed levels, considering a model, which is complete within the subspace of relevant neighboring states, is performed using the Fourier Grid Hamiltonian method. We determine the potential energy curve of the A^{1}\Sigma_{u}^{+} and c^{3}\Pi_{u} states and the strengths of the couplings between them. The c^{3}\Pi_{u} and \as states are of particular importance for the description of collisional processes between calcium atoms in the ground state ^{1}S_{0} and excited state ^{3}P_{1} applied in studies for establishing an optical frequency standard with Ca.Comment: 15 pages, 12 figure