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- ArticleWu M, Wang H, Kong D, Shao J, Song C, Yang T, Zhang Y.PeerJ. 2021;9:e12228.Osteoblast differentiation is a complex process that is essential for normal bone formation. A growing number of studies have shown that microRNAs (miRNAs) are key regulators in a variety of physiological and pathological processes, including osteogenesis. In this study, BMP2 was used to induce MC3T3-E1 cells to construct osteoblast differentiation cell model. Then, we investigated the effect of miR-452-3p on osteoblast differentiation and the related molecular mechanism by RT-PCR analysis, Western blot analysis, ALP activity, and Alizarin Red Staining. We found that miR-452-3p was significantly downregulated in osteoblast differentiation. Overexpression miR-452-3p (miR-452-3p mimic) significantly inhibited the expression of osteoblast marker genes RUNX2, osteopontin (OPN), and collagen type 1 a1 chain (Col1A1), and decreased the number of calcium nodules and ALP activity. In contrast, knockdown miR-452-3p (miR-452-3p inhibitor) produced the opposite effect. In terms of mechanism, we found that Smad4 may be the target of miR-452-3p, and knockdown Smad4 (si-Smad4) partially inhibited the osteoblast differentiation enhanced by miR-452-3p. Our results suggested that miR-452-3p plays an important role in osteoblast differentiation by targeting Smad4. Therefore, miR-452-3p is expected to be used in the treatment of bone formation and regeneration.
- ArticleWei C, Menyuk CR, Hu J.Opt Express. 2016 May 30;24(11):12228-39.We study bend loss in chalcogenide negative curvature fibers with different polarizations, different tube wall thicknesses, and different bend directions relative to the mode polarization. The coupling between the core mode and tube modes induces bend loss peaks in the two non-degenerate modes at the same bend radius. There is as much as a factor of 28 difference between the losses of the two polarization modes. The fiber with a larger tube wall thickness, corresponding to a smaller inner tube diameter, can sustain a smaller bend radius. The bend loss is sensitive to the bend direction when coupling occurs between the core mode and tube modes. A bend loss of 0.2 dB/m at a bend radius of 16 cm, corresponding to 0.2 dB/turn, can be achieved in a chalcogenide negative curvature fiber.
- ArticleDougherty RJ, Ramachandran J, Liu F, An Y, Wanigatunga AA, Tian Q, Bilgel M, Simonsick EM, Ferrucci L, Resnick SM, Schrack JA.Alzheimers Dement (Amst). 2021;13(1):e12228.INTRODUCTION: Higher energetic costs for mobility predict gait speed decline. Slow gait is linked to cognitive decline and Alzheimer's disease (AD). Whether the energetic cost of walking is linked to AD pathology is unknown. We investigated the cross-sectional association between the energetic cost of walking, gait speed, and amyloid beta (Aβ) status (+/-) in older adults.
METHODS: One hundred forty-nine cognitively normal adults (56% women, mean age 77.5 ± 8.4 years) completed customary-paced walking assessments with indirect calorimetry and 11C-Pittsburgh compound B positron emission tomography. Logistic regression models examined associations adjusted for demographics, body composition, comorbid conditions, and apolipoprotein E ε4.
RESULTS: Each 0.01 mL/kg/m greater energy cost was associated with 18% higher odds of being Aβ+ (odds ratio [OR] = 1.18; 95% confidence interval [CI]: 1.04 to 1.34; P = .011). These findings were not observed when investigating gait speed (OR = 0.99; 95% CI: 0.97 to 1.01; P = .321).
DISCUSSION: High energetic cost of walking is linked to AD pathology and may be a potential target for therapeutic intervention. - ArticleKapfenberger D, Sonn-Segev A, Roichman Y.Opt Express. 2013 May 20;21(10):12228-37.In-line holographic optical imaging has the unique capability of high speed imaging in three dimensions at rates limited only by the imaging rate of the camera used. In this technique the 3D data is recorded on the detector in a form of a hologram generated by diffraction between the scattered and unscattered light passing through the sample. For dilute samples of single particles or a small cluster of particles, this technique was shown to result in particle tracking with spatial positioning accuracy of a few nanometers. For dense suspension only approximate reconstruction were achieved with systematic axial positioning errors. We propose a scheme to extend accurate holographic microscopy to dense suspensions, by calibrating the Rayleigh-Sommerfeld reconstruction algorithm against Lorentz-Mie scattering theory. We perform this calibration both numerically and experimentally and define the parameter space in which accurate imaging is achieved, and in which numerical calibration holds. We demonstrate the validity of our approach by imaging two attached particles and measuring the distance between their centers with 36 nm accuracy. A difference of 50 nm in particle diameter is easily measured.
- ArticleQian J, Jiang F, Su K, Li Q, Yuan D, Hong M.Inorg Chem. 2014 Dec 01;53(23):12228-30.A synthetic strategy to construct discrete indium-organic polyhedra has been illustrated based on small three-membered windows from a 2,5-pyridinedicarboxylate (PDC) ligand with an angle of 120°. [Et2NH2]6[In6(PDC)12] (InOF-10) is a high-symmetry octahedron with eight three-membered windows, and [Et2NH2]18[In18(BPDC)6(PDC)30] (InOF-11) is a complex polyhedron derived from 3-edge-removed octahedra with an auxiliary biphenyl-3,3'-dicarboxylate (BPDC) ligand. Moreover, the sorption behavior of the latter is also well investigated.
- ArticleSundaram V, Mohammed S, Zyuzikov N.Heliyon. 2022 Dec;8(12):e12228.Background: The present study aimed to evaluate the effects of whole-body exposure to 150 kHz Intermediate-frequency electromagnetic radiation (IF EMR) on fertility indicators of male rats since human exposure to this frequency has increased in recent years. Fourteen adult male Sprague-Dawley rats were used in this study. The rats were randomly divided into a control and an EMR group (n = 7/group). The EMR group was continuously irradiated with 150 kHz EMR for 8 weeks. Male fertility indicators, body mass, testicular mass, rectal temperature, testicular histology, histometry, sperm analysis, and serum gonadotrophic hormone levels were evaluated.
Results: The study showed no negative effect on body mass (grams) (323.78 ± 37.09 to 305.09 ± 26.36; p = 0.72), rectal temperature (Control: 34.5 °C-35.8 °C; EMR: 34.4 °C-36.1 °C; p < 0.05), and testicular histology. There were significant reductions in left and right testicular mass (1.04 ± 0.10 to 0.96 ± 0.32: p = 0.03 and 1.02 ± 0.08 to 0.96 ± 0.35 p = 0.04, respectively), interstitial cell count/1000 μm2 (5.33 ± 0.56 to 4.47 ± 0.48; p = 0.01), sperm motility trajectories (p = 0.05) and sperm distal cytoplasmic droplet (%) (2.27 ± 2.28 to 6.84 ± 5.01; p = 0.05). A significant increase in follicle-stimulating hormone levels was observed (13.44 ± 6.38 IU/ml to 26.96 ± 8.07 IU/ml; p = 0.01).
Conclusions: Most male fertility parameters of rats in the present study were not affected by 8 weeks of whole-body exposure to 150 kHz EMR. However, significant decreases in testicular mass, interstitial cell count/1000 μm2, sperm motility trajectories, and distal cytoplasmic droplets were observed, as well as an increase in FSH level. - ArticleWu J, Li W, Zhang X, Shi F, Jia Q, Wang Y, Shi Y, Wu S, Wang X.Sci Rep. 2024 05 28;14(1):12228.DNA topoisomerase II alpha (TOP2A) expression, gene alterations, and enzyme activity have been studied in various malignant tumors. Abnormal elevation of TOP2A expression is considered to be related to the development of non-small cell lung cancer (NSCLC). However, its association with tumor metastasis and its mode of action remains unclear. Bioinformatics, real-time quantitative PCR, immunohistochemistry and immunoblotting were used to detect TOP2A expression in NSCLC tissues and cells. Cell migration and invasion assays as well as cytoskeletal staining were performed to analyze the effects of TOP2A on the motility, migration and invasion ability of NSCLC cells. Cell cycle and apoptosis assays were used to verify the effects of TOP2A on apoptosis as well as cycle distribution in NSCLC. TOP2A expression was considerably upregulated in NSCLC and significantly correlated with tumor metastasis and the occurrence of epithelial-mesenchymal transition (EMT) in NSCLC. Additionally, by interacting with the classical ligand Wnt3a, TOP2A may trigger the canonical Wnt signaling pathway in NSCLC. These observations suggest that TOP2A promotes EMT in NSCLC by activating the Wnt/β-catenin signaling pathway and positively regulates malignant events in NSCLC, in addition to its significant association with tumor metastasis. TOP2A promotes the metastasis of NSCLC by stimulating the canonical Wnt signaling pathway and inducing EMT. This study further elucidates the mechanism of action of TOP2A, suggesting that it might be a potential therapeutic target for anti-metastatic therapy.
- ArticleLi M, Li D, O'Keeffe M, Su ZM.Chem Commun (Camb). 2015 Aug 07;51(61):12228-30.The structure of a recently-published metal-organic framework is deconstructed into its underlying net which is found to be of exceptional complexity. It is shown that this is because of local pentagonal symmetry and the structure is in fact the simplest possible (minimal transitivity) given that local symmetry.
- ArticleBege M, Singh V, Sharma N, Debreczeni N, Bereczki I, Poonam, Herczegh P, Rathi B, Singh S, Borbás A.Sci Rep. 2023 07 28;13(1):12228.Drug-resistant Plasmodium falciparum (Pf) infections are a major burden on the population and the healthcare system. The establishment of Pf resistance to most existing antimalarial therapies has complicated the problem, and the emergence of resistance to artemisinin derivatives is even more concerning. It is increasingly difficult to cure malaria patients due to the limited availability of effective antimalarial drugs, resulting in an urgent need for more efficacious and affordable treatments to eradicate this disease. Herein, new nucleoside analogues including morpholino-nucleoside hybrids and thio-substituted nucleoside derivatives were prepared and evaluated for in vitro and in vivo antiparasitic activity that led a few hits especially nucleoside-thiopyranoside conjugates, which are highly effective against Pf3D7 and PfRKL-9 strains in submicromolar concentration. One adenosine derivative and four pyrimidine nucleoside analogues significantly reduced the parasite burden in mouse models infected with Plasmodium berghei ANKA. Importantly, no significant hemolysis and cytotoxicity towards human cell line (RAW) was observed for the hits, suggesting their safety profile. Preliminary research suggested that these thiosugar-nucleoside conjugates could be used to accelerate the antimalarial drug development pipeline and thus deserve further investigation.
- ArticleLi Y, Xu X, Xia C, Zhang L, Pan L, Liu Q.Chem Commun (Camb). 2012 Dec 28;48(100):12228-30.A novel and efficient route for the synthesis of 7-aza-tetrahydroindoles from N-aryl/alkyl-alkenoylacetamides and ethyl isocyanoacetate is described. A mechanism, involving a stepwise [3+2] cycloaddition-intramolecular aza-Michael addition cascade, is proposed that explains the origin of the double nucleophilic attack on the isocyanide carbon atom.
- ArticleZahedifar R, Keymasi Khalaji A.Sci Rep. 2022 07 18;12(1):12228.In this study, an adaptive backstepping method is proposed to regulate the blood glucose induced by meals for type-1 diabetic patients. The backstepping controller is used to control the blood glucose level and an adaptive algorithm is utilized to compensate for the blood glucose induced by meals. Moreover, the effectiveness of the proposed method is evaluated by comparing results in two different case studies: in the presence of actuator faults and the loss of control input for a short while during treatment. Effects of unannounced meals three times a day are investigated for a nominal patient in every case. It is argued that adaptive backstepping is the preferred control method in either case. The Lyapunov theory is used to prove the stability of the proposed method. Obtained results, indicated that the adaptive backstepping controller is stable, and the desired level of glucose concentration is being tracked efficiently.
- ArticleSanderson-Cimino M, Elman JA, Tu XM, Gross AL, Panizzon MS, Gustavson DE, Bondi MW, Edmonds EC, Eglit GML, Eppig JS, Franz CE, Jak AJ, Lyons MJ, Thomas KR, Williams ME, Kremen WS, Alzheimer's Disease Neuroimaging Initiative.Alzheimers Dement (N Y). 2022;8(1):e12228.INTRODUCTION: Practice effects (PEs) on cognitive tests obscure decline, thereby delaying detection of mild cognitive impairment (MCI). Importantly, PEs may be present even when there are performance declines, if scores would have been even lower without prior test exposure. We assessed how accounting for PEs using a replacement-participants method impacts incident MCI diagnosis.
METHODS: Of 889 baseline cognitively normal (CN) Alzheimer's Disease Neuroimaging Initiative (ADNI) participants, 722 returned 1 year later (mean age = 74.9 ± 6.8 at baseline). The scores of test-naïve demographically matched "replacement" participants who took tests for the first time were compared to returnee scores at follow-up. PEs-calculated as the difference between returnee follow-up scores and replacement participants scores-were subtracted from follow-up scores of returnees. PE-adjusted cognitive scores were then used to determine if individuals were below the impairment threshold for MCI. Cerebrospinal fluid amyloid beta, phosphorylated tau, and total tau were used for criterion validation. In addition, based on screening and recruitment numbers from a clinical trial of amyloid-positive individuals, we estimated the effect of earlier detection of MCI by accounting for cognitive PEs on a hypothetical clinical trial in which the key outcome was progression to MCI.
RESULTS: In the ADNI sample, PE-adjusted scores increased MCI incidence by 19% (P < .001), increased proportion of amyloid-positive MCI cases (+12%), and reduced proportion of amyloid-positive CNs (-5%; P's < .04). Additional calculations showed that the earlier detection and increased MCI incidence would also substantially reduce necessary sample size and study duration for a clinical trial of progression to MCI. Cost savings were estimated at ≈$5.41 million.
DISCUSSION: Detecting MCI as early as possible is of obvious importance. Accounting for cognitive PEs with the replacement-participants method leads to earlier detection of MCI, improved diagnostic accuracy, and can lead to multi-million-dollar cost reductions for clinical trials. - ArticleThamphiwatana S, Fu V, Zhu J, Lu D, Gao W, Zhang L.Langmuir. 2013 Oct 01;29(39):12228-33.We report a novel pH-responsive gold nanoparticle-stabilized liposome system for gastric antimicrobial delivery. By adsorbing small chitosan-modified gold nanoparticles (diameter ~10 nm) onto the outer surface of negatively charged phospholipid liposomes (diameter ~75 nm), we show that at gastric pH the liposomes have excellent stability with limited fusion ability and negligible cargo releases. However, when the stabilized liposomes are present in an environment with neutral pH, the gold stabilizers detach from the liposomes, resulting in free liposomes that can actively fuse with bacterial membranes. Using Helicobacter pylori as a model bacterium and doxycycline as a model antibiotic, we demonstrate such pH-responsive fusion activity and drug release profile of the nanoparticle-stabilized liposomes. Particularly, at neutral pH the gold nanoparticles detach, and thus the doxycycline-loaded liposomes rapidly fuse with bacteria and cause superior bactericidal efficacy as compared to the free doxycycline counterpart. Our results suggest that the reported liposome system holds a substantial potential for gastric drug delivery; it remains inactive (stable) in the stomach lumen but actively interacts with bacteria once it reaches the mucus layer of the stomach where the bacteria may reside.
- ArticleGao L, Yang B, Du J, Zhang C, Ma S, Guo Z, Wang Y, Wang J, Li X, Wu D, Lin P.Nanoscale. 2024 Jun 27;16(25):12228-12236.Schottky-type self-powered UV photodetectors are promising for next-generation imaging systems. Nevertheless, conventional device fabrication using high-energy metal deposition brings unintentional interface defects, leading to deteriorated device performance and inhomogeneities. Emerging two-dimensional (2D) metallic materials offer an alternative pathway to overcoming such limitations because of their naturally passivated surfaces and the ease of combining with mature bulk semiconductors via van der Waals (vdW) integration. Here, we report the controllable preparation of MoTe2 in the pure 1T' phase and the fabrication of a high-performance 1T'-MoTe2/GaN vdW Schottky photodiode. With the reduced interface states and suppressed dark current as low as 20 pA at zero bias, the photodiode exhibits a remarkable UV-to-visible (R350/R400) rejection ratio of 1.6 × 104, a stable photoresponsivity of ∼50 mA W-1 and a detectivity of 3.5 × 1012 Jones under 360 nm illumination. The photocurrent ON/OFF ratio reaches ∼4.9 × 106 under 10.5 mW irradiation (360 nm). In particular, the 1T'-MoTe2/GaN Schottky diode shows excellent weak-light detection capability, which could detect a 3 nW 360 nm laser and the light emission from a lighter with a pronounced Ilight/Idark ratio of ∼2. Finally, the applications of the device in self-powered UV imaging and optical communication are demonstrated. These results reveal the great prospects of 2D/3D integration in multifunctional optoelectronics, which may inspire novel 2D-related devices and expand their applications in widespread fields.
- ArticleBathula SS, Srikantha L, Patrick T, Stern NA.Cureus. 2020 Dec 22;12(12):e12228.Objective Tracheostomy is one of the oldest operations for the management of airway obstruction. With time, indications expanded to prolonged mechanical ventilation, and currently, the majority of tracheostomies are done for this reason. There are several techniques used in a tracheostomy procedure, depending on surgeon preference. Immediate complications such as bleeding, pneumothorax, pneumomediastinum, airway fire, and posterior tracheal wall perforation with esophageal injury are rare, although they do occur, and must be managed accordingly. This study aimed to assess differences in types and rates of immediate postoperative complications in patients undergoing tracheostomy when performed under general anesthesia and local anesthesia (awake tracheostomies) at a large academic institution. This is a continuing ongoing literature reporting tracheostomy adverse events. Methods A retrospective chart review was performed to identify patients who underwent tracheostomy placement between January 1, 2013 and December 31, 2019 at the Detroit Medical Center, USA. Postoperative complications such as bleeding, pneumothorax, pneumomediastinum, airway fire, and posterior tracheal perforation were collected along with gender, age, and revision tracheostomy status. IBM SPSS Statistics (IBM Inc., Armonk, USA) was used for statistical analysis with the statical significance defined as a p<0.05. Results A total of 1,469 patient charts were reviewed. Of these, 1,342 met the inclusion and exclusion criteria, of which, males were 57.2% (n=768), and females were 42.8% (n=574). The age range was 18 years to 96 years (mean=58.03; SD= 15.97), and BMI range was 12-83 (mean=28.77; SD=7.885). Multinomial logistic regression was performed to determine whether age, BMI, sex, and revision tracheostomies were represented across both general and awake tracheostomy groups proportionally to their numbers in the total sample. It showed non-significant value for age (χ2=0.776, p=0.378), BMI (χ2=0.004, p=0.947), but significant value for sex (χ2=4.645, p=0.031), revision tracheostomy (χ2=18.282, p<0.001), indicating that males and revision tracheostomies over-represented in awake tracheostomies. Next, Pearson correlation analysis was performed to determine any significant linear relationship between age, sex, and tracheostomy complications. It showed a significant positive correlation between age and tracheal stomal infection [r(1,340)=0.062, p=0.022]. An independent sample t-test showed a statistically significant difference between the mean pneumothorax and pneumomediastinum of general (n=1,277, mean=0.01, SD=0.088) and awake tracheostomies (n=65, mean=0.08, SD=0.269, t=2.069, p=0.043). Pneumothorax pneumomediastinum complications between the general tracheostomy and awake tracheostomy odds ratio (OR)-6.22, indicates the chance of pneumothorax /pneumomediastinum complication is 6.22 times more in awake tracheostomy than general tracheostomy. Based on the above statistical analysis, we rejected the null hypothesis. Conclusions Tracheostomy is the procedure of choice to relieve the upper airway obstruction and treat patients requiring prolonged mechanical ventilation. A slightly higher number of Immediate postoperative complications in awake tracheostomy were noticed in patients with more surgically challenging revision tracheostomies.
- ArticleKoulakov I, Kasatkina E, Shapiro NM, Jaupart C, Vasilevsky A, El Khrepy S, Al-Arifi N, Smirnov S.Nat Commun. 2016 07 19;7:12228.The Toba Caldera has been the site of several large explosive eruptions in the recent geological past, including the world's largest Pleistocene eruption 74,000 years ago. The major cause of this particular behaviour may be the subduction of the fluid-rich Investigator Fracture Zone directly beneath the continental crust of Sumatra and possible tear of the slab. Here we show a new seismic tomography model, which clearly reveals a complex multilevel plumbing system beneath Toba. Large amounts of volatiles originate in the subducting slab at a depth of ∼150 km, migrate upward and cause active melting in the mantle wedge. The volatile-rich basic magmas accumulate at the base of the crust in a ∼50,000 km(3) reservoir. The overheated volatiles continue ascending through the crust and cause melting of the upper crust rocks. This leads to the formation of a shallow crustal reservoir that is directly responsible for the supereruptions.
- ArticlePathak RR, Jangam AP, Malik A, Sharma N, Jaiswal DK, Raghuram N.Sci Rep. 2020 07 22;10(1):12228.Nitrate (N) response is modulated by light, but not understood from a genome-wide perspective. Comparative transcriptomic analyses of nitrate response in light-grown and etiolated rice leaves revealed 303 and 249 differentially expressed genes (DEGs) respectively. A majority of them were exclusive to light (270) or dark (216) condition, whereas 33 DEGs were common. The latter may constitute response to N signaling regardless of light. Functional annotation and pathway enrichment analyses of the DEGs showed that nitrate primarily modulates conserved N signaling and metabolism in light, whereas oxidation-reduction processes, pentose-phosphate shunt, starch-, sucrose- and glycerolipid-metabolisms in the dark. Differential N-regulation of these pathways by light could be attributed to the involvement of distinctive sets of transporters, transcription factors, enriched cis-acting motifs in the promoters of DEGs as well as differential modulation of N-responsive transcriptional regulatory networks in light and dark. Sub-clustering of DEGs-associated protein-protein interaction network constructed using experimentally validated interactors revealed that nitrate regulates a molecular complex consisting of nitrite reductase, ferredoxin-NADP reductase and ferredoxin. This complex is associated with flowering time, revealing a meeting point for N-regulation of N-response and N-use efficiency. Together, our results provide novel insights into distinct pathways of N-signaling in light and dark conditions.
- ArticleFurió V, Garijo R, Durán M, Moya A, Bell JC, Sanjuán R.J Virol. 2012 Nov;86(22):12228-36.Given the parasitic nature of viruses, it is sometimes assumed that rates of viral replication and dissemination within hosts (within-host fitness) correlate with virulence. However, there is currently little empirical evidence supporting this principle. To test this, we quantified the fitness and virulence of 21 single- or double-nucleotide mutants of the vesicular stomatitis virus in baby hamster kidney cells (BHK-21). We found that, overall, these two traits correlated positively, but significant outliers were identified. Particularly, a single mutation in the conserved C terminus of the N nucleocapsid (U1323A) had a strongly deleterious fitness effect but did not alter or even slightly increased virulence. We also found a double mutant of the M matrix protein and G glycoprotein (U2617G/A3802G mutant) with high fitness yet low virulence. We further characterized these mutants in primary cultures from mouse brain cells and in vivo and found that their relative fitness values were similar to those observed in BHK-21 cells. The mutations had weak effects on the virus-induced death rate of total brain cells, although they specifically reduced neuron death rates. Furthermore, increased apoptosis levels were detected in neurons infected with the U2617G/A3802G mutant, consistent with its known inability to block interferon secretion. In vivo, this mutant had reduced virulence and, despite its low brain titer, it retained a relatively high fitness value owing to its ability to suppress competitor viruses. Overall, our results are in broad agreement with the notion that viral fitness and virulence should be positively correlated but show that certain mutations can break this association and that the fitness-virulence relationship can depend on complex virus-host and virus-virus interactions.
- ArticleAndronache I, Marin M, Fischer R, Ahammer H, Radulovic M, Ciobotaru AM, Jelinek HF, Di Ieva A, Pintilii RD, Drăghici CC, Herman GV, Nicula AS, Simion AG, Loghin IV, Diaconu DC, Peptenatu D.Sci Rep. 2019 08 22;9(1):12228.The ever decreasing area of forests has lead to environmental and economical challenges and has brought with it a renewed interest in developing methodologies that quantify the extent of deforestation and reforestation. In this study we analyzed the deforested areas of the Apuseni Mountains, which has been under economic pressure in recent years and resulted in widespread deforestation as a means of income. Deforested surface dynamics modeling was based on images contained in the Global Forest Database, provided by the Department of Geographical Sciences at Maryland University between 2000 and 2014. The results of the image particle analysis and modelling were based on Total Area (ha), Count of patches and Average Size whereas deforested area distribution was based on the Local Connected Fractal Dimension, Fractal Fragmentation Index and Tug-of-War Lacunarity as indicators of forest fragmentation or heterogeneity. The major findings of the study indicated a reduction of the tree cover area by 3.8%, an increase in fragmentation of 17.7% and an increase in heterogeneity by 29%, while fractal connectivity decreased only by 0.1%. The fractal and particle analysis showed a clustering of forest loss areas with an average increase from 1.1 to 3.0 ha per loss site per year. In conclusion, the fractal and particle analysis provide a relevant methodological framework to further our understanding of the spatial effects of economic pressure on forestry.
- ArticlePiazza V, Weinhausen B, Diaz A, Dammann C, Maurer C, Reynolds M, Burghammer M, Köster S.ACS Nano. 2014 Dec 23;8(12):12228-37.Hair cell stereocilia are crucial for hearing and the sense of balance. They include an array of accurately packed, parallel actin filaments and act as levers, which transform mechanical deformation into neuronal signals. The length of vestibular stereocilia reaches several micrometers, whereas, for individual microfilaments, the diameter and therefore the characteristic length scale in the lateral direction is on the order of a few nanometers. These orders of magnitude render X-rays an ideal tool for investigating actin packing, and numerous studies on reconstituted in vitro systems have revealed important information. Here we report on the characterization of intact stereocilia using two nanoscale X-ray techniques. We use X-ray ptychography to image stereocilia with quantitative phase contrast and high dose efficiency, showing stereocilia with diameters and lengths in the expected range. We further employ X-ray nanodiffraction using a nanofocused X-ray beam on the same order of magnitude as the width of a stereocilium. Despite the small probe volume we can clearly visualize the stereocilia bundles. From the individual diffraction patterns we determine the local orientation of the actin structures and can clearly correlate them with the corresponding visible-light fluorescence images. Furthermore, azimuthal integration of individual diffraction patterns reveals distinct intensity curves, showing modulations of the signal, which reflect the relevant length scales and pronounced order in the biological system. The applied techniques are not limited to the studies on stereocilia but have the potential of being applied to many biological and soft-matter systems, in particular if a pronounced degree of order is present.