BER performance analysis of a direct conversion receiver

Direct conversion receivers are increasingly popular for use in mobile terminals. This is due to advantages over other architectures such as heterodyne receivers in terms of cost, electrical current, and physical size. However, a direct conversion receiver often generates a DC-offset that has to be taken care of either by suppressing the DC-offset in the radio-frequency part of the receiver, or by taking care of it during baseband processing. A theoretical analysis of the bit error rate (BER) performance in a direct conversion receiver with different levels of DC-offset suppression is presented. Explicit results are presented on how the BER depends on the signal-to-noise ratio (SNR), the signal-to-DC-level, and the choice of pilot symbols both with M-QAM and M-PSK in a slow, flat Rayleigh fading channel. A design rule, which applies to the design of DC-compensation in direct conversion receivers, is also presented     

Synthesis and Physical Studies of the Organic Salts of Pindolol: Pindolol Benzoate and Pindolol 2-Methoxyphenylacetate

In order to investigate the formation of organic salts of drugs, two salts of pindolol were prepared using salt-forming agents which were crystalline and suitable for physical studies in the solid state. The stoichiometry of the products, pindolol benzoate and pindolol 2-methoxyphenylacetate, was established by elemental analysis. The precipitates formed were assessed by differential scanning calorimetry (DSC), thermogravimetry (TG), x-ray powder diffractometry (XRPD) and Fourier transform-infrared spectrometry (FT-IR). According to the TG and DSC curves, there was no water of crystallization in the precipitates, and the products were thermally stable. Both precipitates gave one sharp melting endotherm which differed from the endotherms of the starting compounds. The x-ray dipaction pattern of the precipitates direred clearly from those of the starting materials, acid and base. The products showed absorption by FT-IR typical of carboxylic acid salts at about 1640-1540 cm^-1. The carbonyl absorption indicative of the carboxylic acid group of benzoic acid or 2-methonyphenylacetic acid was not detectable in the spectra of the precipitates. All this indicates that two new crystalline organic salts (1:1) were formed during the syntheses.     

The State of the Art of Piezo1 Channels in Skeletal Muscle Regeneration

Piezo1 channels are highly mechanically-activated cation channels that can sense and transduce the mechanical stimuli into physiological signals in different tissues including skeletal muscle. In this focused review, we summarize the emerging evidence of Piezo1 channel-mediated effects in the physiology of skeletal muscle, with a particular focus on the role of Piezo1 in controlling myogenic precursor activity and skeletal muscle regeneration and vascularization. The disclosed effects reported by pharmacological activation of Piezo1 channels with the selective agonist Yoda1 indicate a potential impact of Piezo1 channel activity in skeletal muscle regeneration, which is disrupted in various muscular pathological states. All findings reported so far agree with the idea that Piezo1 channels represent a novel, powerful molecular target to develop new therapeutic strategies for preventing or ameliorating skeletal muscle disorders characterized by an impairment of tissue regenerative potential.     

Guidance in computer-supported collaborative inquiry learning: Capturing aspects of affect and teacher support in science classrooms

International Journal of Computer-Supported Collaborative Learning - Technology-enhanced collaborative inquiry learning has gained a firm position in curricula across disciplines and educational...     

The association of distress and sleeping problems with physicians’ intentions to change profession: The moderating effect of job control.

The present study examined whether job control moderated the association between stress indicators (distress and sleeping problems) and intentions to change profession among 2,650 Finnish physicians. Ordinal logistic regression analysis was applied. The authors found that high levels of distress and sleeping problems were associated with higher levels of intentions to change profession, whereas high job control was associated with lower levels of intentions to change profession even after adjusting for the effects of gender, age, and employment sector. In addition, high job control was able to mitigate the positive association that distress and sleeping problems had with intentions to change profession. Our findings highlight the importance of offering more job control to physicians to prevent unnecessary physician turnover. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Site managers’ daily work and the uses of building information modelling in construction site management

The use of building information modelling (BIM) and related software tools is increasingly expanding in the work of site managers in construction projects. The early uses of BIM in the actual tasks of site managers are explored by examining the utilization of BIM in their work and the challenges in the deployment of the new digital tools for traditional project collaboration. The ethnographic method of the study consists of shadowing the site managers’ work. The site managers actively used BIM and found it beneficial for their daily work. However, the use of BIM in construction sites is still limited because only a few managers have the competence to use BIM software tools, mobile tools are lacking, and the information content of the models needed for construction work is insufficient.     

Surface hydrophobization of CNF films by roll-to-roll HMDSO plasma deposition

Cellulosic films are typically sensitive towards moisture which limits their industrial applicability. In this study the films made from cellulose nanofibrils (CNF) were surface silylated with hexamethyldisiloxane (HMDSO) by roll-to-roll plasma deposition. The effects on surface hydrophobicity were clear and indisputable. Water contact angles of non-modified and plasma-deposited CNF films were 23° and 103°, respectively. As a result of surface silylation the relative polarity decreased from 46.8% to 0.6%. Surface hydrophobicity correlated well with the plasma deposition line speeds (0.5, 5, and 10 m/min) and the water vapor barrier properties. Silylation also decreased the oxygen transmission rates both at 50% and 80% relative humidity as compared to non-modified CNF films. All films were completely impermeable to olive oil and intact in contact with castor oil, toluene, and n-heptane or mixtures of them. The developed surface hydrophobization method can be exploited in strengthening the position of cellulosic films in high performance film applications.     

Assessment of bioavailability and effects of chemicals due to remediation actions with caging mussels (Anodonta anatina) at a creosote-contaminated lake sediment site

A study was conducted at Lake J?ms?nvesi in Central Finland, to identify the potential ecotoxicological risks of the remediation operation of a creosote-/PAH-contaminated lake sediment, made by capping during the years 1998-1999. Mussels (Anodonta anatina) were deployed to the lake at the same time as the remediation operation was started in November 1998. The contaminated area (0.5 ha) was covered by a filter geotextile (polypropylene), gravel and sand (1-1.5m) which were spread out on the ice and let to sink onto the bottom of the lake when the ice melted in May 1999. The possible impacts of capping to the adjacent environment were assessed from mussels exposed and particulate material settled (SPM) to collectors placed on the lake bottom. Mussel tissue, SPM, the water inside the collector were analyzed for polycyclic aromatic compounds (PAH)-compounds. Biological endpoints included body condition, glycogen and protein contents of adductor muscle. Mussels and SPM exposed downstream to the contaminated site (Site 3) contained the highest total PAH concentrations. Biota-sediment accumulation factors of acenaphthene, phenanthrene, anthracene, fluoranthene, pyrene and benzo(a)anthracene of mussels varied from 0.79 to 1.45. The glycogen and protein concentrations were lowest in adductor muscle from mussels exposed to conditions at Site 3. Concentrations of some PAH-compounds were found distinctly increased adjacent to the remediated area, possibly due to the agitation of contaminated sediment due to the capping. It is also possible that resuspension of sediment around remediated area (containing some PAHs) spread the deposited PAH-compounds.     

Nonlinear diffusion filtering of images obtained by planar laser-induced fluorescence spectroscopy

The application of nonlinear anisotropic diffusion filtering to reduce noise and enhance contours in images obtained by two-dimensional planar laser-induced fluorescence (PLIF) spectroscopy is presented. In this process the diffusion coefficient is locally adapted, becoming negligible as object boundaries are approached. Noise is efficiently removed, and object contours are strongly enhanced. The technique is demonstrated with PLIF images obtained from the OH radical recorded in turbulent flames. We show that nonlinear diffusion is suitable as a preprocessing step, before image segmentation becomes possible, and we demonstrate how the technique is applied for the quantitative extraction of flame reaction boundaries from PLIF data.     

Empirical studies in reverse engineering: state of the art and future trends

Starting with the aim of modernizing legacy systems, often written in old programming languages, reverse engineering has extended its applicability to virtually every kind of software system. Moreover, the methods originally designed to recover a diagrammatic, high-level view of the target system have been extended to address several other problems faced by programmers when they need to understand and modify existing software. The authors’ position is that the next stage of development for this discipline will necessarily be based on empirical evaluation of methods. In fact, this evaluation is required to gain knowledge about the actual effects of applying a given approach, as well as to convince the end users of the positive cost–benefit trade offs. The contribution of this paper to the state of the art is a roadmap for the future research in the field, which includes: clarifying the scope of investigation, defining a reference taxonomy, and adopting a common framework for the execution of the experiments.