The copepod Calanus spp. (Calanidae) is repelled by polarized light

Both attraction and repulsion from linearly polarized light have been observed in zooplankton. A dichotomous choice experiment, consisting of plankton light traps deployed in natural waters at a depth of 30 m that projected either polarized or unpolarized light of the same intensity, was used to test the hypothesis that the North Atlantic copepod, Calanus spp., is linearly polarotactic. In addition, the transparency of these copepods, as they might be seen by polarization insensitive vs. sensitive visual systems, was measured. Calanus spp. exhibited negative polarotaxis with a preference ratio of 1.9:1. Their transparency decreased from 80% to 20% to 30% in the unpolarized, partially polarized, and electric (e-) vector orientation domains respectively - that is, these copepods would appear opaque and conspicuous to a polarization-sensitive viewer looking at them under conditions rich in polarized light. Since the only difference between the two plankton traps was the polarization cue, we conclude that Calanus spp. are polarization sensitive and exhibit negative polarotaxis at low light intensities (albeit well within the sensitivity range reported for copepods). We hypothesize that Calanus spp. can use polarization vision to reduce their risk of predation by polarization-sensitive predators and suggest that this be tested in future experiments

Measuring Light Pollution with Fisheye Lens Imagery from A Moving Boat, A Proof of Concept

Near all-sky imaging photometry was performed from a boat on the Gulf of Aqaba to measure the night sky brightness in a coastal environment. The boat was not anchored, and therefore drifted and rocked. The camera was mounted on a tripod without any inertia/motion stabilization. A commercial digital single lens reflex (DSLR) camera and fisheye lens were used with ISO setting of 6400, with the exposure time varied between 0.5 s and 5 s. We find that despite movement of the vessel the measurements produce quantitatively comparable results apart from saturation effects. We discuss the potential and limitations of this method for mapping light pollution in marine and freshwater systems. This work represents the proof of concept that all-sky photometry with a commercial DSLR camera is a viable tool to determine light pollution in an ecological context from a moving boat.Comment: 9 pages, 6 figures, accepted at International Journal of Sustainable Lightin

Dugoročno istraživanje ulova (1949-2010) i ribolovnog napora izraelskih koćarica u istočnom dijelu Sredozemlja

The trawl fishery of the Mediterranean coast of Israel was analyzed vis á vis catch and fishing effort for the years 1949-2010. The Maximum Sustainable Yield (MSY) was calculated using the Fox surplus-yield model and was found to be 1,413 ton per annum using 1,415 units of effort (fishing days X engine power divided by 1000). Only during nine years (1997-2005) did fishing effort exceed the value for which the yield is the MSY by an average of 184.9 units of effort, but the yield was similar to that of the previous years. During 10 years the catch exceeded the MSY by an average of 153±119 tons. This result was used to justify the “freezing” of the local trawl fleet at the beginning of the 1990’s.Koćarski ulov na sredozemnoj obali Izraela analiziran je s obzirom na ulov i ribolovni napor od 1949. do 2010. godine. Maksimalni održivi prinos (MSY) izračunat je primjenom Fox modela za viši prekomjerni ulov i utvrđeno je da iznosi 1.413 tona godišnje koristeći 1.415 jedinica napora (dani ribolova x motorna snaga podijeljena s 1000). Tijekom devet godina (1997.- 2005.) ribolovni napor premašuje vrijednost čiji maksimalni održivi prinos (MSY) iznosi u prosjeku 184,9 jedinica, dok je prinos bio sličan onome prethodnih godina. Tijekom 10 godina ulov je premašio, maksimalni održivi prinos (MSY) za prosječno 153 ± 119 tona. Taj rezultat je bio upotrebljen kao argument za „zamrzavanje“ lokalne kočarske flote početkom 1990-ih godina

Habitat availability mediates chironomid density-dependent oviposition

Abstract Knowledge of density-dependent processes and how they are mediated by environmental factors is critically important for understanding population and community ecology of insects, as well as for mitigating harmful insect-borne diseases. Here, we tested whether the oviposition of chironomids (Diptera: Chironomidae; non-biting midges), known to carry the Cholera pathogen Vibrio cholerae, is density dependent and if it is mediated by habitat availability. We used two multiple choice experiments in habitat-limited and habitat-unlimited environments and performed isodar analysis on counts of egg batches after controlling the polarization of light reflected from the habitats, which is known to affect their attractiveness to ovipositing chironomids. We found that, when habitats are limited, egg batch isodars indicate that chironomid selection is density dependent. Although a greater number of individuals selected to oviposit in highly polarized sites, oviposition was also common in sites with low polarization. When habitats are unlimited, chironomid selection is either weakly density dependent, or completely density independent. Chironomids oviposit to a very large extent in sites with high level of polarization, oviposit to a small extent in sites with medium level of polarization, and almost completely disregard unpolarized sites. We suggest that ovipositing females consider the availability of habitats in their surroundings when they choose an oviposition site. When high quality habitats are scarce, more females opt to breed in low quality sites. These findings may be used to limit the spread of Cholera by controlling the habitats available for chironomid oviposition

Financing of entrepreneurial firms in Canada : some patterns

This article analyzes the patterns of financing for entrepreneurial firms in Canada. We compare the predictions of major theories of entrepreneurial finance and some more recent ideas (e.g., crowdfunding-related ideas/theories) with empirical evidence. Regression and correlation analyses were used to analyze the connections between firms’ financing choices (e.g., debt/equity ratio) and different variables such as firm age, firm owner origin, and the fraction of intangibles assets. We found strong evidence that the financing choices of entrepreneurial firms in Canada are consistent with flexibility theory and credit rationing theory. We did not find evidence that taxes play a significant role in explaining these choices. We also found that the likelihood of using crowdfunding is consistent with local bias ideas and internet access. We also provide an overview of literature related to entrepreneurial financing in Canada and discuss its major challenges and directions for future research

Mitigation of Moral Hazard and Adverse Selection in Venture Capital Financing: The Influence of the Country’s Institutional Setting

A venture capitalist (VC) needs to trade off benefits and costs when attempting to mitigate agency problems in their investor-investee relationship. We argue that signals of ventures complement the VC’s capacity to screen and conduct a due diligence during the pre-investment phase, but its attractiveness may diminish in institutional settings supporting greater transparency. Similarly, whereas a VC may opt for contractual covenants to curb potential opportunism by ventures in the post-investment phase, this may only be effective in settings supportive of shareholder rights enforcement. Using an international sample of VC contracts, our study finds broad support for these conjectures. It delineates theoretical and practical implications for how investors can best deploy their capital in different institutional settings whilst nurturing their relationships with entrepreneurs

Connecting the Micro to the Macro: An Exploration of Micro-Behaviors of Individuals Who Drive CSR Initiatives at the Macro-Level

Grounded on a case study on the formation of an inter-corporate CSR initiative in which four corporations from Chennai, India collaborate, this paper explores the micro-behaviors that individual actors engage in to create CSR solutions later adopted at the macro-organizational level. Based on the findings, the paper (1) identifies five categories of micro-behaviors, namely increasing stakeholder salience by turning attention to the ethical and social responsibilities to specific stakeholder groups, emerging as a self-appointed CSR champion by assuming personal responsibility for action, creating CSR initiative prototypes by leveraging personal skills, garnering support by leveraging personal networks and amassing operational resources by organizational resources; (2) explicates the characteristics of individual approach to CSR that makes it different from, but complementary to organizational approach to CSR

Scale-invariance of galaxy clustering

Some years ago we proposed a new approach to the analysis of galaxy and cluster correlations based on the concepts and methods of modern statistical Physics. This led to the surprising result that galaxy correlations are fractal and not homogeneous up to the limits of the available catalogs. The usual statistical methods, which are based on the assumption of homogeneity, are therefore inconsistent for all the length scales probed so far, and a new, more general, conceptual framework is necessary to identifythe real physical properties of these structures. In the last few years the 3-d catalogs have been significatively improved and we have extended our methods to the analysis of number counts and angular catalogs. This has led to a complete analysis of all the available data that we present in this review. The result is that galaxy structures are highly irregular and self-similar: all the available data are consistent with each other and show fractal correlations (with dimension $D \simeq 2$) up to the deepest scales probed so far (1000 \hmp) and even more as indicated from the new interpretation of the number counts. The evidence for scale-invariance of galaxy clustering is very strong up to 150 \hmp due to the statistical robustness of the data but becomes progressively weaker (statistically) at larger distances due to the limited data. In These facts lead to fascinating conceptual implications about our knowledge of the universe and to a new scenario for the theoretical challenge in this field.Comment: Latex file 165 pages, 106 postscript figures. This paper is also available at http://www.phys.uniroma1.it/DOCS/PIL/pil.html To appear in Physics Report (Dec. 1997