A Turbo Detection and Sphere-Packing-Modulation-Aided Space-Time Coding Scheme

Arecently proposed space-time block-coding (STBC) signal-construction method that combines orthogonal design with sphere packing (SP), referred to here as STBC-SP, has shown useful performance improvements over Alamouti’s conventional orthogonal design. In this contribution, we demonstrate that the performance of STBC-SP systems can be further improved by concatenating SP-aided modulation with channel coding and performing demapping as well as channel decoding iteratively. We also investigate the convergence behavior of this concatenated scheme with the aid of extrinsic-information-transfer charts. The proposed turbo-detected STBC-SP scheme exhibits a “turbo-cliff” at Eb/N0 = 2.5 dB and provides Eb/N0 gains of approximately 20.2 and 2.0 dB at a bit error rate of 10?5 over an equivalent throughput uncoded STBC-SP scheme and a turbo-detected quadrature phase shift keying (QPSK) modulated STBC scheme, respectively, when communicating over a correlated Rayleigh fading channel. Index Terms—EXIT charts, iterative demapping, multidimensional mapping, space-time coding, sphere packing, turbo detection

Turbo Detection of Space-time Trellis-Coded Constant Bit Rate Vector-Quantised Videophone System using Reversible Variable-Length Codes, Convolutional Codes and Turbo Codes

In this treatise we characterise the achievable performance of a proprietary video transmission system, which employs a Constant Bit Rate (CBR) video codec that is concatenated with one of three error correction codecs, namely a Reversible Variable-Length Code (RVLC), a Convolutional Code (CC) or a convolutional-based Turbo Code (TC). In our investigations, the CBR video codec was invoked in conjunction with Space-Time Trellis Coding (STTC) designed for transmission over a dispersive Rayleigh fading channel. At the receiver, the channel equaliser, the STTC decoder and the RVLC, CC or TC decoder, as appropriate, employ the Max-Log Maximum A-Posteriori (MAP) algorithm and their operations are performed in an iterative 'turbo-detection' fashion. The systems were designed for maintaining similar error-free video reconstruction qualities, which were found to be subjectively pleasing at a Peak Signal to Noise Ratio (PSNR) of 30.6~dB, at a similar decoding complexity per decoding iteration. These design criteria were achieved by employing differing transmission rates, with the CC- and TC-based systems having a 22% higher bandwidth requirement. The results demonstrated that the TC-, RVLC- and CC-based systems achieve acceptable subjective reconstructed video quality associated with an average PSNR in excess of 30~dB for $E_b/N_0$ values above 4.6~dB, 6.4~dB and 7.7~dB, respectively. The design choice between the TC- and RVLC-based systems constitutes a trade-off between the increased error resilience of the TC-based scheme and the reduced bandwidth requirement of the RVLC-based scheme

Ethyl 4-(2,4-difluoro­phen­yl)-6-methyl-2-oxo-1,2,3,4-tetra­hydro­pyrimidine-5-carboxyl­ate

In the title compound, C14H14F2N2O3, the dihydro­pyrimidin­one ring adopts a flattened boat conformation. The difluoro­phenyl group is disordered over two orientations with occupancies of 0.544 (3) and 0.456 (3). The methoxy­carbonyl group is disordered over two positions with occupancies of 0.580 (8) and 0.420 (8). In the crystal, mol­ecules are linked into centrosymmetric dimers by paired N—H⋯O hydrogen bonds and the dimers are linked into a ribbon-like structure along [100] by further N—H⋯O hydrogen bonds

N′-[(E)-4-Chloro­benzyl­idene]-2-(4-isobutyl­phen­yl)propanohydrazide

The asymmetric unit of title compound, C20H23ClN2O, consists of two crystallographically independent mol­ecules (A and B) in which the orientations of the 4-isobutyl­phenyl units are different. The isobutyl group of mol­ecule B is disordered over two positions with occupancies of 0.850 (5) and 0.150 (5). The dihedral angle between the two benzene rings is 88.70 (9)° in mol­ecule A and 89.38 (9)° in mol­ecule B. The independent mol­ecules are linked together into chains along [100] by N—H⋯O and C—H⋯O hydrogen bonds, and by C—H⋯π inter­actions. In the chain, N—H⋯O and C—H⋯O hydrogen bonds generate R 2 1(6) ring motifs. In addition, C—H⋯N hydrogen bonds are observed. The presence of pseudosymmetry in the structure suggests the higher symmetry space group Pbca but attempts to refine the structure in this space group resulted in high R (0.119) and wR (0.296) values

Retrofitting Crude Oil Refinery Heat Exchanger Networks to Minimise Fouling While Maximising Heat Recovery

The use of fouling factors in heat exchanger design and the lack of appreciation of fouling in traditional pinch approach has often resulted badly designed crude preheat networks that are expensive to maintain. The development of thermal and pressure drop models for crude oil fouling has allowed its effects to be quantified, so that techno-economic analyses can be performed and various design options compared. Application of these fouling models is carried out on two levels: on the assessment of adding extra area to individual exchangers, and the design of a complete network using the Modified Temperature Field Plot. Application to a refinery case study showed that both at the exchanger and network levels, designing for maximum heat recovery using traditional pinch approach results in the least efficient heat recovery over a time period when fouling occurs

4-(Methyl­sulfon­yl)piperazin-1-ium chloride

In the title mol­ecular salt, C5H13N2O2S+·Cl−, the complete cation is generated by crystallographic mirror symmetry, with both N atoms, the S atom and one C atom lying on the reflecting plane. The chloride ion also lies on the mirror plane. The piperazinium ring adopts a chair conformation and the N—S bond adopts an equatorial orientation. In the crystal structure, the component ions are linked into a three-dimensional framework by inter­molecular N—H⋯Cl and C—H⋯Cl hydrogen bonds

Affective disorders, psychosis and dementia in a community sample of older men with and without Parkinson's disease

Background: Dementia and affective and psychotic symptoms are commonly associated with Parkinson's disease, but information about their prevalence and incidence in community representative samples remains sparse. Methods: We recruited a community-representative sample 38173 older men aged 65-85 years in 1996 and used data linkage to ascertain the presence of PD, affective disorders, psychotic disorders and dementia. Diagnoses followed the International Classification of Disease coding system. Age was recorded in years. Follow up data were available until December 2011. Results: The mean age of participants was 72.5 years and 333 men (0.9%) had PD at study entry. Affective and psychotic disorders and dementia were more frequent in men with than without PD (respective odds ratios: 6.3 [95%CI = 4.7, 8.4]; 14.2 [95%CI = 8.4, 24.0] and 18.2 [95%CI = 13.4, 24.6]). Incidence rate ratios of affective and psychotic disorders were higher among men with than without PD, although ratios decreased with increasing age. The ageadjusted hazard ratio (HR) of an affective episode associated with PD was 5.0 (95%CI = 4.2, 5.9). PD was associated with an age-adjusted HR of 8.6 (95%CI = 6.1, 12.0) for psychotic disorders and 6.1 (95%CI = 5.5, 6.8) for dementia. PD and dementia increased the HR of depressive and psychotic disorders. Conclusions: PD increases the risk of affective and psychotic disorders, as well as dementia, among community dwelling older men. The risk of a recorded diagnosis of affective and psychotic disorders decreases with increasing age

Prevalence of mental disorders among older Australians: Contrasting evidence from the 2020–2021 National Study of Mental Health and Wellbeing among men and women and the Health In Men Data Linkage Study

Objective: To determine the prevalence of common mental disorders among older Australians included in the Health In Men Data Linkage Study and compare those with the results of the 2020–2021 National Study of Mental Health and Wellbeing (NSMHW). Method: We used longitudinal record linkage to estimate the prevalence of mental disorders from age 65 years in a random sample of 38173 Australian men aged 65–85 years living in the Perth metropolitan region. Outcome was the proportion of participants affected by depressive episodes or dysthymia, bipolar disorder, anxiety disorder, psychotic disorder and alcohol use disorder. Results: Prevalence estimates for participants aged 65–69, 70–74, 75–79, 80–84 and ≥85 years were 0.9%, 2.0%, 3.6%, 5.8% and 12.6% for depressive, 0.2%, 0.3%, 0.4%, 0.4% and 0.7% for bipolar, 0.1%, 0.5%, 1.3%, 2.2%, 6.9% for anxiety, 0.2%, 0.4%, 0.5%, 0.4% and 0.6% for psychotic and 1.2%, 1.7%, 2.1%, 2.2% and 4.2% for alcohol use disorders. Conclusions: In contrast to the NSMHW, our data indicate that the prevalence of depressive and anxiety disorders increases with age, particularly among the older old. We conclude that the NSMHW should not be relied upon to guide planning or policies to address the mental health needs of older Australians