Competitive Innovation with Codified And Tacit Knowledge

R&D-based models of endogenous technical progress rest on a premise that technical progress is driven by profit-seeking entrepreneurs. This literature led to a dominant view that endogenous technical advance is not consistent with perfect competition with constant returns to scale. Departing from this dominant perspective, we demonstrate that technical progress endogenously occurs in a perfectly competitive economy under constant returns to scale in rivalrous inputs. Our result is based on a hypothesis that R&D creates codified and tacit knowledge as joint products. Empirical and case studies are discussed to support the hypothesis. Using the model, we demonstrate that stronger patent protection can encourage or discourage R&D, depending on the size of an economy.

Suppression of the anti-symmetry channel in the conductance of telescoped double-wall nanotubes

The conductance of telescoped double-wall nanotubes (TDWNTs) composed of two armchair nanotubes ($(n_O, n_O)$ and $(n_O-5, n_O-5)$ with $n_O \geq 10$) is calculated using the Landauer formula and a tight binding model. The results are in good agreement with the conductance calculated analytical by replacing each single-wall nanotube with a ladder, as expressed by $(2e^2/h)(T_+ + T_-)$, where $T_+$ and $T_-$ are the transmission rates of the symmetry and anti-symmetry channels, respectively. Perfect transmission in both channels is possible in this TDWNT when $n_O=10$, while $T_-$ is considerably small in the other TDWNTs. $T_-$ is particularly low when either $n_O$ or $n_O-5$ is a multiple of three. In this case, a three body effect of covalent-like interlayer bonds plays a crucial role in determining the finite $T_-$. When $n_O$ is a multiple of five, the five-fold symmetry increases $T_-$, although this effect diminishes with increasing $n_O$.Comment: Owing to errors of the calculation code, the numerical data shown in Figures are incorrect. Nonetheless, the corrected numerical calculations do not change the essential results. See erratum, PHYSICAL REVIEW B 79, 199902 (2009). The responsibility for the errors lies completely with the first author (Ryo Tamura

Trade and Firm Heterogeneity In A Quality-Ladder Model of Growth

The present paper explores the effect of trade liberalization on the level of productivity as well as the rate of productivity growth in an R&Dbased model with heterogeneous firms. We introduce new and plausible features that are absent in existing studies. First, technical progress takes the form of continual quality improvement of products over time. Second, firm entry and exit are endogenously determined due to creative destruction of products traded. In this framework, we demonstrate that a lower transport cost or export sunk cost unambiguously reallocates resources from non-exporting industries to R&D as well as exporting industries. This means that trade liberalization increases the level of manufacturing productivity and the rate of technical progress. These results are found to be robust in an extended model with population growth without scale effects. In extensions of the basic model, we also endogenize the ex ante distribution of firm heterogeneity and examine the effect of R&D subsidies.

A Software Defined Radio Platform with Direct Conversion: SOPRANO

A new software defined radio platform with multiport-based direct conversion is proposed, named SOPRANO (Software Programmable and Hardware Reconfigurable Architecture for Network). The main features of SOPRANO are a high-level design methodology for digital circuits, a new mixer-less direct conversion method, and software algorithms for multi-band and multi-mode operation. We built the first prototype SOPRANO 1.0, which was able to receive PSK and QAM signals with two different carrier frequencies at 2.45 GHz and 5.25 GHz by changing signal processing software

Technological Leaders and Followers in a World Economy

This paper develops a dynamic general equilibrium model of North-South trade and economic growth in a world economy with a continuum of countries. Countries are different in research productivity. Innovation, imitation and the relative wage between countries are endogenously determined as well as the number of the country that specialize in innovative or imitative R&D. We investigate how equilibrium is affected by globalization, intellectual property right protection, industrial policy, competition and migration. The model is also extended to introduce foreign direct investment.Innovation, imitation, growth, trade, North, South

Influence of Finishing/Polishing Procedures on the Surface Texture of Two Resin Composites

This study compared surface roughness and gloss produced by different finishing/polishing procedures for two resin composites, Clearfil AP-X (AP-X) and Estelite Σ (ES). A total of 70 composite discs (n=35 for each resin composite) were prepared and divided at random into seven finishing/polishing groups (n=5): glass-pressed control; using a super-fine-grit diamond bur (SF); using CompoMaster (CM) after SF-finishing (SF+CM); using White Point (WP) after SF-finishing (SF+WP); using CM after SF+WP-finishing (SF+WP+CM); using Stainbuster (SB) after SF-finishing (SF+SB); and using CM after SF+SB-finishing (SF+SB+CM). After the finishing/polishing procedures, average surface roughness (Ra) and surface gloss (Gs(60°)) of all specimens were assessed with a surface profilometer and specimen gloss meter, respectively. Glass-pressed controls for both AP-X and ES composites showed the best surface finish in terms of both Ra and Gs(60°). SF-finishing produced the roughest surface and led to almost complete loss of gloss. While additional polishing with CM reduced Ra and increased Gs(60°), the additional finishing effect of WP or SB between SF-finishing and CM-polishing was not found for either AP-X or ES

On the Number of p4-Tilings by an n-Omino

A plane tiling by the copies of a polyomino is called isohedral if every pair of copies in the tiling has a symmetry of the tiling that maps one copy to the other. We show that, for every $n$-omino (i.e., polyomino consisting of n cells), the number of non-equivalent isohedral tilings generated by 90 degree rotations, so called p4-tilings or quarter-turn tilings, is bounded by a constant (independent of n). The proof relies on the analysis of the factorization of the boundary word of a polyomino