AEDGE: Atomic Experiment for Dark Matter and Gravity Exploration in Space

Abstract: We propose in this White Paper a concept for a space experiment using cold atoms to search for ultra-light dark matter, and to detect gravitational waves in the frequency range between the most sensitive ranges of LISA and the terrestrial LIGO/Virgo/KAGRA/INDIGO experiments. This interdisciplinary experiment, called Atomic Experiment for Dark Matter and Gravity Exploration (AEDGE), will also complement other planned searches for dark matter, and exploit synergies with other gravitational wave detectors. We give examples of the extended range of sensitivity to ultra-light dark matter offered by AEDGE, and how its gravitational-wave measurements could explore the assembly of super-massive black holes, first-order phase transitions in the early universe and cosmic strings. AEDGE will be based upon technologies now being developed for terrestrial experiments using cold atoms, and will benefit from the space experience obtained with, e.g., LISA and cold atom experiments in microgravity. KCL-PH-TH/2019-65, CERN-TH-2019-12

Layered space-time multiuser communication systems

Wireless communication systems have become very successful in the market place and it is expected that this success will continue when various interactive services and applications such as the Internet are introduced. The next generation of wireless networks will support multiple classes of traffic with different quality of service requirements such as data rate and bit error rate [l, 2]. In particular, Wideband CDMA has been selected as the air interface standard for third generation systems such as IMT-2000 proposed by ETSI/ARIB, and cdma2000 proposed by TIA, due to their various technical advantages. In addition, it has been recently shown that the use of MIMO systems in a rich scattering wireless channel is capable of enormous theoretical capacity improvement provided the scattering is properly exploited through the use of an appropriate processing architecture [3, 4]. The vertical layered space-time architecture proposed by Foschini [5], known as V-BLAST, is one such approach. In this thesis, we investigate the use of layered space-time scheme for multiuser detection over the uplink of a DS/CDMA communication system. The multiple transmit antennas in V-BLAST are treated as individual mobile station transmitters, while the base station consists of multiple receive antennas. The layered space-time algorithm is then invoked to detect the signals from all users. In addition, CDMA is also applied. Users are organized in different groups and users in a particular group are allocated the same spreading code. Therefore, CDMA spreading technique will remove the interference between the groups and the layered space-time scheme will further remove the remaining interference. A decorrelator-type CDMA receiver based layered space-time detection is proposed for both complex and real constellations. For the latter case, we derive our receiver after evaluating and comparing the performance of two decorrelators based on the V-BLAST scheme. It is demonstrated that a significant performance improvement and increase in system capacity is obtained with very low spreading factors. Further results are also introduced by considering reduced complexity receivers based on Serial Layered Space-Time Group Multiuser detection, and Parallel Layered Space-Time Group Multiuser detection. We are also interested in packet transmission mode. The wireless networks will then present packet radio mobile stations transmitting to a single base station. Our primary aim is to assess the impact of the proposed layered space-time multiuser detection technique, over a packetized random access system based on Slotted ALOHA protocol. A significant improvement in system throughput, delay and capacity are achieved. Finally, we considered wireless circuit switched and packet switched modes integrated CDMA systems. The effect of packet mode users on system performance is considered. Throughput and BER performances of packet and circuit mode users are hence investigated, respectively. The robustness of the proposed detection technique is also demonstrated against transmission power variation of packet mode users

Multiple array schemes for achieving high capacity and high diversity gains in wireless MIMO systems

The wireless communications market is one of the most important economic markets in terms of investment. The constant demand for more services of wide applications and requirements has driven the market in one of its fastest evolutions. Communicating with anyone, anywhere, anytime as expected in future wireless systems has proven much stronger needs than what is being provided today in current systems. The need for extreme high data rates and quality of services in heterogeneous networks has made current transmission and detection techniques by far not suitable for the next wireless generations. Viable solutions to this problem include the use of antennas arrays or Multiple Input Multiple Output (MIMO) systems, as well as, powerful signal processing techniques. MIMO systems have been shown to provide unprecedented gains such as diversity or multiplexing rates. The latter is the number of its degrees of freedom and is closely related to its capacity. Most of the previously designed MIMO systems have focused on the maximization of either types of gain and have been categorized as either diversity type systems or high (data) rate ones. Orthogonal designs (OD) and Vertical-Bell Layered Space-Time schemes (V-BLAST) are such examples. By maximizing exclusively one type of gain, these schemes, unfortunately, sacrifice the other type such as the system capacity with OD and diversity with V-BLAST. Designing schemes that can maximize both types of gains is a challenge for future wireless systems, particularly when multiple arrays of antennas are expected to be deployed. The overall objective of this thesis is to design multiple antenna array schemes that achieve both high capacity and high diversity gains. To do so, we consider the use of group detection at the receiver. In multiple antenna arrays environments, signals from one array of antennas arrive at the receiver as one group. Group detection will then preserve their internal structure and its use is justified. We will consider two basic receivers' structures for group detection, a Group Zero Forcing (GZF) and a Group Decision Feedback Detector (GDFD). We will first investigate these receivers in the existence of improper multi-access interference. We will demonstrate that improvement of the detection rules in this case will lead to significant diversity gains. We then consider the application of the GDFD receiver in a multi-user MIMO environment. Particularly, we will show that ordering the received signals from the different arrays is a very important issue to maximize the overall system performance. Optimal and sub-optimal ordering algorithms will then be proposed. Recently, a new performance measure, known as the diversity-multiplexing tradeoff func-tion, has been proposed to measure the tradeoff between the diversity gain and the multiplexing one. Such function has been shown to be a key performance comparison and evaluation tool. This thesis will assess the performance of the GZF and GDFD receivers in terms of diversity-multiplexing tradeoff in a multi-user MIMO system over a richly scattered Rayleigh fading channel. The optimal tradeoff function will be derived and three rate allocation algorithms will be proposed accordingly; namely, equal rate, group size proportional rate and optimal rate allocation. Results will demonstrate how powerful group detection is when applied for multi-ple antenna arrays. In particular, it is shown that group detection achieves significantly high diversity gains and capacities than regular decorrelators and with much less complexity than the optimal receiver. Designing schemes that achieve the optimal performance of group detection will be the focus of the last part of this thesis. We will also propose transmission schemes that will inter-encode the different arrays of antennas with a very special structure allowing various attractive aspects. These include structure flexibility regarding the number of antennas, low complexity receivers such as with Space Time Block Codes, full diversity performance, and high data rata transmission. This inter-array coding will be denoted as Block Orthogonal Linear Dispersion (BOLD) codes and they will be regarded as a parent class of the Space-Time Block codes. Performance analysis will demonstrate unprecedented achieved diversity levels at very high data rates

Antenna Selection for MIMO Systems with Closely Spaced Antennas

Physical size limitations in user equipment may force multiple antennas to be spaced closely, and this generates a considerable amount of mutual coupling between antenna elements whose effect cannot be neglected. Thus, the design and deployment of antenna selection schemes appropriate for next generation wireless standards such as 3GPP long term evolution (LTE) and LTE advanced needs to take these practical implementation issues into account. In this paper, we consider multiple-input multipleoutput (MIMO) systems where antenna elements are placed side by side in a limited-size linear array, and we examine the performance of some typical antenna selection approaches in such systems and under various scenarios of antenna spacing and mutual coupling. These antenna selection schemes range from the conventional hard selection method where only part of the antennas are active, to some newly proposed methods where all the antennas are used, which are categorized as soft selection. For the cases we consider, our results indicate that, given the presence of mutual coupling, soft selection can always achieve superior performance as compared to hard selection, and the interelement spacing is closely related to the effectiveness of antenna selection. Our work further reveals that, when the effect of mutual coupling is concerned, it is still possible to achieve better spectral efficiency by placing a few more than necessary antenna elements in user equipment and applying an appropriate antenna selection approach than plainly implementing the conventional MIMO system without antenna selection

A Quasi-Orthogonal Group Space-Time architecture to achieve a better diversity-multiplexing tradeoff

Most existing MIMO (Multiput-Input Multiput-Output) schemes optimize only either the diversity gain or the multiplexing gain. To obtain a good tradeoff between these two, the Quasi-Orthogonal. Group Space-Time (QoGST) architecture is proposed, wherein the transmit stream is subgrouped but encoded via an inter-group space-time block encoder, with group interference suppression at the receiver. This paper also considers another combined space-time coiling and layered space-time architecture, which we refer to as Group Layered Space-Time (GLST), where space-time block coding is employed within each group. Under the assumption of Rayleigh fading and a prior perfect channel state information at the receiver, a performance analysis will demonstrate that both QoGST and GLST can achieve a good diversity-multiplexing tradeoff. QoGST is even superior to GLST. Simulation results will validate our analysis and further show that compared to the existent Layered Space-Time Block Code (LSTBC) scheme, both QoGST and GLST can achieve a significant performance gain

Genetic analysis of hereditary multiple exostoses in Tunisian families: a novel frame-shift mutation in the EXT1 gene

International audienceHereditary multiple exostoses (HME) is an autosomal dominant orthopaedic disorder most frequently caused by mutations in the EXT1 gene. The aim of the present study is to determine the underlying molecular defect of HME in two multigenerational Tunisian families with 21 affected members and to examine the degree of intrafamilial variability. Linkage analysis was performed using three microsatellite markers encompassing the EXT1 locus and mutation screening was carried out by direct sequencing. In family 1, evidence for linkage to EXT1 was obtained on the basis of a maximum LOD score of 4.26 at theta = 0.00 with D8S1694 marker. Sequencing of the EXT1 revealed a heterozygous G > T transversion (c.1019G > T) in exon 2, leading to a missense mutation at the codon 340 (p.Arg340Leu). In family 2 we identified a novel heterozygous 1 bp deletion in the exon 1 (c.529\₅31delA) leading to a premature codon stop and truncated EXT1 protein expression (p.Lys177LysfsX15). This mutation was associated with the evidence of an intrafamilial clinical variability and considered to be a novel disease-causing mutation in the EXT1 gene. These findings provide additional support for the involvement of EXT1 gene in the HME disease

History of settlement of villages from Central Tunisia by studying families sharing a common founder Glycogenosis type III mutation

International audienceGlycogen storage disease type III (GSD III; Cori disease; Forbes disease) is an autosomal recessive inherited metabolic disorder resulting from deficient glycogen debrancher enzyme activity in liver and muscle. In this study, we focused on a single AGL gene mutation p.W1327X in 16 Tunisian patients from rural area surrounding the region of Mahdia in Central Tunisia. This constitutes the largest pool of patients with this mutation ever described. This study was performed to trace the history of the patients' ancestries in a single region. After extraction of genomic DNA, exon 31 of AGL gene was sequenced. The patients were investigated for the hypervariable segment 1 of mitochondrial DNA and 17 Y-STR markers. We found that the p.W1327X mutation was a founder mutation in Tunisia Analysis of maternal lineages shows an admixture of autochthonous North African, sub-Saharan and a predominance of Eurasian haplogroups. Heterogeneity of maternal haplogroups indicates an ancient settlement. However, paternal gene flow was highly homogeneous and originates from the Near East. We hypothesize that the p.W1327X mutation was introduced into the Tunisian population probably by a recent migration event; then the mutation was fixed in a small region due to the high rate of consanguineous marriages and genetic drift. The screening for this mutation should be performed in priority for GSD III molecular diagnosis, for patients from the region of Mahdia and those from regions sharing the same settlement history

An array CGH based genomic instability index (G2I) is predictive of clinical outcome in breast cancer and reveals a subset of tumors without lymph node involvement but with poor prognosis

Abstract Background Despite entering complete remission after primary treatment, a substantial proportion of patients with early stage breast cancer will develop metastases. Prediction of such an outcome remains challenging despite the clinical use of several prognostic parameters. Several reports indicate that genomic instability, as reflected in specific chromosomal aneuploidies and variations in DNA content, influences clinical outcome but no precise definition of this parameter has yet been clearly established. Methods To explore the prognostic value of genomic alterations present in primary tumors, we performed a comparative genomic hybridization study on BAC arrays with a panel of breast carcinomas from 45 patients with metastatic relapse and 95 others, matched for age and axillary node involvement, without any recurrence after at least 11 years of follow-up. Array-CGH data was used to establish a two-parameter index representative of the global level of aneusomy by chromosomal arm, and of the number of breakpoints throughout the genome. Results Application of appropriate thresholds allowed us to distinguish three classes of tumors highly associated with metastatic relapse. This index used with the same thresholds on a published set of tumors confirms its prognostic significance with a hazard ratio of 3.24 [95CI: 1.76-5.96] p = 6.7x10-5 for the bad prognostic group with respect to the intermediate group. The high prognostic value of this genomic index is related to its ability to individualize a specific group of breast cancers, mainly luminal type and axillary node negative, showing very high genetic instability and poor outcome. Indirect transcriptomic validation was obtained on independent data sets. Conclusion Accurate evaluation of genetic instability in breast cancers by a genomic instability index (G2I) helps individualizing specific tumors with previously unexpected very poor prognosis.</p

An array CGH based genomic instability index (G2I) is predictive of clinical outcome in breast cancer and reveals a subset of tumors without lymph node involvement but with poor prognosis.

International audienceABSTRACT: BACKGROUND: Despite entering complete remission after primary treatment, a substantial proportion of patients with early stage breast cancer will develop metastases. Prediction of such an outcome remains challenging despite the clinical use of several prognostic parameters. Several reports indicate that genomic instability, as reflected in specific chromosomal aneuploidies and variations in DNA content, influences clinical outcome but no precise definition of this parameter has yet been clearly established. METHODS: To explore the prognostic value of genomic alterations present in primary tumors, we performed a comparative genomic hybridization study on BAC arrays with a panel of breast carcinomas from 45 patients with metastatic relapse and 95 others, matched for age and axillary node involvement, without any recurrence after at least 11 years of follow-up. Array-CGH data was used to establish a two-parameter index representative of the global level of aneusomy by chromosomal arm, and of the number of breakpoints throughout the genome. RESULTS: Application of appropriate thresholds allowed us to distinguish three classes of tumors highly associated with metastatic relapse. This index used with the same thresholds on a published set of tumors confirms its prognostic significance with a hazard ratio of 3.24 [95CI: 1.76-5.96] p = 6.7x10-5 for the bad prognostic group with respect to the intermediate group. The high prognostic value of this genomic index is related to its ability to individualize a specific group of breast cancers, mainly luminal type and axillary node negative, showing very high genetic instability and poor outcome. Indirect transcriptomic validation was obtained on independent data sets. CONCLUSION: Accurate evaluation of genetic instability in breast cancers by a genomic instability index (G2I) helps individualizing specific tumors with previously unexpected very poor prognosis