Theoretical Maximum Size Research Articles

Life history traits of the Blackspotted smooth-hound Mustelus punctulatus (Carcharhiniformes: Triakidae) in the Adriatic Sea

We present demographic and reproductive parameters of commercially exploited shark, blackspotted smooth-hound (Mustelus punctulatus), based on samples from 117 males and 108 females from the Adriatic Sea. Calculated size and age at maturity were 83.1 cm in total length (TL) and 6.6 years for males and 100.0 cm TL and 12.5 years for females. The oldest observed male and female were 14 and 19 years old, respectively. The Gompertz growth model provided the best fit and predicted a theoretical maximum size (L∞) of 129.3 cm TL and a growth coefficient (k) of 0.15 year–1 for males, and L∞ = 141.1 cm TL and k = 0.13 year–1 for females. Obtained life history traits classify smooth-hound as slow-growing species, extremely sensitive to fishing, and highlight the need for the development of management strategy for this vulnerable species.

Effective method for further magnifying the image in holographic projection under divergent light illumination.

Divergent light illumination can effectively increase the diffraction angle of holographic projection. However, the achieved maximum image size is limited to the geometric enlargement of the hologram size with the existing double-sampling Fresnel diffraction algorithm. In this paper, an effective method for further magnifying the image is proposed. The theoretical maximum size under divergent illumination is first analyzed. On this basis, a virtual intermediate plane is introduced between the source plane and the image plane. Then three-step diffraction calculation is performed to evaluate the Fresnel diffraction between the hologram plane and the image plane so that the sampling interval on the image plane is related to the position of the virtual plane and can be flexibly tuned. Consequently, the achieved image size can be further enlarged. The feasibility of the proposed method is demonstrated by simulations and experiments.

Was There Ever an Arch in the So-Called Ark-e-Alishah?

The main challenge of any structure is to withstand the thrust during and after construction process. The architectural remnants of the so-called structure of Ark-e-Alishah in Tabriz; Northwest Iran, was for a long time considered the last of a sequence of the large-scale monumental structures, with its hypothesized 29 m diameter arch being the most magnificent made in the Islamic World during Ilkhanid era (1256–1353 CE). Despite this, being likely beyond the theoretical maximum size for this type of construction, this (hypothetical) arch has been identified by more than half a century’s studies of historic architecture, archaeological investigation, as well as in travel reports from later times as being the Great Ali-Shah Mosque. Based on this pre-assumption, it was proposed to build a U-shape structure, including roughly 11-m thickness for its walls; the hope would be to clarify the structural limitations of this building in terms of stability, durability, vulnerability and the impossibility of creating any type of arch or vault in the mentioned span and to shed new light on the incompatibly of the current structure with preexisting results. Contrarily to the historic reports, finite element method was employed as a means to get a better understanding of the essential requisites of this building to remain in equilibrium. The results highlight a paradox of historical engineering, that the tension result of loading due to any kind of vault would exceed the structural standards of buckling failure, causing gross deformation and fracture of vertical units under various loading conditions. From this point of view, there has never been any kind of arch nor vault in this building at anytime. In other words, what is known as today’s remnants of the so-called Ark-e-Alishah is in the complete contradiction with what is known as the medieval Ali-Shah Mosque, including a great vaulted span.

The effects of population density and lake characteristics on growth and size structure of brook trout Salvelinus fontinalis (Mitchill, 1815) in boreal forest lakes in Canada

This paper examines the effect of lake characteristics on population density and how this variation affects growth, mortality and population size structure of brook trout, Salvelinus fontinalis. The study was conducted on 17 recreationally fished, reproductively isolated boreal forest lakes in Newfoundland, Canada from 1993 to 2000. A standardized sampling program, the Fyke Littoral Index Netting program (FLIN) was used to collected data that describes brook trout population parameters and life history attributes. Regression analyses showed significant relationships between fish density and biomass and characteristics of the lakes. Variation in fish density and biomass was explained by lake surface area and littoral habitat area. Significant relationships were found when growth, mortality and size structure were regressed against density. The proportional stock distribution and theoretical maximum size of brook trout were negatively related to density, and natural mortality was positively related to density. The largest maximum length and highest proportional stock densities occurred at brook trout densities of less than 30 fish/ha. In general, the higher the proportion of littoral habitat area the higher the densities of brook trout, which correspondingly had important effects on growth, natural mortality and size structure of the brook trout populations. This information is critical to the development of management strategies aimed at altering size distribution to produce specific fisheries management outcomes.

Pattern of follicular development in sheep subjected to ovarian superstimulation after follicular ablation by laparoscopic ovum pick-up

ABSTRACT: The aim of this study was to determine the pattern of follicular development in ewes following ablation of all follicles associated with ovarian superstimulatory treatment. After confirmation of reproductive cyclicity using ultrasonography and progesterone levels, five adult ewes of undetermined breed received a vaginal pessary containing 60mg of medroxyprogesterone, maintained for 10 days, with the application of 100μg cloprostenol on the fourth day. On the tenth day, 300UI equine chorionic gonadotropin (eCG) was applied together with 80mg FSH, and all visible follicles were aspirated by laparoscopic ovum pick-up (LOPU). Following LOPU, ovarian structures were assessed using sonography every 8 hours for a period of 64 hours, and the number and diameter of small (<2.5mm), medium-sized (2.5-4.5mm), and large (>4.5mm) follicles were recorded. The average diameter of small follicles reduced from 5.6±1.5mm initially to 0.8±1.3mm by 56 hours. Population size of the medium-sized follicles during the observation period followed a parabolic distribution wherein the theoretical maximum size emerged at 34.6 hours with no difference at (P>0.05) 24 (4.6±1.5) and 48 hours (4.8±2.3). It was concluded that in ewes subjected to ovarian superstimulation immediately following LOPU, follicular development is characterized by a new wave of follicle growth with a predominance of medium-sized follicles (2.5-4.5mm) between 24 and 48 hours, and a theoretical population maximum occured at 34.6 hours.

The structural stability of lunar lava tubes

Mounting evidence from the SELENE, LRO, and GRAIL spacecraft suggests the presence of vacant lava tubes under the surface of the Moon. GRAIL evidence, in particular, suggests that some may be more than a kilometer in width. Such large sublunarean structures would be of great benefit to future human exploration of the Moon, providing shelter from the harsh environment at the surface—but could empty lava tubes of this size be stable under lunar conditions? And what is the largest size at which they could remain structurally sound? We address these questions by creating elasto-plastic finite element models of lava tubes using the Abaqus modeling software and examining where there is local material failure in the tube's roof. We assess the strength of the rock body using the Geological Strength Index method with values appropriate to the Moon, assign it a basaltic density derived from a modern re-analysis of lunar samples, and assume a 3:1 width-to-height ratio for the lava tube. Our results show that the stability of a lava tube depends on its width, its roof thickness, and whether the rock comprising the structure begins in a lithostatic or Poisson stress state. With a roof 2m thick, lava tubes a kilometer or more in width can remain stable, supporting inferences from GRAIL observations. The theoretical maximum size of a lunar lava tube depends on a variety of factors, but given sufficient burial depth (500m) and an initial lithostatic stress state, our results show that lava tubes up to 5km wide may be able to remain structurally stable.

Hardware Accelerator for Probabilistic Inference in 65-nm CMOS

A hardware accelerator is presented to compute the probabilistic inference for a Bayesian network (BN) in distributed sensing applications. For energy efficiency, the accelerator is operated at a near-threshold voltage of 0.5 V, while achieving a maximum clock frequency of 33 MHz. Clique-tree message passing algorithm is leveraged to compute the probabilistic inference. The theoretical maximum size of a factor that the proposed hardware accelerator can handle is $2^{(8\times 20)=160}$ entries, which is sufficient for handling massive BNs, such as PATHFINDER, MUNIN, and so on (>1000 nodes). A Logical Alarm Reduction Mechanism (ALARM) BN is used to benchmark the performance of the accelerator. The accelerator consumes 76 nJ to execute the ALARM network using a clique-tree message-passing algorithm, while the same algorithm executed on an ultralow-power microcontroller consumes 20 mJ.

Age, Growth, and Reproductive Biology of Cownose Rays in Chesapeake Bay

AbstractThe Cownose Ray Rhinoptera bonasus is an opportunistic predator of benthic invertebrates and has had a long history of negative interactions with commercial shellfish industries. Most recently, Cownose Rays have been implicated in negatively affecting the recovery of bay scallop Argopecten irradians stocks in North Carolina and oyster restoration and commercial aquaculture efforts in Chesapeake Bay. A mitigation attempt to decrease predation on shellfish has resulted in an unregulated fishery for Cownose Rays. Cownose Ray life history suggests that they are highly susceptible to overexploitation. We determined age, growth, and size at maturity for Cownose Rays collected in Chesapeake Bay. In total, 694 rays were used for the study: 246 males ranging in size from 30.0 to 98.0 cm disc width (DW) and 448 females ranging from 30.0 to 110.5 cm DW. The oldest individual observed was a female (107 cm DW) estimated at age 21. Our data suggested that Cownose Rays grow considerably faster during the first few years than has been previously reported, thus producing higher estimates of the growth coefficient k. The best‐fit growth models (three‐parameter von Bertalanffy models) estimated k‐values of 0.2741 for males and 0.1931 for females. The large sample size and inclusion of many older animals (n = 119 rays over age 10) resulted in theoretical maximum size estimates that matched the observed sizes well. The median size at 50% maturity was 85–86 cm DW for males and females (corresponding to ages of ∼6–7 for males and ∼7–8 for females). Fecundity in Cownose Rays was typically one embryo per mature female, with a gestation period of 11–12 months. Our study confirms that the Cownose Ray is a K‐selected species with late maturity, long gestation, and low reproductive potential, indicating that it could be highly susceptible to overexploitation.Received February 28, 2013; accepted June 3, 2013

The effect of an expanding universe on massive objects

We present some astrophysical consequences of the metric for a point mass in an expanding universe derived in Nandra, Lasenby & Hobson, and of the associated invariant expression for the force required to keep a test particle at rest relative to the central mass. We focus on the effect of an expanding universe on massive objects on the scale of galaxies and clusters. Using Newtonian and general-relativistic approaches, we identify two important time-dependent physical radii for such objects when the cosmological expansion is accelerating. The first radius, $r_F$, is that at which the total radial force on a test particle is zero, which is also the radius of the largest possible circular orbit about the central mass $m$ and where the gas pressure and its gradient vanish. The second radius, $r_S$, which is \approx r_F/1.6$, is that of the largest possible stable circular orbit, which we interpret as the theoretical maximum size for an object of mass $m$. In contrast, for a decelerating cosmological expansion, no such finite radii exist. Assuming a cosmological expansion consistent with a $\Lambda$CDM concordance model, at the present epoch we find that these radii put a sensible constraint on the typical sizes of both galaxies and clusters at low redshift. For galaxies, we also find that these radii agree closely with zeroes in the radial velocity field in the neighbourhood of nearby galaxies, as inferred by Peirani & Pacheco from recent observations of stellar velocities. We then consider the future effect on massive objects of an accelerating cosmological expansion driven by phantom energy, for which the universe is predicted to end in a `Big Rip' at a finite time in the future at which the scale factor becomes singular. In particular, we present a novel calculation of the time prior to the Big Rip that an object of a given mass and size will become gravitationally unbound.

Diffusion of Macromolecule Through Retina After Experimental Branch Retinal Vein Occlusion and Estimate of Intraretinal Barrier

The disposition and diffusion knowledge of intravitreally injected macromolecule drugs through retina in pathological condition is crucial but the related studies are absent. Retinal edema is a common pathological change of fundus diseases and retinal vein occlusion (RVO) pig model were established to emulate it. FITC-dextrans of various molecular weights were dissolved in RPMI-1640 solutions and the rate of transretinal diffusion was determined with a spectrophotometer. Theoretical maximum size of molecule (MSM) was calculated by extrapolating the trend-linear relationship with the diffusion rate. In separate experiments to determine the sites of barrier to diffusion, FITC-dextrans were applied to either the inner or outer retinal surface, processed as frozen sections, and viewed with a fluorescence microscope. Paired-Samples T test was used to compared the diffusion rate of dextrans of the both eyes of one pig. The MSM in RVO tissues and normal tissue was 6.5+/-0.39 nm and 6.18+/-0.54 nm respectively (t=4.143, P=0.0001). FITC-dextrans applying to inner retinal surface, 4.4 kDa dextran were largely arrested at inner nuclear layer (INL). The INL of the 19.6-71.2 kDa dextran diffusion retina section became dark and the nerve fiber layer (NFL) and inner plexiform layer got brighter. As for 150 kDa dextran, the NFL was bright and the other layers were dark. FITC-dextrans applying to outer retinal surface, most dextrans were blocked before outer nuclear layer (ONL). In summary, ONL and INL may act as bottle-neck barriers to diffusion of macromolecules. Compared with normal neuroretina, the MSM of fresh edema retina after RVO increased limitedly.

Age and growth of Carcharhinus leucas in the northern Gulf of Mexico: incorporating variability in size at birth

Age and growth rates of bull shark Carcharhinus leucas[n = 255; 555–2230 mm fork length (LF)] from the northern Gulf of Mexico were estimated from ring counts on vertebral sections collected from fishery‐dependent and ‐independent surveys. Two growth models were fitted to observed data: the von Bertalanffy growth model (VBGM) with t0 as the third parameter and a modified version of the VBGM using a fixed size‐at‐birth intercept as the third parameter. To address the variability in size‐at‐birth, a Monte Carlo simulation was incorporated into the size‐at‐birth intercept. The sex‐specific growth models were not significantly different, allowing a sexes combined model to be generated. The traditional VBGM predicted a theoretical maximum size (L∞) of 3007·1 mm LF, a growth coefficient (K) of 0·042 year−1 and a theoretical age at zero length (t0) of –6·844 years. The modified VBGM with a fixed size‐at‐birth intercept of 565 mm LF predicted an L∞ of 2289·2 mm LF and a K value of 0·089 year−1. When comparing model estimates to previously published information, the traditional VBGM predicted a significantly lower theoretical maximum size and a higher growth coefficient than those produced using data collected during the 1980s. Overall, results obtained using the VBGM with a fixed size‐at‐birth produced more biologically realistic parameters than that of the VBGM with t0. The Monte‐Carlo simulation incorporating variability in size‐at‐birth produced similar results to the VBGM using a fixed size‐at‐birth. This study provides the first attempt to incorporate variability at size‐at‐birth and provide measurements of variability around the individual parameter estimates for an elasmobranch.

Observations on the Age and Growth of Graysby and Coney from the Southeastern United States

Abstract The graysby Epinephelus cruentatus and coney E. fulvus are two uncommon groupers occurring off the southeastern coast of the United States. Limited recreational fishery data suggest that graysbies are being landed with increasing frequency in the area. From 1979 to 1997, 118 graysbies and 55 coneys were collected from the headboat fishery operating from North Carolina through the Dry Tortugas, Florida. Ages were estimated using transverse sections of sagittal otoliths. Graysbies ranged in total length (TL) from 180 to 405 mm and in age from 4 to 13 years. Coneys ranged from 150 to 397 mm TL and from 2 to11 years old. Growth of the graysby is represented by the following models derived from back-calculated lengths (L) at ages (t) and observed lengths at ages, respectively: Lt = 451(1 − e −0.12(t+1.24)) and Lt = 446(1 − e −0.13(t+1.51)). Coneys grew faster and had a smaller theoretical maximum size than graysbies: From back-calculated lengths at ages, Lt = 372(1 − e −0.32(t−0.20)), and from observe...

Physiological energetics of the zebra musselDreissena polymorpha in lakes I. Growth and reproductive effort

Shell growth of tagged zebra mussels (Dreissena polymorpha) was monitored in lakes at 3 sites over 1 1/2 years. It varied greatly with the season and was almost absent during winter months. Shell growth was significantly correlated with seston concentration, but not with water temperature. The theoretical maximum size (L∞) of the v. Bertalanffy growth equation did not vary seasonally. Tissue weight underwent a pronounced seasonal cycle. In animals of 20 mm shell length, minimum weights recorded in September only corresponded to one quarter to one third of the maxima in late spring. Tissue weight of animals from the 3 sites was distinctly different. Carbohydrate content of the tissue stayed below 10 per cent and tended to be highest in spring. Spring maxima of lipids were very pronounced. These lipids were primarily located in the digestive gland. These data were combined with data of gonad size by Borcherding (1991). Results imply that production of reproductive tissue even continues at a retarded rate during winter months, if food conditions were favourable. With poor food conditions, no production of reproductive tissue was estimated during winter; this, however, was followed by an elevated rate of reproductive tissue production in spring. Weight specific production decreased with a weight exponent of −0.24. Shell and byssus production contributed only in the range of 10 per cent to total production. Reproductive effort showed maxima of 30 to 45%. It increased with shell length at 2 sites and decreased at the other site with the largest animals.

Bias in Estimating Growth Parameters Using Fabens' Mark-Recapture Procedure

Simulations of a mark-recapture experiment are used to demonstrate the bias associated with use of a widely accepted equation for-estimating growth rates from data where absolute age is unknown. The bias results in an overestimation of K, the growth rate constant, and an underestimation of 1-, the theoretical maximum size. The bias appears to be associated with a failure to account for the redistribution of the error term when the basic growth equation is transformed to eliminate the necessity of estimating age.