K Krist Vaesen

Multilayer thin-film MCM-D for the integration of high-performance RF and microwave circuits

Thin-film multi-layer MCM-D technology using the system in a package concept is presented as a viable approach for the integration of high performance wireless front-end systems. Due to the high quality dielectrics and copper metallization, high quality transmission lines and inductors are available. This, together with the integrated passives design library containing scalable equivalent models for the inductors, capacitors, resistors, transmission lines and discontinuities, allows easy and accurate co-design between the passive and active devices. Examples of bandpass filters, power dividers, quadrature couplers, microwave feedthroughs, a DECT VCO and a 14 GHz LNA are given.

The cognitive bases of human tool use

This article has two goals. The first is to assess, in the face of accruing reports on the ingenuity of great ape tool use, whether and in what sense human tool use still evidences unique, higher cognitive ability. To that effect, I offer a systematic comparison between humans and nonhuman primates with respect to nine cognitive capacities deemed crucial to tool use: enhanced hand-eye coordination, body schema plasticity, causal reasoning, function representation, executive control, social learning, teaching, social intelligence, and language. Since striking differences between humans and great apes stand firm in eight out of nine of these domains, I conclude that human tool use still marks a major cognitive discontinuity between us and our closest relatives. As a second goal of the paper, I address the evolution of human technologies. In particular, I show how the cognitive traits reviewed help to explain why technological accumulation evolved so markedly in humans, and so modestly in apes.

Ground-measured spectral signatures as indicators of ground cover and leaf area index: the case of paddy rice

A methodology is described to use spectral signatures as indicators of the vegetative status in rice paddy cultures. Ground cover and leaf area index (LAI), considered as indicators of above-ground biomass, and were measured in the field using indirect techniques of digitized close-range vertical photography and Licor 2000 instrument readings, as well as direct destructive sampling. Simultaneously, field reflectance values were collected over specific spectral bandwidths using a handheld radiometer. Several vegetation indices were derived from these spectral measurements and their predictive power (individually or in combination) with respect to field-measured ground cover and LAI quantified. The additional effects of plant chlorophyll content, paddy depth, water sediment load, and bottom layer color were also investigated. None of these variables added significantly to the predictive power of the models. The models were refined for intra-seasonal variability and a new growth-stage-dependent variable improved the models’ predictive capabilities. The results demonstrated that the monitoring of paddy rice crop status by means of its spectral signatures appears very promising. # 2001 Elsevier Science B.V. All rights reserved.

Comparative performance of a modified change vector analysis in forest change detection

Sustainable forest management requires accurate and up‐to‐date information, which can nowadays be obtained using digital earth observation technology. This paper introduces a modified change vector analysis (mCVA) approach and conceptually contrasts it against traditional CVA. The results of a comparative study between this change detection algorithm and three other widely used change detection algorithms: standardized differencing, ratioing and selective principal component analysis are summarized. Landsat Thematic Mappper (TM) imagery and detailed change maps of a forested area in Northern Minnesota were used. Change indicators (vegetation indices) were grouped into three conceptually independent categories corresponding to soil, vegetation and moisture characteristics. Change periods of two, four and six years were considered. All change detection outputs were multidimensional and of a continuous nature, and could therefore be subjected to a supervised maximum likelihood algorithm using identical data training sets. Change extraction accuracies were determined by computing overall accuracy and Kappa coefficients of agreement against independent reference datasets. The mCVA outperformed the three other change detection methods in all cases, and we have shown that there is a clear advantage in running mCVA with three change indicator inputs where each input comes from a different change indicator category. Further validations with more detailed reference data are needed to improve this method and test its performance for other types of change events.

Cumulative cultural evolution and demography

The idea that demographic change may spur or slow down technological change has become widely accepted among evolutionary archaeologists and anthropologists. Two models have been particularly influential in promoting this idea: a mathematical model by Joseph Henrich, developed to explain the Tasmanian loss of culture during the Holocene; and an agent-based adaptation thereof, devised by Powell et al. to explain the emergence of modern behaviour in the Late Pleistocene. However, the models in question make rather strong assumptions about the distribution of skills among social learners and about the selectivity of social learning strategies. Here I examine the behaviour of these models under more conservative and, on empirical and theoretical grounds, equally reasonable assumptions. I show that, some qualifications notwithstanding, Henrich’s model largely withstands my robustness tests. The model of Powell et al., in contrast, does not–a finding that warrants a fair amount of skepticism towards Powell et al.’s explanation of the Upper Paleolithic transition. More generally, my evaluation of the accounts of Henrich and of Powell et al. helpfully clarify which inferences their popular models do and not support.

Knowledge without credit, exhibit 4: extended cognition

The Credit Theory of Knowledge (CTK)—as expressed by such figures as John Greco, Wayne Riggs, and Ernest Sosa—holds that knowing that p implies deserving epistemic credit for truly believing that p. Opponents have presented three sorts of counterexamples to CTK: S might know that p without deserving credit in cases of (1) innate knowledge (Lackey, Kvanvig); (2) testimonial knowledge (Lackey); or (3) perceptual knowledge (Pritchard). The arguments of Lackey, Kvanvig and Pritchard, however, are effective only in so far as one is willing to accept a set of controversial background assumptions (for instance, that innate knowledge exists or that doxastic voluntarism is wrong). In this paper I mount a fourth argument against CTK, that doesn’t rest on any such controversial premise, and therefore should convince a much wider audience. In particular, I show that in cases of extended cognition (very broadly conceived), the most salient feature explaining S’s believing the truth regarding p may well be external to S, that is, it might be a feature of S’s (non-human, artifactual) environment. If so, the cognitive achievement of knowing that p is not (or only marginally) creditable to S, and hence, CTK is false.

Population size does not explain past changes in cultural complexity

Significance Archaeologists have long tried to understand why cultural complexity often changed in prehistory. Recently, a series of highly influential formal models have suggested that demography is the key factor. According to these models, the size of a population determines its ability to invent and maintain cultural traits. In this paper, we demonstrate that the models in question are flawed in two important respects: They use questionable assumptions, and their predictions are not supported by the available archaeological and ethnographic evidence. As a consequence, little confidence can be invested in the idea that demography explains the changes in cultural complexity that have been identified by archaeologists. An alternative explanation is required. Demography is increasingly being invoked to account for features of the archaeological record, such as the technological conservatism of the Lower and Middle Pleistocene, the Middle to Upper Paleolithic transition, and cultural loss in Holocene Tasmania. Such explanations are commonly justified in relation to population dynamic models developed by Henrich [Henrich J (2004) Am Antiq 69:197–214] and Powell et al. [Powell A, et al. (2009) Science 324(5932):1298–1301], which appear to demonstrate that population size is the crucial determinant of cultural complexity. Here, we show that these models fail in two important respects. First, they only support a relationship between demography and culture in implausible conditions. Second, their predictions conflict with the available archaeological and ethnographic evidence. We conclude that new theoretical and empirical research is required to identify the factors that drove the changes in cultural complexity that are documented by the archaeological record.

The acheulean handaxe: More like a bird's song than a beatles' tune?

The goal of this paper is to provoke debate about the nature of an iconic artifact—the Acheulean handaxe. Specifically, we want to initiate a conversation about whether or not they are cultural objects. The vast majority of archeologists assume that the behaviors involved in the production of handaxes were acquired by social learning and that handaxes are therefore cultural. We will argue that this assumption is not warranted on the basis of the available evidence and that an alternative hypothesis should be given serious consideration. This alternative hypothesis is that the form of Acheulean handaxes was at least partly under genetic control.

The empirical case against the ‘demographic turn’ in Palaeolithic archaeology

Recently, it has become commonplace to interpret major transitions and other patterns in the Palaeolithic archaeological record in terms of population size. Increases in cultural complexity are claimed to result from increases in population size; decreases in cultural complexity are suggested to be due to decreases in population size; and periods of no change are attributed to low numbers or frequent extirpation. In this paper, we argue that this approach is not defensible. We show that the available empirical evidence does not support the idea that cultural complexity in hunter–gatherers is governed by population size. Instead, ethnographic and archaeological data suggest that hunter–gatherer cultural complexity is most strongly influenced by environmental factors. Because all hominins were hunter–gatherers until the Holocene, this means using population size to interpret patterns in the Palaeolithic archaeological record is problematic. In future, the population size hypothesis should be viewed as one of several competing hypotheses and its predictions formally tested alongside those of its competitors. This article is part of the themed issue ‘Major transitions in human evolution’.

Integration of passive components in thin film multilayer MCM-D technology for wireless front-end applications

In the current trend towards portable applications, the integration of passive components has become very important. This paper introduces high quality integrated passive components in thin film multilayer MCM-D technology. The main characteristics and modeling issues for use at RF and microwave frequencies are discussed. Also, a number of circuits applicable in wireless front-ends using the integrated passives are presented. These show that MCM-D may be used for the integration of miniature systems for wireless applications.