Electronic correlation effects and the Coulomb gap at finite temperature

We have investigated the effect of the long-range Coulomb interaction on the one-particle excitation spectrum of n-type Germanium, using tunneling spectroscopy on mechanically controllable break junctions. The tunnel conductance was measured as a function of energy and temperature. At low temperatures, the spectra reveal a minimum at zero bias voltage due to the Coulomb gap. In the temperature range above 1 K the Coulomb gap is filled by thermal excitations. This behavior is reflected in the temperature dependence of the variable-range hopping resitivity measured on the same samples: Up to a few degrees Kelvin the Efros-Shkovskii ln$R \propto T^{-1/2}$ law is obeyed, whereas at higher temperatures deviations from this law are observed, indicating a cross-over to Mott's ln$R \propto T^{-1/4}$ law. The mechanism of this cross-over is different from that considered previously in the literature.Comment: 3 pages, 3 figure

About low field memory and negative magnetization in semiconductors and polymers

Ginzburg-Landau bulk magnetization of itinerant electrons can provide a negative effective field in the Weiss model by coupling to localized magnetic moments. The coupling enforces remnant magnetization, which can be negative or positive depending on the sample magnetic history. Stable magnetic susceptibility of coupled nonequilibrium subsystems with magnetization reversal is always positive. Gauss-scale fields could be expected for switching between negative and positive remnant moments in semiconductors with coupling at ambient temperatures. Negative magnetization in ultra-high conducting polymers is also discussed within the developed framework.Comment: 8 pages, no figure

Вплив згодовування хелатних комплексів мікроелементів на середньодобовий баланс Cu, Zn та Мn в організмі корів у період роздою

The questions are considered about the effect of feeding of trace elements of different types and concentrations in premixes on the average daily balance of copper (Cu), zinc (Zn), manganese (Mn) in the organism of cows of Ukrainian black mottled dairy breed of the two months after calving. For the experiment, 40 cows were selected and formed four groups: one control and three experimental. The cows in the control group fed a premix of sulfate salts of copper, zinc and manganese in doses that are 100% covered their lack in a forage. Experimental animals from I, II and III groups were fed premixes with chelate complexes of Cu, Zn and Mn, which offset the deficiency of trace elements in the feed ration for 100, 50 and 25% (calculated on pure element), respectively. The diet was counted on a cow with an average live weight of 550 kg, with a daily milk yield of 20 kg 4% fat and balanced on the basis of the main nutrients in accordance with the norms. Іn the feeds, excrements, urine and milk of cows, the content of trace elements copper, zinc and manganese was determined by the standardized atomic absorption method on the spectrophotometer AAS-30 («SaglZeiss», Germany). Found a higher percentage of trace elements deposition in the body cows of feeding of chelates of copper, zinc, and manganese in the concentrations that cover their deficit in the diet in the 100% and 50% in the experimental I and II groups: Cu – 7.3% (P < 0.05) and 1.4%, Zn by 12.2% and 15.0% (P < 0.001), Mn by 13.2% (P < 0.01) and 9.0% (P < 0.05), respectively, in comparison with their sulfate salts in a 100 % dose. Based on the results of the balance study, the use in the feeding of cows during lactation of chelates of trace elements in concentrations intermediate to different experimental groups was proposed, namely – below normal their input in the form of sulfate salts on 25% for copper, 50% – zinc, and 65% – for manganese (calculated on pure element).Розглянуто питання щодо впливу згодовування мікроелементів різних типів і концентрацій у преміксах на середньодобовий баланс Купруму (Сu), Цинку (Zn), Мангану (Mn) в організмі корів української чорно-рябої молочної породи через два місяці після отелення. Встановлено вищий відсоток відкладання мікроелементів в організмі за згодовування коровам хелатів Cu, Zn і Mn у концентраціях, що покривають їхній дефіцит у раціоні на 100% та 50% в І і ІІ дослідних групах: Cu – на 7,3% (Р < 0,05) та 1,4%, для Zn – на 12,2% і 15,0% (Р < 0,001), Мn – на 13,2% (Р < 0,01) та 9,0% (Р < 0,05) відповідно, порівняно з їх сірчанокислими солями у 100 % дозі. На підставі результатів балансового досліду запропоновано використання в годівлі корів у період лактації хелатів мікроелементів у концентраціях, проміжних відносно різних дослідних груп, а саме – нижчих за норми їх введення у формі сірчанокислих солей на 25% для Cu, 50% – Zn, та 65% – для Мn (у розрахунку на чистий елемент)

Localization length and impurity dielectric susceptibility in the critical regime of the metal-insulator transition in homogeneously doped p-type Ge

We have determined the localization length \xi and the impurity dielectric susceptibility \chi_{\rm imp} as a function of Ga acceptor concentrations (N) in nominally uncompensated ^{70}Ge:Ga just below the critical concentration (N_c) for the metal-insulator transition. Both \xi and \chi_{\rm imp} diverge at N_c according to the functions \xi\propto(1-N/N_c)^{-\nu} and \chi_{\rm imp}\propto(N_c/N-1)^{-\zeta}, respectively, with \nu=1.2\pm0.3 and \zeta=2.3\pm0.6 for 0.99N_c< N< N_c. Outside of this region (N<0.99N_c), the values of the exponents drop to \nu=0.33\pm0.03 and \zeta=0.62\pm0.05. The effect of the small amount of compensating dopants that are present in our nominally uncompensated samples, may be responsible for the change of the critical exponents at N\approx0.99N_c.Comment: RevTeX, 4 pages with 5 embedded figures, final version (minor changes

Cross-comparison of cloud liquid water path derived from observations by two space-borne and one ground-based instrument in northern Europe

Cloud liquid water path (LWP) is one of the target atmospheric parameters retrieved remotely from ground-based and space-borne platforms using different observation methods and processing algorithms. Validation of LWP retrievals is a complicated task since a cloud cover is characterised by strong temporal and spatial variability while remote sensing methods have different temporal and spatial resolutions. An attempt has been made to compare and analyse the collocated LWP data delivered by two satellite instruments SEVIRI and AVHRR together with the data derived from microwave observations by the ground-based radiometer RPG-HATPRO. The geographical region of interest is the vicinity of St. Petersburg, Russia, where the RPG-HATPRO radiometer is operating. The study is focused on two problems. The first one is the so-called scale difference problem, which originates from dissimilar spatial resolutions of measurements. The second problem refers to the land–sea LWP gradient. The radiometric site is located 2.5 km from the coastline where the effects of the LWP gradient are pronounced. A good agreement of data obtained at the microwave radiometer location by all three instruments (HATPRO, SEVIRI, and AVHRR) during warm and cold seasons is demonstrated (the largest correlation coefficient 0.93 was detected for HATPRO and AVHRR datasets). The analysis showed no bias of the SEVIRI results with respect to HATPRO data and a large positive bias (0.013–0.017 kg m−2) of the AVHRR results for both warm and cold seasons. The analysis of LWP maps plotted on the basis of the SEVIRI and AVHRR measurements over land and water surfaces in the vicinity of St. Petersburg revealed the unexpectedly high LWP values delivered by AVHRR during the cold season over the Neva River bay and over the Saimaa Lake and the abnormal land–sea LWP gradient in these areas. For the detailed evaluation of atmospheric state and ice cover in the considered geographical regions during the periods of ground-based and satellite measurements, reanalysis data were used. It is shown that the most probable reason for the observed artefacts in the AVHRR measurements over water and ice surfaces is the coarse resolution of the land–sea and snow–ice masks used by the AVHRR retrieval algorithm. The influence of a cloud field inhomogeneity on the agreement between the satellite and the ground-based data is studied. For this purpose, the simple estimate of the LWP temporal variability is used as a measure of the spatial inhomogeneity. It has been demonstrated that both instruments are equally sensitive to the inhomogeneity of a cloud field despite the fact that they have different spatial resolutions

Electrical properties of isotopically enriched neutron-transmutation-doped ^{70} Ge:Ga near the metal-insulator transition

We report the low temperature carrier transport properties of a series of nominally uncompensated neutron-transmutation doped (NTD) ^{70} Ge:Ga samples very close to the critical concentration N_c for the metal-insulator transition. The concentration of the sample closest to N_c is 1.0004N_c and it is unambiguously shown that the critical conductivity exponent is 0.5. Properties of insulating samples are discussed in the context of Efros and Shklovskii's variable range hopping conduction.Comment: 8 pages using REVTeX, 8 figures, published versio

Hf–Zr anomalies in clinopyroxene from mantle xenoliths from France and Poland: implications for Lu–Hf dating of spinel peridotite lithospheric mantle

Clinopyroxenes in some fresh anhydrous spinel peridotite mantle xenoliths from the northern Massif Central (France) and Lower Silesia (Poland), analysed for a range of incompatible trace elements by laser ablation inductively coupled plasma mass spectrometry, show unusually strong negative anomalies in Hf and Zr relative to adjacent elements Sm and Nd, on primitive mantle-normalised diagrams. Similar Zr–Hf anomalies have only rarely been reported from clinopyroxene in spinel peridotite mantle xenoliths worldwide, and most are not as strong as the examples reported here. Low Hf contents give rise to a wide range of Lu/Hf ratios, which over geological time would result in highly radiogenic εHf values, decoupling them from εNd ratios. The high 176Lu/177Hf could in theory produce an isochronous relationship with 176Hf/177Hf over time; an errorchron is shown by clinopyroxene from mantle xenoliths from the northern Massif Central. However, in a review of the literature, we show that most mantle spinel peridotites do not show such high Lu/Hf ratios in their constituent clinopyroxenes, because they lack the distinctive Zr–Hf anomaly, and this limits the usefulness of the application of the Lu–Hf system of dating to garnet-free mantle rocks. Nevertheless, some mantle xenoliths from Poland or the Czech Republic may be amenable to Hf-isotope dating in the future

Microsatellite instability as prognostic marker in bladder tumors: a clinical significance

BACKGROUND: Carcinoma of urinary bladder is one of the leading causes of death in India. Successful treatment of bladder cancer depends on the early detection & specific diagnostic approaches. In the present study, microsatellite instability (MSI) has been evaluated as a prognostic marker in patients with superficial urinary bladder cancer in lower urinary tract for determining risk of recurrence. METHODS: A total of 44 patients with bladder tumors diagnosed with Transitional Cell Carcinomas [TCC] from lower urinary tract were selected for the study. Tumors were staged and graded according to AJCC-UICC (1997) classification and patients were followed with cystoscopy as per the protocol. Polymerase chain reaction (PCR) was done to amplify microsatellite sequences at mononucleotide BAT – 26, BAT – 40, TGFβ RII, IGFIIR, hMSH3, BAX and dinucleotide D2S123, D9S283, D9S1851 and D18S58 loci in blood (control) and tumor DNA. PCR products were separated on 8% denaturing polyacrylamide gel and visualized by autoradiography. RESULTS: MSI was observed in 72.7% of tumors at BAT – 26, BAT – 40, D2S123, D9S283, D9S1851 and D18S58 loci. Good association of MSI was seen with tumor stage and grade. MSI – High (instability at > 30% of loci) was frequently observed in high stage (40.6%) and high grade (59.4%) tumors. Of 24 tumors of Ta-T1 stage with different grades, 11 (9/18 high grade and 2/6 low grade tumors) recurred in the mean duration of 36 months. MSI positivity was significantly high in patients who had one or more recurrences (p = 0.02 for high grade and 0.04 for low grade tumors). CONCLUSIONS: MSI may be an independent prognostic marker for assessing risk of recurrence in superficial tumors irrespective of the grade. Further studies on progression would help in stratifying the patients of T1G3 for early cystectomy vs bladder preservation protocol

Integrated solution for patients of a very high cardiovascular risk. Final results

Secondary prevention should be actively implemented at all stages of treatment and rehabilitation of patients after acute coronary syndrome (ACS). The integration of remote monitoring of patients with the transfer of vital and laboratory data into clinical practice seems promising.Aim. To evaluate the clinical and patient-centered effectiveness of the original 12-month combined face-to-face and telecare program in patients with recent ACS.Material and methods. For the present analysis the data from 84 (out of 100) patients (median age, 56 (50;61) years, 70 males) was used. These patients had to have hypertension and/or type 2 diabetes and an ACS with percutaneous revascularization within 12 months. Their low-density lipoprotein cholesterol (LDL-C) had to be above 2,4 mmol/L. Telehealth program supplemented routine care. A program contained electronic self-control diaries for blood pressure (BP) and lipid profile, and teleconsulting service (text chat). Mandatory face-to-face visits were carried out at 3 and 12 months after the enrollment. The primary end point was ∆LDL-C. Additional clinical and patient-specific endpoints were evaluated.Results. At the 12-month visit, there was a significant decrease in LDL-C by 1,6 (-2,3;-0,9) mmol/L. Besides the initial LDL-C value, the decrease in LDL-C was associated with the proper adherence to keeping diaries of BP and lipid profile (β=0,7), and the number of text messages sent by the doctor in the 1st month after the enrollment (β=0,04). In more adherent patients, the ∆LDL-C was greater by 0,49 mmol/L (95% CI (-1,2; -0,1)) after adjustment for abovementioned covariates. In 35 patients (42%), target LDL-C was achieved, in 60 patients (71%) — a decrease ≥1 mmol/l. Other lipids also have changed for the better. Moreover, adherent patients were twice as likely to achieve the target LDL-C (OR 2,2; 95% CI (0,6; 3,8)) than non-adherent ones. A decrease in office systolic BP by 5,8 mm Hg was shown (p=0,03). The number of physician-to-patient messages exceeded those from patients to physician (median 143 and 111 per patient for 12 months, respectively). The quality of life has improved, but only in terms of emotions. Satisfaction with the program remained high at all timepoints of the study.Conclusion. Our study showed the effectiveness of the integrated care in ACS patients with the telehealth tool included. Commitment to BP self-monitoring, as well as active consultative support at the first stages of rehabilitation, contributes to additional dynamic control of lipid profile, timely correction of lipid-lowering therapy with the achievement of the target LDL-C level. Most of the patients did not experience any difficulties in using the program and are ready to recommend integrated approach to other peers

Integrated solution for very high cardiovascular risk patients. Rationale and design of a pilot study

Coronary artery disease (CAD) is the most common cardiovascular disease and the leading cause of morbidity and mortality. Acute coronary syndrome (ACS) as an abrupt destabilization of CAD, multiplies the risk of cardiovascular events. To reduce the incidence of recurrent cardiovascular events, timely tackling potentially reversible risk factors such as hypertension and/or hyperglycemia is imperative. However, a solid basis for a secondary prevention lies in the treatment of dyslipidemia and begins in the first hours of hospital admission. Despite considerable evidence regarding the efficacy and safety of lipid-lowering therapy, averagely only one third of patients maintain control of lipids. The main challenges are low adherence, poor continuity of medical care, and the lack of an ambulatory routine follow-up. Telehealth solutions are believed to address these barriers and may be considered as an add-on to in-person patient care. Telemonitoring of vital and laboratory parameters, remote patient counseling can be introduced into routine care delivery. Telemedicine shows promise for fostering better clinical effect, and provides health-related quality of life improvement.It is planned to conduct a pilot observational study aimed to create and to test an integrated solution, i.e. telemonitoring and remote counseling in patients of very high cardiovascular risk with ACS followed by myocardial revascularization. The goal is to determine the clinical effectiveness, i.e achievement of target values of blood pressure, lipid profile and glycemia, and patient-centeredness of this approach