A small proton charge radius from an electron-proton scattering experiment.

Elastic electron-proton scattering (e-p) and the spectroscopy of hydrogen atoms are the two methods traditionally used to determine the proton charge radius, rp. In 2010, a new method using muonic hydrogen atoms1 found a substantial discrepancy compared with previous results2, which became known as the 'proton radius puzzle'. Despite experimental and theoretical efforts, the puzzle remains unresolved. In fact, there is a discrepancy between the two most recent spectroscopic measurements conducted on ordinary hydrogen3,4. Here we report on the proton charge radius experiment at Jefferson Laboratory (PRad), a high-precision e-p experiment that was established after the discrepancy was identified. We used a magnetic-spectrometer-free method along with a windowless hydrogen gas target, which overcame several limitations of previous e-p experiments and enabled measurements at very small forward-scattering angles. Our result, rp = 0.831 ± 0.007stat ± 0.012syst femtometres, is smaller than the most recent high-precision e-p measurement5 and 2.7 standard deviations smaller than the average of all e-p experimental results6. The smaller rp we have now measured supports the value found by two previous muonic hydrogen experiments1,7. In addition, our finding agrees with the revised value (announced in 2019) for the Rydberg constant8-one of the most accurately evaluated fundamental constants in physics.

Ruling out Color Transparency in Quasielastic

Quasielastic ^{12}C(e,e^{'}p) scattering was measured at spacelike 4-momentum transfer squared Q^{2}=8, 9.4, 11.4, and 14.2 (GeV/c)^{2}, the highest ever achieved to date. Nuclear transparency for this reaction was extracted by comparing the measured yield to that expected from a plane-wave impulse approximation calculation without any final state interactions. The measured transparency was consistent with no Q^{2} dependence, up to proton momenta of 8.5 GeV/c, ruling out the quantum chromodynamics effect of color transparency at the measured Q^{2} scales in exclusive (e,e^{'}p) reactions. These results impose strict constraints on models of color transparency for protons.

First Precision Measurement of the Parity Violating Asymmetry in Cold Neutron Capture on

We report the first precision measurement of the parity-violating asymmetry in the direction of proton momentum with respect to the neutron spin, in the reaction ^{3}He(n,p)^{3}H, using the capture of polarized cold neutrons in an unpolarized active ^{3}He target. The asymmetry is a result of the weak interaction between nucleons, which remains one of the least well-understood aspects of electroweak theory. The measurement provides an important benchmark for modern effective field theory and potential model calculations. Measurements like this are necessary to determine the spin-isospin structure of the hadronic weak interaction. Our asymmetry result is A_{PV}=[1.55±0.97(stat)±0.24(sys)]×10^{-8}, which has the smallest uncertainty of any hadronic parity-violating asymmetry measurement so far.

First Observation of P-odd γ Asymmetry in Polarized Neutron Capture on Hydrogen.

We report the first observation of the parity-violating gamma-ray asymmetry A_{γ}^{np} in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. A_{γ}^{np} isolates the ΔI=1, ^{3}S_{1}→^{3}P_{1} component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless effective field theory. We measured A_{γ}^{np}=[-3.0±1.4(stat)±0.2(syst)]×10^{-8}, which implies a DDH weak πNN coupling of h_{π}^{1}=[2.6±1.2(stat)±0.2(syst)]×10^{-7} and a pionless EFT constant of C^{^{3}S_{1}→^{3}P_{1}}/C_{0}=[-7.4±3.5(stat)±0.5(syst)]×10^{-11} MeV^{-1}. We describe the experiment, data analysis, systematic uncertainties, and implications of the result.

Pulmonary alveolar microlithiasis (PAM) in a child.

A 4 year 7 month-old girl of consanguineous parents presented with only fever for 25 days but no cough or respiratory distress. Ches x-ray showed bilateral diffuse nodulo-striate opacities in both lungs. Investigations for any infection were negative including tuberculosis. Thoracoscopic biopsy showed alveolar microliths on histopathology suggesting the diagnosis of pulmonary alveolar microlithiasis (PAM).

Genotypes of rotavirus diarrhoea in a children hospital of Bangladesh.

Globally, rotaviruses are the single most important etiologic agents of severe childhood dehydrating diarrhea that accounts for more than 125 million of cases, 25-55% of all hospital admissions for diarrhea and ≈600,000 deaths every year. In Bangladesh, while overall diarrhea related deaths are declining, the proportion of diarrhea deaths due to rotavirus is increasing. This study was aimed at estimating the burden of rotavirus diarrhea and isolating the genotypes of rotavirus in a children hospital of Bangladesh; thereby endorsing a logical search for an appropriate rotavirus vaccine. This cross sectional study was carried out in the Institute of Child and Mother Health, Matuail, Dhaka, Bangladesh during 2006-2007. Children aged between one month and five years suffering form diarrhea were enrolled in the study. Stool samples were analyzed by ELISA for rotavirus antigen. The rotavirus-positive samples were further analyzed for genotype determination. Among 656 stool samples, 39.5% samples were positive for rotavirus antigen. The mean age of the children studied was 12±9.9 months; the peak being in the second half of infancy. G2 was identified as the most dominant genotype (45.5%) followed by G1 (24.8%), G12 (9.6%), G9 (8.5%) and G4 (2.1%) genotypes. Since G2 were found to be the predominant circulating rotavirus strain in this study and some other studies in Bangladesh, the recommended vaccine for prevention of rotavirus infection in Bangladesh should cover this strain to have maximum effectiveness.

The relationship of placental weight with birth weight.

To assess the relationship between placental weight and birth weight, two hundred forty six pregnant mothers, who were otherwise healthy, were prospectively followed in a city hospital during antenatal period until delivery and immediate post-partum period. Height of mothers was measured initially and weight measured at each visit during the antenatal check-up. Placental weight and birth weight of babies were measured by one of the authors immediately after delivery by a weighing scale. Eighty one percent of the mothers were between the age group of 20-29 years. The BMI of 92% mothers was 18.5 and above. Most of the mothers came both with primigravida (42%) or second gravida (33%) and in 25% cases 3rd or onwards. In 49% cases the placental weight was between 401-500 gm, in 30% cases >500 gm and in 21% cases 400 gm or less. There was delivery of appropriate-birth-weight babies in 85% cases and low-birth-weight babies in 15% cases. It was observed that a very strong correlation existed between placental weight and birth weight (r = 0.391, p<0.001). Even this correlation was stronger in small for gestational age babies. However, there was no correlation between placental weight and APGAR score at one minute. It is concluded that increment of birth weight occurs with increase of placental weight. If placental weight can be measured by ultrasonography in second or early third trimester of pregnancy birth weight is possible to be assessed and appropriate measure can be taken to increase the birth weight.

Asthma, atopic eczema and allergic rhino-conjunctivitis in school children.

International Study of Asthma and Allergies of Childhood (ISAAC) phase one study had already been completed in two age groups in 156 collaborating centers of 56 countries involving a total of 721601 children. Bangladesh did not participate earlier in this worldwide study. To determine the prevalence of asthma, allergic rhinitis and eczema in school children of Dhaka district using ISAAC protocol. A school based cross sectional study done in 2000 by using both written questionnaires (WQ) and video questionnaires (VQ). Students of class-VIII (13-14 years) filled up both the WQ and VQ and the parents of class I (6-7 years) filled up only the WQ on behalf of the students. Sixty five (6)5 primary schools and 39 high schools were randomly selected from all 19 thanas to cover equally both the urban and rural schools of the entire area of Dhaka district. A total of 6260 written questionnaires were eligible for the analysis (3029 form 6-7 years of class I and 3231 from 13-14 years of class VIII). In addition, the validated international video questionnaires were used for the older age group (3231). The symptoms of atopic diseases in the previous 12 months or ever in all children, both age groups, both sexes and in both urban and rural areas. The life time (ever) and 12-month period (recent) prevalence of three allergic conditions with 95% CI were as follows : wheezing 13.8% (12.9-14.6), 7.6% (6.9-8.2); allergic rhinitis 25.0% (23.9-26.1), 20.0% (19.1-21.1) and eczema 8.7% (CI 8.0-9.4), 6.5% (5.9-7.2). respectively. The prevalence of wheezing and other atopic features in both age groups of 6-7 years and 13-14 years showed higher features of recent wheeze in the younger children than in the older children, recent wheeze 9.1% Vs 6.1%; but the other atopic features were found lower in younger age group, recent rhinitis 16.3% Vs 23.5%, 0.001; conjunctivitis 6.4% Vs 8.3%, 0.001; recent eczema 6.0% Vs 7.1% 0.001. Male children were found to be more suffering from all types allergic conditions than their female peers: recent wheeze 9.0% Vs 5.9%, recent rhinitis 21.9% Vs 17.9%, recent allergic conjunctivitis 8.7% Vs 6.7% and recent eczema 6.8% Vs 6.2%). Though the prevalence of asthma and atopic eczema was lower than those of developed countries but still appeared to be a major health problem for our children. Allergic rhinitis was the commonest of all atopic problems in children. The younger children (6-7 years) were more likely to suffer from wheeze (asthma) but other allergic problems were more in older group of children (13-14 years). Male children were more prone to all types of allergic problems, whether wheeze or other atopic conditions, than the female peers.

Rickets among children of a coastal area of Bangladesh.

Many children with rachitic deformities have been reported in southern coastal area of Bangladesh but the actual rate of prevalence was not known. A survey was conducted to determine the magnitude of rachitic problem among the children of Chakaria thana of Cox's Bazar district of Bangladesh. Nine hundred children between 1-15 years selected randomly from 30 villages of total 340 villages. Face to face interview of the parents was taken and the children were examined for evidences of rickets. Serum calcium, phosphorus, alkaline phosphatase (ALP) were estimated and radiology of limbs were done in all clinically suspected cases and in a control of every eighth child. Seventy eight children (8.7%) had physical features suggestive of rickets. Fifty eight (6.4%) children had 'clinical rickekts' (positive physical feature(s) but normal ALP and negative radiology), 12 (1.3%) children had 'biochemical rickets' (positive physical features and raised ALP but negative radiology) and 8 (0.9%) children had 'confirmed rickets' (positive physical features, raised ALP and positive radiology). Out of 78 children with rachitic feature(s), Pectus carinatum was found as the most common clinical feature in 26 (33.3%) children followed by genu valgum in 23 (29.4%) cases. Twenty two normal children (2.2%) had raised level of ALP (>300U/L). The prevalence of rickets is high in children of Chakaria and further study is needed to find out the exact aetiology of rickets in children there.

Evaluation of hospitalized infants and young children with bronchiolitis - a multi centre study.

Four hundred and twenty nine young children with bronchiolitis admitted consecutively in different hospitals of Bangladesh were evaluated. Three hundred and forty eight children studied for their putative risk factors, clinical profile, management and the outcome. Both cases and controls were examined for respiratory syncytial virus (RSV) antibody status. The diagnosis of bronchiolitis was made on the basis of first attack of wheeze in previously healthy children below two years of age. Detailed history including the possible risk factors, the management and daily follow-up on the ward and the outcome at discharge were documented through a structured questionnaire. Chest x-ray was done in each case to find out the radiological changes. Blood of 266 patients and 30 controls were studied for RSV IgM and IgG antibody by ELISA. There were 66% male and 34% female children. The median age of the children was 3.0 months and 82.7% were below 6 months of age. Most of the babies were born term (88%), with ABW (73%), by normal vaginal delivery (88%). Exclusive or predominant breast-feeding were given in 72% cases. The location of the patient was rural in 55% cases. Around half of the parents were illiterate or slightly educated (up to 5 years schooling) fathers 46.5% and mothers 56% and majority of the parents were poor (74%). In 52% cases the number of family members in one room were four or more. Half of the parents (52%) were smokes and there was atopy in 26.5% families. The clinical features of bronchiolitis were mostly cough (99%), respiratory distress (97%), feeding difficulty (93%) and fast breathing (96%) (median RR 68/min). Fever (1000F or more) was in only 33% cases, though parents complained in 90% cases. All children (100%) had wheeze and crackles in lungs in 96% cases. Liver could be palpable in 83% and spleen in 42% cases. Important radiological features were increased translucency (96%), increased interstitial markings (87%), hyperinflation (75%) and streaky densities (61%). In 69.6% cases TLC was 12,000 or less and only 15% with a neutrophil fraction greater than 60%. Children were positive for IgM antibody in 43.6% cases and both IgM and IgG in 5.3% cases. The main modalities of treatment were antibiotics (99%) (Ampicillin, 76%), oxygen therapy (83%), nebulised salbutamol (76%) and intravenous fluid (51%). The median duration of hospital stay was 4 days. Most of the children were discharged with improvement (96%) with 2% mortality. Not a single case was diagnosed as bronchiolitis in hospitals outside Dhaka. Cefrtiaxone (72.5%) and parenteral steroids (70.5%) were the mainstay of therapy there.