ALBERT

Description: Morning and afternoon peaks in daytime critical frequency foF2 defining a mid-day bite-out were found to occur regularly across northern Australia during April 2008. This behaviour was sufficiently repetitive to appear in the monthly median values of foF2. The twin peak and bite-out (TPB) phenomenon was observable across the entire longitudinal range of ionosondes which were accessible for this study, from Niue in mid Pacific to Learmonth on the western side of Australia. The high geographic density of ionosondes operating in Australia enabled the limited latitudinal range of occurrence to be established, the phenomenon ceasing to be present in the southern half of Australia or at equatorial latitudes. While strongest in 2008, the foF2 bite-out and associated variation in hmF2, the peak height of the ionosphere, continued to be seen in monthly April medians from sunspot minimum (2007-2008) to the current low sunspot maximum (2011-2013) whilst diminishing in magnitude. This phenomenon was also present around the September equinox though not of such magnitude or consistency as during the April equinox. The morning and afternoon peaks in foF2 occurred during periods of falling virtual and true height and were associated with the maximum compression of the ionosphere at this time as measured by the sub-peak equivalent parabolic layer thickness ym. Meridional winds in the F2 region are suggested as a driver of the twin peak enhancements in foF2 which may possibly be related to a simultaneous occurrence of strong tidal influences as seen to be present in descending sporadic E.

Description: Abstract Automatic processing of ionograms to extract ionospheric propagation characteristics and electron density profile parameters is an important enabling step toward constructing real time data‐assimilative models of the ionosphere. A robust and reliable feature extraction and fitting algorithm that supports both oblique and vertical incidence ionograms has recently been developed to enhance the regional ionospheric model for Australia's Jindalee Operational Radar Network. The so‐called DST‐IIP algorithm is an autoscaling technique based on a constrained quasi‐parabolic segment profile, which is modified from its climatological estimate to fit a set of key peak, edge, and line features in the ionogram image, representing the E, sporadic‐E (Es), and F2 layers. The F2 fitting, in particular, is performed in the ionogram domain, using analytic ray‐tracing and homing to produce a synthetic trace that reproduces the image features. Following thorough testing on a large database of midlatitude Australian ionograms, the DST‐IIP algorithm now runs routinely on‐board DST Group's Digital Oblique Receiving System. This paper provides an overview of the technique, along with sample results and performance statistics.

Description: Abstract Defence Science and Technology Group's Digital Oblique Receiving System (DORS) is a direct‐digital high‐frequency ionosonde receiver, capable of collecting high‐quality ionograms simultaneously on multiple oblique ionospheric paths. One of the key signal processing steps that run on board the receiver is a novel technique for the detection and removal of radio frequency interference (RFI). In the down‐converted narrow‐band time series, external RFI sources manifest as impulsive noise, often many orders of magnitude stronger than the ionosonde signal of interest. The RFI rejection technique applies a threshold detector to the whitened data, to locate the corrupt samples, and then replaces the bad data using forward and backward linear prediction, based on an autoregressive model of the desired ionosonde signal. Algorithm performance is evaluated using a set of simple statistics and ~6,000 DORS ionograms from central Australia. Compared to a more traditional approach of clipping the strong RFI impulses, the new technique significantly reduces instances of undersuppression and recovers more of the weaker propagation mode content in the ionogram. The result is a much cleaner image for the DORS automatic feature extraction and parameterized fitting technique.

Description: Abstract Defence Science and Technology Group has developed a complete oblique incidence ionosonde system to enhance ionospheric monitoring capabilities in support of the Jindalee Operational Radar Network. The Digital Oblique Receiving System, and its counterpart, the Digital Oblique Transmitting System, feature a direct‐digital, multichannel chirp‐sounder design that allows flexible collection of high‐resolution ionograms across many simultaneous paths, without compromising dynamic range. This paper outlines the hardware and software components of the Digital Oblique Receiving System/Digital Oblique Transmitting System, including the onboard signal processing that removes radio frequency interference and fits a parameterized electron density profile to the ionogram. Additional control and data management tools that have enabled the system to be effectively transitioned into routine operations are also described. The typical performance is illustrated through a selection of sample ionograms, highlighting the applications of Digital Oblique Receiving System/Digital Oblique Transmitting System to a wide variety of ionospheric studies, including those requiring Doppler and angle‐of‐arrival observations.

Description: This paper examines a number of sources of ionospheric variability and demonstrates that they have relationships in common which are currently not recognised. The paper initially deals with medium to large scale travelling ionospheric disturbances. Following sections deal with non-TID ionospheric variations which are often repetitious from day to day. The latter include the temporary rise in F2 height associated with sunset in equatorial latitudes resulting from strong upward drift in ionisation driven by an ExB force. The following fall in height is often referred to as the pre-midnight collapse and is accompanied by a temporary increase in foF2 as a result of ionospheric compression. An entirely different repetitious phenomenon reported recently from middle latitudes in the southern hemisphere consists of strong morning and afternoon peaks in foF2 which define a mid-day bite-out and occur at the equinoxes. This behaviour has been speculated to be tidal in origin. All the sources of ionospheric variability listed above exhibit similar relationships associated with a temporary expansion and upward lift of the ionospheric profile and a fall involving a compression of the ionospheric profile producing a peak in foF2 at the time of maximum compression. Such ionospheric compression/decompression is followed by a period in which the ionospheric profile recovers. Such relationships in travelling ionospheric disturbances (TIDs) have been noted previously. The present paper establishes for the first time that relationships hitherto seen as occurring only with TIDs are also present in association with other drivers of ionospheric variability.

Description: The conversion of batch processes towards continuous operating regimes offers various advantages in terms of safety, efficiency, product quality and production costs. The industrial process development has to be also adapted for this purpose. The focus will be drawn in this essay to the general approach of a process transfer from a batch process towards an intensified continuous process on laboratory scale at Clariant. Process intensification means in this context a holistic approach leading to substantially smaller, cleaner, and more efficient processes, which also result in better products [1].

Description: A thermodynamic analysis is presented for the diffusionless phase diagrams of ferroelectric solid solutions that display a morphotropic phase boundary (MPB) separating adjacent tetragonal and rhombohedral phases. Equations are developed for the shape of the MPB, the locations of triple and tricritical points, and for the line along which the anisotropy of polarization vanishes. The appearance of lower symmetry orthorhombic and monoclinic phases is considered and the topologies of energy surfaces in the region of the phase diagram where these phases may stabilize are illustrated. The theory is applied to the solid solution of lead zirconate with lead titanate (PZT) and relationships between polar anisotropy and the transformation strain, dielectric susceptibility and piezoelectric properties, are discussed. The analysis is used to reproduce phase boundary lines for solid solutions of lead titanate with lead magnesium niobate (PMN-PT) and lead zinc niobate (PZN-PT) and composition–temperature diagrams along isopleths in the ternary system PMN-PZT are estimated. The anisotropies of polarization in solid solutions based on lead titanate and barium titanate are contrasted. The results provide a thermodynamic framework useful for guiding experimental investigations of ferroelectric solid solutions and for generating energy functions used in constitutive modeling and phase field simulations of microstructure and properties.

Description: Abstract 3646 Children with Down syndrome (DS) are at high risk to develop acute megakaryoblastic leukemia (DS-AMKL) and the antecedent transient leukemia (DS-TL). Acquired mutations in the hematopoietic transcription factor GATA1, leading to expression of a shorter GATA1 variant (referred to as GATA1s) truncated at its N-terminus, are consistently present in the affected cells of children with DS-AMKL and DS-TL. Mechanistically, we recently found that in fetal megakaryocytic progenitor cells, GATA1 coordinates proliferation and differentiation by repressing E2F target genes through a direct interaction with E2F activators. Failure of this GATA1-E2F interaction in mutated GATA1s likely converges with overactive IGF signaling to promote cellular transformation. The treatment of DS-AMKL is hampered by their sensitivity against current cytostatic agents, resulting in treatment-related mortality as the main cause of death. To develop novel targeted and less toxic treatment options for DS-AMKL and DS-TL, we conducted a gene expression-based chemical genomic screen. We connected a DS-AMKL gene expression signature (compared to non-DS-AMKL, i.e. GATA1s vs. GATA1) to a reference collection of gene-expression profiles from cultured human cells treated with bioactive small molecules (Connectivity Map). We discovered the histone deacetylase (HDAC) inhibitor valproic acid (VPA) reverses the DS-AMKL gene expression program. Cell viability assays, cell cycle analyses, growths curves and colony-forming assays revealed exceptional sensitivity of DS-AMKL cell lines (CMK, CMY; IC50 1mM) and primary DS-AMKL and DS-TL blasts to VPA treatment compared to control cell lines K562 (IC50 4.75mM), M07 (IC50 6.75mM) and CD34+ hematopoietic stem and progenitor cells (IC50 4.75mM). VPA induces apoptosis (26.8% 7-AAD-)Annexin V+ and 38.8% 7-AAD+ CMK cells after 48h at 2mM VPA) and cell cycle arrest (50% reduction of CMK cells in S-phase at 2mM) via activation of the cell cycle inhibitor p21 and the proapoptotic genes BAX and BAK. Gene expression profiles indicated that VPA interferes with the oncogenic effects of GATA1s by globally repressing the deregulated E2F targets. The effects of VPA on leukemic growth in DS-AMKL could be attributed to its HDAC inhibitory function, as the global HDAC inhibitors SAHA and TSA induced a similar response. Thus, by using a gene expression-based chemical genomic approach, we identified VPA as an efficient and well-tolerated treatment option for DS-AMKL and DS-TL by targeting GATA1s-mediated deregulation of the E2F transcription network. Disclosures: No relevant conflicts of interest to declare.

Description: NFAT is a family of highly phosphorylated proteins residing in the cytoplasm of resting cells. Upon dephosphorylation by calcineurin, NFAT proteins translocate to the nucleus where they orchestrate developmental and activation programs in diverse cell types. CLL is a clonal disorder of mature B cells characterized by the expression of CD19, CD23 and CD5. With respect to prognosis, it constitutes a heterogeneous disease with some patients exhibiting an indolent course for many years and others progressing rapidly and requiring early treatment. A defined subgroup of patients shows enhanced responsiveness to stimulation of the B cell receptor (BCR) complex and more aggressive disease. In contrast, another subset of CLL patients with more indolent course is characterized by an anergic B cell phenotype referring to B cell unresponsiveness to IgM ligation and essential lack of phosphotyrosine induction and calcium flux. Here, we analyzed the role of NFAT2 in the pathogenesis of B-CLL and in anergy induction in CLL cells. For this purpose, we generated conditional CD19-Cre NFAT2 knock out mice, which exhibit NFAT2 deletion limited to the B cell lineage. To investigate the role of NFAT2 in the pathogenesis of CLL, we used the Eµ-TCL1 transgenic mouse model. TCL1 transgenic mice develop a human-like CLL at the age of approximately 14 weeks to which the animals eventually succumb at an average age of 10 months. We generated TCL1+NFAT2 ko mice with TCL1 transgenic mice without an NFAT2 deletion serving as controls. To identify novel NFAT2 target genes in CLL cells, we also performed a comparative gene expression analysis on CLL cells with intact NFAT2 expression and on CLL cells with NFAT2 deletion using affymetrix microarrays. In order to asses the anergic phenotype in CLL cells and the role of NFAT2 in its induction, we performed Ca2+ mobilization assays using a flow cytometric approach and performed Western Blots for multiple downstream signaling molecules. Mice with NFAT2 ko exhibited a significantly more aggressive disease course with accelerated accumulation of CD5+CD19+ CLL cells in different organs, significantly higher proliferation rates and a dramatically reduced life expectancy (200 vs. 325 days) as compared to TCL1 control animals. To identify NFAT2 target genes responsible for the observed alterations in the disease phenotype, we subsequently performed a gene expression analysis with CLL cells from both leukemic cohorts. Here, we detected a substantially altered expression profile of genes associated with B cell anergy in the TCL1+NFAT2 ko mice. The vast majority of these genes was expressed significantly less in the absence of NFAT2 with Lck, Pacsin1 and the E3 ligase Cbl representing the biggest hits. To further delineate the anergic phenotype and the role of NFAT2 in its induction, we subsequently performed Ca2+ mobilization assays. While anergic CLL cells from TCL1 mice exhibited an unresponsive phenotype with respect to Ca2+ flux upon IgM ligation, TCL1+NFAT2 ko mice showed an entirely normal capacity to mobilize intracellular Ca2+. Furthermore, IgM stimulation did not activate normal phosphotyrosine induction (phosphorylation of AKT and ERK kinases) in TCL1 mice while NAFT2-deficient CLL cells exhibited an unremarkable activation pattern with respect to AKT and ERK as assessed by Western Blotting. NFAT2-deficient CLL cells on the contrary exhibited compromised activation of the anergy regulator Lck as assessed by Y394 phosphorylation. Bypassing the BCR by antigen-independent stimulation with CD40 and LPS demonstrated slightly increased proliferation in anergic TCL1 CLL cells while NFAT2-deficient CLL cells exhibited massive proliferation. In summary, our data provide strong evidence that genetic loss of NFAT2 leads to more aggressive disease in CLL which is associated with the loss of the anergic phenotype. We could show that NFAT2 controls the expression of several important anergy-associated genes and identified Lck as a critical target of NFAT2 in this context. Taken together, our data demonstrate that the NFAT2-Lck axis plays an essential role in the pathogenesis of CLL and implicate it as a potential target in its treatment. Disclosures No relevant conflicts of interest to declare.

Description: NFAT2 is a highly phosphorylated transcription factor which regulates developmental and activation programs in diverse cell types. We and others have previously described a significant overexpression of NFAT2 in CLL cells as compared to physiological B cells. Three major isoforms of NFAT2 with different regulatory properties have been described (700aa short isoform, 800aa intermediate isoform, 900 aa long isoform). Here, we analyzed the role of different NFAT2 transcripts in CLL with respect to disease phenotype and cell proliferation. We investigated primary samples from CLL patients (n=30) for their expression profile of different NFAT2 isoforms using RT-PCR. Applying an shRNA approach, we generated stable knock-down cells of the CLL cell line MEC-1 for the long and intermediate isoforms and for the entire NFAT2 gene resulting in the complete ablation of all isoforms. The proliferation properties of the different MEC-1 cell lines was subsequently assessed in xeno-transplant experiments into NSG mice. While physiological B cells express comparable levels of the short and intermediate/long isoforms, we could detect a five fold overexpression of the intermediate/long isoforms in primary CLL samples. To further analyze the differential regulation of the different NFAT2 transcripts on tumor cell proliferation and cell cycle regulation, we injected NSG mice with MEC-1 cells with intact NFAT2 (n=6), MEC-1 cells with a knock-down of the intermediate and long isoforms (n=6) and MEC-1 cells with a complete NFAT2 knock-down (n=6). MEC-1 cells with selective ablation of the intermediate and long NFAT2 isoforms grew significantly faster in NSG mice than MEC-1 cells with intact NFAT2 expression or MEC-1 cells with a complete NFAT2 knock-down. MEC-1 cells selectively lacking the intermediate and long isoforms led to accelerated tumor proliferation upon subcutaneous injection. Cell cycle analysis as assessed by flow cytometry showed a significantly increased number of cells in the G1/S-Phase for the group without expression of the short isoform, while the group with complete NFAT knock-down exhibited a compromised growth pattern as compared to wild-type MEC-1 cells. In summary, our data demonstrate that genetic loss of the intermediate and long isoforms of NFAT2 leads to CLL acceleration Disclosures No relevant conflicts of interest to declare.