Dielectric relaxation of DNA aqueous solutions

We report on a detailed characterization of complex dielectric response of Na-DNA aqueous solutions by means of low-frequency dielectric spectroscopy (40 Hz - 110 MHz). Results reveal two broad relaxation modes of strength 20<\Delta\epsilon_LF<100 and 5<\Delta\epsilon_HF<20, centered at 0.5 kHz<\nu_LF<70 kHz and 0.1 MHz<\nu_HF<15 MHz. The characteristic length scale of the LF process, 50<L_LF<750nm, scales with DNA concentration as c_DNA^{-0.29\pm0.04} and is independent of the ionic strength in the low added salt regime. Conversely, the measured length scale of the LF process does not vary with DNA concentration but depends on the ionic strength of the added salt as I_s^{-1} in the high added salt regime. On the other hand, the characteristic length scale of the HF process, 3<L_HF<50 nm, varyes with DNA concentration as c_DNA^{-0.5} for intermediate and large DNA concentrations. At low DNA concentrations and in the low added salt limit the characteristic length scale of the HF process scales as c_DNA^{-0.33}. We put these results in perspective regarding the integrity of the double stranded form of DNA at low salt conditions as well as regarding the role of different types of counterions in different regimes of dielectric dispersion. We argue that the free DNA counterions are primarily active in the HF relaxation, while the condensed counterions play a role only in the LF relaxation. We also suggest theoretical interpretations for all these length scales in the whole regime of DNA and salt concentrations and discuss their ramifications and limitations.Comment: 15 pages, 9 figure

Analiza ekspozicije, respiratorna funkcija i kožna preosjetljivost u radnika izloženih prašini mekog i tvrdog drva

Ventilatory lung capacity (FVC, FEV1, MEF50 and MEF75) was measured before and after work shift in three groups of workers (356 in total) exposed to softwood (poplar, pine, mixed softwood, resp.) and in three groups (42 in total) exposed to hardwood dust (iroko, mahogany, okoume, resp.). The difference in levels of exposure to different types of wood dust was considerable; it was more expressed for total than for respirable particles. Significant falls over work shift of all the ventilatory capacity measures except FVC were found in exposure to all softwoods. In hardwood dust exposure no acute effect was found on FEV1 or FVC; significant decrease over shift was observed of MEF50 and MEF75 in mahogany exposure and of MEF75 in iroko exposure. The magnitude of acute falls was not wood type specific, but depended on exposure level irrespective of the type of wood. No convincing evidence was found of chronic effects of the exposure to either soft or hardwood dust on ventilatory lung capacity. Low frequencies of skin reaction to allergens prepared from the extracts of the dusts studied were observed.Izmjereni su testovi ventilacijske funkcije pluća (FVK, FEV1, MEP50 i MEP75) prije i nakon radne smjene u tri skupine radnika (ukupno 365) izloženih prašini mekog drva (topola, crnogorica i miješano meko drvo) i u tri skupine radnika (ukupno 42) izloženih prašini tvrdog drva (iroko, ma-hagonij i okume). Razine izloženosti prašinama različitih tipova drva znatno su se razlikovale, više za ukupne nego za respirabilne aerogene čestice. Utvrđeni su značajni akutni padovi svih testova ventilacijske funkcije pluća tijekom radne smjene osim FVK uz ekspoziciju prašini svih mekih drva. Pri ekspoziciji prašini tvrdog drva nisu nađene akutne promjene niti FEV1 niti FVK; utvrđeni su samo značajni akutni padovi vrijednosti MEP50 i MEP75 uz ekspoziciju prašini mahagonija i MEP75 u radnika izloženih prašini iroka. Akutne promjene ventilacijske funkcije nisu bile specifične za pojedinu vrstu drva, nego su ovisile o razini ekspozicije bez obzira na vrstu drva. Nisu utvrđeni uvjerljivi pokazatelji kroničnih učinaka izloženosti prašini bilo mekog bilo tvrdog drva na ventilacijsku funkciju pluća. Testiranje kožne preosjetljivosti alergenima pripravljenim iz prašine drva dalo je nisku prevalenciju pozitivnih kožnih reakcija

Revisiting the Relationship Between Fault Detection,Test Adequacy Criteria, and Test Set Size

The research community has long recognized a complex interrelationship between test set size, test adequacy criteria, and test effectiveness in terms of fault detection. However, there is substantial confusion about the role and importance of controlling for test set size when assessing and comparing test adequacy criteria. This paper makes the following contributions: (1) A review of contradictory analyses of the relationship between fault detection, test suite size, and test adequacy criteria. Specifically, this paper addresses the supposed contradiction of prior work and explains why test suite size is neither a confounding variable, as previously suggested,nor an independent variable that should be experimentally manipulated. (2) An explication and discussion of the experimental design and sampling strategies of prior work, together with a discussion of conceptual and statistical problems, and specific guidelines for future work. (3) A methodology for comparing test-adequacy criteria on an equal basis, which accounts for test suite size by treating it as a covariate. (4) An empirical evaluation that compares the effectiveness of coverage-based and mutation-based testing to one another and random testing. Additionally, this paper proposes probabilistic coupling, a methodology for approximating the representativeness of a set of test goals for a given set of real fault