Why is Real-World Visual Object Recognition Hard?

Progress in understanding the brain mechanisms underlying vision requires the construction of computational models that not only emulate the brain's anatomy and physiology, but ultimately match its performance on visual tasks. In recent years, “natural” images have become popular in the study of vision and have been used to show apparently impressive progress in building such models. Here, we challenge the use of uncontrolled “natural” images in guiding that progress. In particular, we show that a simple V1-like model—a neuroscientist's “null” model, which should perform poorly at real-world visual object recognition tasks—outperforms state-of-the-art object recognition systems (biologically inspired and otherwise) on a standard, ostensibly natural image recognition test. As a counterpoint, we designed a “simpler” recognition test to better span the real-world variation in object pose, position, and scale, and we show that this test correctly exposes the inadequacy of the V1-like model. Taken together, these results demonstrate that tests based on uncontrolled natural images can be seriously misleading, potentially guiding progress in the wrong direction. Instead, we reexamine what it means for images to be natural and argue for a renewed focus on the core problem of object recognition—real-world image variation.     

Formaldehyde cross-linking of gliadin films: effects on mechanical and water barrier properties

In this study, pioneering results on specific chemical modifications of wheat gluten gliadins and the corresponding impact on mechanical and water barrier properties of derived films are presented. Films were prepared from gliadins chemically treated with formaldehyde and subsequently mixed with different concentrations of glycerol as a plasticizing agent. Water vapor barrier and mechanical properties of the films were evaluated as a function of relative humidity and glycerol concentration. Formaldehyde treatment led to enhanced mechanical properties and, to a lesser extent, improved water barrier of the films, effects which point to the formation of new intermolecular bonds between monomeric gliadins. The occurrence of cross-linking was supported by SDS-PAGE analysis. Cross-linked films maintained their integrity after immersion in water and had similar optical properties to control films. The effect of glycerol and humidity on water vapor permeability and the mechanical properties of films was less acute when proteins were treated with formaldehyde. Thus, chemical treatment of proteins is shown to be a very effective route for optimizing the use of these films in packaging applications.     

Muscle fatigue and metabolic responses following three different antagonist pre-load resistance exercises

PurposePreload of antagonist muscles can be achieved by reciprocal actions (RAs) or by opposing muscle actions. However, evidence concerning neuromuscular and fatigue responses are scarce.ObjectiveTo compare the effects of different knee flexor (KF) preload methods on knee extension (KE) vastus medialis muscle fatigue, based on EMG-spectral index (FI), load range (LR), total work (TW), blood lactate (LAC) and biceps femoris co-activation (BFc) during resistance exercise.MethodsTwenty-four healthy men (23.5 ± 3.6 yrs) performed three antagonist pre-load isokinetic exercises (4 sets, 10 repetitions, 60° s^?1, 1 min rest between sets): RA (KF contraction immediately followed by KE); Superset (SS; one KF set immediately followed by one KE set); Multiple Set (MS; four KF sets followed by four KE sets).ResultsTotal work was significantly greater in RA. There was no significant decrease in LR between sets in RA. The BFc did not differ between protocols (p = 0.063). However, RA presented greater biceps femoriscoactivation. The FI was greater during SS compared to RA and MS (p < 0.05). The SS had greater LAC when compared to MS and RA (p = 0.005 and p = 0.007, respectively).ConclusionIt is suggested that the RA protocol is more neuromuscular and metabolic efficient during the performance of knee extension resistance exercise.     

In vitro propagation of three <Emphasis Type="Italic">Agave</Emphasis> species used for liquor distillation and three for landscape

In vitro bud clusters of Calathea orbifolia (Linden) Kennedy were obtained and subcultured in semi-solid (agar) medium and temporary immersion system (TIS) for 12 weeks. Uniform young plants were selected and transferred to soilless mix in a growth chamber for ex vitro acclimatization during 35 days, followed by growing in a shaded greenhouse for 65 days. Comparison of in vitro leaf anatomy, ex vitro photosynthetic behaviors and growth was made between two cultural systems. Plants in TIS produced thicker leaf chlorenchyma and aquiferous parenchyma, lower stomatal frequency and more epicuticular wax than did those in semi-solid medium. Plants from semi-solid medium had consistently lower leaf Fv/Fm values than plants from TIS. Leaf Fv/Fm value in plants from TIS decreased to 0.65 at day 7 after transfer and increased soon up to 0.76 thereafter. In contrast, leaf Fv/Fm value in plants from semi-solid medium reduced to 0.27 at day 7 after transfer and increased slowly up to 0.68 at day 35. During ex vitro acclimatization, plants in TIS had substantial higher photosynthetic rates than plants in semi-solid medium. Plants from TIS had subsequent higher leaf area, fresh and dry weights than plants from semi-solid medium.     

Inhibition of the HIV-1 and HIV-2 proteases by curcumin and curcumin boron complexes

Curcumin, a relatively non-toxic natural product isolated from Curcuma longa, is a modest inhibitor of the HIV-1 (1050 = 100 μM) and HIV-2 (IC₅₀ = 250 μM) proteases. Simple modifications of the curcumin structure raise the IC₅₀ value but complexes of the central dihydroxy groups of curcumin with boron lower the IC₅₀ to a value as low as 6 μM. The boron complexes are also time-dependent inactivators of the HIV proteases. The increased affinity of the boron complexes may reflect binding of the orthogonal domains of the inhibitor in intersecting sites within the substrate-binding cavity of the enzyme, while activation of the ,β-unsaturated carbonyl group of curcumin by chelation to boron probably accounts for time-dependent inhibition of the enzyme.     

Combining simple blood tests to identify primary care patients with unexpected weight loss for cancer investigation: Clinical risk score development,internal validation,and net benefit analysis

BackgroundUnexpected weight loss (UWL) is a presenting feature of cancer in primary care. Existing research proposes simple combinations of clinical features (risk factors, symptoms, signs, and blood test data) that, when present, warrant cancer investigation. More complex combinations may modify cancer risk to sufficiently rule-out the need for investigation. We aimed to identify which clinical features can be used together to stratify patients with UWL based on their risk of cancer.Methods and findingsWe used data from 63,973 adults (age: mean 59 years, standard deviation 21 years; 42% male) to predict cancer in patients with UWL recorded in a large representative United Kingdom primary care electronic health record between January 1, 2000 and December 31, 2012. We derived 3 clinical prediction models using logistic regression and backwards stepwise covariate selection: Sm, symptoms-only model; STm, symptoms and tests model; Tm, tests-only model. Fifty imputations replaced missing data. Estimates of discrimination and calibration were derived using 10-fold internal cross-validation. Simple clinical risk scores are presented for models with the greatest clinical utility in decision curve analysis. The STm and Tm showed improved discrimination (area under the curve ≥ 0.91), calibration, and greater clinical utility than the Sm. The Tm was simplest including age-group, sex, albumin, alkaline phosphatase, liver enzymes, C-reactive protein, haemoglobin, platelets, and total white cell count. A Tm score of 5 balanced ruling-in (sensitivity 84.0%, positive likelihood ratio 5.36) and ruling-out (specificity 84.3%, negative likelihood ratio 0.19) further cancer investigation. A Tm score of 1 prioritised ruling-out (sensitivity 97.5%). At this threshold, 35 people presenting with UWL in primary care would be referred for investigation for each person with cancer referred, and 1,730 people would be spared referral for each person with cancer not referred. Study limitations include using a retrospective routinely collected dataset, a reliance on coding to identify UWL, and missing data for some predictors.ConclusionsOur findings suggest that combinations of simple blood test abnormalities could be used to identify patients with UWL who warrant referral for investigation, while people with combinations of normal results could be exempted from referral.

Dr. Brian D Nicholson and colleagues investigate whether combinations of routine blood tests could be used to stratify patients in UK with unexpected weight loss based on their risk of cancer.     

Interaction of benzocaine with model membranes

We measured the absorption properties, water solubility and partition coefficients (P) between n-octanol, egg phosphatidylcholine (EPC) liposomes and erythrocyte ghosts/water for benzocaine (BZC), an ester-type always uncharged local anesthetic. The interaction of BZC with EPC liposomes was followed using Electron Paramagnetic Resonance, with spin labels at different positions in the acyl chain (5, 7, 12, 16-doxylstearic acid methyl ester). Changes in lipid organization upon BZC addition allowed the determination of P values, without phase separation. The effect of BZC in decreasing membrane organization (maximum of 11.6% at approx. 0.8:1 BZC:EPC) was compared to those caused by the local anesthetics tetracaine and lidocaine. Hemolytic tests revealed a biphasic (protective/inductive) concentration-dependent hemolytic effect for BZC upon rat erythrocytes, with an effective BZC:lipid molar ratio in the membrane for protection (RePROT), onset of hemolysis (ReSAT) and 100% membrane solubilization (ReSOL) of 1.0:1, 1.1:1 and 1.3:1, respectively. The results presented here reinforce the importance of considering hydrophobic interactions in the interpretation of the effects of anesthetics on membranes.     

Purification, immobilization, and characterization of a specific lipase from Staphylococcus warneri EX17 by enzyme fractionating via adsorption on different hydrophobic supports

Staphylococcus warneri strain EX17 produces three lipases with different molecular weights of 28, 30, and 45 kDa. The 45 kDa fraction (SWL-45) has been purified from crude protein extracts by one chromatographic step based on the selective adsorption of this lipase by interfacial activation on different hydrophobic supports at low ionic strength. The adsorption of SWL-45 on octyl-Sepharose increased the enzyme activity by 60%, but the other lipases were also adsorbed on this support. Using butyl-Toyopearl, which is a lesser hydrophobic support, the purification factor was close to 20, and the only protein band detected on the sodium dodecyl sulfate-polyacrylamide electrophoresis analysis gel was that corresponding to the SWL-45, which could be easily desorbed from the support by incubation with triton X-100, producing a purified enzyme. SWL-45 was immobilized under very mild conditions on cyanogen bromide Sepharose, showing similar activities and stability as for its soluble form but without intermolecular interaction. The effects of different detergents over the activity of the immobilized SWL-45 were analyzed, which was hyperactivated by factors of 1.3 and 2.5 with 0.01% Tween 80 and 0.1% Triton X-100, respectively, while ionic detergents produced detrimental effects on the enzyme activity even at very low concentrations. Optimal reaction conditions and the effect of other additives on the enzyme activity were also investigated.