RF self-interference canceller prototype for 100-W full-duplex operation at 225-400 MHz

Military applications require more and different characteristics from in-band full-duplex radio technology than what the research prototypes developed for civil/commercial applications can offer. While the challenge of cancelling the strong transmit-receive coupling, i.e., self-interference (SI), in a full-duplex radio has been largely resolved at higher ultra high frequency (UHF) bands for low-power transmission, tactical communication and electronic warfare applications require major research efforts toward supporting lower military-relevant frequencies and significantly higher transmission power levels. In this paper, we present a prototype of a radio-frequency SI cancellation circuit for the lower UHF band at 225-400 MHz and transmit power of up to 100-200 W. The experimental results demonstrate that the canceller can suppress SI by 40-50 dB depending on the operation frequency within the band. It is targeted for the military application of simultaneous full-duplex jamming and interception of communications, where we can estimate that a 5-W signal-of-interest could be intercepted from 10 km away when simultaneously jamming with 100 W power.publishedVersionPeer reviewe

Design of RF Self-interference Cancellation Circuit for 100-W Full-Duplex Radio at 225-400 MHz

The full-duplex (FD) technology enables future military radios to simultaneously transmit and receive (STAR) on the same and adjacent frequencies. This enhances spectral efficiency and makes simultaneous integrated tactical communications and electronic warfare operations possible as opposed to the current time- or frequency-division radios used in military applications. The main challenge in implementing full-duplex radios is the strong self-interference (SI) between the transmitter and the receiver requiring solutions how to cancel the coupling, which has been largely resolved at higher ultra high frequency (UHF) bands for low power transmission. This paper presents a radio-frequency SI cancellation circuit suitable especially for very high-power military applications at military-relevant lower UHF band (225-400 MHz). The circuit couples power from the transmitter and tunes the phase and amplitude of the signal to destructively combine with the received SI, and thus isolates the receiver and transmitter. The paper introduces a concept consisting of a 90° vector modulator and switchable delay lines for a low-loss and high-power-handling cancellation circuit that enables operation with very-high transmit powers of even up to 1 kW.acceptedVersionPeer reviewe

Mesenchymal cell-derived Wnt1 signaling regulates subchondral bone remodeling but has no effects on the development of growth plate or articular cartilage in mice

Chondrocyte differentiation is a principal progress in endochondral ossification and in the formation of secondary ossification center (SOC) during the long bone development. We have previously reported that targeted deletion of Wnt1 in mesenchymal progenitors (Wnt1Prrx-/-) leads to spontaneous fractures and severe osteopenia in mouse long bones, suggesting that Wnt1 is a key regulator of bone metabolism. However, the effect of Wnt1 on the regulation of cartilage development and chondrocyte differentiation remained unknown. In this study, WNT1 protein expression was observed in lateral superficial cartilage and growth plate pre-hypertrophic chondrocytes in mice. Wnt1 mRNA expression was detected in epiphyseal cartilage from E16.5 to 3 month-old mice. Detailed histological analyses revealed that the average thickness and chondrocyte density of proximal tibial articular cartilage and growth plate were unchanged between Wnt1Prrx-/- and control mice. However, mu CT analysis of tibial epiphyses showed that the subchondral bone mass was reduced in Wnt1Prrx-/- mice compared to control mice, as demonstrated by decreased bone volume, trabecular number, trabecular thickness, and increased trabecular separation in Wnt1Prrx-/- mice. Mechanistically, histomorphometric analyses showed that the reduced subchondral bone mass in Wnt1Prrx-/- mice was due to impaired bone formation and enhanced bone resorption. In vitro, exogenous Wntl inhibited chondrogenesis and chondrocyte hypertrophy in both cell autonomous and juxtacrine manners, while matrix mineralization and the expression of Mmp13, Mmp9 and Opn were induced in a juxtacrine manner. Taken together, mesenchymal cell-derived Wntl is an important regulator of subchondral bone remodeling, although it has no effect on the regulation of growth plate or articular cartilage.</p

In Vivo and In Vitro Study of a Polylactide-Fiber-Reinforced β-Tricalcium Phosphate Composite Cage in an Ovine Anterior Cervical Intercorporal Fusion Model

A poly-70L/30DL-lactide (PLA70)–β-tricalcium phosphate (β-TCP) composite implant reinforced by continuous PLA-96L/4D-lactide (PLA96) fibers was designed for in vivo spinal fusion. The pilot study was performed with four sheep, using titanium cage implants as controls. The composite implants failed to direct bone growth as desired, whereas the bone contact and the proper integration were evident with controls 6 months after implantation. Therefore, the PLA70/β-TCP composite matrix material was further analyzed in the in vitro experiment by human and ovine adipose stem cells (hASCs and oASCs). The composites proved to be biocompatible as confirmed by live/dead assay. The proliferation rate of oASCs was higher than that of hASCs at all times during the 28 d culture period. Furthermore, the composites had only a minor osteogenic effect on oASCs, whereas the hASC osteogenesis on PLA70/β-TCP composites was evident. In conclusion, the composite implant material can be applied with hASCs for tissue engineering but not be evaluated in vivo with sheep

Suljettujen ja hylättyjen kaivannaisjätealueiden kunnostustarpeen arviointi

Ohjeistus suljettujen ja hylättyjen kaivannaisjätealueiden riskiperusteisesta kunnostustarpeen arvioinnista käsittelee ensisijaisesti metallimalmikaivoksille ominaisia riskejä, kuten happamien ja haitta-aineita sisältävien valumavesien muodostumista, pölyämistä ja rakenteiden sortumavaaraa sekä niiden vaikutuksia ihmisten terveyteen ja ympäristöön. Riskiperusteisella kunnostustarpeen arvioinnilla voidaan vastata mahdollista vakavaa ympäristön pilaantumista tai sen vaaraa aiheuttavien suljettujen ja hylättyjen kaivannaisjätealueiden kartoituksissa tunnistettuun jatkotoimenpidetarpeeseen. Ohjeistuksessa käydään läpi riskinarvioinnin sisältöä ja toteutustapaa siten, että keskiössä ovat taustatietojen kerääminen, käsitteellisen mallin luominen, tutkimusmenetelmien valinta ja riskien määrittäminen. Ohjeistuksessa käsitellään lyhyesti myös muita kunnostustarpeeseen vaikuttavia tekijöitä sekä riskinhallinta- ja kunnostusratkaisuja. Ohjeistuksen tavoitteena on riskinarvioinnin soveltaminen tapauskohtaisesti siten, että arvioinnin sisältö, laajuus ja toteutustapa huomioivat kohteen ominaisuuksille sekä arvioinnille asetetut tavoitteet. Alan toimijoille suunnattu ohjeistus noudattaa pääpiirteiltään pilaantuneiden alueiden riskinarvioinnista annettua ympäristöministeriön ohjetta 6/2014, ja voi kohteesta ja valituista menetelmistä riippuen edellyttää sen rinnakkaista soveltamista

Combined fit to the spectrum and composition data measured by the Pierre Auger Observatory including magnetic horizon effects

The measurements by the Pierre Auger Observatory of the energy spectrum and mass composition of cosmic rays can be interpreted assuming the presence of two extragalactic source populations, one dominating the flux at energies above a few EeV and the other below. To fit the data ignoring magnetic field effects, the high-energy population needs to accelerate a mixture of nuclei with very hard spectra, at odds with the approximate E$^{-2}$ shape expected from diffusive shock acceleration. The presence of turbulent extragalactic magnetic fields in the region between the closest sources and the Earth can significantly modify the observed CR spectrum with respect to that emitted by the sources, reducing the flux of low-rigidity particles that reach the Earth. We here take into account this magnetic horizon effect in the combined fit of the spectrum and shower depth distributions, exploring the possibility that a spectrum for the high-energy population sources with a shape closer to E$^{-2}$ be able to explain the observations