On the existence of the solution for one-dimensional discrete phase retrieval problem

We consider the discrete form of the one-dimensional phase retrieval (1-D DPhR) problem from the point of view of input magnitude data. The direct method can provide a solution to the 1-D DPhR problem if certain conditions are satisfied by the input magnitude data, namely the corresponding trigonometric polynomial must be nonnegative. To test positivity of a trigonometric polynomial a novel DFT-based criterion is proposed. We use this DFT criterion for different sets of input magnitude data to evaluate whether the direct method applied to the 1-D DPhR problem leads to a solution in all explored cases.     

如何为多媒体显示屏幕提供高性能的照明管理

高集成度的照明管理单元内置多个发光二极管驱动器(见图1),能以极高的效率驱动新一代蜂窝式手机彩屏的白色及红绿蓝(RGB)发光二极管,有助于节省能源,延长电池寿命。由于3G手机须采用彩色显示屏幕及发光技术,例如翻盖照明、彩色指示灯、相机闪光灯、辅助照明、以及环境光感测功能等,因此有必要用更先进的照明管理解决方案以满足照明方面的种种要求。为手机提供背光的白色发光二极管目前几乎所有蜂窝式手机都有一个或两个彩色显示屏幕。虽然它们要求的背光技术水平会因所需白色发光二极管数目的不同而各异,但目前大部分手机的主显示屏幕都采…     

C++ lambda expressions and closures

A style of programming that uses higher-order functions has become common in C++, following the introduction of the Standard Template Library (STL) into the standard library. In addition to their utility as arguments to STL algorithms, function parameters are useful as callbacks on GUI events, defining tasks to be executed in a thread, and so forth. C++’s mechanisms for defining functions or function objects are, however, rather verbose, and they often force the function’s definition to be placed far from its use. As a result, C++ frustrates programmers in taking full advantage of its own standard libraries. The effective use of modern C++ libraries calls for a concise mechanism for defining small one-off functions in the language, a need that can be fulfilled with lambda expressions.This paper describes a design and implementation of language support for lambda expressions in C++. C++’s compilation model, where activation records are maintained in a stack, and the lack of automatic object lifetime management make safe lambda functions and closures challenging: if a closure outlives its scope of definition, references stored in a closure dangle. Our design is careful to balance between conciseness of syntax and explicit annotations to guarantee safety. The presented design is included in the draft specification of the forthcoming major revision of the ISO C++ standard, dubbed C++0x. In rewriting typical C++ programs to take advantage of lambda functions, we observed clear benefits, such as reduced code size and improved clarity.     

Spatial and temporal changes in Actinobacterial dominance in experimental artificial groundwater recharge

Artificial groundwater recharge (AGR) is used in the drinking water industry to supplement groundwater resources and to minimise the use of chemicals in water treatment. This study analysed the spatial and temporal changes of microbial communities in AGR using two test systems: a nutrient-amended fluidized-bed reactor (FBR) and a sand column. Structural changes in the feed lake water (Lake Roine), FBR, and sand column bacterial communities were determined by denaturing gradient gel electrophoresis (DGGE) and the length heterogeneity analysis of amplified 16S rRNA genes (LH-PCR). Two clone libraries were created to link the LH-PCR results to the dominant bacterial groups. The lake water bacterial community was relatively stable, with three bands dominating in all LH-PCR products. The most dominant fragment accounted for up to 72% and was derived from Actinobacteria. Based on the clone libraries and LH-PCR data, Actinobacteria also dominated in the unattached bacterial community of the FBR, whereas several Proteobacterial groups were more abundant on the FBR carrier particles. In the stabilised AGR system a major change in the community structure of the lake water bacteria took place during passage within the first 0.6 m in the sand column as the community composition shifted from Actinobacteria-dominated populations to a diverse, mainly Proteobacterial communities. Concurrently, most of the dissolved organic carbon (DOC) was removed at this stage. In summary, the study showed that the make-up of microbial communities in experimental AGR systems responded to changes in their environment. LH-PCR showed potential as a method to determine microbial community dynamics in long-term studies at real-scale AGR sites. This is the first step to provide data on microbial community dynamics in AGR for drinking water production.     

Degradative and mechanical properties of a novel resorbable plating system during a 3-year follow-up in vivo and in vitro

We tested the tissue reactions and mechanical strength of a novel biodegradable craniomaxillofacial plating system, Inion CPS™, in the course of degradation. Plates and screws composed of l-lactide, d-lactide and trimethylene carbonate were implanted to the mandible and dorsal subcutis of 12 sheep. The animals were sacrificed at 6–156 weeks. Histological evaluation was done using paraffin and methylmetacrylate techniques. Degradative and mechanical properties during the follow-up were measured both of in vivo and in vitro implants. In light microscopy, the in vivo implant material began to fragment at 52 weeks and could not be detected at 104 weeks. No significant foreign body reactions were seen in the mandibles. The dorsal subcutis disclosed mild reactions, which were, however, not of clinical significance. The implants in vitro maintained their entire mass for 26 weeks and lost 63–80% of the mass by week 104. The inherent viscosity of the implants in vitro and in vivo diminished uniformly. The screws retained their shear strength for 12–16 weeks. The plates maintained their tensile strength for at least 6 weeks. The maximum capacity of the plates in 3-point bending tests diminished gradually by 87% in 26 weeks. In conclusion, the plates and screws examined maintain adequate strength for the healing period of a bone fracture or osteotomy, producing no harmful foreign body reactions. Dr Nieminen is a consultant for Inion Ltd., while the other co-authors do not have any conflicts of interest. Inion Ltd. has financed the costs related to the study sheep, including their housing.     

Evaluation of Software Tutoring for a Speech Interface

Speech applications are typically designed to be used without any instructions or manuals. More complex applications commonly come with web-based or printed manuals. An alternative approach, software tutoring, has been studied in the context of graphical user interfaces. In software tutoring, a software component guides users while they work with an application new to them. To evaluate the viability of software tutoring in speech-based applications a two-condition between-participants experiment (N = 18) was conducted. Participants learned to use a speech-based e-mail reading application and performed several tasks with it. In the first condition the e-mail application included an embedded tutoring component that guided the participants on using the application. In the second condition, a web manual was used. All interactions with the systems were recorded and annotated. Participants also filled in questionnaires that reported their attitudes towards the guidance they received and towards the e-mail reading application. The speech-based tutor performed equally well with web-based manual with no significant differences between the conditions on how well the participants managed to accomplish the tasks with the e-mail application or in participants’ attitudes towards the application or the guidance. In addition, during the learning period the participants in the tutored condition had significantly fewer problems with the speech interface.     

Aspects of Compositionality

We introduce several senses of the principle ofcompositionality. We illustrate the difference between them with thehelp of some recent results obtained by Cameron and Hodges oncompositional semantics for languages of imperfect information.     

Increasing trends of total organic carbon concentrations in small forest lakes in Finland from 1987 to 2003

Trends in total organic carbon (TOC) concentrations over the period 1987-2003 were studied in 13 small forest lakes. Recovery from acidification (reduced SO(4) deposition) and long-term changes in runoff as potential drivers for the trends were examined. The results showed that TOC concentrations have increased throughout Finland. Ten of the 13 lakes showed a significant increasing TOC trend (p<0.05), and included both clear water and humic lakes. The largest annual increase in TOC occurred in lakes with the largest average concentrations. The magnitude of the TOC trends were not significantly related to the proportion of peat soils in the catchment but the catchment size was an important predictor. Decreasing SO(4) deposition and improved acid-base status in soil due to the recovery from acidification implied an increased mobilisation of organic acids and TOC. There was little evidence that the long-term increasing trend in TOC concentrations was related to long-term changes in runoff. However, large seasonal and inter-annual fluctuations in runoff did appear to affect TOC concentrations for a number of years.