Reactions with 1.3 propane sultone for the synthesis of cation-exchange membranes

For several reasons it is interesting for membrane technology to introduce strongly anionic groups in membranes. Therefore the possibilities of 1.3 propane sultone were studied to modify cellulose, cellulose acetate and polyacrylonitrile.\ud \ud The results showed that cellulose and cellulose acetate could be modified by a direct reaction of 1.3 propane sultone with the available hydroxyl groups. The nitrile groups in polyacrylonitrile had to be reacted first with hydrogen sulphide to give reactive thioamide groups, able to react with the sultone. These results give evidence for 1.3 propane sultone being a useful chemical for modification of polymers, its carcinogenic properties will however prevent application

Annual Report of the Town Officers of the Town of Alfred Maine For the Year Ending February 15, 1913

A novel dielectric resonator antenna (DRA), working at 28 GHz with a peak gain of 12.4 dBi over a fractional bandwidth of 12.6%, is presented. The novel design achieves side-lobe levels below -10 dB for both the E and H-planes so to meet the requirements of the new generation 5G wireless communications systems

Towards a Generic Model for MU-MIMO Analysis Including Mutual Coupling and Multipath Effects

A network model which accounts for antenna mutual coupling and multipath effects in a wireless channel is proposed as a tool to qualitatively evaluate the performance of a multi-user multiple-input multiple-output (MU-MIMO) system. The system performance is assessed when a zero-forcing (ZF) beamformed conventional uniform linear array (ULA) and a sparse array are employed as one sector of a base station antenna (BSA) in a single-cell network. It is shown that highly correlated user equipments (UEs) in a line-of-sight (LOS) scenario can be decorrelated to some extents, by a scattering environment in a non-line-of-sight (NLOS) scenario. This occurs due to increase of the spatial variation by a multipath effect. Furthermore, in both environments a sparse array realized by an increased interelement spacing is also capable for correlation reduction among users due to the narrower beams

A morphological algorithm for improving radio-frequency interference detection

A technique is described that is used to improve the detection of radio-frequency interference in astronomical radio observatories. It is applied on a two-dimensional interference mask after regular detection in the time-frequency domain with existing techniques. The scale-invariant rank (SIR) operator is defined, which is a one-dimensional mathematical morphology technique that can be used to find adjacent intervals in the time or frequency domain that are likely to be affected by RFI. The technique might also be applicable in other areas in which morphological scale-invariant behaviour is desired, such as source detection. A new algorithm is described, that is shown to perform quite well, has linear time complexity and is fast enough to be applied in modern high resolution observatories. It is used in the default pipeline of the LOFAR observatory.Comment: Accepted for publication in A&

Periodic mass loss episodes due to an oscillation mode with variable amplitude in the hot supergiant HD50064

We aim to interpret the photometric and spectroscopic variability of the luminous blue variable supergiant HD\,50064 ($V=8.21$).CoRoT space photometry and follow-up high-resolution spectroscopy, with a time base of 137\,d and 169\,d, respectively, was gathered, analysed and interpreted using standard time series analysis and light curve modelling methods as well as spectral line diagnostics.The space photometry reveals one period of 37\,d, which undergoes a sudden amplitude change with a factor 1.6. The pulsation period is confirmed in the spectroscopy, which additionally reveals metal line radial velocity values differing by $\sim 30\,$km\,s$^{-1}$ depending on the spectral line and on the epoch. We estimate \teff$\sim$13\,500\,K, \logg$\sim$1.5 from the equivalent width of Si lines. The Balmer lines reveal that the star undergoes episodes of changing mass loss on a time scale similar to the changes in the photometric and spectroscopic variability, with an average value of $\log\dot{\rm M}\simeq-5$ (in M$_\odot$\,yr$^{-1}$). We tentatively interpret the 37\,d period as due to a strange mode oscillation.Comment: 4 pages, accepted for publication in Astronomy & Astrophysics Letter

A System-Performance-Based Comparison of Sparse Regular and Irregular Antenna Arrays for Millimeter-Wave Multi-User MIMO Base Stations

A system-level study was conducted that evaluated the system performance of various dense and sparse antenna array configurations for application in millimeter-wave multi-user multiple-input multiple-output base stations. The performance was evaluated by investigating the probability that a user experiences an outage when a zero-forcing pre-coder is used in a random line of sight scenario. This paper shows that the outage probability significantly decreased when irregular sparse arrays were used rather than regular sparse or regular dense arrays. A re-configurable linear array was designed and realized as a demonstrator. It used 3D-printed aluminum box horn antenna elements that had wide scanning range in the azimuthal plane and a small scanning range in the elevation plane. For the demonstrator, it was shown that the outage probability was reduced from 3.85% to 0.64% by moving from a sparse regularly spaced array to a sparse randomly spaced array. This amounted to an improvement of a factor of six. The sparse topology allowed for the usage of large antenna elements that had an increased gain and still achieved wide-angle scanning, while reducing mutual coupling to a minimum

Cerebral Cortical Circuitry Formation Requires Functional Glycine Receptors

The development of the cerebral cortex is a complex process that requires the generation, migration, and differentiation of neurons. Interfering with any of these steps can impair the establishment of connectivity and, hence, function of the adult brain. Neurotransmitter receptors have emerged as critical players to regulate these biological steps during brain maturation. Among them, α2 subunit-containing glycine receptors (GlyRs) regulate cortical neurogenesis and the present work demonstrates the long-term consequences of their genetic disruption on neuronal connectivity in the postnatal cerebral cortex. Our data indicate that somatosensory cortical neurons of Glra2 knockout mice (Glra2KO) have more dendritic branches with an overall increase in total spine number. These morphological defects correlate with a disruption of the excitation/inhibition balance, thereby increasing network excitability and enhancing susceptibility to epileptic seizures after pentylenetetrazol tail infusion. Taken together, our findings show that the loss of embryonic GlyRα2 ultimately impairs the formation of cortical circuits in the mature brain