Medical Biophysics

Music therapy as a non-invasive therapeutic modality is gaining prominence worldwide both in hospital settings as an adjunct therapy as well as for community wellbeing. Music therapy offers encouraging evidence-based outcomes for stabilising vital parameters to improve symptoms associated with complex illnesses such as autism spectrum disorder or major depressive disorders. The purpose of this review is to 1) identify scientific literatures that offer insights on the effect of music therapy on oxygen saturation levels of patients undergoing treatments for diverse conditions; 2) compare the effects of music therapy based on identified parameters 3) analyse the critical reviews of the researchers of studies included in this literature scan and 4) synthesise the review findings for the benefit of future scientific researches on the effect of music therapy on oxygen saturation levels. In this review, an analysis of relevant scientific papers published in the last 80 years from 1940 to 2020 (as available) was done by searching databases such as PubMed, Cochrane Library, Wiley Online Library, Gray Literature sources such as Google Scholar, Worldcat; DOAJ, and WHO Global Index Medicus. Eighteen relevant papers describing music therapy's effect on the patient's oxygen saturation levels (under different conditions) were included in the review. The results and discussions respectively compare and analyse characteristics of included studies, music therapy administered, measuring device used, the effectiveness of music therapy on oxygen saturation levels, and critical reviews of authors of the scanned literature.

The National Health and Nutrition Examination Survey (NHANES 1999e2004) includes adult and pediatric comparisons for total body bone and body composition results. Because dual-energy x-ray absorptiometry (DXA) measurements from different manufacturers are not standardized, NHANES reference values currently are applicable only to a single make and model of Hologic DXA system. The purpose of this study was to derive body composition reference curves for GE Healthcare Lunar DXA systems. Published values from the NHANES 1999e2004 survey were acquired from the Centers for Disease Control and Prevention website. Using previously reported crosscalibration equations between Hologic and GE-Lunar, we converted the total body and regional bone and soft-tissue measurements from NHANES 1999e2004 to GE-Lunar values. The LMS (LmsChartMaker Pro Version 3.5) curve fitting method was used to generate GE-Lunar reference curves. Separate curves were generated for each sex and ethnicity. The reference curves were also divided into pediatric ( 20 years old) and adult (O20 years old) groups. Adult reference curves were derived as a function of age. Additional relationships of pediatric DXA values were derived as a function of height, lean mass, and bone area. Robustness was tested between Hologic and GE-Lunar Z-score values. The NHANES 1999e2004 survey included a sample of 20,672 participants' (9630 female) DXA scans. A total of 8056 participants were younger than 20 yr and were included in the pediatric reference data set. Participants enrolled in the study who weighed more than 136 kg (over scanner table limit) were excluded. The average Z-scores comparing the new GE-Lunar reference curves are close to zero, and the standard deviation of the Z-scores are close to one for all variables. As expected, all measurements on the GE-Lunar reference curves for participants younger than 20 yr increase monotonically with age. In the adult population, most of the curves are constant at younger age and drop moderately as age increases. We have presented NHANES reference curves applicable to DXA whole-body scans acquired on GE Healthcare Lunar systems by age, sex and ethnicity. Users of GE Healthcare GE-Lunar DXA systems can now benefit from the large body composition reference data set collected in the NHANES 1999e2004 study.

Mobilisierung der Strahlenforschung im Nationalsozialismus. Der Fall Boris Rajewsky, in: Moritz Epple, Johannes Fried, Raphael Gross u. Janus Gudian (Hgg.): „Politisierung der Wissenschaft“. Jüdische Wissenschaftler und ihre Gegner an der Universität Frankfurt vor und nach 1933, Göttingen: Wallstein 2016: 395-424 (= Schriftenreihe des Frankfurter Universitätsarchivs 5).

Alexander v. Schwerin (Berlin) opens his essay, Mobilisierung der Strahlenforschung im
Ntttionalsozialisrnw- Der Fall Boris Rajewsky (>>Mobilization of Radiation Research
under National Socialism- the Case of Boris Rajewsky«), with the observation rhar
Rajewsky's scientific expertise made him indispensable in both the Third Reich and
West Germany and that he enjoyed a successful career under both political systems.
Against this background, it is scarcely credible that such a powerful seieneist (he had
around 22 postdoctoral students and became the mostsenior radiation protection scientist
in the West German nuclear program) could escape the political demands of
rhe time. According to v. Schwerin, the Russian emigrant very quickly succeeded in
gaining rhe trust of influential Nazisand thereby in defusing the questions regarding
his trustworrhiness raised by his origin. As the former assistant ofFriedrieb Dessauer,
he was in a good position to succeed the latteras the director of the Institute for rhe
Physical Faundarions of Medicine (subsequently rhe Kaiser Wilhelm Institute for
Biophysics, which was housed in the villa of the banker Georg Speyer, a founding patron
of the University ofFrankfurr, that had been expropriatcd by the Nazis). Rajewsky
argued after the war that joining the SA served the sole purpose of making his
person credible in the eyes of the Nazis and thus also of saving his imtitute. Von
Schwerin contrasts these Statements with a Ietter by Rajewsky to the head of the
Frankfurt Dozentenbund (the National Sodalist university lecturers' association), in
which Rajewsky expressed his willingness to promote the interests of members of the
Dozentenbund in his capacity as a member of the Administrative Board of the
Helmholtz Association.

In his work, Rajewsky was an able science manager and science politician who
maintained an extensive system of comacts reaching into the highest state offices of
the Third Reich. In addition, he benefited from ehe fact that his field, the usc of
radiation techniques and radioactive substances, rapidly acquired economic relevance
and that his institutewas entrusted with monitaring and measuring radioactivity co
determine harmfullimits and maximum tolerance doses. Rajewsky became all but indispensable,
however, when x-rays also began to be used for armaments. Later in the
war, the Army High Command commissioned Rajewsky's institute co study thc
effects of radiological weapons. As a result, some members of the institute's staff ran
experiments with Rajewsky's knowledge using radioactive inhalants on patients wichout
informing them. Von Schwerin concludes that Rajewsky collaborated activdy
with National Socialism, to which he accommodated his way of thinking and working.
The practical side ofhis work testifies to this, even though he never exposed himself
to ideological reproach. In his denazification trial, only Rajewsky's personal ourlook
was subjected to examination but not his practical work as a scientisr or rhe
research of the institute that he headed. However, under Rajewsky's leadership scientific
research rook full advantage of the opporrunities afforded by thc political
climate.

The resting membrane voltage of excitable cells such as neurons and muscle cells is determined by the electrochemical equilibrium of potassium and sodium ions. This voltage is calculated by using the Goldman-Hodgkin-Katz equation. However, from the quantum perspective, ions with significant quantum tunneling through closed channels can interfere with the electrochemical equilibrium and affect the value of the membrane voltage. Hence, in this case the equilibrium becomes quantum electrochemical. Therefore, the model of quantum tunneling of ions is used in this study to modify the Goldman-Hodgkin-Katz equation in such a way to calculate the resting membrane voltage at the point of equilibrium. According to the present calculations, it is found that lithium-with its lower mass-shows a significant depolarizing shift in membrane voltage. In addition to this, when the free gating energy of the closed channels decreases, even sodium and potassium ions depolarize the resting membrane voltage via quantum tunneling. This study proposes the concept of quantum electrochemical equilibrium, at which the electrical potential gradient, the concentration gradient and the quantum gradient (due to quantum tunneling) are balanced. Additionally, this concept may be used to solve many issues and problems in which the quantum behavior becomes more influential.

Increase in emitting electromagnetic waves sources (cell phone antennas, mobile phone, etc.) is a worry the local
population. This type of pollution is certainly invisible; however, but its effects on health are increasingly evident.
The purpose of this study is to verify if the different cell phone antennas at Kimwenza mission emit according
to the stipulated standards and if their electromagnetic radiation is reassuring for the surrounding population. 
We performed in situ measurements of electromagnetic fields of the relay antennas using a field meter and a
spectrum analyzer. The procedure followed is that proposed by the protocol of the National Agency of Frequencies
(ANFR) of France.
Of the twenty-four measurement points considered, field value varies between 0.03 and 6.71 V / m. After
extrapolation, the largest of value of 0.31 V/m is that of GSM 1800’s and this is 187 times lower than the norm.
And therefore, the results obtained shows that the radiation conformed to the standards of the ICNIRP in use.

Tre sensori che controllano temperatura, ossigenazione dei tessuti e frequenza respiratoria per rilevare indici anticipatori di problemi psicofisici che possono essere presenti in soggetti sintomatici e soprattutto negli asintomatici affetti dal COVID-19. In caso di rilevamento di anomalie in tutti i tre i parametri, effettuato a distanza ravvicinata e senza contatto, si può predire un possibile contagio da approfondire successivamente con altri controlli medici, quali il test del tampone.

The priming dose effect, called also the Raper-Yonezawa effect or simply the Yonezawa effect, is a special case of the radiation adaptive response phenomenon (radioadaptation), which refers to: (a) faster repair of direct DNA lesions (damage), and (b) DNA mutation frequency reduction after irradiation, by applying a small priming (conditioning) dose prior to the high detrimental (challenging) one. This effect is observed in many (but not all) radiobiological experiments which present the reduction of lesion, mutation or even mortality frequency of the irradiated cells or species. Additionally, the multi-parameter model created by Dr. Yonezawa and collaborators tried to explain it theoretically based on experimental data on the mortality of mice with chronic internal irradiation. The presented paper proposes a new theoretical approach to understanding and explaining the priming dose effect: it starts from the radiation adaptive response theory and moves to the three-parameter model, separately for two previously mentioned situations: creation of fast (lesions) and delayed damage (mutations). The proposed biophysical model was applied to experimental data-lesions in human lymphocytes and chromosomal inversions in mice-and was shown to be able to predict the Yonezawa effect for future investigations. It was also found that the strongest radioadaptation is correlated with the weakest cellular radiosensitivity. Additional discussions were focussed on more general situations where many small priming doses are used.

Harzianins HC are a series of 14-residue peptaibols containing three Aib-Pro motives separated by sequences of two Ž . usual amino acids Aib-Pro-Xaa-Xaa n. They are organized in a subtype of the 3 -helix, which results in an approximate 10 length of about 27-30 A for the helical rods, allowing them to span a bilayer. Permeabilization of small unilamellar vesicles Ž . composed of zwitterionic lipids egg phosphatidylcholinercholesterol 7r3 and 8r2 by harzianins HC was observed, as Ž . well as voltage-gated macroscopic conductance and single-channel formation in planar lipid bilayers DOPErPOPC 7r3 . The permeabilization process was shown to increase with increasing the helix global hydrophobicity. The ion channel-forming properties appeared rather favoured by an increase in the peptide amphipathicity. The set of conductance levels increasing in geometrical progression, reflecting the sequential uptake and release of monomers which is characteristic of the barrel-stave model for ion-channels described for alamethicin was not observed. The passage of ions through the bilayer would rather be the result of a set of aggregates with fixed numbers of monomers formed in the bilayer. The permeability process and the voltage-gated properties could thus result from different mechanisms showing that harzianins HC can permeabilize membranes via bilayer destabilization or channels, depending on the membrane system, composition and application of voltage.

To determine the mean and range of location-averaged breast skin thickness using highresolution dedicated breast CT for use in Monte Carlo-based estimation of normalized glandular dose coefficients. Methods: This study retrospectively analyzed image data from a clinical study investigating dedicated breast CT. An algorithm similar to that described by Huang et al. ["The effect of skin thickness determined using breast CT on mammographic dosimetry," Med. Phys. 35(4), 1199-1206 (2008)] was used to determine the skin thickness in 137 dedicated breast CT volumes from 136 women. The location-averaged mean breast skin thickness for each breast was estimated and the study population mean and range were determined. Pathology results were available for 132 women, and were used to investigate if the distribution of location-averaged mean breast skin thickness varied with pathology. The effect of surface fitting to account for breast curvature was also studied. Results: The study mean (± interbreast SD) for breast skin thickness was 1.44 ± 0.25 mm (range: 0.87-2.34 mm), which was in excellent agreement with Huang et al. Based on pathology, pair-wise statistical analysis (Mann-Whitney test) indicated that at the 0.05 significance level, there were no significant difference in the location-averaged mean breast skin thickness distributions between the groups: benign vs malignant (p = 0.223), benign vs hyperplasia (p = 0.651), hyperplasia vs malignant (p = 0.229), and malignant vs nonmalignant (p = 0.172). Conclusions: Considering this study used a different clinical prototype system, and the study participants were from a different geographical location, the observed agreement between the two studies suggests that the choice of 1.45 mm thick skin layer comprising the epidermis and the dermis for breast dosimetry is appropriate. While some benign and malignant conditions could cause skin thickening, in this study cohort the location-averaged mean breast skin thickness distributions did not differ significantly with pathology. The study also underscored the importance of considering breast curvature in estimating breast skin thickness.

Assessment of the dielectric properties of red blood cells requires several steps for preparation and isolation from whole blood. These steps may result in changes in the cells properties, and they are time consuming. The present study aims to compare the properties of both whole blood and isolated red blood cells and the effect of gamma radiation on these properties. Adult male rats were exposed to 1, 3.5 and 7 Gy as single dose, from Cs-137 source. The dielectric properties studies, in the frequency range 40 kHz to 5 MHz, and light scattering studies for suspensions of whole blood and isolated red blood cells from the same groups were performed. The obtained results showed that whole blood and red blood cells suspensions followed the same trend in their response to radiation, which suggests the possibility of using whole blood suspension for the evaluation of the red blood cells properties.

Biocomputing is a recently growing and highly interdisciplinary field of research that investigates models and computational techniques inspired by biology and related sciences. Here, cyclic behavior (redox cycling) of purified horseradish peroxidase protein among native enzyme and its two electron-oxidized and single electron-oxidized intermediates known as Compounds I and II was algebraically expressed as a cyclic additive group Z 3 = {C 0 , C 2 , C 1 } = {C 0 , 1C 2 , 2C 2 } = {0, 2, 1}, and a cyclic multiplicative group Z * 3 = {C 1 , C 2 } = {C 1 , C 1 2 } = {1, 2}, with C 2 as the common generator. Above algebraically expressed features of the enzyme's redox cycle was applied to help determining the coefficients in polynomials formed after additive and/or multiplicative operations between polynomial rings f (x) and g(x) over a coefficient field derived from Z 3. Similarly, use of a pair of small DNA molecules was proposed for determining the coefficients for additively and multiplicatively obtained polynomials over F , (Z 2 ; +, ×); where Z 2 = {C 0 , C 1 } = {0, 1}. Discussion includes the required designs of two distinct DNA molecules for performing binary logical conjunction (AND) and exclusive disjunc-tion (XOR), upon polymerase-chain reactions.

The National Health and Nutrition Examination Survey (NHANES 1999e2004) includes adult and pediatric comparisons for total body bone and body composition results. Because dual-energy x-ray absorptiometry (DXA) measurements from different manufacturers are not standardized, NHANES reference values currently are applicable only to a single make and model of Hologic DXA system. The purpose of this study was to derive body composition reference curves for GE Healthcare Lunar DXA systems. Published values from the NHANES 1999e2004 survey were acquired from the Centers for Disease Control and Prevention website. Using previously reported crosscalibration equations between Hologic and GE-Lunar, we converted the total body and regional bone and soft-tissue measurements from NHANES 1999e2004 to GE-Lunar values. The LMS (LmsChartMaker Pro Version 3.5) curve fitting method was used to generate GE-Lunar reference curves. Separate curves were generated for each sex and ethnicity. The reference curves were also divided into pediatric ( 20 years old) and adult (O20 years old) groups. Adult reference curves were derived as a function of age. Additional relationships of pediatric DXA values were derived as a function of height, lean mass, and bone area. Robustness was tested between Hologic and GE-Lunar Z-score values. The NHANES 1999e2004 survey included a sample of 20,672 participants' (9630 female) DXA scans. A total of 8056 participants were younger than 20 yr and were included in the pediatric reference data set. Participants enrolled in the study who weighed more than 136 kg (over scanner table limit) were excluded. The average Z-scores comparing the new GE-Lunar reference curves are close to zero, and the standard deviation of the Z-scores are close to one for all variables. As expected, all measurements on the GE-Lunar reference curves for participants younger than 20 yr increase monotonically with age. In the adult population, most of the curves are constant at younger age and drop moderately as age increases. We have presented NHANES reference curves applicable to DXA whole-body scans acquired on GE Healthcare Lunar systems by age, sex and ethnicity. Users of GE Healthcare GE-Lunar DXA systems can now benefit from the large body composition reference data set collected in the NHANES 1999e2004 study.

Using two independent physical methods (Rayleigh light scattering and electron paramagnetic resonance), the effect of lead, toxic heavy metal on proteins in aqueous solutions (including blood serum proteins) was studied. A physical mechanism of interaction between heavy metal ions and charged biopoiymers which is based on formation of strong bonds of metal ions with the surface of macromolecules is discussed. Based on the results obtained, a method to monitor natural liquid media pollution with heavy metals is proposed.

The National Health and Nutrition Examination Survey (NHANES 1999e2004) includes adult and pediatric comparisons for total body bone and body composition results. Because dual-energy x-ray absorptiometry (DXA) measurements from different manufacturers are not standardized, NHANES reference values currently are applicable only to a single make and model of Hologic DXA system. The purpose of this study was to derive body composition reference curves for GE Healthcare Lunar DXA systems. Published values from the NHANES 1999e2004 survey were acquired from the Centers for Disease Control and Prevention website. Using previously reported crosscalibration equations between Hologic and GE-Lunar, we converted the total body and regional bone and soft-tissue measurements from NHANES 1999e2004 to GE-Lunar values. The LMS (LmsChartMaker Pro Version 3.5) curve fitting method was used to generate GE-Lunar reference curves. Separate curves were generated for each sex and ethnicity. The reference curves were also divided into pediatric ( 20 years old) and adult (O20 years old) groups. Adult reference curves were derived as a function of age. Additional relationships of pediatric DXA values were derived as a function of height, lean mass, and bone area. Robustness was tested between Hologic and GE-Lunar Z-score values. The NHANES 1999e2004 survey included a sample of 20,672 participants' (9630 female) DXA scans. A total of 8056 participants were younger than 20 yr and were included in the pediatric reference data set. Participants enrolled in the study who weighed more than 136 kg (over scanner table limit) were excluded. The average Z-scores comparing the new GE-Lunar reference curves are close to zero, and the standard deviation of the Z-scores are close to one for all variables. As expected, all measurements on the GE-Lunar reference curves for participants younger than 20 yr increase monotonically with age. In the adult population, most of the curves are constant at younger age and drop moderately as age increases. We have presented NHANES reference curves applicable to DXA whole-body scans acquired on GE Healthcare Lunar systems by age, sex and ethnicity. Users of GE Healthcare GE-Lunar DXA systems can now benefit from the large body composition reference data set collected in the NHANES 1999e2004 study.

Dewasa  ini  cukup  banyak  masyarakat  yang  menderita  cacat  fisik.  Salah  satunya  adalah  mengalami
ketidakmampuan untuk melihat, yang sering dinamai dengan istilah tunanetra. Alat bantu yang u mumnya di
gunakan  sebagai  alat  bantu  bagi  para  tunanetra  adalah  tongkat.  Secara  umum  belum  ada  inovasi
terbarukan  yang  bisa  mempermudah  para  tunanetra  dalam  bergerak.  Penelitian  ini  bertujuan  merancang
sebuah sistem baru yang dirancang khusus untuk para tunanetra yang diberi nama yaitu SST (Sistem Sonar
Tunanetra).  SST  di  rancang  menggunakan  sensor  ultrasonik  untuk  mendeteksi  jarak  dar i  tempat  para
tunanetra berada. Sensor ultrasonik adalah alat elektronika yang kemampuannya bisa mengubah dari energi
listrik menjadi energi mekanik dalam bentuk gelombang suara  ultrasonik,  melalui gelombang  ultrasonik ini
para tunanetra bisa mendeteksi jarak di sekitarnya.  Perangkat ini    dilengkapi dengan mikrokontroler sebagai
prosesornya.  Disamping  itu,  SST  juga  dilengkapi  dengan  buzzer  yang  akan  berbunyi  saat  sensor
berdekatan  dengan  objek  lain.  Pengujian  keakurantan  perangkat  SST  dalam  mengukur  jarak  dilakukan
dengan cara mencari error dari 2 jenis kondisi pengukuran.  Hasil pengukuran menunjukkan bahwa rata-rata
error untuk  semua pengukuran adalah 2,965 % Jadi, dapat disimpulkan bahwa perangkat ini cukup efektif
untuk digunakan oleh para penderita tunanetra.

Kata-kata kunci: SST, tunetra, buzzer, mitrokontroler

Thalassemia is the world's most common hereditary disease; therefore, more interest has been devoted for the development of the screening procedure of this disease. In b-thalassemia major, the subject of the current study, impaired biosynthesis of beta-globin leads to accumulation of unpaired alpha-globin chain. The objective of the present study, was to examine many of the biophysical properties of b-thalassemia major red blood cells (RBCs) and to study the possibility of use of any of them as a preliminary screening tool for b-thalassemia. The percentage of normal hemolysis, osmotic fragility test, turbidity test, rheological properties, and dielectric properties, were studied in 20 regularly blood transfused thalassemia major patients who were under chelation therapy and their status were compared with those of 10 healthy subjects. There was an increase in the percentage of hemolysis for b-thalassemia by 114.6% compared to the normal RBCs. The fragility curve for b-thalassemia RBCs showed a shift toward lower NaCl concentration compared to the normal curve. The average osmotic fragility (H 50 : the NaCl concentration producing 50% homolysis) for b-thalassemia was found to be 3.21 ± 0.67 g/l, whereas for normal RBCs it was 5.5 ± 0.31 g/l. The turbidity curve of the b-thalassemic RBCs showed a shift toward higher detergent concentration of the normal curve, with higher value for the average membrane solubilization (S 50). The viscosity value of whole blood b-thalassemia was found to be 3.916 ± 0.56 cp whereas for normal blood was 2.516 ± 0.36 cp. The relative permittivity, dielectric loss, and AC conductivity of RBCs decreased significantly compared to normal samples. This could be attributed to the loss of the insulating properties of the membrane and loss of its surface charge of thalassemic RBCs. As can be noticed, several factors showed clear difference between thalassemic and normal blood samples. Some of these parameters could be measured immediately after sample withdrawal and require short time to perform the measurements. This offers the advantages of being effective, low cost, and fast techniques, therefore, we suggest that these techniques could be applied for b-thal-assemia major screening purposes.

The resting membrane voltage of excitable cells such as neurons and muscle cells is determined by the electrochemical equilibrium of potassium and sodium ions. This voltage is calculated by using the Goldman–Hodgkin–Katz equation. However, from the quantum perspective, ions with significant quantum tunneling through closed channels can interfere with the electrochemical equilibrium and affect the value of the membrane voltage. Hence, in this case the equilibrium becomes quantum electrochemical. Therefore, the model of quantum tunneling of ions is used in this study to modify the Goldman–Hodgkin–Katz equation in such a way to calculate the resting membrane voltage at the point of equilibrium. According to the present calculations, it is found that lithium—with its lower mass—shows a significant depolarizing shift in membrane voltage. In addition to this, when the free gating energy of the closed channels decreases, even sodium and potassium ions depolarize the resting membrane voltag...

Atrial fibrillation (AF) is a cardiac arrhythmia characterized by rapid and irregular atrial electrical activity with a high clinical impact on stroke incidence. Best available therapeutic strategies combine pharmacological and surgical means. But when successful, they do not always prevent long-term relapses. Initial success becomes all the more tricky to achieve as the arrhythmia maintains itself and the pathology evolves into sustained or chronic AF. This raises the open crucial issue of deciphering the mechanisms that govern the onset of AF as well as its perpetuation. In this study, we develop a wavelet-based multi-scale strategy to analyze the electrical activity of human hearts recorded by catheter electrodes, positioned in the coronary sinus (CS), during episodes of AF. We compute the so-called multifractal spectra using two variants of the wavelet transform modulus maxima method, the moment (partition function) method and the magnitude cumulant method. Application of these methods to long time series recorded in a patient with chronic AF provides quantitative evidence of the multifractal intermittent nature of the electric energy of passing cardiac impulses at low frequencies, i.e., for times (0.5 s) longer than the mean interbeat (≃ 10 −1 s). We also report the results of a two-point magnitude correlation analysis which infers the absence of a multiplicative timescale structure underlying multifractal scaling. The electric energy dynamics looks like a "multifractal white noise" with quadratic (log-normal) multifractal spectra. These observations challenge concepts of functional reentrant circuits in mechanistic theories of AF, still leaving open the role of the autonomic nervous system (ANS). A transition is indeed observed in the computed multifractal spectra which group according to two distinct areas, consistently with the anatomical substrate binding to the CS, namely the left atrial posterior wall, and the ligament of Marshall which is innervated by the ANS. In a companion paper (II. Modeling), we propose a mathematical model of a denervated heart where the kinetics of gap junction conductance alone induces a desynchronization of the myocardial excitable cells, accounting for the multifractal spectra found experimentally in the left atrial posterior wall area.

The nucleation and growth theory, described by the Avrami equation (also called Johnson-Mehl-Avrami-Kolmogorov equation), and usually used to describe crystallization and nucleation processes in condensed matter physics, was applied in the present paper to cancer physics. This can enhance the popular multi-hit model of carcinogenesis to volumetric processes of single cell's DNA neoplastic transformation. The presented approach assumes the transforming system as a DNA chain including many oncogenic mutations. Finally, the probability function of the cell's cancer transformation is directly related to the number of oncogenic mutations. This creates a universal sigmoidal probability function of cancer transformation of single cells, as observed in the kinetics of nucleation and growth, a special case of a phase transition process. The proposed model, which represents a different view on the multi-hit carcinogenesis approach, is tested on clinical data concerning gastric cancer. The results also show that cancer transformation follows DNA fractal geometry.

Samples of soil, grass and organs of herbivore mammal were collected from different sampling locations in five states within the southwestern area of Nigeria. The activity concentrations of natural radionuclides such as 40 K, 238 U and 232 Th present in the collected samples were detected with a method of gamma spectrometry using High Purity Germanium detector. These activity measurements and other ecological (site-specific) data were loaded into ERICA Tool (Version 1.2) to examine the radioactivity level of terrestrial non-human biota. Basic statistics like kurtosis, skewness, histogram alongside spatial distribution calculation were performed in order to understand the radionuclide distribution pattern within the samples. The study also examined the radionuclide transfer factor between the soil and the grass samples. The highest activity concentration was recorded for samples collected from Abeokuta and lowest from samples from Iwo. The calculated concentration is in the order of 40 K > 238 U > 232 Th. The transfer factor calculation revealed the uptake of 232 Th by the collected grass samples is larger than that of 238 U and 40 K. The dose rates acquired with the use of the application of ERICA Tool indicates that higher contribution to the total dose is from internal exposure derived from exposure to 238 U and 228 Th with a joint contribution of 95.7% for mammals and 96.9% for grasses. The contribution of 40 K corresponds to 4.3% for mammals and 3.1% for grass which is quite a low contribution to total dose. The RQ exp value for sampled location is below unity while the RQ cons exceeds unity for Lagos and Abeokuta. The result of this study would hearten the use of software application to a wide range of ecosystems and could also serve as a reference or pilot for further research regarding ionizing radiation on non-human biota.

The mathematical modelling of electric current flow in excitable cells (fibres and interrelated cells networks) is briefly reviewed and three fundamental problems of the stimulation by external electrodes are defined and posed, in terms of suitably space-averaged fields. Then, it is given an outline of a new procedure to study just-threshold dynamics when certain target elements in excitable tissues are stimulated by external electrodes. The concept of " region of influence " of an external field of applied electric current over the target element is introduced as a first step towards a nonlinear modal analysis of membrane's polarization. In a suitable defined mode amplitude space, a threshold manifold, a decaying set and an amplifying set are introduced to study the emergence of an action potential. It is then outlined a general method to derive strength-duration formulae, giving the derivation of Lapicque-Hill's formula as an example. A. Introduction. Strength duration curves measure the excitability of a certain target element in a given electrode-tissue system. The target element may be a single cell (such as a nerve or skeletal muscle fibre) or even a whole network of electrically coupled cells (such as the myocardium or visceral smooth muscle). The response of the target element is the all or none emergence of a propagated action potential. The results of the experiments show that the parameters of the strength-duration curve depend not only of the excitability properties of the membranes of the target element, but depend also of certain geometric and bioelectric parameters of the system formed by the electrodes, the tissues and the target element. For example: radius of the excitable fibre, distance between the electrode and the target element, size and shape of the active electrode (if it is located close enough to the target element), amongst others (1, 2, 3). So, strength duration curves measure something that may be called a " global excitability " of the target element in the framework of a given electrode-tissue system, by opposition to the " local excitability " of the membranes of the target element. This local excitability could be measured, at least in principle, determining the strength-duration curves for the uniformly polarized membranes (by a patch-clamp technique, for example) and relating its parameters with the known properties of the ionic channels. The explanation of the experimental results that show a relation between the phenomenological parameters of the strength-duration curve and certain parameters of the electrode-tissue system has remained as an open problem from more than seventy years. This problem has more than an academic interest, because it is closely related with two basic questions of clinical electro stimulation: Which elements will be excited by a given current pulse in a given electrode-tissue system? How to reach a selective stimulation of certain target elements in a whole excitable tissue? In order to get some kind of solution to the aforementioned problem, it seems necessary to solve first the following three problems of the electric stimulation by external electrodes: (1) Given a certain electrode array in a certain volume conductor formed by biological tissues, to find the resulting field of electric current density.

Most of the known self-assembly processes occur in solution, where nanosized objects interact each other forming new structures. Their real-time characterization in terms of the size and optical properties of these objects is vital for understanding those interactions. We report a novel application of nonlinear optics to study molecular structures and assemblies. By measuring the power of the third harmonic generated in a solution of nanoparticles, we determined both the size and the third-order nonlinear optical susceptibility of those nanoparticles. The newly developed technique was successfully employed to observe the structural organization of collagen (type I) molecules in solution.

We report on the novel application of nonlinear optics to study molecular assemblies. By using the third-harmonic generation in solution we were able to determine both the third-order nonlinear susceptibility of collagen and the size of fibrils. The developed approach also helped us in revealing the helix-coil transformation of collagen in solution.

To determine the mean and range of location-averaged breast skin thickness using highresolution dedicated breast CT for use in Monte Carlo-based estimation of normalized glandular dose coefficients. Methods: This study retrospectively analyzed image data from a clinical study investigating dedicated breast CT. An algorithm similar to that described by Huang et al. ["The effect of skin thickness determined using breast CT on mammographic dosimetry," Med. Phys. 35(4), 1199-1206 (2008)] was used to determine the skin thickness in 137 dedicated breast CT volumes from 136 women. The location-averaged mean breast skin thickness for each breast was estimated and the study population mean and range were determined. Pathology results were available for 132 women, and were used to investigate if the distribution of location-averaged mean breast skin thickness varied with pathology. The effect of surface fitting to account for breast curvature was also studied. Results: The study mean (± interbreast SD) for breast skin thickness was 1.44 ± 0.25 mm (range: 0.87-2.34 mm), which was in excellent agreement with Huang et al. Based on pathology, pair-wise statistical analysis (Mann-Whitney test) indicated that at the 0.05 significance level, there were no significant difference in the location-averaged mean breast skin thickness distributions between the groups: benign vs malignant (p = 0.223), benign vs hyperplasia (p = 0.651), hyperplasia vs malignant (p = 0.229), and malignant vs nonmalignant (p = 0.172). Conclusions: Considering this study used a different clinical prototype system, and the study participants were from a different geographical location, the observed agreement between the two studies suggests that the choice of 1.45 mm thick skin layer comprising the epidermis and the dermis for breast dosimetry is appropriate. While some benign and malignant conditions could cause skin thickening, in this study cohort the location-averaged mean breast skin thickness distributions did not differ significantly with pathology. The study also underscored the importance of considering breast curvature in estimating breast skin thickness.

"The separation between two liquids that won't mix, like oil and water, is known as 'liquid-liquid phase separation', and it's central to the function of many proteins," said Sagar Setru, a 2021 Ph.D. graduate who worked with both Sabine Petry, a professor of molecular biology, and Joshua Shaevitz, a professor of physics and the Lewis-Sigler Institute for Integrative Genomics. A Virginia Commonwealth University researcher has developed a procedure for identifying the source of cells present in a forensic biological sample that could change how cell types are identified in samples across numerous industries. [25] In work at the National Institute of Standards and Technology (NIST) and the University of Maryland in College Park, researchers have devised and demonstrated a new way to measure free energy. [24] A novel technique developed by researchers at the ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP) will help shine new light on biological questions by improving the quality and quantity of information that can be extracted in fluorescence microscopy. [23] Micro-computed tomography or "micro-CT" is X-ray imaging in 3-D, by the same method used in hospital CT (or "CAT") scans, but on a small scale with massively increased resolution. [22] A new experimental method permits the X-ray analysis of amyloids, a class of large, filamentous biomolecules which are an important hallmark of diseases such as Alzheimer's and Parkinson's. [12] Thumb through any old science textbook, and you'll likely find RNA described as little more than a means to an end, a kind of molecular scratch paper used to construct the proteins encoded in DNA. [20] Just like any long polymer chain, DNA tends to form knots. Using technology that allows them to stretch DNA molecules and image the behavior of these knots, MIT researchers have discovered, for the first time, the factors that determine whether a knot moves along the strand or "jams" in place. [19]

Increased intraocular pressure (IOP) is a significant risk factor for the development of glaucoma. Timolol maleate is a beta-adrenergic receptor blocking agent and it is used for the treatment of glaucoma in order to reduce the elevated IOP that is characteristic of this eye disease. Systemic toxicity from topical timolol occurs more frequently than local toxicity and can affect the pulmonary, cardiac and central nervous systems. The objective of the present study, therefore, was to formulate multilamellar vesicles (MLVs) liposomal preparations of timolol maleate using their advantage of being less toxic compared with non-liposome-based drugs to be applied topically and to evaluate the in vivo performance of the prepared liposomes to extend the time of reduced IOP of glaucomatous rabbit's eye measured using a standard Shiotz tonometer. The encapsulation efficiency of MLVs was measured using a spectrophotometric technique. Differential scanning calorimetry (DSC) was used to monitor the effects of timolol maleate in the absence and presence of cholesterol on liposome thermal behaviour. Positively charged MLVs of timolol in the presence of a lower amount of cholesterol (DPPC(7):Chol(2):Timolol(2):SA(1) molar ratio) were found to be superior compared with other formulations in extending the ocular hypotensive effect approximately for 1 week (160 h) which encourages its physiological effectiveness. The increase of the cholesterol molar ratio in the prepared liposomal formulations serves to decrease the permeability of the lipid bilayer that is manifested by a low rate of drug release, an increased percentage of entrapment efficiency and a consequently lower bioavailability.